Tim KilleenDirector, National Center for Atmospheric Research

President, American Geophysical Union

AGI Geoscience Leadership Forum 30 April 2007

Communicating Climate Change Science

(Intergovernmental Panel on Climate Change)

• National Science Foundation funded Center, >1,000 Scientists and engineers, 48 year history

• Earth System Sciences: Computational and Observational Science and facilities for Weather, Climate, Chemistry, Space Weather, Society-Environment Interactions

National Center for Atmospheric Research

American Geophysical Union• World’s largest Geophysics Society (>49,900

members, 20% students, 130 countries)• Interdisciplinary science for the atmospheric and

ocean sciences; solid-Earth sciences; hydrologic sciences; and space science

AGU Mission AGU Council, 2005

EOS, Vol. 86, No. 23, 219, 2005

• AGU is a worldwide scientific community that advances, through unselfish cooperation in research, the understanding of Earth and space for the benefit of humanity.

• AGU is advancing the Earth and space sciences by catalyzing and supporting the efforts of individual scientists within and outside the membership. We are organizing and disseminating information for the scientific community. As a learned society we meet our obligation to serve the public good by fostering quality in the Earth and space sciences and bringing the results of research to the public. These efforts are yielding greater numbers and diversity of well-educated students and young professionals in the Earth and space sciences, and are increasing the public's understanding and appreciation of the value of science and support for it.

The Two CulturesWhat scientists say:• 90% of scientists think few members of the press

understand the nature of science and technology• 66% said most press members have no idea how to

interpret scientific results• 69% said most reporters have no understanding of

scientific method• More than 50% have had a bad experience

What journalists say:• 85% of reporters think scientists are somewhat or not at all

accessible • 62% think scientists are so intellectual or immersed in their

jargon that they cannot communicate

Results from survey, used in NCAR media training, 2007

NCAR ScientistsInvolved in IPCCWorking Group I

AGU’s Climate Statements

1998 (reaffirmed in 2002)

AGU believes that the present level of scientific uncertainty does not justify inaction in the mitigation

of human-induced climate change and/or the adaptation to it.

2003:The global climate is changing and human activities

are contributing to that change.

2007:

Planned

The Challenge of Simulating the Global Earth System

Atmosphere Hydrosphere Cryosphere Biosphere

The Earth System

From Andi Andreae

CCSM Working GroupsPolar

ClimateOcean Model

Land Model

Model-centric

Atmosphere Model

Software Engineering

Climate Variability

Biogeochemistry

PaleoClimate

Crosscutting

Climate Change

Need for High Resolution

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Science Driven Demand for Supercomputing

Modern Climate Model Simulations

NCAR’s Bluesky Supercomputer:• 1600 Processors• Peak speed: 8.3 Teraflops

Characteristics of NCAR Model:

• ~1 quadrillion operations/simulated year

• UN IPCC ~10,800 years simulated

• Rate of simulation: 3.5 sim. years/day

• Output: 10 GB/simulated year

• Data volume for IPCC: ~110 TB (~200,000 Data CDs)

• Development effort: ~1 person-century

Community Climate System Model and the IPCC

Intergovernmental Panel on Climate Change (IPCC)

Fourth Assessment Report

NCAR Community Climate System Model (CCSM-3).

Open Source

8-member ensembles

11,000 model years simulated

“T85” - high resolution

IPCC 2007 Summary for Policymakers:

Higher confidence in projected patterns of warming and regional-scale features, continuing currently observed trends:

– warming greatest over land and at most high northern latitudes (least over Southern Ocean and parts of NA ocean)

– snow cover will contract– widespread increases in thaw depth over most permafrost regions– sea ice will shrink in both Arctic and Antarctic, in some projections late

summer sea ice disappears in the Arctic by latter part of 21st century– very likely that hot extremes, heat waves, and heavy precipitation

events will continue to become more frequent– likely that typhoons and hurricanes will become more intense – extra-tropical storm tracks will move poleward– precipitation at high latitude very likely to increase, while decreases are

likely in most subtropical land regions– Very likely that meridional overturning circulation of the Atlantic Ocean

will slow down during the 21st century. Average reduction by 2100 is 25% (0-50%). Very abrupt transition is very unlikely in 21st century.

Anthropogenic warming and sea level rise will continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were stabilized

Higher confidence in projected patterns of warming and regional-scale features, continuing currently observed trends:

– warming greatest over land and at most high northern latitudes (least over Southern Ocean and parts of NA ocean)

– snow cover will contract– widespread increases in thaw depth over most permafrost regions– sea ice will shrink in both Arctic and Antarctic, in some projections late

summer sea ice disappears in the Arctic by latter part of 21st century– very likely that hot extremes, heat waves, and heavy precipitation

events will continue to become more frequent– likely that typhoons and hurricanes will become more intense – extra-tropical storm tracks will move poleward– precipitation at high latitude very likely to increase, while decreases are

likely in most subtropical land regions– Very likely that meridional overturning circulation of the Atlantic Ocean

will slow down during the 21st century. Average reduction by 2100 is 25% (0-50%). Very abrupt transition is very unlikely in 21st century.

Anthropogenic warming and sea level rise will continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were stabilized

So, how best to communicate?(some results)

Tony Blair

“What is now plain is that the emission of greenhouse gases…is causing global warming at a rate that began as significant,

and is simply unsustainable in the long-term. And by long-term I do not mean centuries ahead, I mean within the lifetime of my

children certainly; and possibly within my own. And by unsustainable I do not mean a phenomenon causing problems of adjustment. I mean a challenge so far-reaching in its impact and irreversible in its destructive power, that it alters radically

human existence.”

A lifetime of climate change…

NASA

Global mean temperatures are rising faster with time

150 0.0450.012100 0.0740.018

50 0.1280.026 25 0.1770.052

Warmest 12 years:1998,2005,2003,2002,2004,200

6, 2001,1997,1995,1999,1990,200

0

Period Rate

Years /decade

Time Scales in the Climate System

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 1 2 3 4 5 6 7GLOBAL-MEAN TEMPERATURE CHANGE FROM 1990 ( oC)

PROBABILITY DENSITY ((

oC)

-1)

PROBABILISTIC PROJECTIONS OF GLOBAL WARMING

TAR RANGE

1990-2030

1990-2070

1990-2100

Probabilistic Outcomes

Wigley

Ann avg 1980-1999

ice thickness

IPCC AR4

Dash=March extent

White=Obs Extent

Simulated late 20th century ice conditions

Abrupt Ice Retreat Could Produce Ice-Free Arctic Summers by 2040

• Recent retreat of Arctic sea ice is likely to accelerate so rapidly that Arctic Ocean devoid of ice during summertime as early as 2040

• Study by Marika Holland and teams from University of Washington, and McGill University

• Several reasons for the abrupt Ice loss in a gradually warming world.

• “Positive Feedback” • As the ice retreats, the ocean

transports more heat to the Arctic and the open water absorbs more sunlight, further accelerating the rate of warming and leading to the loss of more ice

Ice Retreat Animation

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Projections of Degradation of Near-Surface Permafrost

Lawrence and Slater, 2005

Future changes in frost days from the climate model show greatest decreases in the western and southwestern U.S., similar

to late 20th century

Changes in snowpacks/ timing of runoff have occurred & will continue

Large circles indicate sites with trends that differ significantly from zero at a 90% confidence level;

(Courtesy of Michael Dettinger USGS, based on Stewart et al. 2005.)

Observed streamflow timing changes (Center of mass)

Observed: 1948-2002

Trends are projected to continue through the 21st Century…

with increased winter flood risks & lower summer low-flows in many rivers.

Ozo

ne (

Dob

son

Uni

ts)

NCC

A1B

1980 2030 2050

Global Average Total Ozone Column

Ozone Recovery in the 21st Century

National Security and the Threat of Climate Change

CNA Corporation, 2007:• National security consequences of climate change should be

fully integrated into national security and national defense strategies

• US should commit to a stronger national and international role to help stabilize climate changes at levels that will avoid significant disruption to global security and stability

• U.S. should commit to global partnerships that help less developed nations build the capacity and resiliency to better manage climate impacts

• DoD should enhance its operational capability… through energy efficiency

• DoD should conduct an assessment of the impact on U.S. military installations world-wide of rising sea levels, extreme weather events, and other possible climate change impacts over the next 30 to 40 years.

National Security and the Threat of Climate Change

CNA Corporation, 2007:• “There is no known natural forcing that can account for the

severity of the recent warming. For example, while claims are made that the variation in the intensity of the Sun is responsible, the solar radiation’s effect on the climate is estimated to be less than 5% as strong as that of human-induced greenhouse gases.”

• Precipitation patterns have changed• Extreme weather events are more frequent and Ice and snow

cover is disappearing• Oceans are warming• Sea levels are rising• Ocean salinity has changed

1985 1990 1995 20000

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LegendPsychologyEngineeringBiolog SciComp SciMathChemistryGeosciPhysics

Total number of bachelor's degreesgranted by discipline, 1985 to 2000

YEAR

Lessons LearnedLarge efforts to develop comprehensive scientific viewpoints can be extremely significant in influencing public debate

The key question “what do we do about climate change?” is much less well addressed than the scientific case for climate change itself.

Issues of timescales, rates, “greenhouse effect”, and uncertainty all need careful treatment.

The propensity of the media to describe arguments continues to lead to public confusion.

Responsibly informing societal decision makers with the best available science is tough for individuals trained as scientists.

Bottom line: “The IPCC Fourth Assessment Report is currently the most comprehensive assessment of the scientific literature on climate change, and effectively and accurately communicates to policymakers and the public the state of human knowledge on this topic.”