An important point which often gets missed is that we are adding to the atmosphere gases of known properties: they cause the atmosphere to retain heat.
And, if the atmosphere didn't already contain gases which retain heat, the Earth would be very much colder than it is. There are many secondary effects of adding these gases; but for the last 140 years of calculations, the secondary effects tend to balance out and the net effect resembles the primary effect. There is a separate question which is: is there a trend of actually increasing temperature of the Earth's surface, due to the gases we have added, detectable through the normal variation of weather year to year. In 1988 Dr, James Hansen said yes, and since then his opinion has become the scientific consensus as more and more information has come in and more analysis has been done. As of 1988, Environment Canada estimated that CO2 was responsible for about half of the total warming influence of gases added to the atmosphere by humans. As I recall, flurocarbons like Freon, and its chlroflurocarbon replacemnets, accounted for about a quarter, wuth methane and some lesser gases providing another quarter. I surmise that CO2 probably accounts for more than half now, as methane losses in the former Soviet Union have reportedly decreased considerably. A rough chronology of climate science and CO2 goes something like this: 1824 - Fourier in France pointed out that the atmosphere must be retaining heat. 1858 - John Tyndall in Britain made the first measurements of the heat retaining properties of CO2 and water vapour. 1862 - Tyndall published and pointed out the role of these gases in retaining heat in the atmosphere. 1898 - Svante Arrhenius (Sweden) pointed out the burning coal might eventually modify the climate through CO2 emissions 1920's - Milankovic (Serbia) published his calculations on the effect of cycles in the Earth's orbit on climate. For more see Simple models of climate (history) http://www.aip.org/history/climate/simple.htm Bibiliography http://www.aip.org/history/climate/bibdate.htm Books Global warming: the complete briefing by John Houghton Cambridge University Press, 2nd edition 1997 Our threatened climate: ... by Wilfrid Bach Dordrecht, Boston: D. Reidel Pub. Co. (Kluwer Academic), 1984 The Ages of Gaia by James Lovelock 1988 It's true that the Earth's climate is a complex and ill-understood system. The evidence of past climates has shown wide variations, some extremely fast and "turbulent". It seems that climate may have a couple of extreme states between which it oscillates. Human imfluences are superimposed on this "natural" variation. Buildup of peat and methane hydrates in cold periods may tend to provide the wherewithal for prolonged increase of temperature once it exceeds some critical value. The Sun is very gradually increasing its heat output and the long term trend of Earth's temperature appears to be up. This may eventually put an end to life on Earth even before the Sun's expected red-giant phase. To me it doesn't seem like a good idea to try to hurry this process along, but this is what "business as usual" is doing. As Dr. Wallace Broecker has put it, "The climate is an angry beast, and we are prodding it with sticks." Doug Woodard St. Catharines, Ontario, Canada On Wed, 23 Feb 2005, Greg Harbican wrote: [snip] > I personaly am not 100% sure, that CO2 and other green house gasses are the > cause of global warming, in fact that I am totaly 100% certian about global > warming, because I perceve ( correcly or incorrectly ) varables, that I > don't know have been accounted for. I am not saying that I am a better > person, amd know more, than the scientest that support the theory of global > warming. I just have lingering doubts, because I know the mistakes that > science makes, and after all the science of global warming is what, 10-15 or > so years old? OTOH, I am sure, that there is currently a disturbing > trend, that needs to be delt with, be it short term or long term. [snip] _______________________________________________ Biofuel mailing list [EMAIL PROTECTED] http://wwia.org/mailman/listinfo.cgi/biofuel Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuel archives at Infoarchive.net (searchable): http://infoarchive.net/sgroup/biofuel/
