Session: Invited talks
Author: Emilie Capron / firstname.lastname@example.org / Niels Bohr Institute, University of Copenhagen (Denmark); British Antarctic Survey (UK)
Co-author: Aline Govin, LSCE/IPSL (CEA-CNRS-UVSQ), Universite Paris-Saclay (France);
Ran Feng, Climate and Global Dynamics Laboratory, NCAR (USA);
Bette L. Otto-Bliesner, Climate and Global Dynamics Laboratory, NCAR (USA);
Emma J. Stone, BRIDGE, School of Geographical Sciences, University of Bristol (UK);
Eric W. Wolff, Department of Earth Sciences, University of Cambridge (UK);
The Last Interglacial (LIG, ~129-116 thousand years ago, ka) represents an excellent case study to investigate the response of sensitive components of the Earth System and the associated mechanisms to a climate globally warmer than preindustrial. However, a spatio-temporal representation of the LIG climatic changes remains difficult to obtain, mainly because aligning paleoclimatic records from various archives from around the globe is challenging.
First, we summarize our recent studies that highlight how the coupling of HadCM3 equilibrium experiments with a synthesis of surface air and sea temperature records associated with harmonized chronologies from the appropriate time interval improved our spatio-temporal representation and understanding of the LIG high-latitude climate evolution. In particular, our integrated model-data approach shows that a freshwater input into the North Atlantic (due to the Northern Hemisphere ice sheet early melting) needs to be accounted for, in addition to the orbital and greenhouse gas concentration forcing, in 130 ka HadCM3 simulations, to explain the evolution of the early LIG climate.
Second, we present a new 127 ka surface temperature time slice associated with quantitative uncertainty estimates to serve as benchmark for the upcoming CMIP6/PMIP4 127 ka equilibrium simulations. At 127 ka, summer sea surface temperatures were on average 1.1°C and 1.8°C warmer relative to preindustrial in the North Atlantic and in the Southern Ocean respectively. In Antarctica, average 127 ka annual surface air temperature was 2.2°C warmer compared to preindustrial.
Finally, we provide a critical evaluation of the latest four LIG surface climate compilations and guidance on the use of these syntheses for upcoming model-data comparison exercises in the framework of the CMIP6/PMIP4 127 ka experiments. Overall, we do not recommend the use of LIG peak warmth-centered syntheses. Instead we promote the use of the most recent syntheses that are based on coherent chronologies between paleoclimatic records and provide spatio-temporal reconstruction of the LIG climate.