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Simon Waters wrote:
Read a report today about methane under the sea starting to bubble up from hydrates that are warming up - these could be released catastrophically fast and methane is 20* as warming as CO2 and may warm us a few degrees in a few years. Not many people seem to be aware of the positive feedback effects and, while a lot of people think global warming is over hyped a lot of the stuff is seriously under hyped.Philip Whateley wrote:What I found interesting was the recent British Antarctic Survey Ice Dome C data for the last 800000 years. It shows that every inter-glaciation temperature spike for the past 500kyears has gone to around 5degC above present.It would be interesting to know whether the predicted anthropogenic 2-3degC rise is in addition to the 5degC we can expect as a result of solar activity, or whether the 2-3deg is the net effect of solar activity, greenhouse gas emissions and particulate emissions reducing solar absorption.The temperature rise forecast is CO2 forced, so it is a warming that is expected over recent historical averages including any expected changes in climate due to additional CO2 (and methane), but I don't think there are any substantive changes in natural climate expected over the time scales of interest (i.e. next 100 years). The larger historical fluctuations as I understand it are on a much longer time scale (100,000 year cycle). I don't think the fluctuations you mention are due to solar activity but due to variations in the earth's orbit (Milankovitch cycles). The peak of the current interglacial was 21,000 years ago as I understand it. Where did you get the idea it would get 5 degrees warmer naturally, or are you meaning in 75,000 years when the cycle would repeats? http://stratus.astr.ucl.ac.be/textbook/chapter5_node13.html
I just hope I can get out and get a few loads of fossil fuel in tomorrow! Tom te tom te tom -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html