Three fascinating papers were published in Science (Vol 310, 25th November 2005) last week on climate change and the relationship between carbon dioxide, methane and nitrous oxide levels and temperature over the last 650,000 years.
They report on new findings from the European Project for Ice Coring in the Antartica.
A graph in the ‘perspectives section’ by Brook (pg 1286) summarizes the findings,
view image (70 kbs).
The data tells me that:
1. The greenhouse gases are at higher levels now than they have been over the last 650,000 years.
2. Carbon dioxide levels correlated with temperature and have peak during previous interglacial warm periods just below 300ppm, view image (120 kbs).
3. In the past, increases in atmospheric carbon dioxide levels have tended to follow, rather than preceded, rises in temperature.
4. We are currently in an interglacial warm period and these periods tend to be followed by very cold periods.
I find the graphs fascinating.
While atmospheric carbon dioxide levels have clearly fluctuated with temperature in the past, they have tended to lag behind temperature. This doesn’t accord with the current perception – what is understood to be the current consensus which is that carbon dioxide drives temperature?
I find the prospect of another ice age really scary. The graphs suggest to me that one is imminent – like in the next few hundred or thousand years? However, greenhouses gases have never been so high.
It is perhaps interesting to ponder …. If we were able to influence climate in a predictable way, and if we could delay indefinitely the onset of the next ice age, should we?
Many, many thanks to the reader of this blog who sent me copies of the papers. There has been some discussion of the papers at the Real Climate blog, http://www.realclimate.org/index.php?p=221&lp_lang_view=en .