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Index of Subjects
Index of Subjects --Apple-Mail-94--903038351 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=WINDOWS-1252; format=flowed > > > Based on a chart of global temperature over the last 860,000 years=20= > included in this 1975 article, on which there are about 10 peak=20 > temperatures and 11 glacial advances, we are due for a glacial advance=20= > within the next 20,000 years or so. > > Since this 1975 article was written (I think) these or similar =20 > fluctuations in temperature have been explained to a major extent by=20= > periodic astronomical fluctuations (orbital distance, axis tilt and=20 > (?) sun output). Does anyone know how temperature fluctuations of the=20= > last several centuries compare with fluctuations that would be=20 > expected on the basis of this astronomical model ? Is the current=20 > positive residual exceptional as compared with residuals over the last=20= > 15,000 years ? Was this astronomical model constructed from=20 > independently established astronomical constants or were the=20 > astronomical fluctuations derived by being fitted to the temperature=20= > curves ? Hi everyone: The "cooling" trend was explained in The Weather Makers by Tim=20 Flaherty. It has been a while since I read the book, but a lot of the=20 "discrepancy" was due to a difference between lower and upper=20 atmospheric temperatures which were going in opposite directions. I=20 might be able to track it down. One of the things about long term trends that comes out in both The=20 Weather Makers and An Inconvenient Truth is that we are now well=20 outside the historical range of temperatures. If you look at the=20 Wikipedia entry on "global warming" there are number of graphs of=20 temperatures and CO2 concentrations that now go back hundreds of=20 thousands of years. This one illustrates the close correlation between=20= temperature and CO2 concentrations. http://en.wikipedia.org/wiki/Image:Co2-temperature-plot.svg Note that the recent increase in CO2 concentrations is: a) well outside the normal range b) a change which is essentially instantaneous on the geological time=20 scale, and c) expected to become much higher over the coming 50 years. As Al Gore pointed out, the historical range means that at the peaks it=20= is sweltering in New York City in the summer; at the bottoms, New York=20= City is under several kilometres of ice. One would assume that there=20 will be serious consequences to the climate if the temperature changes=20= to match the new CO2 levels. One possible reason for the "attack the doubters" approach may be=20 driven by recent studies on climate change. While papers in=20 peer-reviewed scientific journals show that almost 99% of research=20 papers show evidence that climate change is a fact, in the popular=20 press the articles are more like 50-50 or give the impression that=20 scientists do not agree on the matter. It reminds me somewhat of the=20 past debates about the link between smoking and cancer; even when the=20 evidence was overwhelming, there were still a lot of people (mostly in=20= the tobacco industry) who were able to get the message to the public=20 that there was still lots of doubt.=85 Coming from a background in astronomy I tend to be of the opinion that=20= I would rather err on the side of caution when the sustainability of my=20= home world is concerned. The current best thought is that planets like=20= the Earth are rare, and intelligent life even rarer, (I highly=20 recommend Rare Earth: Why Complex Life is Uncommon in the Universe by =20= Peter Ward, Donald Brownlee) It is quite unlikely that anyone else is=20 going to show up to save us. There is precedent: we know that the collapse of the civilization on=20 Easter Island was brought about by clear-cutting the trees, By carbon=20 dating we know that at some point someone stood on one of the highest=20 hills where the last tree was; saw that all of the other trees were=20 gone, and still cut down the last one. I wonder if some archaeologist=20 in the distant future (either human or alien) will sift through the=20 ruins of our civilization, piece together what happened, and just shake=20= their head (or heads) and think "What a bunch of morons=85" Patrick Kelly RR#2 159 Town Road Falmouth NS B0P 1L0 Canada --Apple-Mail-94--903038351 Content-Transfer-Encoding: quoted-printable Content-Type: text/enriched; charset=WINDOWS-1252 <excerpt> Based on a chart of global temperature over the last 860,000 years included in this 1975 article, on which there are about 10 peak temperatures and 11 glacial advances, we are due for a glacial advance within the next 20,000 years or so. Since this 1975 article was written (I think) these or similar=20 fluctuations in temperature have been explained to a major extent by periodic astronomical fluctuations (orbital distance, axis tilt and (?) sun output). Does anyone know how temperature fluctuations of the last several centuries compare with fluctuations that would be expected on the basis of this astronomical model ? Is the current positive residual exceptional as compared with residuals over the last 15,000 years ? Was this astronomical model constructed from independently established astronomical constants or were the astronomical fluctuations derived by being fitted to the temperature curves ? </excerpt> Hi everyone: The "cooling" trend was explained in The Weather Makers by Tim Flaherty. It has been a while since I read the book, but a lot of the "discrepancy" was due to a difference between lower and upper atmospheric temperatures which were going in opposite directions. I might be able to track it down. One of the things about long term trends that comes out in both The Weather Makers and An Inconvenient Truth is that we are now well outside the historical range of temperatures. If you look at the Wikipedia entry on "global warming" there are number of graphs of temperatures and CO2 concentrations that now go back hundreds of thousands of years. This one illustrates the close correlation between temperature and CO2 concentrations. http://en.wikipedia.org/wiki/Image:Co2-temperature-plot.svg Note that the recent increase in CO2 concentrations is: a) well outside the normal range b) a change which is essentially instantaneous on the geological time scale, and c) expected to become much higher over the coming 50 years.=20 As Al Gore pointed out, the historical range means that at the peaks it is sweltering in New York City in the summer; at the bottoms, New York City is under several kilometres of ice. One would assume that there will be serious consequences to the climate if the temperature changes to match the new CO2 levels. One possible reason for the "attack the doubters" approach may be driven by recent s