Geoscience Reference
In-Depth Information
are stored in the earth's crust for millions of years and thus have little if any
C
14
, presented just such a source. The dilution of atmospheric carbon with
fossil fuel carbon is known as the Suess effect. It provided a radiochemical
confirmation of a contention made in 1938, by an obscure British steam
engineer named Guy Stewart Callendar, that fossil fuel use contributed
CO
2
to the atmosphere.
7
At first, Revelle and Suess both assumed— like many other scientists—
that the oceans would absorb this excess CO
2
, and the two men hoped to
study and trace radioactive CO
2
as it circulated through the atmosphere
and found its way into the seas. Shortly before they sent their paper on
the subject to the journal
Te l l u s
in 1957, however, it occurred to Revelle
that they had failed to account for the tendency of seawater— a complex
and often poorly stirred chemical mélange— to retain a generally constant
acidity through a self-regulating “buffering” mechanism involving CO
2
.
8
The CO
2
that most scientists assumed would be absorbed might just as
easily be re-released while still at the ocean surface, resulting in the over-
all increase in atmospheric CO
2
that Callendar, for different reasons, had
predicted. That increase could in turn have interesting and far-reaching
geophysical significance.
“Human beings,” Revelle famously wrote, “are now carrying out a large
scale geophysical experiment of a kind that could not have happened in the
past nor be reproduced in the future. Within centuries we are returning
to the atmosphere and oceans the concentrated organic carbon stored in
sedimentary rocks over hundreds of millions of years. This experiment, if
adequately documented, may yield far-reaching insight into the processes
determining weather and climate.”
9
In retrospect, Revelle's “grand experiment” statement has been framed
as an early warning on global warming, but at the time Revelle and Suess
were more curious and excited than anxious. As a colleague later remem-
bered, “Roger wasn't alarmed at all . . . he liked great geophysical experi-
ments.”
10
Indeed, Revelle's realization about buffering was a late addition to
the Revelle-Suess paper, which on the whole actually challenged the extent
of the so-called Callendar Effect. Nevertheless, the paper's conclusion—
and, more importantly, its authors— made an impact on the way scientists
and their government sponsors interpreted atmospheric CO
2
for the next
half century. That impact began with the advent of the Keeling Curve.
For Revelle, the immediate danger in the grand experiment was that
