Temperature spikes in ancient Antarctica

Physics Today : A new study of Antarctica’s past climate reveals that temperatures during the warm periods between ice ages (interglacials) may have been higher than previously thought.The findings, reported in Nature by scientists from the British Antarctic Survey (BAS), the Open University and University of Bristol could help us understand more about rapid Antarctic climate changes. The conclusions come the latest analysis of ice core records that suggests that Antarctic temperatures may have been up to 6°C warmer than the present day. (see image left. This Slice of ice core from Berkner Island, was dug up from a depth 120 meters below the surface. Trapped air bubbles (an archive of the past atmosphere) are visible in the ice. Photo credit: BAS)Previous analysis of ice cores has shown that the climate consists of ice ages and warmer interglacial periods roughly every 100,000 years.This new investigation shows temperature ‘spikes’ within some of the interglacial periods over the last 340,000 years. This suggests Antarctic temperature shows a high level of sensitivity to greenhouse gases at levels similar to those found today."We didn’t expect to see such warm temperatures, and we don’t yet know in detail what caused them,” says Louise Sime of the British Antarctic Survey and the lead author of the author. “But they indicate that Antarctica’s climate may have undergone rapid shifts during past periods of high CO2."During the last warm period, about 125,000 years ago, sea level was around 5 meters 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 may contribute to sea level rise,” says BAS’s Eric Wolff . Related Links Antarctic temperature spike surprises climate researchers Evidence for warmer interglacials in East Antarctic ice cores