Science Digest
September 1982, p. 65
Side article to "The Lost Seas of Venus"
Note that the 2 in CO2 should be a subscript


GREENHOUSE ADVANTAGE

Most of us have heard dire warnings that Earth could become another Venus
because of the greenhouse effect. The carbon dioxide (CO2) pollution we spew
into our environment allows the sun's warm rays to penetrate the atmosphere, but
it traps more and more of the heat reradiated from the ground. As a result, it
is said, global temperatures could begin to rise at an alarming rate and wreak
havoc. But recent studies suggest a different, brighter scenario: this pollution
may cause only a slight greenhouse effect, which may be beneficial.

By burning coal, oil and gas over the past century, we have sent about 150
billion tons of CO2 into the atmosphere. Through deforestation, we have
prevented the photosynthetic conversion of billions of tons of CO2 into oxygen.
The result has been about a 15 percent increase in the level of atmospheric CO2,
with the level rising at a rate of about 0.4 percent annually. By early in the
next century, say some climatologists, CO2 levels could double and cause a rise
in atmospheric temperatures of between 2 degrees and 4 degrees Celsius.

Scientists have predicted that such a warming trend could trigger a series of
cataclysms. Polar ice caps could melt, flooding coastal cities; wind circulation
could diminish, reducing wind-driven ocean currents and thus depleting fish
resources; fluctuations in regional weather patterns could trigger droughts and
floods, endangering wildlife and making formerly arable land and and vice versa.

But according to Sylvan Wittwer, director of the Michigan State University
Agricultural Station, there is no threat of disaster. Greater amounts of CO2, he
points out, have long been known to stimulate plant photosynthesis and will
increase leaf, root and flower growth and fruit yield. "The prospect of a
climate change from increasing atmospheric levels of CO2 does not frighten U.S.
agriculturists and foresters," says Wittwer. "There's no such thing as a normal
climate. We have dealt with weather fluctuations all along in agriculture."

Sherwood Idso, a research physicist at the U.S. Water Conservation Laboratory in
Arizona, concurs. His 12-year study of the greenhouse effect indicates that
doubling atmospheric CO2 would increase Earth's temperature by only about 0.25
degrees, less than our climate's natural variations. Furthermore, he claims that
temperatures would not rise significantly even if CO2 levels increased 10-fold.
According to Idso, doubling or tripling the amount of CO2 is actually desirable,
since it could increase global agricultural productivity by 20 to 50 percent.

-Dennis Meredith