Apparently, new research (you know, that empirical evidence thing, not just computer models) shows that Antarctica has been far warmer in the recent geologic past – all without Man’s intervention:
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 latest analysis of ice core records suggests that Antarctic temperatures may have been up to 6°C warmer than the present day.
The findings, reported this week by scientists from the British Antarctic Survey (BAS), the Open University and University of Bristol in the journal Nature could help us understand more about rapid Antarctic climate changes.
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.
Lead author Louise Sime of British Antarctic Survey said,
“We didn’t expect to see such warm temperatures, and we don’t yet know in detail what caused them. 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 metres higher than today.
Of course, nothing yet establishes that CO2 is a cause of warming, not an effect of it. That the temperature was much higher then at CO2 levels “similar to today” hints at an independent factor. Obviously, more research is needed, hopefully without the a priori assumption that CO2 causes global warming.
Regardless, the key fact to note here is that this happened in the past with no human input.
(hat tip: Heliogenic Climate Change)