Biomolecules tell us about how climate changed in the past... and how it might change in the future

Rich Pancost, The School of Chemistry

Outline

• A bit about global warming…

• What can the past tell us– First, how I study the past

• Biological compounds are diverse and some compounds – particularly lipids – can be robust tracers of environmental processes

• Analytical chemistry (i.e. CSI science) underpins this research

– Studying a global warming event in the past

Global Warming

How should we talk about climate change?

• What do we know?

• What do we probably know?

• What do we think?

• What do we have no idea about?

How do we study climate change?

• We try to measure changes

How do we study climate change?

• We try to measure changes

• We make computer models of climate

How do we study climate change?

• We try to measure changes

• We make computer models of climate

• We study the past

What do we KNOW?That Carbon Dioxide and Methane Concentrations in the Atmosphere are Increasing

Data from Scripps CO2 Program.

What do we KNOW?

Directmeasurement

INDUSTRIAL REVOLUTION

• CO2 concentrations are higher than they have been for 1000 yrs

But how do we know what CO2 was before we could measure it?

What do we KNOW?• CO2 concentrations are higher than they have been for 650 kyr

What do we KNOW?• CO2 concentrations are higher than they have been for 20

MILLION years

Pagani et al., 2005 Alkenone-derived pCO2 record

13C versus 12C 8 million 40 million

Summary

That carbon dioxide and methane concentrations are higher than then at any time in the past 1 million years

We think that they are higher than at any time in the past 30 million years (alkenone pCO2 proxy; Pagani et al., 2005)

We think that they are not at all close to the highest levels in Earth history

We think that they are changing faster than at any time in Earth history

What do we KNOW

• CO2 concentrations are increasing due to fossil fuel burning

• CH4 concentrations are probably increasing because of– Increased rice cultivation and ruminant animal agriculture – Natural gas pipeline leakage– Offset by wetland destruction– But also thawing of permafrost?– Increased production due to warmer/wetter climate?

• Other greenhouse gas concentrations are also increasing– N2O– CFCs

What do we KNOW? That higher CO2 will cause ocean pH to decrease

CaCO3(s)

H2CO3 + CO32- 2HCO3

-

+Ca2+

CO2(aq)

H2O+

Calcium Carbonate Dissolves

What do we THINK? That lower pH will adversely affect sealife

What do we KNOW? That higher CO2 will cause temperature to increase.

What do we KNOW?• That elevated carbon dioxide WILL cause warming.

• We are fairly certain that it has already caused warming– 0.6°C temperature increase over the past century

– 3 hottest years on record are post-1998

– 19 of 20 occurred since 1980

Compiled by the Climatic Research Unit of the University of East Anglia and the Hadley Centre of the UK Meteorological Office

What do we KNOW?• That elevated carbon dioxide WILL cause warming.

• We are fairly certain that it has already caused warming

What do we THINK?That elevated greenhouse gases WILL cause warming

of about 4C

What do we KNOW?That elevated greenhouse gases WILL cause warming

That warming will cause

– Sea level rise

– Melting of glaciers

– Increased aridity in some places and wetter conditions in others

– Increased likelihood of extreme weather events

– Warming will stress certain biomes

What do we THINK?• That warming will cause sea level rise from thermal

expansion of the ocean and probably from melting of glaciers

What do we KNOW?• Warming will make some places drier and some

places wetter

What do we KNOW?• There will be more hurricanes

So what is the debate all about?

• How much will CO2 and CH4 levels increase?– What are the sinks (the ocean, trees, soil)?

• How much will temperature increase?– What are the feedbacks?

• How much will sea level rise?– How do ice sheets respond to climate?

• REGIONAL AND LOCAL EFFECTS– Will some countries be flooded or suffer drought?– How will that affect political stability in some regions?– Or biodiversity?– How will that affect global economics

What can we learn from the past?

Based on the Permo-Triassic mass extinction event270 Million years ago

Has catastrophic (rapid) methane release occurred in the past?

What was its impact?

What do I do to study it??

Lipid structural variability

OH

O

CCC

CC

C

H H H HH H

HH H H H H

C

HH

H

Lipid structural variability

Green sulfur bacteria

Cyanobacteria

Nitrospira

Gram positive bacteria

Green non-sulfurbacteria

MethanopyrusMethanococcus

Halobacterium

Archaeoglobus

Thermoplasma

MethanobacteriumPyrococcus

Thermoproteus

Sulfolobus

PyrodictiumThermotoga

Microsporidia

Slime moulds

Ciliates

Plants

Animals

Fungi

Flagellates

Diplomonads

Archaea

Eucarya

Bacteria

O

OHOH

OH

O

O

OHO

OOH

O

O

OH

O

O

OH

OH

O

O

OHO

X'

X

12C 13C

98.9%

1.11%

Carbonate

CO2(aq)

p

0 ‰

-8 ‰

-22 ‰

-26 ‰

13Cvalues

More13C

Less13C

Biomass

Kerogen

Lipids

Methane

What can carbon isotopes tell us?

Biomarker Geochemistry is built on a foundation of robust analytical chemistry

Aim: To isolate a complex extract containing hundreds of compounds and separate it into discrete groupings of compound class amenable to GC or LC analysis

Raw sample GC sample

Biomarker Geochemistry is built on a foundation of robust analytical chemistry

Aim: To isolate a complex extract containing hundreds of compounds and separate it into discrete groupings of compound class amenable to GC or LC analysis

Sample Analytical Protocol

Neutral fraction Acid fraction Polar fraction

Chromatography

Total lipid extract Residue

Sample

Extraction

• Soxhlet

• Ultrasonication

• Bligh-Dyer

• Liquid/liquid extraction

• Autoextraction

Eluent

1 2 3

Appropriate DerivatisationGC-FIDGC-MSLC-MS

GC-C-IRMS

Analyses – Hyphenated Techniques

Retention Time

Rel

ativ

e A

bund

ance

• Gas Chromatograph

• Py – Gas Chromatograph

• Liquid Chromatograph

• Flame Ionisation Detector

• Mass Spectrometer

• Combustion – Isotope Ratio Mass Spectrometer

• Thermal Conversion – Isotope Ratio Mass Spectrometer

Long-Term Cenozoic Climate ChangeT

emperature

Adapted from Zachos et al., 2001

The Paleoene-Eocene Thermal Maximum

Zachos, James, Mark Pagani, Lisa Sloan, Ellen Thomas, and Katharina Billups (2001). "Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present". Science 292 (5517): 686–693.

13C-depleted carbon

Methane!

Questions:

1. What triggered the methane release?

2. How much methane was released?

3. When it became CO2, how much warming did it cause?

4. What were the impacts on the climate, environment and life?

Questions:

1. What triggered the methane release?

2. How much methane was released?

3. When it became CO2, how much warming did it cause?

4. What were the impacts on the climate, environment and life?

How much warming did it cause?

Zachos et al., 2006

O

OOH

O

O

OH

O

O

OH O

OH

O

O

O

OH

O

OOH

Questions:

1. What triggered the methane release?

2. How much methane was released?

3. When it became CO2, how much warming did it cause?

4. What were the impacts on the climate, environment and life?

• Back to Tanzanian and New Zealand sites

• Lots of biomarkers from plants washed out to sea

• But how abundant are they?

Changes in storms?

Standard

Hydrocarbon Fraction

21

29

2325

3327

31

10 20 30 40

Re

lativ

e I

nte

nsi

ty

Retention Time

13C (‰)

35

30

25

20

15

10

5-36 -34 -32 -30 -28 -26

Dep

th (

m)

0 1 2 3 4

Abundance g g-1

HMW fatty acids (Higher Plant)

Average Chain Length

Fatty Acids

22 23 24 25 26 27 28

O

OH

OH

O

Changes in storms?

Conclusions: Implications for future climate change?

• Global warming is an important concern, but we need to know more

• Insight can come from studying the past

• This requires the application of good geological knowledge but new approaches to study the chemistry of the rocks also helps

• What have we learned about the PETM– There was a large release of greenhouse gases– This caused climate to warm by about 5C– This appears to have caused an increase in storms– But more dramatic changes – such as those discussed in the article

in The Independent – are not observed

• We must be cautious in how we use this approach…

The Cobham Lignite – a PETM terrestrial setting (With D. Steart, M. Collinson and A. Scott, Royal Holloway)

Collinson et al., 2001

The Cobham Lignite

Pancost, R. D., Steart, D. S., Handley, L., Collinson, M. E., Hooker, J., Scott, A. C., Grassineau, N. J., and Glasspool, I. J. (in press) Terrestrial Methanotrophy at the Paleocene-Eocene Thermal Maximum. Nature.

The Cobham Lignite

Heterotrophs

Methanotrophs

Conclusions: The Larger Picture

• A wide variety of environmental processes can be studied using lipids and similar biomarkers

– Modern: • AOM in the ocean and methanogenesis in wetlands

• Petroleum (and other OM) degradation and preservation

• Role of OM in releasing arsenic into aquifers

• Extreme environments (geothermal springs)

– Ancient Extreme Events• PETM

• Extinction events

• The change from a greenhouse climate to our current climate

• This requires the skilful application of state-of-the art analytical chemistry techniques and instrumentation

Acknowledgements

• Ian Bull and Rob Berstan (and the NERC Life Sciences Mass Spectrometry Facility)

• The EU for funding the METROL programme and an EST grant (BIOTRACS) that supports A. Aquilina’s PhD studentship

• The NERC for a grant to P. Pearson, R. Pancost and T. Elliott; and for supporting L. Handley’s PhD Studentship

• Joyce Singano and all other members of the TDP

• The Leverhulme Trust for a grant to M. Collinson, R. Pancost and A. Scott

• The NZ Marsden Fund for a grant to E. Crouch, H. Morgans and R. Pancost