Antarctica has experienced significant temperature changes, especially since the last glacial period.
Antarctica has experienced significant temperature changes, especially since the last glacial period. An international collaboration including scientists from the CNRS has now challenged previously accepted estimates of these variations, using new measurements published on June 4, 2021 in Science. Their study highlights differences in behaviour between East and West Antarctica, connected in particular to differing variations in their altitude.
Surface temperatures in Antarctica have risen sharply since the last glacial period. Understanding this increase is key to understanding changes in climate at any given time and to testing our ability to model them. A study involving French scientists now provides the most reliable estimates to date of past temperature variations in Antarctica. Whereas warming since the last glacial period was until now estimated at +9 °C across the entire continent, the new measurements reveal a variation of +10 °C in West Antarctica and between +4 and +7 °C in East Antarctica.
Scientists previously estimated past temperatures using an isotopic thermometer, in other words, by analysing the ratio of different isotopic forms of water. However, the accuracy of this method relies on a calibration that is hard to implement in Antarctica. Now, two new independent methods have been developed in order to overcome this problem. The first consists in measuring the temperature in the boreholes resulting from coring. The tremendous thickness of the Antarctic ice sheet means that records are well-preserved and can be used to reconstruct past temperatures. The second method is based on the process of snow densification, which is temperature-sensitive and can be measured by analysing the air trapped in ice cores. The two measurements gave similar results, confirming their reliability.
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Image: Testing the prototype of the Mini-Subglacior experimental probe. (Credit: © Thibaut VERGOZ/IPEV/LGGE/CNRS Photothèque)