INFOTERRA: Solar activity and human influence on climate change


To Infoterra List <infoterra@cedar.at>
From Ashwani Vasishth <vasishth@usc.edu>
Date Sun, 14 Dec 2003 15:58:42 -0800 (PST)
Cc Envirosoc <ENVIROSOC@LISTSERV.BROWN.EDU>
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Reply-to Ashwani Vasishth <vasishth@usc.edu>
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On Mon, 15 Dec 2003, Ferdinand Engelbeen wrote:

> But if the sun's activity was enhanced in pre-industrial times, that
> should be the case now too, as the sun's activity is very high,
> compared to a few centuries ago. That means that the current climate
> models (which only count the sun's influence for direct energy input),
> underestimate the sun's role and overestimate the influence of
> greenhouse gases.
>

Read James Lovelock's Gaia Hypothesis.  Please do.  (See particularly,
Lovelock and Margulis's Daisyworld Model.  Its simple-minded, but
irrefutably powerful.)

The sun's temperature is substantially higher today, than it was in
pre-historic times.  But the planet's temperature has not increased to the
extent that this increase in solar radiation would suggest.  Why?
Because planetary bio-geo-chemical processes have been systematically
drawing-down stratospheric greenhouse gases (specifically, CO2), in a
bio-geo-chemically evolutionary response to increases in solar radiation,
thus maintaining the *very* narrow parameters for existing life-forms,
including humans.

Given the fact that the sun will continue to get hotter--until it burns
out--the laws of physics demand that the planet's heat-trapping abilities
(a direct function of stratospheric GHGs) continue to abate, if the
planet's life-support parameters are to remain substantially the same as
they have been, historically.

Now, note that, whatever other petty nuances and hair-splitting factoids
the flat-earthers might pull out of their stale bag of tricks, human
activity has almost constantly pushed to increase the amount of
stratospheric GHGs.  So, the question.  Are humans helping or hindering
the planetary bio-geo-chemical modulating response to increases in solar
radiation?

By the way, when scientists speak of the likely 2-4 degree increase in
*global* temperatures, this is in no way equivalent to a 2-4 degree change
in local temperatures.  Global "warming" is not the key issue.  Gloabl
"climate change" is what we need to care about.

About deep-historic human influinces on the planet's heat trapping
properties, and hence human influences in global climate, see the news
story appended below.

Cheers,
 Ashwani
     Vasishth         vasishth@usc.edu         (213) 236-1908
              http://www-rcf.usc.edu/~vasishth
         http://groups.yahoo.com/group/envecolnews/
            http://groups.yahoo.com/group/airqual/


 * * *

Date: Wed, 10 Dec 2003 22:56:48 -0800
From: ashwani vasishth <vasishth@usc.edu>
To: Environmental Ecology News <envecolnews@yahoogroups.com>
Subject: News: Historical Influence of Human Civilization On Global
    Climate

http://www.nytimes.com/2003/12/10/science/10WARM.html

December 10, 2003

Scientist Links Man to Climate Over the Ages
By KENNETH CHANG

SAN FRANCISCO, Dec. 9 - Humans have altered the world^s climate by
generating heat-trapping gases since almost the beginning of civilization
and even prevented the start of an ice age several thousand years ago, a
scientist said on Tuesday.

Most scientists attribute a rise in global temperatures over the past
century in part to emissions of carbon dioxide by human activities like
driving cars and operating factories.

Dr. William Ruddiman, an emeritus professor at the University of Virginia,
said at a meeting of the American Geophysical Union here that humans^
effect on climate went back nearly 10,000 years to when people gave up
hunting and gathering and began farming.  Dr. Ruddiman is also reporting
his findings in the journal Climatic Change.

In a commentary accompanying the article, Dr. Thomas J. Crowley of Duke
University, said he w as first taken aback by Dr. Ruddiman^s premise.
^But when I started reading,^ Dr. Crowley wrote, ^I could not help but
wonder whether he just might be on to something.^ The climate of the last
10,000 years has been unusually stable, allowing civilization to flourish.
But that is only because people chopped down swathes of forest in Europe,
China and India for croplands and pastures, Dr. Ruddiman said. Carbon
dioxide released by the destruction of the forests, plus methane, another
heat-trapping gas, produced by irrigated rice fields in Southeast Asia,
trapped enough heat to offset an expected natural cooling, he said.

^The stability is an accident,^ Dr. Ruddiman said.  Levels of carbon
dioxide and methane rise and fall in natural cycles lasting thousands of
years, and both reached a peak at the end of the last ice age 11,000 years
ago. Both then declined as expected.

Both should have continued declining through the present day, leading to
lower temperatures, and a new ice age should have begun 4,000 to 5,000
years ago, Dr. Ruddiman said.

Instead, levels of carbon dioxide reversed 8,000 years ago and starting
rising again. The decline in methane levels reversed 5,000 years ago,
coinciding with the advent of irrigation rice farming.

 * * *

Copyright 2003 The New York Times Company

**   NOTICE: In accordance with Title 17 U.S.C. Section 107, this
material is distributed, without profit, for research and educational
purposes only.   **



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