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US Continental Scientific Drilling and Coring

Science Plan 2018-2028

DRAFT April 2018

for review and comment

Content from Paleorecords community only;portions for other scientific disciplines to be added.

US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018

EXECUTIVE SUMMARYUS CONTINENTAL SCIENTIFIC DRILLING AND CORING SCIENCE PLAN 2018-2028:

PALEORECORDS COMMUNITY

Drilling and coring on the Earth’s continents are vital to many subdisciplines within the Earth sciences, including both hard and soft rock research, the intersection of the Earth and biological sciences, and a variety of topics highly relevant to humans. Drilling and coring represent the only means of accessing unexposed parts of the rock record; in cases where outcrops do exist, drilling provides unweathered material that expands the analytical methods that can be employed and therefore the scientific questions that can be answered.

Continental scientific drilling (CSD) requires coordination and deployment of relatively large and complex technical, logistical, and human resources. Coring, by contrast, is often carried out by small teams with simple equipment; however, coring often provides the scientific basis for deeper drilling of the same site, and a continuum exists between coring and drilling. The cost of a single CSD field project can represent a large fraction of the annual science budget for the NSF programs that typically fund such projects; therefore, the communities served by CSD must collectively prioritize high-reward sites that advance goals across multiple communities.

The NSF-supported Continental Scientific Drilling Coordination Office (CSDCO) is charged with assisting in this process of prioritization, by facilitating the scientific community to articulate the most important – ideally cross-cutting – questions that can be addressed by drilling and coring on the continents. Although in this report these “big questions” are organized by topic (hydroclimate, temperature, ecology/biology, and the human dimension), numerous intersections emerge. Common research emphases identified include testing Earth system linkages in time periods particularly similar to or divergent from current conditions; generation of information needed by modelers and planners; improving chronological control and temporal resolution of paleorecords; linking of continental records with those from marine and ice cores; understanding forcings and feedbacks; using networks of paleorecord sites; quantitative technique development and standardization; and community coordination. The disparate topic groups also recognized the central role of geochronology in the successful resolution of nearly every topical question documented.

The critical human and infrastructural resources needed to address the “big questions” also bridge subdisciplines. Specific resources are identified in three categories: (a) improved support for project development; (b) a dynamic 21st century tool kit for drilling/coring and analysis; and (c) optimized workflows and integrated facilities and data management operations.

The paleorecords community has collectively declined at this point to rank specific drilling/coring sites relative to one another, although the rationale for prioritization, and parameters to be considered, are a part of this report. The CSDCO will convene paleorecords community workshops in 2018-2019 with the express goal of prioritization among the sites and networks of sites that have been proposed.

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018The structure of this report, which places primacy on science questions and then recommends resources to answer them – while always seeking commonalities in goals and means – is the best method that the community has for providing NSF with strong rationale for funding allocation and prioritization among competitive proposals.

Suggested reading order: The reader with limited time is encouraged to read the Science Plan sections in the following order:

1. Science Planning: Preamble; 2. Paleorecords Community: Introduction; 7. Resources

and then to read the one or two Science Questions and Priorities section(s) most relevant to the reader’s own field, domain, or program:

4.I. Hydroclimate4.II. Biotic Processes4.III. Temperature4. IV. The Human Dimensionand/or please read: 5. The Central Role of Geochronology6. Outreach, Diversity, and Education (to be written by future workgroup)

Please also see the US Continental Scientific Drilling Science Plan: Paleorecords - Highlights brochure for a concise summary of this document. The brochure is available at CSDCO.org.

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1. Science Planning: Preamble

Scientific drilling and coring on Earth’s continents is fundamental for the advancement of the Earth sciences, unlocking new frontiers across a range of disciplines. The lines of scientific inquiry enabled by continental scientific drilling and coring are diverse, and include plate tectonics, Earth-life system interactions (paleoclimate, paleobiology, other paleorecords), bolide impacts, Critical Zone processes, magmatism, geothermal dynamics, hydrology, fault mechanics and seismicity, ecology of the deep biosphere, early Earth system establishment and evolution, archeology and hominid evolution, rock weathering processes, geochemistry, and others.

Drilling and coring constitute the primary means of directly accessing materials at depth below the Earth’s surface; they provide a means of obtaining fresh sample material where lack of geologic exposure or surface weathering limit access or sample integrity; they are required for accessing deeper locations where subsurface processes, fluids, solids, and biota can be observed and analyzed or monitored in real time through instrumented borehole observatories; and they provide an irreplaceable mechanism for validating surface-based observations and models. These activities are consistently identified as critical priorities of science

funding (e.g., PAGES, 2009; Evans, 2009; Evans, 2010; Evans, 2011; NRC, 2012; CPB, 2012; Russell et al., 2012; TRANSITIONS, 2012; Cohen and Zur, 2013).

Scientific drilling and coring are complex operations, bringing together collaborative international teams of researchers and students from disciplines across the geosciences. Substantial resources are invested in drilling and coring operations by NSF and other funding agencies around the world. The best results are achieved when the scientific community focuses its intellectual, physical, and financial resources on the highest-priority, highest-reward drilling targets and frameworks. It is therefore critical that the scientific community prioritize amongst the wide range of available drilling and coring concepts, to maximize research efficiency and ultimate scientific output.

The Continental Scientific Drilling Coordination Office (CSDCO) and LacCore Facility constitute the primary NSF facilities for continental scientific drilling and coring. Through support of research, these facilities promote project-specific development and realization of the consensus priorities developed by the drilling and coring communities. The US Continental Scientific Drilling Science Plan seeks to more explicitly identify and articulate these priorities on behalf of the various interested research communities for the upcoming decade.

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Paleorecords Community Workshop Participant List

First name Last name Institution Email addressMark Abbott Univ of Pittsburgh [email protected] Ballard Pellissippi Community College/TVA [email protected] Benison West Virginia Univ [email protected] Berke Univ of Notre Dame [email protected] Brahney Utah State Univ [email protected] Beverly Georgia State Univ [email protected] Bird Indiana Univ-Purdue Univ Indianapolis [email protected] Kristina Brady Shannon CSDCO / Univ of Minnesota [email protected] Julie Brigham-Grette Univ of Massachusetts-Amherst [email protected] Erik Brown U of MN Duluth [email protected] Chris Campisano Arizona State Univ. [email protected] Isla Castañeda Univ of Massachusetts Amherst [email protected] Christine Chen MIT / WHOI [email protected] Doug Clark Western Washington Univ [email protected] Cormier Univ of Rhode Island [email protected] Chris Crosby Univ of Minnesota [email protected] Rene Dommain Smithsonian - NMNH [email protected] Douglas Fils Ocean Leadership [email protected] Curry Illinois State Geological Surv [email protected] Foreman Western Washington Univ [email protected] Fritz Univ of Nebraska - Lincoln [email protected] Harrison Central Michigan Univ [email protected] Heil Univ of Rhode Island - GSO [email protected] Hynek USGS [email protected] Ito CSDCO / Univ of Minnesota [email protected] Ivory Brown Univ [email protected] Kuehn Concord Univ [email protected] Lane Univ of North Carolina Wilmington [email protected] Lehnert Columbia Univ [email protected] Leithold North Carolina State Univ [email protected] Marchetti Western Colorado Univ [email protected] Maxbauer Univ of Minnesota [email protected] McGee MIT [email protected] McGlue Univ. of Kentucky [email protected] McLauchlan Kansas State Univ [email protected] Moerman Smithsonian - NMNH / Univ of Michigan [email protected] Myrbo CSDCO / Univ of Minnesota [email protected] Noren CSDCO / Univ of Minnesota [email protected] Olsen LDEO/Columbia Univ [email protected] Park Boush Univ of Connecticut [email protected] Patterson Binghamton Univ [email protected] Pietras Binghamton Univ [email protected] Rabideaux Georgia State Univ [email protected] Ramdeen Univ of North Carolina at Chapel Hill [email protected] Reyes Univ of Alberta [email protected] Robinson USGS [email protected] Rodysill U.S. Geological Survey [email protected]

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018Jim Russell Brown Univ [email protected] Scholz Syracuse Univ [email protected] Self-Trail U.S. Geological Survey [email protected] Shapley Univ of Minnesota [email protected] Silva Univ of houston [email protected] Smith Kent State Univ [email protected] Smith Smithsonian / Johns Hopkins Univ [email protected] Stockhecke Univ of Minnesota [email protected] Stoner Oregon State Univ [email protected] Stroup MIT / Tufts [email protected] Taylor Berry College [email protected] Taylor Univ of Texas - Austin [email protected] Teed Wright State Univ [email protected] Tryon Harvard Univ [email protected] Tuite Jet Propulsion Lab, Caltech [email protected] Vilanova Argentine Museum of Nat Hist [email protected] Werne Univ Pittsburgh [email protected] Willard USGS [email protected] Yuan Cleveland State Univ [email protected] Zimmerman Lawrence Livermore Nat’l Laboratory [email protected]

Others who have contributed to the document:

Dave Adam Clear Lake Env Res CtrLesleigh Anderson USGS [email protected] Arnaud Université Grenoble Alpes [email protected] Atekwana Oklahoma State Univ [email protected] Ballard Univ Tennessee-Knoxville [email protected] Boutt Univ of Massachusetts [email protected] Clyde Univ of New Hampshire [email protected] Brunelle Univ of Utah [email protected] Cohen Univ Arizona [email protected] Condon British Geological SurveyAl Deino Berkeley Geochronology Center [email protected] Escobar Universidad del Norte(Colombia) [email protected] Ferreira Gomes Universidade Federal da Bahia [email protected] Gibert Beotas Univ of Barcelona [email protected] Greenwood Brandon Univ [email protected] Gross Universalmuseum Joanneum, GrazScott Harris College of Charleston [email protected] Harris [email protected] Heaven Hampton Univ [email protected] Huang Brown Univ [email protected] Britta Jensen Univ of Alberta [email protected] Janick Keystone CollegeTom Johnson Univ Minnesota Duluth [email protected] Kaufman Northern Arizona Univ [email protected] Kehrwald USGS [email protected] King Univ of Rhode Island [email protected] Matt Kirby Cal State Fullerton [email protected] Kohler Washington State Univ [email protected] Kuehn Concord Univ [email protected]

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018Jennifer Latimer Indiana State Univ [email protected] Leithold North Carolina State Univ [email protected] Lowenstein Binghamton Univ [email protected] Lund Univ Southern California [email protected] Lukzaj Univ Wisconsin - Green Bay [email protected] MacDonald Harvard UnivAndrea Marzoli Univ of PadovaLeeAnn Munk Univ of Alaska Anchorage [email protected] Olson Binghamton Univ [email protected] Ombori Università degli Studi di Ferrara [email protected] Piller KFU Graz [email protected] Polissar LDEO/Columbia UnivDana Royer Wesleyan Univ [email protected] Schultz Brown Univ [email protected] Power Univ of Utah [email protected] Silva Universidade Federal FluminensePeter Siver Connecticut College [email protected] Soreghan Univ Oklahoma [email protected] Stone Indiana State Univ [email protected] Tierney Univ of Arizona [email protected] Williams Oxford-Brookes Univ [email protected]

Alex Wolfe Univ of Alberta [email protected] Claudia Wrozyna KFU Graz [email protected] Marcello Zarate Universidad Nacional de la Pampa

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2. Paleorecords Community: Introduction

The continental paleorecords community conducts research on all aspects of environmental history and process, basing its work upon nonmarine sedimentary sequences formed in an extraordinary diversity of depositional settings. Researchers in this community contend with this complexity, despite the pole-to-pole historical sampling of the oceans and cryosphere provided by marine and ice cores, because continental sites record spatial variability in Earth parameters across land masses and the Earth system feedbacks produced by terrestrial processes. Continental sediments record conditions at locations and time scales relevant to human evolution and survival. Most essentially perhaps they provide records of the continental ecosystems and hydrologic processes upon which terrestrial life depends. In their very heterogeneity, continental paleorecords record the critical complexities of the continental response to global climatic and geological phenomena.

This plan focuses primarily on projects that call for careful prioritization relative to one another by the community and funding agencies such as NSF. These are projects that require large grants, often with large teams including several principal investigators (PIs), longer planning timeframes, and typically the use of shared facilities. Such projects typically involve deep drilling by mechanized equipment to depths of several tens to hundreds or even thousands of meters, deep water at target sites, logistical complexity, remote locations, challenging lithologies, or a combination of these factors. At the other end of the spectrum, shallower coring projects, in the soft sediments of modern lakes, rivers, estuaries, or other continental sedimentary basins, can often be accomplished at low cost, by small, agile teams, using

hand-operated coring equipment, with short lead times, and are not considered at length in this science plan. These shallower coring activities may, however, precede deeper drilling to demonstrate the potential of a site to produce a robust, dateable paleorecord. Deep drilling and shallow coring communities are contiguous and overlapping, and the LacCore/CSDCO facility supports both equally.

Members of the paleorecords community come from a range of disciplines, including the geosciences, ecology, biology, anthropology, archeology, and geography. Continental cores contain myriad sedimentary components and physical and chemical features, and members of the community apply a wide variety of analytical techniques, in order to address questions that derive from their own fields, and that often intersect with questions from other fields. The paleorecords community’s science plan therefore ranges widely in focus, reflecting the conceptual breadth inherited from its diverse intellectual underpinnings. Unifying themes across disparate sub-communities are clear, however, and include the following priority research emphases:

● Long time scales, and specific periods in time that allow the best possible tests of the understanding of Earth-system linkages, e.g., (1) periods with known similarities to projected future Earth climate, and (2) times with substantially different environments and conditions from which we can learn about novel triggers and responses within the Earth-life system.

● Targeted information needed by modelers, planners, and analysts, whose applications range from simulating fundamental Earth-system processes, to designing strategies for societal resilience, to supporting global security planning.

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● Improved chronological control of sedimentary paleorecords.

● Refined temporal resolution of key time windows.

● Linking continental, marine, and ice core paleorecords, promoting globally unified interpretations of Earth system history.

● Understanding forcings (e.g. greenhouse gases, orbital cycles, tectonics, nutrient limitation) and their representation in depositional sequences.

● Understanding feedbacks between the biosphere (surface and subsurface) and abiotic processes including climate.

● Developing and improving networks of paleorecord sites to better define spatial variations in climate and their dynamics over time, optimizing the scientific yield of existing and proposed paleorecords.

● Integration of data from site networks to effectively synthesize efforts between subdisciplines.

● Technique development, including standardization of applications and interpretation, with an emphasis on quantitative reconstruction and calibration.

● Fundamental processes of sedimentation and sediment preservation that affect paleoenvironmental interpretation.

● Community coordination through ongoing workshop planning and other mechanisms.

3. Subdisciplines within the Paleorecords Community

The paleorecords community encompasses researchers with a diversity of distinct but interrelated emphases, each guiding its members in the recognition of interlinked, overarching scientific questions.

1. Hydroclimate. The Hydroclimate community includes those researchers with a primary focus on reconstructing spatio-temporal changes in the global and regional water cycle. Often this is accomplished through the application of stable isotope and other geochemical techniques providing proxy records of global water transport vectors and the intensity of continental water cycling. This realm interfaces with that of modern hydrology as well as with other elements of the paleorecords community, and provides critical tests of Earth system modeling carried out at global and regional scales.

2. Biology/Ecology. With a focus on changes in ecosystem function and structure over time, this research community incorporates direct (fossils and subfossil remains) and less direct (biologically sensitive geochemistry) lines of evidence into inferred ecosystem histories. Through this approach, members of this community are uniquely positioned to both draw inferences about the physical environments of the past, and interpret the sensitivity of ecosystems to forcing by the physical environment. By interfacing with the other paleorecord communities and with the fields of neo-ecology and microbiology, this community generates critical knowledge of the all-important feedbacks between biota and Earth’s physical processes and climate.

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3. Temperature. Temperature history has a central role in unraveling Earth-surface and atmospheric processes. Members of this community are therefore on a continuing search for novel geochemical techniques that can yield quantitative temperature reconstructions at key points around the planet, and characterize natural variability at various temporal and spatial scales between these points. As with the hydroclimate community, their research emphasis contributes in critical ways to the testing and validation of Earth system models and to reconstruction of climate during extremes of the Earth’s climate history.

4. Human Influences and Impacts; Paleoanthropology; Archeology; Natural Hazards. This research community occupies the interface between human evolution, human activities, and variability in the physical environment. Fundamental to our understanding of the origins of the human species and of cultures, the work of this community is also central to humanity’s task of developing expectations and adaptation strategies for future environments and climates outside of recent experience, and for the effects that geohazards will have on a growing human population.

Important questions also derive from the chronological control on paleorecords and geochronological methods themselves . . .

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4. Science Questions and Priorities

The following sections discuss the leading research questions in each of the paleorecord community subdisciplines identified above. These outstanding questions are presented in the context of historic and recent discoveries, and interdisciplinary opportunities are identified. These science questions provide the basis and rationale for the community’s prioritization of resources, infrastructure, funding structures, and likely targets (geographic and conceptual), which are discussed later in the science plan.

I. Hydroclimate

Science Framework and Questions: How does the water cycle vary in changing climates?

Water has been a pivotal driver in the expansion of human civilization and is critical for the development of ecosystems and of life itself. Future changes in the distribution of water resources will severely stress human societies and natural ecosystems, and could rival past oil shortages in economic impact. Today, nearly 20% of the world’s population lives in areas with inadequate water supply, and studies predict that by 2025 up to two-thirds of the world will live with water scarcity due to changes in climate and deteriorating water quality (UNESCO 2015). The water cycle broadly consists of atmospheric processes associated with evaporation, vapor transport and precipitation, as well as surface and subsurface processes involving the storage and movement of water. All of these components are fundamental in controlling water distribution and availability. Precipitation patterns (both spatial and temporal) govern the supply of fresh water at the Earth’s surface. Thus it is critical to understand the

mechanisms within the climate system that influence precipitation patterns and ultimately control water availability. The movement of water over and beneath the Earth’s surface determines the availability of water for the biosphere, including for human and ecosystem use. The interaction of water with crustal materials through coupled biogeochemical processes alters water quality, and storage and flow of water within Earth’s crust affects the distribution and availability of this important economic resource. Continental scientific drilling seeks to address key problems in all of these aspects of the water cycle, in the terrestrial settings that are relevant for human life.

What are the processes governing large-scale changes in precipitation and how do they change through time?

Context: Decades of research have documented substantial changes in precipitation amount and distribution throughout Earth’s history. Intervals of flooding and drought have varied widely in magnitude and ranged from short-term changes observed over tens to hundreds of years to long-term transience extending over millennia. Tracking these changes, and interpreting their interactions within the climate system, is critical for understanding their causal mechanisms and improving our ability to predict changes in the water cycle in the future.

Our current understanding of precipitation changes in the past has advanced tremendously, particularly for changes that have occurred since the last ice age. For example, we now know that tropical rainfall generally declined during the last global glacial advance, particularly in the northern tropics, due to southward shifts in the tropical rain belt during the cooler ice-age climate. During this time, lake levels and precipitation in the western US rose, as mid-

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018latitude storm tracks shifted southward in response to the expanded ice sheet. The last glacial termination is peppered with extreme, millennium-long hydrological transitions that are antiphased between the hemispheres, driven by pulses of meltwater flushed into the high latitude oceans as the ice sheets melted. The Holocene, once thought to be a period of climate stability, has also witnessed extreme changes in hydrology. Only 6000 years ago, the Sahara desert was covered by large lakes. These and other extreme hydrological changes of the past have provided fundamental insight into the mechanisms governing global precipitation patterns, and have become benchmark records to test the ability of climate models to simulate changes in hydroclimate. Nevertheless the climate of the last ~20,000 years presents an extremely limited range of climate boundary conditions, and does not speak to hydroclimatic changes occurring in response to climates that were warmer than the present.

In the future, as our climate warms, theory suggests that high-precipitation regions should receive more rainfall, and dry regions less, in response to higher global temperatures. Climate model simulations of future rainfall patterns support this theory, suggesting relatively smooth increases in precipitation in wet regions and decreases in dry regions in response to rising greenhouse gas concentrations. However, it is not clear that this “wet-get-wetter” expectation holds over land. The paleoclimate record, albeit incomplete, suggest that precipitation changes during warm intervals in the past often involved conversion of dry regions into wet regions, and vice versa. Examples include the expansion of western US lakes during the warmer Pliocene, and the conversion of the Sahara desert from a verdant savannah during the warmer Miocene to a hyperarid state as climate cooled. We do not fully understand the rates of these transitions, nor their governing mechanisms. Paleoclimate records allow

tests of climate model performance and theory outside the range of the instrumental data, and they record the water cycle’s response to much larger changes than we have been able to directly observe . Given the importance of water to human well-being, a critical for of the paleoclimate community is to provide reliable and societally-relevant information about past changes in hydrology via a strategically distributed network of high resolution reconstructions, with a particular emphasis on past warm periods.

To address these issues, we need long records that register hydroclimate change at spatial and temporal scales relevant to climate model testing and to societal decision-making. Drilling and core recovery from continental sites are essential to these objectives, and particularly to understand the functioning of the water cycle in past time periods with high atmospheric greenhouse gas concentrations (e.g. the Pliocene and older). Lakes and other continental basins can provide reliable and societally-relevant information about past changes in precipitation and hydrology, and can address questions such as:

Questions:

● How do global spatial patterns of rainfall over land change in response to climate forcing (insolation changes, greenhouse gases, ENSO and other short-term variability)? Do past patterns of precipitation have spatial fingerprints that are consistently tied to specific climate forcings?

● What is the response of precipitation patterns to changes in regional and global temperature? What is the response of global precipitation in high-precipitation tropical areas and subtropical drylands in past warmer and cooler worlds? To what extent do these precipitation changes reflect global

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temperature rather than other related factors, such as ice sheet size and surface vegetation? Are there specific land regions for which the “rich-get-richer” paradigm holds?

● How does precipitation vary temporally within regions (from the frequency of extreme events such as droughts and floods to centennial scale average precipitation) under different mean climate states? What patterns of ocean and atmospheric variability govern the frequency and intensity of major droughts and floods?

● What are the rates and dynamics of step-like changes in precipitation? Precipitation is known to change abruptly within regions in response to abrupt forcing, but are there non-linearities or tipping points in response to gradual forcing?

● Are climate model estimates of past precipitation and hydrologic changes accurate in terms of regional magnitudes, rates of change, and large-scale spatial patterns ?

● Are temperature, precipitation, and water availability coupled? If so, over what temporal and spatial scales?

How did past changes in regional boundary conditions (e.g. tectonics, vegetation, sea levels) influence precipitation patterns and surface hydrology?

Context: Hydrological variability is influenced by and influences a wide range of surface processes, forming an integral part of the Earth system. Tectonic changes raise mountain ranges that alter precipitation patterns, and open and close ocean gateways that impact sea surface temperatures and poleward heat transport. Vegetation determines the amount of solar radiation absorbed at the Earth’s surface and modulates the transfer of water and energy to the

atmosphere. Changes in ice sheet size directly impact mid- and high-latitude atmospheric circulation and remotely affect tropical precipitation patterns through atmospheric teleconnections. Changes in sea level can expose land areas during sea level lowstands, and flood land areas as sea level rise, which may alter the spatial patterns of water vapor input to the lower atmosphere and transport into continental interiors. In turn, each of these systems is affected by changes in precipitation, which erodes mountain ranges, determines vegetation distributions, and alters the mass balance of ice sheets.

In other cases, scientific drilling can improve our knowledge of past changes in climate boundary conditions themselves. For instance, although meltwater fluxes are known to strongly influence climate during the last deglaciation (Clark et al 2012), there is a gap in our understanding of the role of megafloods or enhanced meltwater flux to the Gulf of Mexico during the last glacial maximum and older time periods. To date, most work has focused on Meltwater Spike 1A and other floods from about 18,000 yr B.P. to the present. Improving this understanding will help provide appropriate boundary conditions for GCM analysis of Laurentide deglaciation (Tarasov et al., 2012).

Questions:● How do ecosystems and vegetation control

the supply and availability of water at the surface and subsurface in a changing climate? Can regional changes in vegetation influence larger scale (e.g., global) precipitation patterns?

● What are the couplings and feedbacks between hydrological processes (precipitation, atmospheric composition and circulation, surface hydrology) and tectonics? Is hydroclimate a major factor in modulating fault movement and uplift rates?

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● What is the response of precipitation patterns to past and future changes in ice sheet topography and size?

● Can changes in sea level induce large changes in precipitation, or unique spatial patterns in precipitation?

● Can these feedbacks – between climate and vegetation, precipitation and the ice sheets, ice-sheets and sea level, or tectonics and precipitation – induce abrupt changes in hydroclimate, both regionally and globally? If so, what are the rates and thresholds involved?

● How does the sedimentary architecture of the ice-sheet hinterland influence the dynamics of deglaciation, meltwater pulses and the Earth-system response to altered boundary conditions? What is the sedimentary architecture and occupation history of marginal buried valleys and ice-walled lake plains along the Laurentide ice front, and how do they inform our understanding of the evolution of the Laurentide ice sheet?

How do surface and subsurface hydrology respond to changes in climate?

Context: Although precipitation sets water supply at the Earth’s surface and shallow subsurface, water movement and storage ultimately govern the availability of water for use by human societies and ecosystems. Moreover, water interacts with crustal materials, changing the quality and chemistry of water as well as the distribution of Earth resources (e.g. salts and ores). Existing paleohydrologic records suggest that ‘tipping points’ may exist not only in climate, but in regional hydrologic systems. For instance, the western US may have oscillated between a system in which freshwater is stored primarily at the surface, in the form of large lakes, to a system in which significant quantities exist only in

the subsurface. Moreover, such transitions may involve highly heterogeneous changes in precipitation and hydrology within regions, challenging our modeling capabilities.

Questions:

● Are there hydrological tipping points within basins and regions that control water availability, and if so, what are the key processes that control these thresholds?

● What is the response of regional groundwater systems (e.g., water table position) to past changes in precipitation and climate?

● How heterogeneous is the hydrological response of precipitation and surface hydrology to climate changes within specific regions? How large is the area represented by individual paleorecords? What is the most cost-effective way of building regional networks of sites with high chronological precision in order to map the spatial fingerprint of past changes? What are the drivers of spatial heterogeneity?

● How have the interactions of precipitation, tectonics, and surface hydrology in the geologic past influenced the distribution and availability of Earth resources, for instance fossil fuels, evaporite-hosted resources, and water itself?

● How did changes in past climate influence water-rock interactions and subsurface water quality?

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II. Biotic Processes

Science Framework and Questions

Since the emergence of life on Earth approximately 3.6 billion years ago, the biosphere and geosphere have been tightly linked. This linkage dynamically influences all four realms of Earth function: the biosphere, geosphere, hydrosphere, and atmosphere. Much of this linkage is accomplished by microbes at the molecular/elemental level. Having developed a wide variety of metabolic strategies, they contribute critically to the flux of elements into and out of biomass. In an ongoing and evolving cycle, microbes both adapt to changing environmental conditions and alter those conditions. As life has proliferated on Earth it has diverted a number of bio-necessary elements – particularly carbon, but also N, O, P and a number of metals, from the inorganic geosphere to the biosphere. Over geologic time this has affected the evolution of the atmosphere, as well as the proliferation of minerals. Signatures of these dynamics in the geologic record provide key insights about how biological systems function. Continental drilling enables the study of life during conditions no longer present on Earth. Additionally, the continuous and long-term records from drill cores capture feedbacks among drivers and responses in biotic systems. In turn, lessons from the past inform our understanding of future geosphere-biosphere dynamics.

The records from continental drilling offer vital insight into a range of environmental conditions not present on the modern Earth, as well as a means to study Earth system responses to environmental conditions that we may encounter in the future. Questions addressed by modern studies of ecosystem

processes, evolution, and biodiversity can be complemented by the longer timescales of paleobiology. For example, while it is well-known that biotic systems are sensitive to climate conditions, the rate of biotic response to climate change has been difficult to quantify using modern observations and models. Past records of biological communities and their associated environmental conditions can provide these rates. Because of this biological climate sensitivity, paleobiological research does more than benefit from associated studies of hydroclimate and temperature: it can also contribute to those studies. Similarly, analysis of events that date back billions of years (e.g., Crosby et al. 2014), such as global oxidation events and colonization of the continents by organisms, provide insight into early life-Earth dynamics. Efforts to develop new proxies and sampling techniques are poised to revolutionize our understanding of the dynamic relationships between the biosphere and geosphere. A diverse range of environments, ecosystems, and organisms can be assessed with continental drilling: potentially all taxonomic groups in both terrestrial and aquatic systems.

Several aspects of the biosphere can be effectively studied with continental drilling. Here, we focus on two major areas: (1) evolution, biodiversity, and community assembly, and (2) ecosystem processes.

EVOLUTION, BIODIVERSITY, AND COMMUNITY ASSEMBLY

What are the patterns, rates, and drivers of speciation and extinction through time?

Context: We have an incomplete understanding of the mechanisms that produced the biodiversity evident on Earth today. We know that the number of species inhabiting Earth has varied throughout its history as a result of speciation and extinction, yet we

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018do not know the major factors driving these processes, nor do we understand the patterns and rates of change in diversification (e.g. gradual vs. punctuated). This incomplete understanding prevents us from predicting future changes in biodiversity as a consequence of future global changes and from understanding how changes in biodiversity affect critical ecosystem services that are vital for human survival. In the past two centuries, many species have been lost or become severely threatened, yet it is difficult to compare these extinctions with previous mass extinctions. Continental scientific drilling of strata deposited during various periods of Earth history provides a unique tool to document aquatic and terrestrial species assemblages, their diversification and extinction, and their responses to external forcings over time.

Questions:

● How have geologic variation and abrupt events (e.g. tectonics, fluvial evolution, geographic barriers, volcanic eruptions, bolide impacts) driven speciation and extinction? (Antonelli et al. 2009, Ribas et al 2012, Bacon et al. 2015) How does diversity recover after extreme events/extinctions of differing character? (Peters and Gaines 2012)Does biological diversity increase progressively with time or does it change episodically in response to geologic or climatic events? (Hoorn et al. 2010, Rull 2011) How do the pace and mode of evolutionary patterns vary at different spatial and temporal scales? (Rolland et al. 2014)

● How is species richness correlated with variations in climatic conditions, particularly changes in the mean state of hydroclimate and temperature, and the pace of changes in these mean states? Are some types of abiotic

conditions (solar radiation, chemical substrate, nutrient status) correlated with high species richness? Under what conditions does environmental variability versus environmental stability function as a driver of speciation? (Willis et al. 2010, Dick et al. 2013, Cheng et al. 2013, Graham et al. 2010, Cermeno 2011, Kroll et al. 2012)

● Which types of environmental responses can be generalized across taxonomic groups and which are unique to particular groups of organisms, and which taxonomic groups are most sensitive (showing adaptive radiation or extinction) to climate or environmental change through time? (Weinkauf et al. 2014, Seehausen 2006)?

● What are the climatic and environmental thresholds (tipping points) that affect diversity, species composition, and ecosystem function in different systems and under different boundary conditions? (Khursevich et al. 2005,Willis et al. 2010, Dick et al. 2013, Snyder et al. 2013, Fritz et al. 2012, Cvetkoska et al. 2016)

● In what environmental settings is there congruence between paleoenvironmental histories and inferences of speciation derived from phylogenetic reconstructions, and how can these tools best be integrated to better understand the linkages between biotic evolution and landscape change? (Baker et al. 2014, Schultheiss et al. 2009, Pedersen et al 2016)

How do communities disassemble and reassemble through time?

Context: A biological community is a group of species interacting in the same time and space. Community composition changes over long time scales, as a result of migration, adaptation, or extinction of species in

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018response to environmental changes of varied character and rates. Paleobiotic data from drill core records can be paired with reconstructions of climate and environmental change derived from geophysical data, mineralogy, sedimentology, and geochemistry in the same core to yield continuous observations of species presence, absence, and abundances across abrupt events and periods of dramatic environmental change, as well as over times of gradual change. Thus, drill core records can be used to infer how individual species and species interactions are influenced by various types and rates of environmental change. Both macroscopic and microscopic species and communities can be assessed, taking into account taphonomic and diagenetic factors that may differentially affect each taxonomic group and depositional environment.

Questions:

● How do changes in atmospheric chemistry affect community structure and species interactions? (Willis et al. 2010, Callegro et al. 2014, Montañez et al., 2016)?

○ E.g. Low CO2 led to the evolution of plant species with the C4 photosynthetic pathway (Edwards et al. 2010)

● How have changing land-sea teleconnections resulting from continental reconfiguration from the Paleozoic to the present influenced community composition (Bacon et al. 2015, Willis et al. 2010, Bloch et al. 2016)?

● What groups of organisms commonly co-occur over time as opposed to behaving more individualistically, and what does this suggest about the mechanisms of species interactions?

● How do introductions of new species or the extinction of key species affect community

composition and species interactions (Gill 2014)?

● What microbial communities inhabit the deep biosphere, and what does this suggest about environmental drivers and modes of adaptation of microbial communities? (Torti et al. 2013, Lejzerowicz et al. 2013)

● How do thermal and hydrologic gradients relate to range extension/retraction of organisms, and what are the rates at which organisms can respond to changes in environmental conditions?

● What are the adaptations (e.g. morphology, body size, behavior) that organisms undergo in response to environmental perturbations on ~1,000 to 100,000 year time scales? (Weinhauf et al. 2014).

What ancient environments offer the best analogs for past life on Mars?

Context: Astrobiology is a key collaborative science for geobiology in extreme earth environments. The search for life on other planets complements research into early life on Earth. Life on Earth experiences extremes of temperature, pressure, and nutrient limitation that define the potential for life to exist elsewhere in the universe.

Questions:

● What are the roles of seeps and hydrothermal systems for life in Earth history?

● What are the biosignatures associated with deep subsurface hydrogen-supported ecosystems (e.g. sites of past/present serpentinization)?

● Which biosignatures are preserved in Mars analogs? What are the mechanisms of preservation?

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● What are the biosignatures associated with fossil ecosystems preserved in surface-mineral fluid inclusions, such as halite and gypsum?

ECOSYSTEM PROCESSES

What have been the feedbacks among drivers and responses in ecosystem processes, including carbon and nutrient cycles, and rates of weathering/transport?

Context: Ecosystems are strongly linked to climate. However, feedbacks between climate (hydroclimate, temperature) and biota, as well as between biological systems, the geosphere, and biogeochemical cycles, are not well constrained on millennial time scales and longer. Further, key Earth system processes, such as nutrient limitation and weathering, have not been adequately captured in Earth system models, because of their slow rates and the difficulties in parameterizing pre-Industrial conditions (Thomas et al. 2015). There is clearly a need to build a robust framework of ecosystem processes applicable to Earth’s various climatic, geomorphic, tectonic, and biotic settings (Porder 2014).

Chemical and physical weathering processes are intrinsically linked to all biogeochemical cycles as well as serving as a link between terrestrial and aquatic ecosystems. Changes in these processes therefore have important influences on ecosystem services such as soil and water quality and fisheries health. To understand the slow development of the Earth surface, we have traditionally been limited to comparing the modern landscape to source rock: the intermediate steps, rates, and controls of weathering processes are unknown on timescales up to 105 or 106 years. Several new proxies are being developed

to link information between drill cores and the Earth’s Critical Zone-- the permeable near-surface layer from the tops of the trees to the bottom of the groundwater (Brantley et al. 2011). Drilling records will complement space-for-time approaches commonly used to study slow processes.

In deep time, weathering and erosional processes are hypothesized to have influenced major biotic evolutionary patterns and extinctions (e.g., Snowball Earth and stromatolites, Cambrian Explosion, end-Devonian mass extinction) on the multi-million year timescale (Kump et al., 2000). On shorter timescales of 10,000-100,000 years there appear to be weathering and erosional responses to hyperthermal events of the early Paleogene that correlate with ecosystem response (Zachos et al., 2008). Shifts associated with vegetation regimes may enhance erosional processes on these timescales. Moreover, there appear to be feedbacks between geomorphic processes, biotic communities, and soil formation. Additional sites and refined age models are needed to resolve the spatial scale of patterns in weathering and erosion.

Atmospheric levels of oxygen, carbon dioxide, and greenhouse gases have varied significantly in the past. Photosynthesis is extremely sensitive to concentrations of oxygen and carbon dioxide, and plants experienced severe stress under low CO2 conditions of the Late Glacial [Gerhart and Ward 2010]. Additionally, variations in atmospheric CO2 interact strongly with chemical weathering rates. Drill cores that access times of differing CO2 concentrations will be extremely valuable for testing hypotheses about biotic function under changing atmospheric conditions (see section on Evolution, Biodiversity, Community Assembly). Earth history has provided natural experiments with which to test hypotheses about interactions of the biosphere, lithosphere, and atmosphere. Records of biotic

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018processes during deep time intervals are essential, as they provide the only examples of previous times when atmospheric CO2 values matched those of today.

Several factors can limit net primary production, particularly nutrients, such as nitrogen and phosphorus (Elser et al., 2007). Water limitation has also been demonstrated, related to past hydroclimate conditions reconstructed through independent proxies. Carbon limitation of terrestrial and aquatic systems has been demonstrated in modern systems and likely occurred under past Earth conditions such as low atmospheric CO2. The mechanisms of origin and maintenance of nutrient limitation can be studied through continuous, long records of ecosystem development that can only be obtained through coring and drilling.

Questions:

● How have major elemental cycles changed over time and what are the control and feedback mechanisms involved? (e.g., McLauchlan et al. 2013a and b)

● What different roles have microorganisms played as biogeochemical cycles (e.g., C, H, N, O, P, S, Fe, Ca, Si) evolve through time?

● When and how have changes in carbon turnover times over ~1000 to 1,000,000 year time scales been reflected in the overall global carbon cycle?

● What have been the limiting factors (e.g., nutrients) for terrestrial and aquatic ecosystems on different timescales? (e.g., examples in Schlesinger and Bernhardt, 2013)

● What have been the coupled roles of biota (microbes and plants) and atmospheric chemistry (pCO2 and pO2) in determining chemical and physical weathering rates, and

how have these rates affected ecosystems? (Berner 1992, Drever 1994, Banfield et al. 1999, Algeo et al 2001)

● How do source-to-sink dynamics change over time, particularly the relative contributions of processes operating in different portions of the landscape (e.g. uplands and lowlands)?

● How do rates and geographic extent of environmental and evolutionary change vary?

● How are chemical cycles modified by mass extinction events?

● What is the biogeochemical context of biotic radiations?

● Can we identify environmental trigger mechanisms and measure recovery rates of the biosphere?

● How is global change manifested differently in different coeval environments? (e.g., shelf-to-slope-to-deep-marine transects or across paleo-ecotones)

● What are the causes, consequences, and frequency of ocean anoxic events?

● What are the strengths of feedbacks between ecosystem evolution and landscape change?

● How does vegetation change affect fluvial geomorphology and sediment provision to lake basins?

● Can we understand the influence of atmospheric nutrient fluxes and long-term aerosol nutrient subsidy development in terrestrial and freshwater ecosystems? How have atmospheric dust loading and volcanic aerosols varied in the past, and how have those variations affected biogeochemical cycling (e.g., marine Fe fertilization)? How has the mass flux of material through the atmosphere changed through space and time?

● Are natural cycles that are well-constrained in the modern system (e.g. Milankovitch cycles) resolvable in the biogeochemical record in deep time?

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● How do rates of change (e.g. of atmospheric gases) influence the magnitude and persistence of ecosystem response?

What is the role of disturbances in driving ecosystem structure and function, and what are the implications for future ecosystem stability?

Context: Although climate is important for controlling ecosystem change, feedbacks within the Earth system complicate the relationship between climate and ecosystems. One of these key feedbacks involves ecosystem disturbances - relatively abrupt reductions in biomass due to various agents such as fires, severe weather events, insect outbreaks, mass movement, volcanic eruptions, and bolide impacts (Jackson et al. 2015). These disturbance events occur at a range of spatial and temporal scales, with varying consequences for ecosystems (McLauchlan et al. 2014). Both primary and secondary successional sequences, such as those resulting from glaciations or volcanic eruptions, provide an opportunity to test mechanisms of ecosystem resilience to disturbance. Drilling projects hold immense potential both for reconstructing these disturbance events and characterizing their impacts on ecosystems.

Sedimentary records have yielded excellent reconstructions of fire events and fire regimes on millennial timescales. Recent syntheses of global charcoal records show changes in biomass burning during the Holocene (Marlon et al. 2016) and climate control of fire activity on regional spatial scales [Calder et al. 2015]. However, longer-term records need to be developed to understand direct versus indirect climate drivers on fire regime change. Additionally, new proxies like levoglucosan (Elias et al. 2001) demonstrate potential to achieve records of past fires in places without good charcoal preservation. Early Paleogene records of hyperthermal events (using polycyclic aromatic

hydrocarbons, PAHs) suggest minor increases in fire frequency spanning high CO2 conditions; continuous records would provide important and complementary data.

Long records that access pre-Industrial conditions help determine baselines for ecosystem processes, and therefore a way to assess changes in disturbance regimes and consequences for ecosystem structure and function. Furthermore, such records can be used within the framework of the emerging discipline of conservation paleoecology, which is being used to demonstrate baseline conditions, mitigate the consequences of ecosystem change, and manage ecosystems under changing conditions (Jeffers et al. 2016; Dietl and Flessa 2011).

Questions:

● Are fire regimes changing during the Anthropocene? If so, where and how?

● How does disturbance influence weathering processes and rates?

● What is the interaction between wildfire return interval and the rate of forest regeneration under different climate conditions and soil types?

● Where have prehistoric human-induced changes to disturbance regimes led to ecosystem changes? (example: McWethy et al. 2009)

● What have been the feedbacks between climate and disturbance regimes?

● How have disturbance regime changes affected global biogeochemical cycles (C, N)?

● Which aspects of ecosystem function are vulnerable, and which are resilient to disturbance?

● Can we identify vulnerable ecosystems where rapid change is likely to occur, particularly with regard to important resources for

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human societies, such as fisheries or freshwater resources? (e.g., Scheffer et al 2009; Carpenter ??)

● Why do fire proxies (e.g., inertinite in coal) track fire triangle proxies (temperature, pCO2, pO2) well prior to the early Triassic but not subsequently (Diessel, 2010)? (Or why are there only minor changes in fire during hyperthermals?)

III. Temperature

Science framework and questions

Our world is warming at a rate that is unprecedented in the instrumental record, driven by rapid and massive burning of fossil fuels that is changing the composition of our atmosphere at rates that exceed those seen during the Paleocene-Eocene thermal maximum (PETM; Zeebe et al., 2016). Increases in atmospheric carbon dioxide are directly linked through atmospheric physics and planetary feedbacks to changes in global temperatures that result in the thermal expansion of oceans and drive the collapse of polar ice sheets. Such changes are causing rises in sea level that already impact coastal cities and transportation infrastructure (Clark et al. 2016; Deconto and Pollard, 2016). At the same time, changes in Earth’s temperature are altering equator-to-pole gradients that are driving changes in regional to hemispheric weather patterns (Francis et al, 2014, 2016; others...). The frequency of temperature extremes has risen over the past decade with long lasting heat waves having deadly impacts (2003 in Europe; 2015 and 2016 in India). 2016 saw fifteen $1 billion dollar weather and climate related disasters, second only to those that occurred in 2012 (NOAA, http://www.ncdc.noaa.gov/billions/). In recent

years, particular attention has been paid to ocean acidification and deoxygenation, additional problems associated with the rapid release of anthropogenic CO2 to the atmosphere and global warming, given their potentially severe effects on marine biological activity and geochemical cycles.

Scientific investigations of high resolution sediment records from lakes and continental basin systems are among the best approaches for determining the history of global climate change at adequate spatial and temporal scales to be relevant to current and future societies. The ability to provide reliable and societally-relevant information about past changes in temperature (and associated hydrologic and biologic impacts) requires a strategically distributed network of high resolution sites especially focused on past warm periods. Presently many spatial and temporal gaps exist in past temperature reconstruction. Filling in these gaps is critical for understanding regional temperature variability, the mechanisms driving global climate change, and for improving climate models.

The high latitudes are particularly sensitive to climate change yet at present relatively few continental temperature reconstructions exist from these regions. Furthermore, there is a mismatch between the available temperature records and climate models at high latitude sites. Overall there is a general need for additional temperature reconstructions from Arctic and Antarctic sites as well as for Paleocene-Eocene sites with better chronology to examine early Cenozoic greenhouse climates. In addition, there is a need for the development of mid-latitude continental temperature records, which many view as a current gap in our understanding of climate dynamics (e.g. Lake Issyk-Kul).

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018What are the spatial and temporal patterns of temperature change at different times in the geological past?

Context: Contemporary climate exhibits strong spatial and temporal patterns of variability that pose substantial adaptational challenges. For example, the magnitude of climate warming is highest at polar latitudes, leading to associated ecosystem and landscape changes that are already disrupting human economic and subsistence activities (e.g. Hinzman et al. 2005; Smith 2011). Temporal temperature variability, at scales ranging from interannual/interdecadal (e.g. ENSO, PDO) to millennial (e.g. D-O cycles), poses similar adaptational challenges. Over the last two decades, substantial progress has been made in understanding spatiotemporal climate variability on Holocene and late Pleistocene timescales, in particular through the development of high-resolution temperature proxies and integration of proxy and modeling efforts. This progress can now be brought to bear on longer timescales of investigation through continental drilling, with focus on several broad scientific questions:

Questions:

● How do geologic archives record extreme events, seasonal variability, and mean climate states with respect to temperature?

● What do high resolution records of temperature change during past warming events, both transient and persistent, reveal about natural variability in the climate system at different temporal scales?

● How does our understanding of the current climate system influence site selection for extracting regional climate variability? How might these regional site selections be

different as we investigate deeper times in the geologic record?

● What mechanisms control regional variability in temperature versus global change?

● What additional sites can be targeted to link high-elevation climate from equilibrium line altitudes (ELA) of valley glaciers to climate records in nearby basin and lake systems?

● What are the key locations to fill gaps and what records are most needed to help the modeling community?

What are the key time intervals that can better inform climate models of future conditions?

Context: Geologic time intervals in Earth’s past have inferred conditions similar to those of today and those predicted in Earth’s future. For example, the Pliocene represents the most recent time in Earth’s history when atmospheric CO2 concentrations were similar to today (~400 ppm). Understanding the magnitude and spatial patterns of temperature variability during the Pliocene has specific importance to our understanding of the sensitivities and feedbacks that determine climate response to CO2 forcing under near-modern geographic boundary conditions. New, broadly distributed, chronologically robust Pliocene paleorecords are therefore essential in assessing the skill of climate models under near-future conditions.

Questions:

● How do we make forward models more informative in a high CO2 world?

● Where do we need to go for records that discriminate regional vs global events?

● What areas are more susceptible to adverse effects in a high CO2 environment? (e.g. what is the magnitude and effect of arctic amplification in the high-CO2 past?)

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● Do deglaciations always trigger lake highstands in the topics?

● What was the nature of regional variability during warm sub-stadials? Were interstadial events expressed globally or only regionally on land (5a & 5c)? What about smaller events like MS 5b and 5d? Where do we go for high-resolution records of interglacials?

What are the geological constraints (forcings and feedbacks) for the role of atmospheric CO2 in regulating regional and global temperature changes discernible from pre-Quaternary records in Earth’s history?

Context: Paleoclimatic records from pre-Quaternary systems are fundamental to our understanding of how earth system processes act on long timescales and in non-analog climate states (e.g. greenhouse climates). Constraining regional and global patterns of temperature change in pre-Quaternary systems is a major challenge in the geosciences, complicated by discontinuous outcrop exposures, poor constraints on chronologies, and the limited array of robust proxy methods for temperature reconstruction. Insight into pre-Quaternary paleoclimate has been traditionally gleaned from continuous marine sediment sequences, with far less access to paleoclimate records at continental sites. Yet, spatial patterns of temperature across continental interiors can be complex and there is a pressing need to improve our understanding of terrestrial temperature dynamics during previous intervals of global change in order to provide paleoclimatic insight regarding regional responses to future climate change.

In particular, paleoclimates of “greenhouse” intervals are natural experiments on equilibrium and transient

climatic responses to higher-than-present atmospheric CO2 concentration. Efforts to understand the linkage between CO2 and temperature, both regionally and globally, are increasingly urgent as anthropogenic emissions are projected to drive atmospheric CO2 to concentrations unprecedented in at least the last several million years. Climate models provide some insight into Earth system response to high greenhouse gas forcing, but models commonly underestimate the magnitude of warming relative to warming reconstructed in climate proxy records for past “greenhouse” intervals, such as the mid Cretaceous and early Eocene. The proxy-model mismatch is particularly acute for continental interiors at high latitudes. As such, there is a compelling need for continental drilling to address several outstanding scientific questions related to paleoclimatic change:

Questions:

● How is temperature change in the tropics related to climate forcings? Can temperature shifts in tropical systems be independent of CO2?

● What is the time-lag associated with atmospheric CO2 concentration forcing on global temperature?

● What role do forcing mechanisms (atmospheric CO2 and other greenhouse gases; atmospheric aerosols; solar insolation, orbital cycles) play during climate transitions in Earth’s history?

● In the geologic record, what are the regional and global patterns of temperature response to projected atmospheric CO2 scenarios (doubling of pre-industrial CO2; 280 (1x), 560 (2x), 840 (3x), 1120 (4x) ppmv)?

● What is the Earth system’s long-term sensitivity to CO2?

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● What geological constraints do we have for teleconnections between sea ice loss and aridity in the western United States during warm intervals with dramatically reduced cryosphere component (e.g., Pliocene)?

● What are the forcing mechanisms for temperature changes in high CO2 climate states? How do patterns of regional cooling in generally warm climates relate to forcing and feedback mechanisms?

● How does bias introduced from comparing records for paleotemperature and CO2 with poor temporal constraints impact our understanding of long-term climate sensitivity in the Earth system? Can we resolve this bias with improved records for paleotemperature with direct constraints on forcing mechanisms?

● What are the relative roles of different forcing mechanisms (atmospheric CO2 and other greenhouse gases; atmospheric aerosols; solar insolation, orbital cycles) on temperature excursions during major climate change events in Earth’s history?

How can the community most efficiently improve on past temperature reconstructions?

Context Temperature proxies (indirect measurements) are required to extend short instrumental records (direct measurements) further back in time, allow for the examination of longer scale processes, and to study past warm intervals on Earth. The generation of absolute past temperature reconstructions is critical for understanding the forcings driving global climate variability, for ground truthing climate models, and for evaluating climate sensitivity. Many of the available tools for past temperature reconstruction are based on the biological remains of organisms and most, if not all, are influenced by other factors in addition to

temperature (e.g. salinity, light limitation, growth rate, seasonal growth bias). Some are also subject to modification by pre- and post-depositional processes. The need exists to understand and constrain these effects in order to refine calibrations and improve paleotemperature reconstruction. Furthermore, the scientific community needs to ensure that measurements are reproducible between laboratories and that errors are evaluated and reported in a standardized manner. Some of the key outstanding questions regarding the explanatory power of temperature proxies include:

Questions:

● What is the potential bias in a given proxy? How does the bias vary spatially and temporally?

● What is the sensitivity to changes in temperature? To changes in additional factors?

● How reproducible are the results both within a single laboratory and between laboratories?

● What corrections to different temperature proxies are being made or should be made?

● What sites, or site types, are best suited to establishing and calibrating specific temperature proxies?

● How can we use multiproxy records to characterize the influence of complex feedbacks on temperature?

● For some proxies, for example pollen, how do regional/cultural differences impact taxonomies?

● How is error evaluated?

As a state variable of the climate system, planetary surface temperature and its history have broadly cross-cutting importance to paleorecord analysis.

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018Improved methods for past temperature reconstruction are therefore important for the larger community as they benefit diverse studies spanning a wide variety of timescales.

IV. The Human Dimension

Understanding the interplay between humans and their environment requires both scientific drilling (to study potential climate change effects on human evolution over hundreds of thousands of years) and coring (to see the effects that humans have had on ecosystems and landscapes in the recent several thousand years). Studying the recurrence and severity of the risks of natural hazards to humans occurs over both time- and depth-scales, a continuum involving both coring and drilling.

Science framework and questions: Human Impacts on the Environment / Environmental Impacts on Humans

Humans are unquestionably playing a major role in shaping modern ecosystems and environments, but deep time perspectives are essential to contextualize the extent of human impacts, and somewhat paradoxically, to understand the role that environmental change has played in shaping contemporary human societies.

When do we first see anthropogenic impacts?

Context: Simple division of impacts into “anthropogenic” and “natural” reflect an artificial divide that intentionally or otherwise places humans outside of nature, violating basic ecological principles. While it is clear that concepts such as the Anthropocene capture a very real uptick in the trend

of human impacts on the landscape, studies of the Anthropocene often downplay the longer-term impacts of Homo sapiens. The potential solution is to reframe the questions, and to use new tools to refine the chronology of human presence and population sizes. Newer proxies such as fecal sterols provide direct evidence of humans in an area, but people need to leave behind traces close to shore in order for these materials to be preserved in the paleorecord. Short cores near known archeological sites can help determine the strengths and weaknesses of proxies such as fecal sterols .

● When do we first see evidence of anthropogenic impacts on the landscape?

● What does “anthropogenic” mean? Biologically, H. sapiens date to ~200 ka, and by some definitions, ‘modern’ humans may be somewhat younger, dating to the last ~50 kyr.

● Because the hominin record is much deeper, it is reasonable to ask, when did ‘human’ impacts first began? Impacts on animal communities through overharvesting or overhunting seem to have great antiquity, and other landscape modifications such as deliberate burning may be as old as 40 ka in Australia, although distinguishing between the impacts of human and climatic variables driving the change remain controversial (as reviewed in O’Connell and Allen, 2015).

● What are the impacts on the landscape from increased/concentrated herbivory via pastoralism? What about land clearing and other agricultural practices during the Holocene? Lake records as archives of basin-scale change have the potential to record some of these changes, particularly through the development of new proxies (e.g. fecal sterols) or a better understanding of existing

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paleorecords (e.g., charcoal, erosion, vegetation structure, and diversity).

How can we disentangle the effects of humans on climate vs. of climate on humans?

Context: Human, plants, and animals co-evolved through thousands of years of domestication (Zeder 2016). Whereas traditional understanding emphasizes that human interventions with plant and animal breeding have made them dependent on us, more recent approaches have emphasized mutual dependence; following the advent of domestication, people become more dependent upon domesticated plants and animals.

● To what extent do human impacts on lakes leave a consistent signature?

● Do human fishing practices substantially alter existing biological ecosystems?

● Does the creation of dams or irrigation channels fundamentally alter base level or other patterns of deposition or erosion?

● In what ways are humans “amplifiers” of climate change? For example, if deforestation and agriculture lead to increased runoff, higher lake levels, and higher sedimentation rates, in turn affecting the location of farms, pasturage, and modifications to soil productivity (e.g., manuring, fertilization using shells, etc.) what are the direction and strength of feedback processes between land use and hydroclimatic sensitivity? The extent and consequences of these more recent impacts obtained from short cores can only be understood in the context of long-term records of change provided by deep-sediment drilling..

Context: In addition to understanding the human impact on the environment and natural processes,

there is clearly the need to address the environmental impacts on human history.

● On a deep-time scale, do evolutionary patterns (e.g., speciation and extinction rates or changes in behavior) track global patterns in climate/habitat change (such as addressed by HSPDP [Cohen et al 2016])?

● How do rates of change in drill core paleorecords compare to evolutionary responses in terrestrial vertebrate fauna and flora?

● For the Holocene, what is the impact of climate and environmental change on issues such as human migrations and the onset and expansion of agriculture and pastoralism? These sorts of questions gain particular traction following recent aDNA studies that demonstrate, for example, that the LBK archaeological cultures of mid-Holocene Europe reflect migrations (the movement of human populations) from Anatolia, and thus the local adoption of agriculture cannot be explained solely by in situ cultural adaptations to climate change.

● For modern and future impacts, is climate change a “threat multiplier?” That is, does it initiate new or exacerbate existing problems (e.g., socio-political unrest related to drought or flooding)? This is an issue touched upon in the popular press for the past two decades, most strikingly in the popular (and Pulitzer Prize-winning) books by Jared Diamond (e.g., Collapse). There are clear archaeological precedents for the modern condition.

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018How have prehistoric human societies shaped ecosystems that we often view as ‘pristine’ in North America and elsewhere?

Context: Two classic studies/regions demonstrate the long history of human impacts on modern ecosystems: the Serengeti in eastern Africa and the northeastern US. Although substantial conservation efforts and tourism dollars have gone towards maintaining the Serengeti as a ‘pristine’ natural landscape, a number of studies have emphasized the importance of regular burning by cattle-caprine pastoralists for ~5 kyr; in this case the type and density of grasses and trees and associated fauna are strongly impacted by human populations whose archaeological impacts are otherwise minimal and poorly studied (Sinclair et al 2008). In North America, Cronon’s landmark study Changes in the Land (1983) outlines in detail European perceptions of ‘pristine’ landscapes upon arrival in North America with the fact that the landscape was in fact the outcome of thousands of years of burning and other management practices by indigenous populations. Following initial contact and population decline (e.g., smallpox, etc.), forest structure rapidly changed from old to largely new growth, clearly documented in existing short cores. The extent to which these examples can be generalized is not fully understood, and should be a research effort towards the development of new proxies to recognize human impact and to date its inception.

● Are we able to obtain direct evidence of “pristine” landscapes before the presence of humans (such as in small Pacific islands and/or the Americas)?

● Are we able to quantify the impact of prehistoric human societies on ecosystems? (E.g. fecal sterols can demonstrate the presence of humans, and pollen can

demonstrate contemporaneous vegetation change, but direct causation is lacking).

How susceptible were prehistoric human societies to climate changes? Is there any evidence that resource stress to systems near carrying capacity made these populations more susceptible to change (i.e., acted as a threat multiplier)? What are the limits of technology in the human response to climate change??

Context: Human societies are inherently susceptible to changes in climate. While technology can mitigate many of these risks, it also has the potential to make societies even more vulnerable to large and/or rapid changes in climate. Future research should pair high-quality, high-resolution, multi-proxy paleo-records with detailed archaeological histories to assess the ability of societies to respond to climate change through time and through different stages of technological development. While many studies have focused on responses of prehistoric societies to climatic change, it remains unclear if these past events can serve as true analogues for modern or future societal responses to climate change. Examples for study might include the Viking occupation of and subsequent abandonment of Greenland during the Little Ice Age, a shift from from farming/agropastoralism to hunting-gathering-fishing by (smaller) indigenous populations.

Science framework and questions: Paleoanthropology and archeology

Paleoanthropology is the study of human evolution that draws on ancient archaeological, fossil, genetic, and environmental data. Current evidence suggests that the human lineage split from a last common ancestor with chimpanzees sometime between 5-8 Ma, the genus Homo is at least 2 million years old, and that hominins began expansions across and out

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018of an African homeland shortly thereafter, by 1.8 Ma. Our own species, Homo sapiens, is about 200,000 years old, with expansions out of Africa by 50 ka if not before, occupying all of the continents (except Antarctica) by 15 ka, if not before.

What is the relationship between climate change and human evolution?

Context: Understanding the role of climate change in human evolution requires long, well-dated records of climatic and environmental change in regions significant to understanding the evolution and dispersal of early humans. This requires selecting regions that can yield high-resolution geological data that also have, or have significant potential for, a rich paleoanthropological record (i.e., one with a large number or archaeological sites or human and non-human fossils). A key issue here is one of geographic and temporal scales. Areas selected for drilling typically sample large catchments that cover 10s of square km, areas that may be significantly larger than that sampled by an archaeological excavation or the home ranges of the early humans being studied. Similarly, because of their frequently more-or-less continuous records of sedimentation, core data can often be resolved temporally at fine scales, whereas archaeological sites typically have a larger margin of chronological uncertainty (see discussion in Blome et al., 2012).

● To what extent does climate change explain past human adaptations in biology and behavior?

● Did environmental change contribute to the diversification of the human lineage through repeated habitat expansion, contraction, and fragmentation that led to isolation and adaptation?

● Are human dispersals linked with periods of climate change that altered the extent of

favorable habitats or the removal of barriers to dispersal (e.g., the Sahara or Negev deserts)?

● What role(s) did climate change play in the dispersal of early humans?

Science framework and questions: Addressing the Impacts of Natural Hazards

Context: Historic records and the human timescale of observation are short relative to the recurrence intervals of natural hazards. Lakes record in their sediment stratigraphy the histories of earthquakes, volcanic eruptions, tsunamis, droughts, and storm events, and potentially their environmental impacts as well, over periods of hundreds to millions of years. Therefore, analysis of long-term paleo-archives is a uniquely important element in assessing future hazards. Teasing out the long-term record of hazard events from lakes and lagoons can help evaluate the risk to nearby populations, and be used to best prepare for and mitigate the next event. More fundamentally, stratigraphic records provide data necessary for understanding the underlying processes that control the recurrence and severity of natural hazards.

Some continental targets in the US and its territories need increased attention for the meaningful characterization of earthquake, tsunami, volcanic, flooding, drought, or hurricane hazards. Many countries around the world are exposed to similar hazards, and there is much to learn from comparing the stratigraphic records from sites that are subject to similar hazards. General questions applicable to geohazard records generally include:

● What does the stratigraphic record indicate about the periodicity, clustering, or randomness of these events?

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● How does the sensitivity of lakes as recorders of natural hazards vary over space and time?

● What can the stratigraphic record tell us about the possible linkages between various natural hazards (e.g. earthquakes and volcanic eruptions) and the aggregate impacts of independent processes (e.g. earthquakes and storm-triggered landslides)?

● What is the response of ecosystems (including human ecosystems) to natural hazards? Is there a preserved stratigraphic record of biological turnover and/or changes in productivity or ecosystem structure following extreme events?

● How do precursor events influence stratigraphic registration of episodic event deposits?

Earthquakes. Sediments in lakes in tectonically active regions and in some cases directly straddling active fault zones preserve stratigraphic records of earthquake events (seismites, turbidite-homogeneities). The lakes, moreover, may also record earthquake impacts on surrounding catchments , including landsliding and post-seismic increases in sediment flux to fluvial networks. Likewise, coastal lagoons along convergent margins may preserve in their stratigraphy a record of tsunamis and co-seismic subsidence, and thus also tell us about the frequency and magnitude of such events. In addition to the general questions about hazards posed above, these stratigraphic records provide a means to address a number of questions about earthquakes, including:

● How can we resolve earthquake magnitude and the length of fault ruptures from lacustrine sedimentary records? Can we resolve ruptures on adjacent fault segments that are closely spaced in time from a single rupture?

● How are ruptures detected in lakes at convergent margins linked to earthquakes occurring at the subduction interface?

● How is fault movement recorded in scarp-dammed lakes, or lakes where lake outlet elevation is modified by fault scarp movement?

Volcanism. Volcanic ashes (tephras) are excellent markers of nearby, or even distal, volcanic eruptions, and are typically well preserved in lake deposits. In fact, lake cores may preserve more complete records about the evolution of a volcano than the volcano itself, as both erosion and more recent eruptions may destroy and rework or bury any traces of a previous eruption. Geochemical correlations of tephra between proximal and distal locations define geographical distributions, eruption magnitudes and volumes, and reveal patterns of atmospheric circulation which transport tephra particles (e.g. Ponomareva et al., 2015, Tephra without borders; Stevenson et al., 2015). The composition of tephras also provides information on evolving magmatic compositions and magma sources. Lastly, and most significantly for other fields of science, each tephra provides a distinct chronostratigraphic marker that can be used to correlate the stratigraphic record from location to location at regional and increasingly even beyond continental scales (Lowe 2011, Tephrochronology and its application; Jensen et al., 2014, Transatlantic distribution of the Alaskan White River Ash). In some instances, preservation of the same ash deposit in lacustrine and adjacent terrestrial deposits provides a uniquely temporally narrow (‘isochronous’) layer to compare basin-scale changes in lakes and on land, as is the case for a number of the rift- and rift-adjacent lakes in eastern/central Africa. In other instances, tephras may connect and synchronize terrestrial-lacustrine records with marine and ice core records making it possible to examine magnitudes and relative timings

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018of temperature and hydroclimate changes across large areas and multiple environments.

● How can integration of proximal and distal tephra records help to assess the extent to which proximal records are incomplete?

● How can integrated proximal-distal records improve hazards assessment and understanding of long-term patterns (and periodicities?) in volcano-magmatic-tectonic processes?

Drought. Drought as a climatic phenomenon is a long-established subject of the Hydroclimate research community’s efforts, where the response of lakes is often registered in terms of geochemical changes in lake sediment composition (reflecting changes in lake water composition) or in shoreline changes reflecting lake water balance. Of course drought also represents a natural hazard with profound implications for human societies, past and future, highlighting the need to reconstruct the severity, spatial extent and duration of drought and its effects on human systems. Lake systems register both proximal effects of drought on the lake watershed (through water balance effects), and distal drought signals produced through the deposition of exogenous dust transported over regional or hemispheric distances from source areas. Proximal and distal signals are best served by depositional basins with differing characteristics, e.g., high sensitivity to local hydrologic balance (proximal signals amplified) versus minimal local sediment flux (distal signals most visible). While the topic has been primarily a focus of Quaternary studies, high-resolution pre-Quaternary sediments suitable for analyzing both proximal and distal drought recurrence under pre-Quaternary climates and forcing exist, and should be brought to the fore in evaluating future drought risk and strategies for mitigation.

● What can temporal trajectories of past drought tell societies about hazard evaluation and response?

● How have the spatial scale and patterns of drought changed under past climate regimes?

● How have human societies responded to past droughts of different scope and duration?

Rapid lake level change. Abrupt lake level changes may pose hazards and lead to economic disruption for populations , and may arise through a number of processes. A striking example of abrupt lake level change is the recent history of Lake Azuei (Haiti), which has risen ~5 m in the past ~10 years for reasons that remain under debate, displacing the surrounding population and flooding infrastructure. Hypotheses to explain this disruptive trend include increased precipitation, shifts in the subsurface network of karst, increased sedimentation due to deforestation, and/or increased fluid seepages into the lake as a result of recent tectonic activity. Drilling and instrumentation of sediments and lake-basin boundaries may help distinguish the processes of importance, while recovering sedimentary records of past patterns in lake-level change.

● What are the dominant drivers of disruptive, rapid lake-level change under different climatic and tectonic regimes?

● How have communities and societies dealt with the effects of transient lake levels? How do mitigation strategies fit into the larger picture of hydrologic risk management?

Hurricanes and other storm events. What is the variability of hurricane recurrence and intensity over time? Most climate models predict that hurricanes should become more frequent and intense with increased sea surface temperature. Lakes and small coastal lagoons preserve a detailed record of past storm surges associated with hurricanes, an archive

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018that could be calibrated against the past ~400 years of historical records and used to evaluate possible changes in future trends.

● What are the relationships between hurricane frequency and trajectory, and decadal-scale climate patterns (e.g., ENSO, NAO, PDO)?

● Are there trends in the trajectories of hurricanes, affecting the Gulf of Mexico versus the US east coast differently over time?

● How have the distribution, intensity and effects of convective storms changed over time?

● How are the impacts of earthquakes exacerbated by subsequent storms? Might the effects of future earthquakes be impacted by climate change?

Landslides. Landslides represent one of the most common natural hazards facing modern society, and their frequency will likely increase in response to population pressures and increases in extreme precipitation events forecast for many regions as a result of anthropogenic climate change. Recent US experience includes the tragic 2014 Oso landslide disaster, Washington State, which stimulated new detailed mapping of all of the potentially active landslide zones in the state. Oregon has also undertaken a similar program. However, two of the primary characteristics of these landslides, their ages and recurrence intervals of activity, are poorly known because of difficult access to datable material associated with their formation. Age and frequency constraints are crucial for developing rigorous probabilistic hazard and risk maps.

Cores provide arguably the most accessible and reliable means of dating many of these slides, yet little effort has been devoted to this, because of a lack of coring resources and expertise in the landslide research community. Two types of core recovery can

help improve understanding of these destructive hazards: Drill holes that penetrate the slide mass itself, and coring of depressions on landslide surfaces, which often harbor small lakes, bogs, or sag ponds. Many of the published models of slide initiation, release, and runout, presume various conditions of the typically unexposed pre-slide surface to explain the movement and dynamics of the slide (e.g., Coe et al., 2016). Drilling often provides the only realistic means to directly observe this surface. Coupled with subsurface geophysical tools, results of drilling can be extrapolated across a slide. Coring of deposits formed on landslide surfaces can provide two different types of age constraints: minimum limiting 14C ages from basal lake deposits, and direct dates of the event, through recovery of macrofossils entrained in the slide and preserved by overlying lacustrine deposits.

Core-based chronologies and stratigraphies of landslide activity can address key geohazard risk questions including:

● How do frequency and magnitude of land surface failures relate to triggering mechanisms?

● What role do quasi-periodic phenomena (e.g. seismicity; ENSO) play in landslide hazard risk?

● How do human activities and land-use decisions influence landslide mechanics and hazard management?

5. The Central Role of Geochronology

Geochronology is often considered a tool or method in the same category as chemical or isotopic measurements, floral or faunal analysis, sedimentology, or other analyses that contribute to the multiproxy study of paleorecords. Dates and

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018rates, though, are overarching concerns, and because geochronology is arguably essential for every paleorecord study (no matter which proxies are chosen to investigate), this science plan treats geochronology with the subdisciplines above rather than within the discussion of methods later in this document.

The scientific questions being investigated by the continental drilling community rely heavily on having robust, high-quality chronologies for the geologic sequences being drilled. The science of geochronology investigates the time dimension of Earth’s history, and seeks to answer fundamental questions of process rates, periodicity, spatial patterns, and sequence and synchroneity, by advancing the precision, range, and application of existing chronological tools and by developing new tools with the power to transform our understanding of Earth’s history and processes.

What are the fundamental rates at which Earth processes proceed, and how do rates change under different boundary conditions?

Context: Modern rates of processes such as the retreat of ice shelves/sheets, uplift of mountains, and warming of the poles can be measured quite precisely with GPS and remote sensing equipment, but determining past rates for these and other processes requires measurement of the amount of time a change took to occur. As boundary conditions such as atmospheric CO2 concentration, sea level, and ocean-atmosphere circulation have changed, rates are likely to have changed in response, and so chronological control points must be closely associated with the processes being investigated. This can become very difficult when examining processes in deep time, where age control points may be tens of millions of years apart and celestial

mechanics and astronomical parameters themselves are subject to important changes.

Questions:

● Do transient events such as landscape erosion, speciation and extinction, and warming or cooling have characteristic rates through geologic time? How large is the range of timescales possible for a particular process, and how do the controls on rate change under different geologic conditions?

● How do the spatial patterns of changes scale with the amount of time being considered? Are changes that affect areas of hundreds of square kilometers over a million years actually changes that affect much smaller regions when examined on millennial timescales?

● How abrupt are responses to discrete or continuous system forcing, and how much does apparent abruptness depend on the temporal resolution of the record or its age model? For example, is a warming event that appears abrupt on glacial-interglacial timescales still abrupt when examined on centennial timescales?

● What is the pace at which biotic communities adapt or migrate in response to an environmental forcing? How quickly does biotic diversity recover after environmental extremes or catastrophes?

How do past patterns of recurrence help to predict future events of various Earth processes, and how long and highly resolved do paleorecords need to be to make useful predictions of future probability?

Context: When natural hazards such as earthquakes, floods, volcanic eruptions, and hurricanes affect

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018population centers, the resulting destruction can have high costs in human lives and infrastructure and economic loss. Geologic hazards commonly recur on timescales much longer than historical observations, and thus require paleorecord reconstructions to make probabalistic predictions of future events. Furthermore, events such as floods, hurricanes, and drought that have climatic drivers are proving to be difficult to predict because teleconnections described from historical patterns are already non-stationary due to changing climate. More skillful prediction of future events requires understanding of the pre-anthropogenic climate system reconstructed from well-dated geological archives. Models give ambiguous interpretations of how ENSO and other cyclic phenomena will change in frequency and intensity in a future with higher greenhouse gas (GHG) concentrations. To guide modeling and forecasting of the effects of GHG warming on these natural cycles, we must consult the past regarding how ENSO and other climate teleconnections have been different in the past under climate regimes including both cooler and warmer conditions.

Questions:

● What are the recurrence intervals of sporadic events such as earthquakes, tsunamis, floods, volcanism, and hurricanes: are they periodic? Clustered in time? Randomly distributed? How long a record is required to predict the next occurrence with a precision that is useful to decision-makers?

● Have atmosphere-ocean oscillations observed in the modern climate system, such as ENSO, the North Atlantic Oscillation, and the Pacific Decadal Oscillation, sustained their periodicities over time? Can the frequency and drivers of regime shifts (e.g., from positive to negative PDO phases) be reconstructed with confidence?

● What parts of the climate system transmit periodic variability rapidly and clearly to continental archives, and what archives most faithfully record those signals?

How can proper sequencing of events in Earth’s past help to identify events or components of the Earth system that have driven major physical or biological shifts, and to distinguish feedbacks and responses from triggers?

Context: Correctly determining the order of events or changes in Earth’s past is critical to identifying the initial trigger of a change, and to distinguishing the chain of responses that occur later in time and the feedback loops in various parts of the Earth system. Precise determination of synchroneity (as opposed to sequence) may also help to identify the part of the system that transmits a signal; for example, the troposphere mixes on monthly timescales, and can therefore transmit changes much more quickly than the ocean, which circulates on multi-centennial timescales.

Questions:

● In what systems and under what conditions do gradual forcings produce tipping points or non-linear responses, for example in species composition, ecosystem stability, glaciation, or water availability?

● What are the drivers of long-term changes through time, for example in the evolution of a genus or the development of fossil-fuel and evaporite resources?

● What are the climatic linkages between the poles and the tropics? Have major climatic changes in the past typically been initiated in one region or the other, or does that depend on the background climate state,

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arrangement of the continents and oceans, or other larger controls?

● To what extent were the landscapes encountered by Europeans in the Americas the result of landscape management by early peoples?

● How do ecosystems respond to the introduction of a new species, or to the extinction of a key species? What are the timescales needed for establishment of a new state of stability?

What spatial patterns emerge from paleorecords that have age models with resolution and precision similar to the proxy records that are being correlated?

Context: The accurate description of spatial patterns of past changes relies completely on accurate and precise time control. Although in some cases quite accurate correlations can be made based on identifying widespread tephras, changes in the geomagnetic field, or sudden extinctions or speciation events, without absolute age information the description of spatial patterns is limited to records that contain that event. Ultimately, mapping the spatial patterns of change and describing the areas that were (or were not) affected by an event provides a very different set of insights into Earth’s past than can be gained from examination of individual records or set of records in relative isolation.

Questions:● What insights can be gained by iteration

between climate models and paleorecords accurately correlated across regions and continents? Are the links predicted from climate model experiments also observed in paleorecords from key locations? Can model experiments provide the physical

mechanisms to explain “wiggle-match” correlations between paleorecords?

● What do regional networks of records suggest about the mechanism that trigger changes? For example, can comparison of the spatial pattern of historical droughts with the reconstructed spatial pattern of ancient droughts suggest similar causes?

● What are the links between continental records and the global framework reconstructed from marine and ice core records? For example, what was the state of continental biotic communities during extinction events known mostly from marine records? How do hydroclimatic shifts on land correspond to stadial or interstadial conditions in the North Atlantic?

● Can interpretations of change be drawn from multiple lines of evidence, to increase confidence in the proxy reconstructions - e.g., correlation between warming reconstructed from geochemical proxies in lakes and from rising equilibrium line altitudes in co-existing glacial moraines?

● How do global changes affect different environments differently, e.g., changes in temperature, sea level, or atmospheric composition expressed in biotic communities along transects from coastal-shelf-slope-deep marine?

Recommended Initiatives:Despite its clear importance, chronology is often the critical limitation on interpretation of continental drilling records. This is sometimes due to the difficulty of determining accurate and precise ages for deposits of various ages and lithologies; in these cases, investments in improving chronological tools have great potential for increasing the robustness and significance of drilling-based studies and for advancing our understanding of the dynamics of past

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018and future environmental change. In other cases, the limitation is the lack of funding to measure enough dates to build an age model with time resolution similar to that of the proxy reconstruction. This often results in correlation of high-resolution proxy records based on age models that are low-resolution or have large (often unacknowledged) uncertainties. To address these challenges and strengthen the temporal reference frame within which records of Earth history are interpreted, we recommend support for the following initiatives:

Collaborative inter-laboratory comparisons

With some exceptions (in particular, accelerator mass spectrometry [AMS]), the U.S. geochronology community is dominated by single-PI labs centered around a particular method, often specializing in a particular rock or mineral matrix, time period, or geologic question. As a result, sample preparation and data analysis techniques are often tailored to the lab’s particular specialty, so routine comparisons between laboratories are needed to assure that results are comparable across labs. Formal round-robin intercomparisons have been performed by the radiocarbon community for several decades (e.g., Scott et al.,1990 Radiocarbon v. 32(3)) with the Sixth International Radiocarbon Intercomparison (SIRI) on-going (www.radiocarbon.org; ). One result of the IRI series is a collection of materials of a variety of matrices and ages with consensus 14C values, available to routinely measure alongside unknowns (Scott et al. 2003). In addition, the discussions following the measurement campaigns have provided opportunities for practitioners and users of radiocarbon to assess current sample preparation and analysis techniques as well as data-reporting conventions.

Similarly, the EarthTime effort (Palike and Hilgen 2008) united the U-Pb community to identify inter-lab biases and develop calibrated isotope tracer

materials, resulting in major increases in precision. Similar intercalibration efforts have been undertaken by the cosmogenic nuclide community in the CRONUS program and the tephrochronology community (Kuehn et al, 2011), and are currently underway by the 40Ar/39Ar community and are in their initial stages in the U/Th community, and other geochronology communities should be encouraged to begin their own efforts to compare sampling, chemical, analytical, and data-reduction techniques. Such efforts require funding support for sample collection/distribution, making measurements, development of standards, spikes, and software, and workshops for discussions, but the impacts of well-designed intercomparison exercises are transformative and enduring.

OSL - new improvements in this technique?

Inter-method comparisons: inter-method calibration at highly suitable sites

Although radiocarbon is the most widely used geochronology method for sediments less than 40,000 years old, coring projects covering hundreds of thousands or millions of years and projects focused on deep time are proliferating. Such projects commonly use multiple dating techniques on different matrices, for example combining radiocarbon on organic matter less than 40,000 years old, both 40Ar/39Ar and U-Pb on minerals in tephra layers, fission-track on tephra glasses, and luminescence on sands <200,000 years old. Since each dating method carries its own combination of strengths, uncertainties, and assumptions, building robust multi-chronometer age models requires that ages from multiple techniques be comparable.

The identification of sediment sequences, in outcrop or core, that can be dated by multiple chronometers would provide the basis for identifying systematic

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018causes of disagreement between methods. This was one of the goals of EarthTime (Palike and Hilgen 2008).

Feasibility funding for high-risk, high-reward chronometer innovation: new time periods for established methods; new methods for difficult lithologies

The potential to be able to build a high-resolution age model is an important attribute of proposed projects, but the significance of specific questions is largely independent of geochronologic potential, and compelling scientific questions are frequently associated with time periods or lithologies that are difficult to date. Certain time periods are particularly problematic; for example, the interval from ~40-780 ka encompasses many climatic transitions relevant to human history but is too old for radiocarbon dating, and too young for paleomagnetic reversal stratigraphy. Suitable tephras for 40Ar/39Ar dating are often infrequent in this time interval except in some unusual settings (e.g., East Africa and Italy), and paleointensity-based chronologies may be difficult to measure or uniquely match to global averages. Further, while paleomagnetic reversals provide relatively high-resolution chronological control for the Triassic Period (250-201.6 Ma), the Cretaceous SuperNorm is a period of 40 Ma with no paleomagnetic reversals.

In other instances, specific paleoenvironments are often devoid of suitable material for geochronology. Tephras often provide opportunities for direct dating of mineral phases, or by tephrochemical correlation to dated stratigraphies, but are not ubiquitous and may prove unsuitable due to distance from volcanic sources, or alteration. For example, tephrochronology is a very powerful tool for studying human evolution in the tectonically active East African Rift, but potentially rich fossil sites in southern Africa are far from volcanic centers and

thus are usually devoid of ash beds or cryptotephra, and have been much less studied. Where tephra horizons are poorly preserved or otherwise unsuitable mineralogically for direct dating, detrital zircon geochronology may indirectly aid dating when the youngest zircons constrain maximum depositional age.

Some sedimentary lithologies, such as halite, gypsum, and iron oxides, rarely contain radiometrically useful isotopes. For some of these lithologies, other chronological methods, such as paleomagnetostratigraphy in iron oxides, have proven useful. In addition, local hiatuses caused by erosional processes in some high-energy fluvial, eolian, and lacustrine environments may lead to discontinuous records. For example, evaporite sequences formed in ephemeral saline lakes and associated saline mudflats present frequent age gaps due to chemical dissolution, physical erosion, and/or non-deposition. In the absence of well-preserved tephras, these sediments/rocks typically must rely on relative dating, using absolute ages of underlying and overlying strata to constrain their age. For example, fluvial red beds and saline-lake evaporites are common in the late Permian, and thus often must rely on interpolation between absolute ages of under- and overlying rocks.

Scientifically successful continental drilling will, therefore, require application of cutting-edge geochronology not only to obvious targets, but also to methods and materials where the risk of failure is much higher, but where success would transform our understanding of Earth’s past. Funding with a tolerance for risk should be available for proposals aimed at: development of new methods, whose validity or practicality has not been demonstrated; application of established chronological methods to new rock or mineral matrices; and pushing the younger and older limits of established techniques.

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018High-resolution dating of regional and global reference records: isotopic, paleomagnetic, and tephrostratigraphic

In many periods and archives that pose challenges for radiometric dating techniques, correlation to “master” reference curves of regional or global change in a component of the Earth system can be key to putting a proxy record in context. For example, marine oxygen isotopes in the Quaternary period record shifts between glacial and interglacial conditions, and the pattern of these shifts often appears in continental records. Similarly, strontium isotopes over much of the Phanerozoic (last ~500 Ma; Zachos et al. 2001 Science v 292 p686-693) and carbon isotopes in the Neoproterozoic (>541 Ma; Walter et al. 2000 Precambrian Res. v100 p. 371-433), although not entirely decoupled from the climate system, nonetheless provide important age information for suitable records.

Tephras, in addition to their usefulness for direct dating, can also be assembled into regional stratigraphies such as those for New Zealand (Lowe et al. 2008), the Cascades (Sarna-Wojcicki et al. 1987), and Europe (Bronk Ramsey et al., 2015) with multiple opportunities for dating in different locations. If a distinctive tephra or set of tephras can be identified chemically or mineralogically in a new record, dates associated with that tephra elsewhere provide an age for the new record without the need to date the new deposit directly. Discovery of a distinctive tephra in a drilling sequence where radiometric age control is good may also provide new chronological information that can be added to the regional tephra stratigraphy.

Perhaps the best-known example of a reference sequence is the imprint of geomagnetic field reversals on rocks containing magnetite and other magnetic minerals. Because polarity reversals are both global and decoupled from the climate system,

they provide independent age control that can be used to assess leads and lags in suitable climate records. Changes in inclination (deviation from horizontal in the vertical plain), declination (deviation from north in the horizontal plain) and intensity of the Earth’s magnetic field are known as paleosecular variation (PSV). Similar to the use of magnetic reversals for stratigraphy and dating when calibrated to the Geomagnetic Polarity Timescale, PSV is a powerful tool for correlating paleorecords. Unlike reversals that are ostensibly global, PSV changes on centennial to millennial timescales are regional, with some regions extending several thousand kilometers and others potentially much smaller; the boundaries of these regions are poorly constrained. On shorter timescales, independently dated records of the paleointensity of the magnetic field, of short-lived directional excursions (102-103 yr), and of the paleosecular variation of field direction can be used as chronological control. Because the geomagnetic field lacks a theory to predict geomagnetic change, it must be learned rather than predicted, so the geomagnetic community also benefits from development of such records.

Technology to enable magnetically oriented cores in all drilling situations

Magnetic intensity and inclination can sometimes provide chronological reference in cores that are not oriented when drilled, but in order to recover absolute declination, the geographic orientation of cores needs to be preserved when they are drilled. At low latitudes where the field is dominant horizontal, azimuthal orientation allows polarity to be unambiguously determined. At mid- and high-latitudes, PSV-based studies would also be significantly enhanced as less ambiguous patterns of declination can be reconstructed and both declination and inclination are required to make truly convincing correlations.

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018Oriented cores require [describe equipment/drilling protocols]. In situation such as [X-Y-Z], controlling the orientation of the core is relatively simple, and should be the default protocol for all drilling projects. In other cases, especially where [A-B-C occur], the [specialized tools needed/danger of losing core/blowing out, etc.] make recovering oriented core is [not possible, would require development of X tool, etc.]. The double power of PSV for giving a unique, robust three-parameter correlation between records, and fully describing the variation of the magnetic field in time and space should strongly motivate advances in oriented drilling.

Access to geochronologists

Improved access to geochronological expertise and expedited communication between geochronologists and others within the paleorecord community represent critical opportunities that are central to the goal of advancing chronological effectiveness in continental drilling. Specifically, we recommend the following strategies:

Pilot funding for initial age models. The ability to frame a potential record in the proper time period and demonstrate the potential resolution of proxy records is fundamental to the transition from a small project to a full drilling proposal. In the current landscape, this work is often done on a volunteer basis by a geochronologist with an interest in the time period or science question; in other cases projects founder at this stage because geochronology laboratories’ human and analytical resources are already oversubscribed. Establishment of a program to subsidize geochronology laboratories for pilot or bridging projects, or to supply small pots of money (on the scale of $10,000) directly to investigators, would enable the measurement of a few dates near the beginning of a project, to address specific science questions and assess the ability of a site or core to answer those questions. While the subsidizing of

specific geochronology facilities to reduce prices or support staff is valuable, small awards to researchers would provide the flexibility to choose the combination of techniques and experts most appropriate to the project at hand. The NSF-supported Earthscope AGeS program is a potential model (http://www.earthscope.org/research/geochronology).

Intellectual engagement between geochronology experts and users. The involvement of geochronology experts in the life-cycle of a project, including idea development, fieldwork, sample preparation and analysis, and data interpretation, can have a significant impact on the quality of the resulting ages. Close interactions between researchers producing chronology information and those developing proxy records can result in an environment where technical advances in the measurements help to solve previously intractable problems, and unanswered scientific questions motivate improvements in sample preparation and analysis. Strong intellectual engagement between geochronologists and the researchers using the dates was a key recommendation of the 2012 New Research Opportunities for the Earth Sciences report of the National Academy of Sciences, commissioned by NSF’s Division of Earth Sciences (NRC, 2012).

Experienced technicians to allow better flow through labs. One of the most important components of any successful user facility is a knowledgeable, engaging technical staff in charge of the day-to-day aspects of the lab. Technicians are often the people introducing students and other visitors to the equipment and procedures of the lab and answering questions; maintaining and repairing equipment to minimize costly down-time; and handling invoicing, visitor logistics, data reporting, ordering of supplies, and the

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018myriad other paperwork required to keep a lab running smoothly. In many situations, the technician is also the repository for the practical wisdom and variations of technique accumulated through experience, and can often be the one to innovate new solutions to tricky samples or unusual scientific questions. Support for full-time technicians by institutions and funding agencies has waned in recent years, a trend that must be reversed.

Education of geochronology users. The best users of dates are people who understand the details of a technique, the decisions required to apply a technique in different circumstances, and the uncertainties remaining in the final result. Various kinds of educational opportunities are important to producing good dates and building the most robust age models. These may include short courses taught at conferences, community best-practice documents and related training materials, visits to the lab to prepare one’s own samples, or field experiences that begin at a sampling site and end with data interpretation. Even one experience making the practical decisions involved in sample preparation and measurement can transform the way a researcher understands and applies a geochronology technique in the future.

Rogue’s gallery of geochronologists. Drilling projects often encounter unexpected lithologies or periods where the anticipated dating target (e.g., microfossil, tephra) is absent, and by design they capture time periods not recovered at that site before. In such situations, a resource for identifying appropriate geochronological techniques and contacting the specialist(s) equipped to apply a method to the lithology and age range encountered in a drilling project would be highly desirable. An example is the website of the Earthscope AGeS program (http://www.earthscope.org/research/geochronology), which secured funding for small geochronology

projects in the context of Earthscope’s goals, and assembled a list of labs willing to be contacted by students. Such a list could be broadened to the continental drilling community and posted at the CSDCO website.

Standardization of reporting age data and age models. Age model development is a crucial component of paleorecord research. The scientific drilling community has identified the need to standardize methods for developing age models across all time scales and different types of chronological information. We suggest that the scientific coring and drilling community devise a set of best practice standards at a geochronology workshop and the products of the workshop be published and made publicly available in accessible media, such as international databases and the CSDCO website. In particular, the standards should include requirements for treatment and reporting of chronological data (Grimm et al 2014).

Transparency of methods and publication of raw data

Synthesizing paleorecords and utilizing model data are key to understanding the patterns and processes that drive paleoclimate, environmental, and biotic changes. Current and future synthesis efforts and the integration of proxy and model data require access to raw data and age model parameters. As chronological measurement techniques and age calibrations advance, there becomes a need to update age models of existing paleorecords. Therefore, we suggest that it is necessary that the original publication state the following parameters, and that as much of this information as possible also be submitted to an appropriate database:

● Raw data on a depth scale

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● Information for relating drill/coring drive depth to section/core depth and estimated uncertainty (e.g. differences between length driven and core recovery length, gaps or overlaps between sections)

● Information for relating section/core depth to composite depth

● Reference point from which composite and section depth is reported (e.g. water surface, sediment surface, ground surface)

● The reference point for the age value (e.g. BP = before 1950 AD in radiocarbon age)

● The uncertainty in the proxy measurement● The uncertainty in the depth of each proxy

measurement● Propagation and reporting of ages and age

uncertainties

Each method of age determination is associated with uncertainty from several factors including:

● The depth range from which each age data sample was collected

● The method of age determination● Whether the dated sample material reflects

the age of the sediment horizon from which it was collected

● The age calibration curve used● Assumptions about the behavior and rate of

sedimentation between age control points● Hiatuses

These uncertainties should be propagated and included in age models. The age model techniques and model parameters should be reported in the publication such that the age model can be easily recalculated (Grimm et al, 2014).

6. Outreach, Diversity, and Education

The Science Planning Workshops in 2016-2017 did not address Outreach Diversity, and Education (i.e., Broader Impacts). A specialist workshop is planned for spring 2019, and in the meantime an ad hoc group will develop issues for discussion and expansion. These might include:

● The importance of engaging local communities early on in the process of both coring and drilling. Rationale for community-driven research

● Diversity - enabling scientists to bring their whole selves; engaging scientists at different career stages, from different types of institutions, from underserved communities in other countries.

● Eliminating harassment and microaggressions from field and lab settings.

● Normalizing asking for appropriate (i.e., larger, sufficient) amounts of money for broader impacts; bringing it out of the basement of proposals.

● Support for better broader impacts - CSDCO/Myrbo provides sounding board, development resources, training, help carrying out broader impacts activities.

● Reviewers and panelists need to take broader impacts seriously.

7. Resources

For US-led drilling projects to compete successfully for oversubscribed international funding and maintain US leadership in continental scientific drilling, we need (a) improved support for project development; (b) a dynamic 21st century tool kit for sediment core drilling/coring and analysis; and (c) optimized workflows and integrated facilities

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018operations and data management during drilling operations and in post-drilling sediment core processing. Capabilities in these broad areas will be advanced most effectively through efforts focused on the following themes identified by the paleorecords community:

Tuning of Funding Structure to Better Support Site Characterization and Process Analysis

Site characterization, both in terms of understanding process controls on sediment deposition and to evaluate a basin’s record quality, represents critical groundwork for any core-based science. Yet resources for site characterization are limited and the community has noted, in particular, that it is difficult to fund pilot investigations at specific drilling targets, which are needed to assess the record potential and optimize drilling strategies for proposed research.

To remain competitive in the 21st century, the community needs a clear intermediate pathway and funding stream to support site surveys and project development; for geophysical site surveys (e.g. seismic imaging and gravity profiling) to determine basin shape, sediment extent, depocenter location, and buried fault locations (particularly challenging for subaerially exposed sediment sequences); for pilot sediment core; and for logistical planning in advance of drilling proposals. The lack of these resources leads to project inefficiencies, increased costs, and decreased US leadership. Our international colleagues are able to access drilling-specific funds for project development. This support provides critical bridge funding for projects to evolve from programs led by small groups of PIs, with exciting preliminary data, to large teams carrying out drilling efforts supported by professionals. Existing facilities can provide support in some cases. However, for many lake drilling targets and recent projects, site surveys arguably have been inadequate, and

additional bridge funds are required to support project development efforts.

In concert with demonstrating overall basin record length and quality, understanding the inputs and transport pathways of a particular sedimentary signal to a given site is critical to interpreting the resulting data. Collecting modern data (e.g. vegetation, soil, water, suspended particulate material filtered from the water column, lake surface sediments) and identifying critical system processes, either prior to or during drilling operations, are indispensible steps in paleorecord analysis.

Archiving material and metadata for use in future calibration studies is also important, as new proxies are continually being developed and may be applied to previously collected core materials and data sets. The continental drilling funding structure should recognize the fundamental importance of such context, and strive to expedite its integration into the matrix of funded research. This could best be accomplished through a set-aside budget at NSF supporting site surveys, preliminary chronological analyses, and pilot data and process analyses, all dedicated to proof of concept for full-scale drilling projects.

Flexibility and cost-effectiveness of scientific drilling can benefit from new mechanisms to take advantage of drilling performed by oil and natural gas industries and for engineered water-supply wells. To foster science-industry partnerships, new infrastructure would be required to enable partnership formation, funding, and data handling. A forum within which industries could post potential collaborative projects to attract scientists would enable collaboration. Since commercial drilling projects may occur with little prior notice and finish quickly, a funding infrastructure for smaller grants that could be applied for and awarded quickly (such as the NSF

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018RAPID) would be optimal. Researchers could then take advantage of opportunities provided by the existing infrastructure and operations of industry, leading to savings relative to a ground-up drilling project proposal. This collaboration would also benefit industries by providing them with more information about geologic structures and processes that affect the success of their operations.

The formulation of such a forum must be sensitive to the needs of industry in order to encourage their collaboration with scientists. For example, these types of projects are rare at the moment because the oil industry tends to guard its drill site locations, especially new formations, against competitors. They are unlikely to advertise certain projects that disclose the drilling location until they finish in the area. Another issue is the proprietary ownership of data; industries would likely be more willing to collaborate if the financial responsibility of data belonged to the scientists - an issue that reiterates the need for a funding infrastructure for smaller, rapid grant submissions.

Human capital: availability, allocation, engagement

The community recognizes three interrelated human resource challenges. Addressed together, these represent an opportunity to enhance the productivity and broaden the impact of continental core sciences.

● Availability: There is a recognized need to increase the human resources pool available to support planning and implementation of drilling projects; the number of trained and experienced science staff supporting continental drilling is very small, and logistical support, core processing and curatorial functions currently operate at capacity or beyond.

● Allocation: The community recognizes the need (shared by most scientific fields) to expand access to drilling resources and projects for scientists from underrepresented groups.

● Engagement: Planning and implementation of continental scientific drilling should seek opportunities to normalize engagement and inclusion of stakeholders around target research sites, particularly where conservation implications might help locals manage resources. These opportunities are clearly present, for instance, in paleohydrological studies focused on drought and/or flood histories. Other opportunities may arise in research surrounding questions of past ecosystem dynamics, where community advocates with population and public-health interests may find particular connections to the objectives of researchers. Where appropriate, community-driven research approaches (Pandya 2014), enacted early in project planning, may allow stakeholders to help develop the research questions to be addressed.

Developing and promoting best practices

The diversity of scientific backgrounds represented within the paleorecords community can foster differing site survey, core collection and handling, and analytical practices. While the field takes strength from the spectrum of experience brought by its practitioners, in many cases methodological standardization is possible and strengthens scientific outcomes. CSDCO should further develop this role in continental scientific drilling, reviewing and revising community-developed best practice guidelines on an ongoing basis in order to incorporate the accumulating knowledge of the community and to expedite the most current core science. For example, a wide variety of analytical approaches exist for many

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018temperature proxies. Community efforts to develop best practices guidelines for sample processing, storage, measurement, and error reporting of individual proxies will improve temperature data generated and help facilitate comparison of records from different sites.

CSDCO should explore various avenues to make knowledge of best practices accessible and organized, and to encourage their adoption. These may include 1) CSDCO-sponsored workshops 2) the creation and dissemination of training videos ahead of drilling expeditions and CSDCO-hosted core processing events, and 3) the maintenance of a tutorial website focused on scientific drilling practices, drill-core processing, and broadly-applicable elements of core sampling and analysis. Even the most optimal of preferred practices will encounter contravening circumstances, and so to maximize their utility CSDCO guidelines would also 4) build and maintain a catalog of suggested modifications called for by specific material and scientific objectives. CSDCO should take all available opportunities to disseminate community-recognized best practice guidelines widely, including ensuring their ready availability to manuscript authors, editors and reviewers.

Continental core science and the regulatory environment

Globalization of paleorecords research, the ever-growing array of scientific methods in use, principles of scientific sovereignty, and heightened attention to the transport of exotic organisms all contribute to an increasingly complex regulatory and ethical environment surrounding scientific drilling and coring. Through its project support and outreach roles, CSDCO should interact with research teams (throughout proposal preparation and project implementation phases), with local and regional permitting authorities, and with local communities to

maximize information exchange regarding scientific goals, compliance with legal and regulatory frameworks, and sensitivity to cultural practices and norms. CSDCO can both 1) help researchers sensitively navigate the complex regulatory and cultural terrain of field sites, and 2) encourage local communities and officials to understand scientific practices and apply regulations appropriately. CSDCO can help provide the institutional memory needed by the Paleorecords community to make these interactions more mutually productive and efficient over time.

Meeting the expanding technical demands of scientific drilling

The development of the GLAD800 and Deep Lake Drilling System (DLDS) has stimulated the recovery of many new lake drill core records from around the world during the past 17 years. These records have sparked many critical new discoveries; however, many of these projects encountered coarse-grained sediments that ultimately limited the length of the drilled sections, or alternating soft/hard sediment types that limited core recovery. Similar challenges exist for shallow marine drilling programs. Moreover, many of these lake drilling projects reached these limitations within fairly short sedimentary sections, spanning only a couple of glacial-interglacial cycles. Many of the projects currently in the planning stage seek to recover much longer drill cores to address the societally critical goal of understanding warm climates of the past. It is thus imperative that the community develop drilling technologies to improve both depth capacity, and the efficiency and integrity of core recovery from these challenging drilling environments. Capabilities must target deep drilling in larger basins and extant lakes, with possible collaborations with near-shore marine drilling programs (e.g., IODP mission specific platform program). Capital equipment required for such projects includes drilling rigs capable of handling

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018drill string of up to 2000 m combined water and sediment depth; new technologies such as aluminum drill string and deep anhydrous drilling; dynamic positioning systems for deep water environments; and large modular barge systems.

Planning core recovery in challenging drilling environments. A CSDCO-organized workshop for scientists, drilling companies, and engineers focused on drilling technologies, similar to the highly successful workshop that led to the construction of the GLAD-800 barge, will stimulate technology development for the upcoming generation of scientific drilling projects. This workshop could define key drilling issues encountered in past projects, as well as new types of challenges anticipated in upcoming drilling priorities. This will allow specific definition of the new technologies needed to support scientific drilling targets of the coming decade.

Community access to enhanced coring capabilities. Another pressing infrastructural issue is the need for community-accessible systems for intermediate sediment depth coring (e.g., 10s of meters) in a wide range of water depths. This gap in the community tool kit manifests itself as an inability to access the long records that exist in very deep lakes without drilling, as well as difficulty in carrying out affordable pilot investigations on prospective drilling projects in deep-water settings. Capital equipment acquisitions that can efficiently serve both these needs are a high priority, and include tools like the dual-tower Uwitec percussion piston coring platform. Such a system would extend our ability to sample extant lakes ~150-200 m deep, to collect cores covering multiple glacial-interglacial cycles, and to validate lithologies, assess geochronological potential, and scrutinize available proxy materials ahead of drilling-level field expenditures.

Ancillary field infrastructure. In conjunction with the needed advances in scientific drilling and advanced coring technology, the community recognizes several priorities for the development and deployment of mid-scale ancillary infrastructure. On-site instrumentation available for whole-core scanning during projects can produce real-time information that supports critical decisions at the point and time of core collection. Similarly, to best correlate drill cores to seismic site survey data, check shot surveys (or vertical seismic profiles) are required immediately following drilling. A shared tool-kit and trained personnel dedicated to site surveys and down-hole logging can help expedite the acquisition of critical contextual data in support of full-scope drilling. There is a real need for the development of portable field laboratories designed for specialized core handling and sampling (such as aseptic sampling of the subsurface biosphere, redox-sensitive trace element sampling, and curating and sampling cores for ancient DNA). The assembly of an easily mobilized pool of coring and water sampling equipment that can be rapidly deployed to remote locations to collect time-sensitive data in the wake of (or in anticipation of) geohazard events is another recognized priority.

Advancing core and sample integrity

Just as importantly as refining scientific drilling technology, techniques promoting core and sub-sample integrity must be developed in support of new advances in analytical techniques and core science priorities. The directions of current science initiatives and recent CSDCO experience highlight needs for:

● More routine and cost-effective techniques to avoid contamination and enhance preservation of in situ microbes (aseptic core recovery), microfossils, geochemistry, and aDNA during drilling. For example, techniques and practices to best avoid

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contamination by drilling fluids under different conditions, how to effectively and efficiently sample cores for OSL dating, and how to minimize core loss during deep drilling (>1000m) are all issues with immediate priority.

● Best core quality guidelines for proposal and project planning, emphasizing multiple cores per project, and effective targeting of sequences with low thermal maturity and good continuity.

● Improved continuity of the recovered sediment record and optimization of of soft sediment collection using tools such as HPC.

● Refinement of software such as Correlator to expedite the development of continuous stratigraphic sections from multiple offset holes using geophysical data sets.

● Improved protections against potential organic contaminants during drilling, core recovery, and curation.

● Development of contamination proxies and measurement strategies to monitor the effectiveness of core integrity practices.

● Approaches for recovering biologically and geochemically pristine cores from permafrost.

● Best planning practices for collecting oriented cores for paleomagnetic analysis.

● More effective tests for diagenesis, and techniques to quantify its effects on sedimentary records. Drill core may provide new opportunities for estimating diagenesis and distinguishing surface alteration (weathering) from subsurface alteration processes . Can we measure diagenesis in real-time and develop models accounting for differences between ecosystem types?

● Geochemical tools for the most effective correlation between unweathered cores and (weathered) outcrop equivalents.

Optimizing the analytical toolkit

CSDCO has taken a leadership role in making non-destructive front-end core analysis tools accessible to the continental coring and drilling community. Expansion of this community capacity into at least two new areas is actively sought by researchers. CSDCO also has a role in expediting timely access to analytical capabilities available through other institutions, by providing a focused information portal for the scientific drilling community.

CT scanning. Computed tomography (CT) scanning of intact cores provides nondestructive 3D density information, with the resolution to discriminate between sediment and fossils and sub-fossil materials (including plant macrofossils useful for radiocarbon dating), This technology also supports mapping of dropstones and ice-rafted debris, patterns of sediment deformation, and sedimentary structures of all types. Expanding the capability for community CT-scanning of whole sediment cores at core repositories will greatly enhance post-drilling core processing efficiency, as it will allow us to rapidly identify lithologically distinctive zones of cores prior to splitting, and to identify important unexploited opportunities in curated cores. Such a tool will be of substantial value to other emphasis areas (such as paleobiology, where the capability to prospect for fossiliferous intervals may be expedited by CT) as well.

Hyperspectral reflectance scanning. Surface reflectance/absorbance of light across discrete bands in UV, visible and near-IR wavelengths can yield rapidly-obtained maps of surface composition, including sediment mineralogy and organic constituents including pigments. Rapid, nondestructive elemental analysis through scanning XRF has proven transformative for elemental analysis of cores; hyperspectral imaging has the potential to provide similar advances in other areas of

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018compositional analysis. Recognizing the interest of the continental drilling and coring community, CSDCO is actively pursuing options for incorporating both CT and hyperspectral scanning into ICD and special-studies workflows, meanwhile maintaining links to other labs able to provide these analyses now for paleorecord community members who need them.

Micro-analytical chemistry. Enhanced access to geochemical tools such as Raman microspectroscopy and fluid inclusion geochemistry can improve understanding of water-rock interactions, sedimentary organic matter evolution, and the (paleo) chemistry of saline waters. These tools have broad temporal usefulness, and will improve our understanding of hydroclimatic conditions in deep geological time as well as in the more recent past and in modern systems. These and other techniques such as electron microprobe analysis (see below) rely on instrumentation and expertise that, while widespread, is not always easy for the paleorecord community to access. CSDCO should develop the web tools and research community contacts necessary to serve as a nexus for access to scientists using these techniques, both on collaborative and service bases.

Cryptotephra identification. Cryptotephras represent widespread (but difficult to recognize) correlative time horizons, frequently of known absolute date. It follows that their more routine recognition and identification can be a high-yield strategy for synthesizing regionally and globally distributed paleorecords. Compositional analyses by well-known methods such as electron microprobe analysis are maintained in numerous tephra databases around the world. The most evident barrier to wider exploitation of cryptotephra chronologies is the time-consuming challenge of identifying dilute volcanigenic material and recovering it from cores. There is a clear benefit to be gained through

developing more sensitive methods of identifying dilute tephra occurrences in cores, and automated techniques of extracting dilute distal glass from mixed-sediment matrices.

Detecting exogenous materials. Desertification and increased human land-use are exacerbating soil erosion and atmospheric entrainment of dusts around the world (Mahowald 2010). These changes have led to increased exogenous material accumulation in lake sediments (Neff 2008, Marx 2011, Mulitza 2010). Because national scale monitoring networks rarely monitor particles larger than 10um, the amount of material that moves through the atmosphere represents a large and relatively unknown biogeochemical disturbance (Brahney 2015), particularly in the continental USA where dust emissions continue to rise (Brahney 2013, Clow 2016, Hand 2016). A targeted sampling strategy can shed light on the spatial and temporal changes in dust deposition in recent history, however several challenges in both identifying exogenous dusts and their source region remain.

Integration and field validation of X-ray techniques. Scanning-X-Ray fluorescence (XRF) has potential to provide information about nutrient cycling, weathering proxies, and source material, but more protocols need to be developed about dwell time, target elements, and sample resolution to generate the most useful data to answer these questions (Croudace and Rothwell 2015). Scanning XRF has been used to assess changes in sediment sources between glacial and interglacial periods in recent drilling projects such as at sites with very long records such as Les Échets in France [Kylander et al. 2011], Lake Van in Turkey [Kwiecen et al. ], and Lake El'gygytgyn in Siberia [Wennrich et al. 2014]. Process models for interpreting ratios and methods for converting counts to concentrations need to be further developed and validated. Additionally,

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018samples of the source materials at drill sites, both lithological and biological, need to be routinely collected and analyzed for elemental concentrations. X-Ray diffraction (XRD) and recently scanning XRD provides an excellent tool to identify mineral composition that can help assess sedimentary source material. In combination, these techniques will be essential for studying weathering rates and mineral transformations.

Developing & improving temperature calibrations. Owing to the large diversity in the physical and chemical properties of lakes, and thus the likelihood for differing biological and microbial communities between sites, the global calibration approach that is common for marine temperature proxies may not be applicable for some types of reconstructions applied to lacustrine systems. Improved calibrations for use in lacustrine environments should entail comparing multiple proxies at the same site, characterizing potential biases for individual sediment components as well as how such biases may vary spatially, determining the sensitivity of individual temperature indicators, and exploring whether global, regional, or site specific calibrations are appropriate. Different statistical approaches to temperature calibration should be explored and evaluated for individual proxies. Laboratory-based studies are also important for development of temperature relationships to sediment indicators. Increased funding for these types of framework studies is needed, which are often field intensive or laborious but have far reaching outcomes for the scientific community. For many of the commonly used temperature proxies, shared reference materials measured and reported by individual laboratories are lacking. Having such standards is important as workup protocols and instruments vary widely between laboratories. Greater support for community development of reference materials as well as for well-designed inter-laboratory comparison studies is needed.

Full incorporation of diagenetic processes into paleoenvironmental interpretation. Immediately upon burial sediments undergo biological and chemical changes that affect proxies routinely measured to infer ecosystem and environmental change. Particularly troublesome is the focus of diagenetic effects in near surface sediments, which represent a period of time through which paleolimnologists seek to understand recent anthropogenic effects on the environment. To illustrate, up to 95% of the organic matter can be lost through bacterial respiration during sedimentation and post-burial (Meyers and Ishiwatari 1993). This can lead to significant uncertainty in interpreting ecosystem response such as changes in primary production and carbon sequestration rates. Of equal importance is that diagenesis can impart small and systematic changes through sediment cores over long periods of time, which can amount to a change viewed as ecological

relevant. For example, a change of 2‰ of d15N through the late Holocene represents a change of just

0.0004‰ per year. A recent study found that diagenetic overprinting can account for up to 70% of the isotopic effects in nitrogen and can cause

excursions of more than 2‰ that are preserved within the sediment record (Brahney et al 2014). In addition to changes in the concentration and composition of the organic fraction, other geochemical properties of lakes sediment can change over time due to redox-controlled cycling in the surface sediments. These processes can lead to upcore increases in elements of interest including phosphorus and many heavy metals emitted by human activities. Because these effects compromise our capacity to interpret and respond to environmental change, a coordinated effort from the community is needed to both recognize the processes and resolve issues of interpretation that arise.

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018Genomics and other advanced biological methods

Human-climate interactions in the paleorecord. Existing proxies of human occupation and land use are primarily restricted to biological evidence of cultigens (e.g. maize pollen and phytoliths), invasive weeds (e.g. Ambrosia rise), and vegetation disturbance (increased charcoal influx; charcoal typing; increased erosion). Such proxies are flawed as cultigen pollen and phytoliths are not widely dispersed and changes in vegetation and fire occurrence can result from natural environmental processes. The development of proxies specific to human presence and activity will allow for more direct hypothesis testing related to human impacts and responses in lacustrine basins. Proxies such as fecal sterols, (coprophilous) fungal spores, or ancient DNA could provide unequivocal evidence of human occupation even in low population densities. Should ancient human DNA (aDNA), or aDNA from other non-human taxa be recovered from lake cores from tropical settings such as Africa, this would be a fundamental advance, shifting the current research emphasis away from higher latitudes, where aDNA is better preserved. For human evolution, we would be able to learn something about the deep history of our lineage, rather than only something about extinct Eurasian lineages (e.g., Neanderthals and Denisovans) that made at best modest contributions to extant human populations. The development of these proxies, and broader aDNA surveys, should thus be targets for research.

Ancient DNA and phylogenetic studies. Ancient DNA (aDNA) methods need to be developed and standardized for major taxonomic groups. This technique would allow population and community dynamics to be resolved with unprecedented taxonomic resolution. This is a huge potential area for development, with unique opportunities to access past biological communities from the drilling projects. European labs are leading the way with

sterile coring techniques and techniques such as plasmid balloons that enable quantitative reconstructions [see Willerslev, Taberlet]. Permafrost and high-latitude systems have the best potential for preservation of aDNA but other possibilities are being developed. Independent assessments of the evolutionary history of taxonomic groups, particularly those with molecular clocks, could potentially be compared or constrained with core records and vice versa. The emerging field of geogenomics (Baker et al 2014) and collaborations with molecular biologists are underway. Further, molecular geneticists could conduct phylogenetic studies directly from aDNA samples from drill cores. These collaborations should be initiated early in project planning. For an example of how these linkages can be made, see Cohen and Salzburger 2017 Scientific Drilling in press workshop report.

Data quality assurance

Data quality assurance, methodological transparency and reporting consistency are critical to all analytical fields. These are a particular challenge to a group as multifaceted as the paleorecords community, within which practitioners employ many different analytical techniques, some emerging and others more mature, directed toward shared interpretations. Some of the contributing fields (e.g., stable isotope analysis; elemental analysis by ICP-MS) have well-established and broadly available reference materials, and internationally recognized processes for conducting inter-laboratory comparisons and proficiency tests. Other, more recently emerging, fields (e.g., recently developed temperature proxies; aDNA; hyperspectral scanning) are still in the process of developing equivalent mechanisms and reference materials. Financial and logistical support should be made available for developing accepted reference standards and strengthening the institutions for interlaboratory comparison and proficiency across additional areas of analytical paleorecord analysis

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018where these are not yet fully developed. Data on reference material properties and reproducibility must be published and added to repositories as a matter of routine best practices.

There is a related need for fuller characterization and reporting of uncertainty in new data, both in analytical space and in sample depth and related spatial characteristics. How best to characterize uncertainty in curated data used in new analyses and publications is an important element of this need.

Data quality assurance can also be enhanced through ‘strategic multiproxy’ planning of analytical priorities, where the strengths of different data sets are leveraged in ways to explicitly cross-check signal integrity over time. Funding organizations should support such strategic project design.

Software development and enhancement

The scientific drilling community recognizes the value of digital tools (software, apps) that assist with consistency of terminology and metadata collection used during field sampling. Emerging tools such as Strabo (NSF funded and developed at UW Madison and the University of Kansas as a data collection and data sharing tool for tectonics and structural geology) can serve as models for applications tuned to drilling, coring and ancillary field data collection.

PSICAT is under active development at LacCore/CSDCO and is used by most groups using the Facility for sediment description and development of stratigraphic columns. Current development priorities include incorporating a more flexible structure for core description into PSICAT, expanding and refining lithologic libraries, and refining stratigraphic column output. Likewise the core visualization tool Corelyzer is an integrated component of CSDCO workflows, facilitating

description, sampling and data sharing within and between user groups. Greater integration of visualization and core description functions of these tools is a recognized CSDCO/LacCore cyberinfrastructure priority, for which funding should be made available.

Staffing limits the pace at which competing CSDCO software development priorities can be accomplished; bringing additional programming resources to bear would increase the rate and scope of cyberinfrastructure development.

Databases and tools for data discovery, integration, and application

There is a great need for systems to store and manage ever increasing volumes of scientific data. When combined with software tools, these databases can provide powerful ways to locate and examine information, reveal fundamental patterns and relationships, and test models. Databases support archival functions expected of research data management plans. Databases can also store more than just field, laboratory, and analytical data: they can be used e.g. to track samples, researchers, and methods.

Existing database systems have limitations which, if remedied, could enhance the paleorecord community's ability to address the research questions outlined above. Currently, some types of data and metadata do not have a place in a readily accessible system, nor are linkages between data types and interoperability between different database systems sufficiently established. An ideal system would link, for example, geochemistry to researchers, publications, laboratories, methods, and samples. The samples, in turn, would be linked to cores and repositories. Many other connections are also possible. With such linkages and system

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018interoperability, a database search on, for example, tephra geochemistry could enable discovery of a related sample, the lab that did the analyses, the core that the sample came from, photos of the core, and perhaps even submission of a request to the relevant core repository to examine the core in person even if the related information is spread across multiple systems. With system interoperability, each individual database could continue to be operated by a particular agency for a particular purpose, but could then serve broader uses through its links to other databases. This way, a database built primarily to store e.g. lake core data could serve multiple other disciplines as well, in this example both tephra and pollen.

Key steps of achieving this vision include consistent use of persistent identifiers like International GeoSample Numbers (IGSNs) and DOIs, complete documentation (metadata), and Application Programming Interfaces (APIs) for interoperability. IGSNs registering sample provenance should be assigned and registered as early in the coring sample process as possible even if not used as the primary identifier. When data are published, the IGSN number of all samples should be cited. Digital Object Identifiers (DOIs) should be assigned to every data set and publication generated by a coring activity. APIs supply the interface for simultaneously searching multiple databases, defining methods and terminology to query multiple databases and receive information back. Simply stated, the criteria for successful achievement of this integration would be: Can someone from a different discipline find my data, access it, and use it with full knowledge of all the relevant metadata?

Databases must also accommodate both new and legacy data, and support (funding and human resources) is needed to move legacy data into more secure and accessible management systems. Data

collected decades ago may retain great value by current standards, but many data sets are at risk of losing value due to inaccessible or insufficiently documented storage, or through retirement of scientists who leave behind samples and unpublished data. Replacing legacy data can be expensive, and may be impossible, as in the case of now-inaccessible field sites or lost, consumed or degraded cores. Data at risk is an underappreciated crisis, which has not received the funding attention it calls for.

A key consideration is planning for curation and data organization from the beginning of projects - using formalized mechanisms such as the ICDP sample registration system and avoiding ad hoc sample tracking systems - in order to prevent the need for later modifications to the current generation of data. Maintenance and updating of databases should be a core funding commitment, as it is key to the integration of interinstitutional resources (statewide databases, state museum collections, federal databases) with cross-disciplinary perspectives (geologic, genetic, paleobiology, paleoclimate data streams) over different spatial and temporal scales.

Over the course of drilling proposal development and project execution, communication tools to efficiently link researchers with complementary expertise and interests can lead to more fully integrated implementation and increase the scientific yield from project support.

At the proposal stage, CSDCO can amplify the impact of drilling projects with supporting effort facilitating connections between PIs and other researchers with the interest and capability to address questions or materials that may be addressed by the field site but are outside the PI’s primary areas of endeavor. PIs should be encouraged to consider how such ancillary efforts can be efficiently accommodated by proposed work. At the stage of active project implementation,

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018communication tools are needed to optimize adjustments in core recovery, sampling, and analysis required when unexpected drilling conditions or materials are encountered. Options to be explored for CSDCO to accomplish this include establishing a community listserv, maintaining a resource pool or ‘rogues gallery’ of people with known expertise, and/or adapting networks of communication used by other communities (Facebook page, My Fossil, EarthCube, various listservs, ESWN, VIVO, etc.). Communications arising from the larger community could range from short pieces of advice, to establishment of new consensus best practices, to formalized research collaborations arising out of the activation of a problem-solving network of researchers.

Depth models and age-depth models

Stratigraphic depth is a fundamental reference for all samples and data obtained from cores, and underlies the development of chronologies. If multiple proxies in a core are to be compared effectively, they must all share the same depth scale at both the core segment and whole core level. Development of whole core depth models requires a clearly-defined, shared point of reference for all core segments. In lake coring, this may be the water surface or the sediment water interface, both of which can change and complicate the comparison of cores taken at different times from the same lake. Alternatively, a prominent horizon within the sedimentary sequence could be used as a datum if it is easily recognized and widely present.

Depth uncertainties propagate into correlation uncertainties, from there into age model uncertainties, and ultimately into data interpretation and the scientific conclusions drawn. Therefore, it is essential to minimize depth uncertainties. Among the approaches used to reduce this uncertainty are offset parallel cores (used almost universally) and downhole geophysical logging (used in some but not

all drilling projects). For a relatively modest cost, down hole logging can provide a continuous, depth referenced stratigraphy to which individual core segments can be linked. It is especially valuable in the common case of incomplete core recovery where down hole logs can substantially reduce or eliminate depth uncertainty and eliminate the problem of “floating” core segments. Improving access to logging equipment through development of a community pool and/or through CSDCO-expedited institutional links should make routine down-hole logging of all major drilling projects a near-term goal. In conjunction with the considerations discussed above (5. The Central Role of Geochronology), these steps can lead to more robust age modeling and consequent strengthening of paleorecord interpretations.

Modeling: spatial, process, and calibration

Modeling of 1) the spatial distribution of planetary phenomena, of 2) complex depositional system behavior, and of 3) correlation between forcings and proxy indicators each contribute in distinctly important ways to paleorecord interpretation and reconstruction of earth system history. Modeling analyses help direct geological investigations toward critical questions in earth system behavior, and paleorecords in turn produce the observations by which model behavior is tested and validated. The relative success of this symbiosis is a key element in earth system analysis at all scales.

Leveraging a spatial network of hydroclimatic reconstructions to understand the fundamental processes that govern the water cycle requires continued support and improvement in data management, and new tools for data analysis and modeling. Climate models have dramatically improved in terms of their spatial resolution and the diversity of processes they simulate (e.g, Earth System Models). However, it is still challenging to

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018conduct apples-to-apples comparisons and tests of geological data and model simulations. Data from sediment cores and other paleoclimate archives are typically interpreted in a qualitative manner (wetter/drier) rather than being used to offer quantitative constraints on past precipitation amounts. As a result, it is difficult to assess data-model agreement. Parallel efforts need to be made within the data and model communities to improve data-model comparisons. On the data side, efforts need to be made to calibrate proxies to offer quantitative estimates of past hydrologic changes with uncertainty estimates. One promising path forward is the development of sediment core records from basins in which paleo-shoreline deposits preserve records of past lake level variations. As lake level can often be quantitatively linked to past changes in precipitation and evaporation through hydrologic modeling, sediment core data from times of known lake extents can be used to calibrate sediment proxies to offer higher-resolution records than strictly shoreline-based reconstructions allow.

Process models are emerging that offer frameworks for simulating a geochemical response to a modeled climate change, acting as a translator from model output to proxy signal. Continued improvements in system models are needed to better link models to data, and to test model predictions and hindcasts of precipitation and hydrology. Testing the predictions of transient climate models against data and improving model predictions remains challenging, requiring improved statistical and data analytical methods (e.g. paleoclimate reanalysis). Stable isotopic reconstructions (e.g. hydrogen and oxygen isotope methods) provide similar opportunities. Interpreting the isotopic composition of paleowaters from solid phases has rapidly expanded to encompass a variety of materials, from organic matter to glasses, at the same time that isotope-enabled climate models have also become widely

available. There are needs for better biophysical modeling on scales from organism-level through the Earth system as a whole, in order to enable us to understand the responses we are seeing in the geological record. For example, does anyone know how individual tree species would respond to a high O2 atmosphere? Continental drill-core records have important contributions to make to the next generation of Earth System Models, particularly in calibrating new weathering and nutrient cycling functions that are being developed.

8. Prioritization of drilling targets

Groups engaged at the 2016-2017 Science Planning Workshops preferred not to rate or rank specific sites proposed before or during the workshops. They did, however, discuss and propose numerous criteria that should be considered in future prioritization of sites. General principles related to the scope and efficiency of paleoenvironmental research achievable at any given site can help guide the selection and prioritization of drilling targets. These principles include:

● Long-term records in basins or lakes with high sedimentation rates carry enhanced value through continuity and high temporal resolution.

● Drill sites that can address multiple research questions simultaneously stand to amplify the value of science outcomes; lithological diversity of target stratigraphic sections can enhance these opportunities by increasing the array of techniques applicable to a given record.

● Preservation of materials suitable for the reconstruction of temperature (annual and/or seasonal) over key times of transition in climate make for crucial target archives, and opportunities to reconstruct paired (or

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nearly paired) estimates of temperature and atmospheric CO2 concentration are of particular interest as a critical model validation tool.

● The potential for developing reliable chronological constraints is an overarching consideration in evaluating project potential.

● Where possible, robust spatial correlations between continental and marine stratigraphic records should be developed.

● Spatially distributed networks of sites covering latitude and longitude at various scales are of great importance in testing and validation of climate models and ecosystem response trajectories.

● Scaling of depositional systems and sensitivities is a concept to exploit; long records from large basins provide regional climate backdrop, while the embedded sub-basins may provide clearer evidence of specific processes.

● For human impacts and hazards, research site value may be enhanced by (a) dense human populations today, (b) tectonically active zones that are susceptible to multiple interacting natural hazards, or (c) well-characterized human records with sharp changes in occupation history or human ecology.

● Drilling targets that maximize the range of time-scales of variability within a single record (event-based, supra-orbital, deep time) are critical for testing the impacts of climate forcings.

● Records linked to systems well-calibrated in modern settings through observation or process-based models represent high-value targets.

● Time periods of warmth such as the Pliocene and older “hothouse” climate periods, and super interglacials (e.g., MIS 11 [424-374 ka],

MIS 31 [1,081-1,062 ka]),represent high priorities in improving understanding of the water cycle.

● Time periods in which the climate boundary conditions are well-known (e.g. the last 1 Ma), provide important opportunities for climate model testing.

CAPTION, Fig **. Global distribution and targeted time windows for continental scientific core recovery proposals advocated through the 2016-2017 Paleorecords Community Science Planning process.

In 2018-2019 CSDCO will sponsor a workshop with the purpose of asking the paleorecords community to prioritize the specific continental drilling proposals presented through abstracts and project proposals submitted during the 2016-17 Paleo Community Science Plan. The exact mechanisms for developing consensus priorities remain to be established; however, CSDCO anticipates that the criteria for ranking will flow from the fundamental science concepts and research optimization strategies articulated in the Plan.

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References that need to be added:

Carpenter; please specify this paper

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US Continental Scientific Drilling Science Plan 2018-2028DRAFT April 2018Diessel, 2010 Please specify this paper

Jeffers et al. 2016; can’t find this - is it the 2015 paper that was intended?

Flessa refs PLease specify citation

Francis et al, 2014, PLease specifiy this citation.

Smith 2011. PLease specifiy this citation.

Williams et al 2014(?) PLease specify this citation

Scraps from end of geochron section:

Geosciences Papers of the Future: http://onlinelibrary.wiley.com/doi/10.1002/2015EA000136/full

Nature Methods: Points of Significance & Error Bars: http://www.nature.com/nmeth/journal/v10/n10/full/nmeth.2659.html

10Be:26Al (see Shen, G., Gao, X., Gao, B. & Granger, D. E. Nature 458, 198-200 (2009).)

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