From: Damien Broderick (d.broderick@english.unimelb.edu.au)
Date: Wed Jun 20 2001 - 02:32:43 MDT
COLUMBUS, Ohio -- Global warming is a natural geological process that could
begin to reverse itself within 10 to 20 years, predicts an Ohio State
University researcher.
The researcher suggests that atmospheric carbon dioxide -- often thought of
as a key "greenhouse gas" -- is not the cause of global warming. The
opposite is most likely to be true, according to Robert Essenhigh
<http://rclsgi.eng.ohio-state.edu/people/essenhigh.html> , E.G. Bailey
Professor of Energy Conservation in Ohio State's Department of Mechanical
Engineering <http://www.mecheng.ohio-state.edu/> . It is the rising global
temperatures that are naturally increasing the levels of carbon dioxide,
not the other way around, he says.
Essenhigh explains his position in a "viewpoint" article in the current
issue of the journal Chemical Innovation
<http://pubs.acs.org/journals/chtedd/> , published by the American Chemical
Society <http://www.acs.org/>
Many people blame global warming on carbon dioxide sent into the atmosphere
from burning fossil fuels in man-made devices such as automobiles and power
plants. Essenhigh believes these people fail to account for the much
greater amount of carbon dioxide that enters -- and leaves -- the
atmosphere as part of the natural cycle of water exchange from, and back
into, the sea and vegetation.
"Many scientists who have tried to mathematically determine the
relationship between carbon dioxide and global temperature would appear to
have vastly underestimated the significance of water in the atmosphere as a
radiation-absorbing gas," Essenhigh argues. "If you ignore the water,
you're going to get the wrong answer."
How could so many scientists miss out on this critical bit of information,
as Essenhigh believes? He said a National Academy of Sciences
<http://www.nationalacademies.org/> report on carbon dioxide levels that
was published in 1977 omitted information about water as a gas and
identified it only as vapor, which means condensed water or cloud, which is
at a much lower concentration in the atmosphere; and most subsequent
investigations into this area evidently have built upon the pattern of that
report.
For his hypothesis, Essenhigh examined data from various other sources,
including measurements of ocean evaporation rates, man-made sources of
carbon dioxide, and global temperature data for the last one million years.
He cites a 1995 report from the Intergovernmental Panel on Climate Change
(IPCC) <http://www.ipcc.ch/> , a panel formed by the World Meteorological
Organization <http://www.wmo.ch/indexflash.html> and the United Nations
Environment Programme <http://www.unep.org/> in 1988 to assess the risk of
human-induced climate change. In the report, the IPCC wrote that some 90
billion tons of carbon as carbon dioxide annually circulate between the
earth's ocean and the atmosphere, and another 60 billion tons exchange
between the vegetation and the atmosphere.
Compared to man-made sources' emission of about 5 to 6 billion tons per
year, the natural sources would then account for more than 95 percent of
all atmospheric carbon dioxide, Essenhigh said.
"At 6 billion tons, humans are then responsible for a comparatively small
amount - less than 5 percent - of atmospheric carbon dioxide," he said.
"And if nature is the source of the rest of the carbon dioxide, then it is
difficult to see that man-made carbon dioxide can be driving the rising
temperatures. In fact, I don't believe it does."
Some scientists believe that the human contribution to carbon dioxide in
the atmosphere, however small, is of a critical amount that could
nonetheless upset Earth's environmental balance. But Essenhigh feels that,
mathematically, that hypothesis hasn't been adequately substantiated.
Here's how Essenhigh sees the global temperature system working: As
temperatures rise, the carbon dioxide equilibrium in the water changes, and
this releases more carbon dioxide into the atmosphere. According to this
scenario, atmospheric carbon dioxide is then an indicator of rising
temperatures -- not the driving force behind it.
Essenhigh attributes the current reported rise in global temperatures to a
natural cycle of warming and cooling.
He examined data that Cambridge University <http://www.cam.ac.uk/>
geologists Nicholas Shackleton and Neil Opdyke reported in the journal
Quaternary Research <http://www.academicpress.com/www/journal/qr.htm> in
1973, which found that global temperatures have been oscillating steadily,
with an average rising gradually, over the last one million years -- long
before human industry began to release carbon dioxide into the atmosphere.
Opdyke is now at the University of Florida <http://www.ufl.edu/> .
According to Shackleton and Opdyke's data, average global temperatures have
risen less than one degree in the last million years, though the amplitude
of the periodic oscillation has now risen in that time from about 5 degrees
to about 10 degrees, with a period of about 100,000 years.
"Today, we are simply near a peak in the current cycle that started about
25,000 years ago," Essenhigh explained.
As to why highs and lows follow a 100,000 year cycle, the explanation
Essenhigh uses is that the Arctic Ocean acts as a giant temperature
regulator, an idea known as the "Arctic Ocean Model." This model first
appeared over 30 years ago and is well presented in the 1974 book Weather
Machine: How our weather works and why it is changing, by Nigel Calder, a
former editor of New Scientist <http://www.newscientist.com/> magazine.
According to this model, when the Arctic Ocean is frozen over, as it is
today, Essenhigh said, it prevents evaporation of water that would
otherwise escape to the atmosphere and then return as snow. When there is
less snow to replenish the Arctic ice cap, the cap may start to shrink.
That could be the cause behind the retreat of the Arctic ice cap that
scientists are documenting today, Essenhigh said.
As the ice cap melts, the earth warms, until the Arctic Ocean opens again.
Once enough water is available by evaporation from the ocean into the
atmosphere, snows can begin to replenish the ice cap. At that point, the
Arctic ice begins to expand, the global temperature can then start to
reverse, and the earth can start re-entry to a new ice age.
According to Essenhigh's estimations, Earth may reach a peak in the current
temperature profile within the next 10 to 20 years, and then it could begin
to cool into a new ice age.
Essenhigh knows that his scientific opinion is a minority one. As far as he
knows, he's the only person who's linked global warming and carbon dioxide
in this particular way. But he maintains his evaluations represent an
improvement on those of the majority opinion, because they are logically
rigorous and includes water vapor as a far more significant factor than in
other studies.
"If there are flaws in these propositions, I'm listening," he wrote in his
Chemical Innovation paper. "But if there are objections, let's have them
with the numbers."
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