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Evidence for warmer interglacials in East Antarctic ice cores

Changes in the proportion of different types of atoms of the same chemical element, or isotope, in Antarctic ice cores record temperature. When it’s cold, water made with the heavy version of hydrogen — deuterium — falls out of the sky as snow sooner than water made with normal hydrogen, because it’s heavier than normal water. Previously scientists have assumed that snowfall recording of yearly temperatures hardly vary over East Antarctica. But this work analysing ice cores from three regions of East Antarctica containing 340,000-year-old ice, has found different changes between the snowfall recording of yearly temperature at the three places in East Antarctica.

This latest analysis of ice core records alongside numerical model results suggests that temperatures in Antarctica during the warm interglacial periods between ice ages may have been higher than scientists previously thought. Until now researchers had thought maximum temperatures during interglacials were a little warmer than today’s temperatures. But this work shows that they may have been up to 6°C warmer — around double earlier estimates. Results suggest that Antarctica warmed rapidly in the past. It might be that at higher CO₂ levels Antarctic temperatures are more sensitive to small variations, due to regional warming feedbacks. The findings could help researchers understand more about how the climate can quickly change on the Antarctic continent. Further data on interglacial climates from, Greenland would be invaluable to help understand what’s going on.

Find link to the full paper in the NERC Open Research Archive

Authors

L. C. Sime, E. W. Wolff, K. I. C. Oliver (Open Univ.) & J. C. Tindall (Univ. of Bristol)

Publication

Nature, Vol 462| 19 November 2009| doi:10.1038/nature08564