Tom> Dear Doug and the Left Business Observers, A few "old timers"
Tom> have asked me an interesting question.
how old do you have to be to be an old-timer?
Tom> Vice-President Al Gore has stated that the earths temperature
Tom> hasn't been this warm in 400 years. The "old timers" want to
Tom> know what caused the earth to be this warm 400 years ago?
if Al is looking at the same data as I am, then the answer is nothing. what he means is, for as far back as we can reasonably extrapolate 'paleo-climatological' data (tree ring widths, ice pack data, etc), there has been no time in the last 600 years when the earth has been warmer than now.
here is some data if you like looking at squiggly lines:
http://www.ngdc.noaa.gov/paleo/pubs/mann1998/fig5.htm
Notice that 'Houston, we have a problem' sometime starting in the 1940's. The grey lines above and below the back represent best estimates of the range in errors associated with this extrapolation.
This is data from a study just recently published in Nature:
http://www.ngdc.noaa.gov/paleo/pubs/mann1998/frames.htm
Tom> After all there was little or no use of fossil fuels used
Tom> back then. No internal combustion engines. No airplanes.
Tom> Hmm. Space rockets?
from the preface to the paper:
"In addition to the possibility of warming due to enhanced greenhouse gases during the past century, there is evidence that both solar irradiance and explosive volcanism have played an important part in forcing climate variations over the past several centuries. The unforced 'natural variability' of the climate system may also be quite important on multidecadal and century timescales."
Here is an ABC news blurb on this technical paper, in 'layperson' woids:
http://www.abcnews.com/sections/science/DailyNews/warm980422.html
Here is all the data and ilnks to global climatology a web busybody could want:
http://www.ngdc.noaa.gov/paleo/recons.html http://www.met.utah.edu/jhorel/companion/ http://libweb.sonoma.edu/Resources/climatology.html
Here is a set of pages designed for 6-12-th graders:
http://www.covis.nwu.edu/Geosciences/projects/GLOBAL_WARMING/GLOBAL_WARMING.html
-- ____ Les Schaffer godzilla at netmeg.net ___| ------->> Engineering R&D <<-------- Theoretical & Applied Mechanics | Designspring, Inc. Westport, CT USA Center for Radiophysics & Space Research | les at designspring.com Cornell Univ. schaffer at tam.cornell.edu |