Geoscience Reference
In-Depth Information
A Unique Experiment of Planetary Dimensions
Heat Seeker
One reason that Callendar's 1938 paper did not inspire follow-up was that scient-
ists could think of nothing to do to test the CO 2 theory. In the short run it did not
appear to be true, as through the 1940s global temperatures fell. And as Callendar
had pointed out, the oceans might well soak up enough excess CO 2 so that even
though the greenhouse effect is real, it is too small to matter. Then came a world
war. New instruments and methods, whose origins lay in their military applica-
tions, brought a revolution in the practice of science.
During the war and in the Cold War years that followed, infrared radiation be-
came the subject of intense study and generous government funding, as detecting
and interpreting the heat radiation given off by a jet engine or a human body had
obvious military benefits. One result was the heat-seeking missile, an early version
of which the United States nicknamed the Sidewinder for its curving and ominous
flight pattern.
OneofthemostaccomplishedinfraredresearchersofthepostwaryearswasGil-
bertN.Plass,whowrotesix topics andmorethanonehundredtechnical articles on
infrared radiation and a wide variety of other topics in physics. Early in the 1950s,
like Hulburt and Callendar before him, Plass realized that enough new information
had become available to allow a reappraisal of the CO 2 theory of climate change.
In addition, a new machine, the digital computer, could reduce the tedium of the
calculations.
PlasshadreadTyndall,Callendar,andthemeteorologists whohaddismissed the
CO 2 theory. In a 1956 paper, he cited as an example C. E. P. Brooks, who had writ-
ten in 1951 that scientists had abandoned the theory “when it was found that all the
long-wave radiation absorbed by CO 2 , is also absorbed by water vapour.” 1 With
the primitive instruments available to them, the early spectroscopists saw infrared
absorption as taking place in broad, virtually opaque frequency bands, as though
blocked by a board fence with no gaps between the boards. By Plass's day, scient-
ists had learned that CO 2 and other molecules have complex, multifaceted spectra
whose effect more resembles a picket fence, some of whose laths are exceedingly
thin. Plass understood that “the [carbon dioxide saturation] argument neglects the
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