Year unknown•Bern Open Repository and Information System (University of Bern)Open access
Greenland temperature response to climate forcing during the last deglaciation
Christo Buizert, Vasileios Gkinis, J. P. Severinghaus, Feng He, Benoit S. Lecavalier, P. Kindler, Markus Leuenberger, Anders E. Carlson, Bo Vinther, Masson-Delmotte, Valérie, White, James W. C., Liu, Zhengyu, Otto-Bliesner, Bette, Brook, Edward J.
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Abstract
Greenland ice core water isotopic composition (δ(18)O) provides detailed evidence for abrupt climate changes but is by itself insufficient for quantitative reconstruction of past temperatures and their spatial patterns. We investigate Greenland temperature evolution during the last deglaciation using independent reconstructions from three ice cores and simulations with a coupled ocean-atmosphere climate model. Contrary to the traditional δ(18)O interpretation, the Younger Dryas period was 4.5° ± 2°C warmer than the Oldest Dryas, due to increased carbon dioxide forcing and summer insolation. The magnitude of abrupt temperature changes is larger in central Greenland (9° to 14°C) than in the northwest (5° to 9°C), fingerprinting a North Atlantic origin. Simulated changes in temperature seasonality closely track changes in the Atlantic overturning strength and support the hypothesis that abrupt climate change is mostly a winter phenomenon.