posted on May, 25 2008 @ 11:23 PM
No one has stated that the only way for a planet to warm up is to drive SUV's around (or produce carbon dioxide in some other way). After all, no
one suggests that SUV's brought us out of the last Ice Age.
It's well accepted that there are non-human phenomena that periodically warm or cool our planet. Changes in the Sun's radiation output, variations
in the Earth's orbit (Milankovitch cycles), increased or decreased volcanic activity are some of the primary factors.
The main concern now is really the rate of temperature change. For example, the earth warmed gradually by about .4 degrees C during the millenium
from 1 A.D. to 1000 A.D. Then there was a similarly gradual cooling until about 1800 A.D. when the trend bottomed out and began to warm again. At
around 1900 A.D. the warming trend really took off and the planet has warmed about .6 degrees C in the past century.
(2000 Year Reconstructed Temperature Chart
That means that the average rate of temperature change in this last century is 1500% greater than it was during the first millenium A.D. Even worse,
the more recent rate of temperature change since 1979 has been calculated to be about .25 degrees C over land and .13 degrees C in the oceans per
decade. (Smith, Thomas M.; Reynolds, Richard W. (2005-05-15). "A Global Merged Land–Air–Sea Surface Temperature Reconstruction Based on
Historical Observations (1880–1997). Journal of Climate 18 (12): 2021–2036. doi:10.1175/JCLI3362.1. ISSN 0894-8755. Retrieved on
The earth may very well be in a natural warming trend, but even if so, there is every reason to believe that it is being greatly exascerbated by human
activity. The dramatic increase in heating corresponds roughly with the start of the Industrial Revolution lending strong credence to the idea that
greenhouse gasses are the principal factor.