Dan Lunt EGU 2013 Dan Lunt Can Cretaceous and Eocene Data Inform Estimates of Future Climate Sensitivity? Dan Lunt, Claire Loptson, Paul Markwick Introduction Using the palaeo to inform the future The Cretaceous and Eocene Questions to be addressed Results Experimental Design Results Summary and future directions
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Dan LuntEGU 2013Dan Lunt Can Cretaceous and Eocene Data Inform Estimates of Future Climate Sensitivity? Dan Lunt, Claire Loptson, Paul Markwick Introduction.
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Dan Lunt EGU 2013Dan Lunt
Can Cretaceous and Eocene Data Inform Estimates of Future Climate Sensitivity?
Dan Lunt, Claire Loptson, Paul Markwick
Introduction Using the palaeo to inform the future The Cretaceous and Eocene Questions to be addressed
Results Experimental Design Results
Summary and future directions
Dan Lunt EGU 2013Dan Lunt
Introduction – using the palaeo to inform the future
QUALITATIVE INFORMATION
QUANTITATIVE INFORMATION
PALAEO DATAe.g. existence of fossilised leaves in Cretaceous Antarctica
e.g. ice core CO2 records
e.g. proxy reconstructions of temperature and CO2
provide estimates of past climate sensitivity[see Rohling et al, 2012]
PALAEO MODEL-DATA COMPARISONS
e.g. model-data comparisons reveal model strengths and weaknesses
e.g. weighting future model simulations according to palaeo model-data comparisons
+ ‘analogues’ and representation of long-term feedbacks in models
Dan Lunt EGU 2013Dan Lunt
Introduction – using the palaeo to inform the future
QUALITATIVE INFORMATION
QUANTITATIVE INFORMATION
PALAEO DATAe.g. existence of fossilised leaves in Cretaceous Antarctica
e.g. ice core CO2 records
e.g. proxy reconstructions of temperature and CO2
provide estimates of past climate sensitivity[see Rohling et al, 2012]
PALAEO MODEL-DATA COMPARISONS
e.g. model-data comparisons reveal model strengths and weaknesses
e.g. weighting future model simulations according to palaeo model-data comparisons
+ ‘analogues’ and representation of long-term feedbacks in models
Dan Lunt EGU 2013Dan Lunt
“Warm Climates of the Past – A lesson for the future?”
There is a state dependence of climate through the Cretaceous (~ 1.5 oC).
There is a state dependence of climate sensitivity through the Cretaceous and Eocene (~ 2 oC)
For these time periods....
(1) Inferring climate trends from single paleo data points is dangerous. Depending on region, the error (even after correcting for paleolat/lon) can be as much as 8 oC.
(2) Inferring climate sensitivity from paleo data is dangerous, Depending on time period, the error (even if you can estimate the global mean and forcing correctly), can be as much as x2.
Dan Lunt EGU 2013Dan Lunt
Introduction – using the palaeo to inform the future
QUALITATIVE INFORMATION
QUANTITATIVE INFORMATION
PALAEO DATAe.g. existence of fossilised leaves in Cretaceous Antarctica
e.g. ice core CO2 records
e.g. proxy reconstructions of temperature and CO2
provide estimates of past climate sensitivity[see Rohling et al, 2012]
PALAEO MODEL-DATA COMPARISONS
e.g. model-data comparisons reveal model strengths and weaknesses
e.g. weighting future model simulations according to palaeo model-data comparisons
+ ‘analogues’ and representation of long-term feedbacks in models
Dan Lunt EGU 2013Dan Lunt
Future Work
Much still to do....
Complete ‘matrix’ of 2x and 4x simulations through Cretaceous to modern.