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Constraining Hydrological Cycle
Characteristics of Early Eocene Hyperthermals
Srinath Krishnan
Reasons for study
Rainfall has direct impact on human society Impact of anthropogenic activity on rainfall
patterns is not well understood Modern studies suggest intensification of
hydrological cycle with warming Wet Wetter Dry Dryer
Lack of data inhibits validation of these models in a complex natural system
Reasons for study
Rainfall has direct impact on human society Impact of anthropogenic activity on rainfall
patterns is not well understood Modern studies suggest intensification of
hydrological cycle with warming Wet Wetter Dry Dryer
Lack of data inhibits validation of these models in a complex natural system
Reasons for study
Rainfall has direct impact on human society Impact of anthropogenic activity on rainfall
patterns is not well understood Modern studies suggest intensification of
hydrological cycle with warming Wet Wetter Dry Dryer
Lack of data inhibits validation of these models in a complex natural system
Reasons for study
Rainfall has direct impact on human society Impact of anthropogenic activity on rainfall
patterns is not well understood Modern studies suggest intensification of
hydrological cycle with warming Wet Wetter Dry Dryer
Lack of data inhibits validation of these models in a complex natural system
Early Eocene HyperthermalsPaleocene-Eocene
Thermal Maximum
• ~3-50C rise in temperature
• Negative carbon isotope excursion of 2.5-6‰
Eocene Thermal Maximum-2
• Smaller rise in temperature compared to the PETM set on a warming trend
• Carbon isotopic excursion about half of the PETM
Adapted from Zachos et al. (2001)
Early Eocene Hyperthermals
Causes Methane Hydrates (Dickens et al., 1995) Burning of terrestrial organic matter (Kurtz et al.,
2003) Estimates of greenhouse gas concentrations
Pre-PETM: ~600 – 2,800 ppm of CO2
PETM: ~750 – 26,000 ppm of CO2 ~1,500 – 55,000 Gt C in the atmosphere ~3,900 – 57,000 Gt C released in the oceans
Modern atmospheric CO2 concentration: ~360 ppm Modern Conventional fossil fuel reserves: ~5,000 Gt C
Early Eocene Hyperthermals
Causes Methane Hydrates (Dickens et al., 1995) Burning of terrestrial organic matter (Kurtz et al.,
2003) Estimates of greenhouse gas concentrations
Pre-PETM: ~600 – 2,800 ppm of CO2
PETM: ~750 – 26,000 ppm of CO2 ~1,500 – 55,000 Gt C in the atmosphere ~3,900 – 57,000 Gt C released in the oceans
Modern atmospheric CO2 concentration: ~360 ppm Modern Conventional fossil fuel reserves: ~5,000 Gt C
GOAL
Use early Eocene hyperthermals as analogues to study changes in the hydrological cycle during extreme warming events
Schematic of a Water Cycle
Adapted from NASA Goddard Flight Center
Expected changes with warming Increased lower tropospheric water vapor
In the extra-tropics, the important components of the hydrological cycle that affect isotopic signals are Horizontal poleward flow of moisture Changes in precipitation and evaporation
Dr. Raymond Schmitt: http://www.whoi.edu/sbl/liteSite.do?litesiteid=18912&articleId=28329
Variations in Precipitation with warming
Held and Soden (2006)
Increased Evaporation
2.80c in 2100
Held and Soden (2006)
Increased Precipitation
Variations in Precipitation with warming
2.80c in 2100
Isotopes and Precipitation
Modern annual precipitation
http://www.waterisotopes.org
Rayleigh Distillation
Clark and Fritz, 1997
Rayleigh Distillation
Clark and Fritz, 1997
Increased depletion with progressive rainout events
Hypotheses
There is a systematic change in moisture transport to the higher latitudes during warming events Are there similar changes in δD between
the two hyperthermals at the higher latitudes?
Can these changes be detected on a global scale?
Can this theoretical model be reproduced with an isotope coupled climate model?
Proxies
n-alkanes: Single chain hydrocarbon with long chain lengths (n-C23-35) indicating terrestrial plant/leaf wax sources
Compound-specific hydrogen isotopic composition represents meteoric water modified by evapotranspiration
Compound-specific carbon isotopic compositions represents environmental and ecological conditions
Proxies
n-alkanes: Single chain hydrocarbon with long chain lengths (n-C23-35) indicating terrestrial plant/leaf wax sources
Compound-specific hydrogen isotopic composition represents meteoric water modified by evapotranspiration
Compound-specific carbon isotopic composition represents environmental and ecological conditions
n-alkanes and precipitation
Adapted from Sachse et al., 2006)
Deute
rium
n-alkanes
Biomarker transport
Adapted from Eglinton and Eglinton, 2008
Continent Oceans
Wind
Terrestrial Plants Rivers
Aerosols (with
waxes)
Methods
Samples
Total Lipid Extract
n-alkane and biomarker fractions
Compound Detection & Identification
Compound-specific Deuterium & Carbon isotope compositions
Crushing and Extraction
Compound Separation
Gas ChromatogramAnalyses
Compound-specific Isotope Ratio Mass Spectrometer
Clean-up Procedures
Analytical Uncertainty: ±5‰
IODP-302 Arctic Coring Expedition
Arctic Paleocene-Eocene Thermal Maximum
Modified from Pagani et al., 2006
~55.6 MaDuration: ~150-200 kyrs
Arctic Eocene Thermal Maximum-2
This work
~54 MaDuration: ~75-100 kyrs
Preliminary Conclusions
Enrichment at the onset for both events with different magnitudes Decreased rainout for moisture reaching the
poles
15-20‰ magnitude depletions during the events Similar variations during both the events
Preliminary Conclusions
Enrichment at the onset for both events with different magnitudes Decreased rainout for moisture reaching the
poles
15-20‰ magnitude depletions during the events Similar variations during both the events
Hypotheses There is a systematic change in
moisture transport to the higher latitudes during hyperthermal events Are there similar changes in δD during the
two hyperthermals at the higher latitudes?
Preliminary Conclusion: Enrichments in δD do correspond with the hyperthermals at the onset of the event with similar magnitude depletions during the eventNumber of samples
Arctic ETM-2: 29 samples
Hypotheses
There is a systematic change in moisture transport to the higher latitudes during hyperthermal events Are there similar changes in δD during the
two hyperthermals at the higher latitudes?
Can these changes be detected on a global scale?
Can this theoretical model be reproduced with an isotope coupled climate model?
Tropical PETM: Tanzania (Handley et al., 2008)
Tropical PETM: Colombia (This work)
Mid-latitudes PETM: Bighorn Basin Smith et al. (2006)
PETM: High LatitudesPagani et al. (2006)
Summary of changes during PETM Tropics
Tanzania – 15‰ enrichment Colombia - ~30‰ depletion
Mid-latitudes Lodo – No change during the event with hints of depletion at
the onset and the end Bighorn Basin – No significant change Forada - ~10‰ enrichment at the onset followed by a10‰
depletion during the event High Latitudes
Arctic – 60‰ enrichment at the onset followed by 20‰ depletion through the event
Summary of changes during PETM Tropics
Tanzania – 15‰ enrichment Columbia - ~30‰ depletion
Mid-latitudes Lodo, California – No change during the event with hints of
depletion at the onset and the end Bighorn Basin – No significant change Forada, Italy - ~10‰ enrichment at the onset followed by
a10‰ depletion during the event High Latitudes
Arctic – 60‰ enrichment at the onset followed by 20‰ depletion through the event
Summary of changes during PETM Tropics
Tanzania – 15‰ enrichment Columbia - ~30‰ depletion
Mid-latitudes Lodo – No change during the event with hints of depletion at
the onset and the end Bighorn Basin – No significant change Forada - ~10‰ enrichment at the onset followed by a10‰
depletion during the event High Latitudes
Arctic – 60‰ enrichment at the onset followed by 20‰ depletion through the event
Hypotheses There is a systematic change in
moisture transport to the higher latitudes during hyperthermal events Can these changes be detected on a
global scale? Preliminary Conclusion: Existing data not
sufficient to draw conclusions about regional & hemispherical changes. Requires further studies on a global scale
Ongoing Work
Ongoing Work: Giraffe Core
C29
Ongoing Work: 1051
C29
Ongoing Work: 1263
C29
Ongoing Work: 690
C29
Hypotheses
There is a systematic change in moisture transport to the higher latitudes during hyperthermal events Are there similar changes in δD during the
two hyperthermals at the higher latitudes? Can these changes be detected on a global
scale? Can these changes predicted be
reproduced with an isotope coupled climate model?
Future Work: Eocene Modeling Goal
To utilize the global dataset developed to compare the hydrological response in terms of isotopes, temperatures and precipititation signals
Simulations planned Hyperthemal scenarios (PETM vs. ETM2)
Different CO2 concentrations
Background Eocene
Thank You
AcknowledgmentsJoint Oceanographic Institute, ODP/IODP
Mark Pagani, Matt Huber, Appy Sluijs, Carlos JaramilloPeter Douglas, Sitindra Dirganghi, Micheal Hren, Brett Tipple, Katie French, Keith Metzger, Courtney Warren, Matt Ramlow,
Gerry Olack, Dominic ColosiYale G&G Faculty, Staff & Students
Mid-latitudes PETM: Forada Tipple (unpublished)
Mid-latitudes PETM: Lodo Tipple (unpublished)
Paleogeography
C-3 Biosynthetic pathway
C-4 Biosynthetic pathway
Modern mean annual poleward flux
Changes in northward polar flux with doubling of CO2 – IPCC AR-4 scenario
Held & Soden, 2006
Proxies
TEX-86
Derived from marine pico plankton Crenarchaeota
Vary membrane fluidity and composition depending on the temperature
Has recently been applied to analyze paleo-SST
Changes in GWML
Theoretical Model Warming results in increased lower tropospheric
water vapor Scales according to the Clausius-Clayperon
relationship
In the extra-tropics, the important components of the hydrological cycle that affect isotopic signals are horizontal poleward flow of moisture and changes in precipitation and evaporation
Simple models have been developed by scaling with the Clausius-Clayperon relation
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Energy Use Phase
Energy generation Phase
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