Scientists from the British Antarctic Survey (BAS), the Open University and the University of Bristol, explain that until now temperatures during the warm periods between ice ages – known as interglacials – were thought to be slightly warmer than those of the present day. However, some brief ‘spikes’ in temperature, which recur roughly every 100 000 years and last a few thousand years seem to have been a lot warmer.
Lead author, Louise Sime from BAS, said: “We analysed Antarctic ice cores to look at climate during past warm periods and were surprised to find relatively high Antarctic temperatures during some spikes. We don’t yet know what caused these peaks, but we would like to be sure we haven’t missed anything important about how Antarctica is set to change in a warming world.”
Julia Tindall, an author of the paper from the University of Bristol, added: "It is quite difficult to reconstruct temperatures from long ago. Although it is generally accepted that the climate was warmer 125,000 years ago, our results suggests it was much warmer than previously thought. It will be interesting to see if other studies agree with our findings".
Ice cores from East Antarctica contain the oldest drilled ice on Earth, and provide a unique record of past climate. Analysis of the ice cores has revolutionized our understanding of how Antarctic climate has varied in the past.
Ice core scientist Eric Wolff of British Antarctic Survey is a world-leading expert on past climate. He said: “During the last warm period, about 125 000 years ago, sea level was around 5 metres higher than today. If we can pin down how much warmer temperatures were in Antarctica and Greenland at this time, then we can test predictions of how melting of the large ice sheets will contribute to sea level rise.”