European warming linked to Greenland melting during the Last Interglacial North Atlantic climate optimum
Abstract
Recent models and data synthesis suggest that the Last Interglacial North Atlantic warm optimum, ~130 ±2 ka, corresponded with a sea level stand of 4-9 m higher than that of the present-day implying that a substantial part of the Greenland Ice Sheet (GIS) melted at that time. This makes this interglacial a good analogue for understanding the impact of the ongoing global warming and GIS melting on the Atlantic Meridional Overturning Circulation (AMOC) and adjacent landmasses. Here we provide new insights on the impact of insolation and AMOC changes on western European ecosystems and climate and their regional transmission during an episode of GIS melting that can be considered somehow similar to that predicted for 2100 C.E. from IPCC projections. We have revisited three pollen-rich western European margin sequences distributed from 37 to 45°N, MD04-2845, MD95-2042 and MD99-2331, which span all of MIS 5 and are directly affected by the descending branch of the North Atlantic Drift. The analysis of these sequences allows us to directly correlate marine tracers of AMOC variability and changes in ice volume, sea surface temperature (SST), iceberg discharges and pollen-derived European vegetation and climate. The comparison of these observations with those inferred from other locations in the North Atlantic region directly affected by the AMOC and records from the Eirik Drift off southern Greenland document the response of North Atlantic climate to GIS melting during the Last Interglacial. Large and rapid increase in the Western European forest cover and mid-latitude North Atlantic SST at the beginning of MIS 5e benthic isotopic plateau following the YD-like event coincide with strong GIS melting. Despite continued GIS melting during this interval, AMOC strength gradually increases. The dramatic expansion of western European forest could be the result of both AMOC and insolation increase. Subsequently sustained warm SSTs and strong AMOC do not preclude the long term forest reduction which parallels insolation decrease. On millennial time scales, repeated decreases in GIS runoff occurred when Europe and the adjacent ocean cooled and AMOC strength weakened. Contrary to what would be expected if GIS melting triggering reduced AMOC with attendant forest reductions and cooling in western Europe and the North Atlantic Ocean, our study suggests that GIS melting increases at the same time as the subpolar and mid latitudes of the North Atlantic and adjacent landmasses experienced warming with AMOC reinvigoration. Given the potential analogue between the Last Interglacial and the end of this century, we suggest that in contrast to GIS melting weakening AMOC, increased radiative forcing leading to future GIS melting may be associated with increased AMOC strengthwarming of Western Europe and a larger extent of temperate forests, in the absence of human intervention.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMPP44A..02S
- Keywords:
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- 1616 GLOBAL CHANGE / Climate variability;
- 1632 GLOBAL CHANGE / Land cover change;
- 4936 PALEOCEANOGRAPHY / Interglacial;
- 4952 PALEOCEANOGRAPHY / Palynology