[ Date Index ] [ Thread Index ] [ <= Previous by date / thread ] [ Next by date / thread => ]
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 500k > years 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 -- 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