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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 - PowerPoint PPT Presentation
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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
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