Environmental Engineering Reference
In-Depth Information
in the atmosphere longer and its concentration was going
up faster than scientists had believed possible. It is worth a
bit of time to tell the story of how something so important
to today
'
s discussions could have been hidden for so long.
.
The First Climate Models
The
first serious attempt to understand climate in terms
of the interaction of the Earth
s energy budget with the
contents of the atmosphere was made in
'
by Swedish
chemist Svante Arrhenius, who went on to win the Nobel
Prize in Chemistry in
for other work. His much
simpli
ed climate model took into account the green-
house effect, including CO
. He calculated that reducing
the CO
in the atmosphere by half would lower the global
temperature by about
C), which is as much as it
was actually reduced in the last ice age. He also calculated
that the temperature would increase by about
F(
F(
þ
C) if the CO
in the atmosphere were doubled, not very
different from today
þ
s far more sophisticated models.
This brilliant work introduced for the
'
first time the
notion of feedback loops into the discussion of the atmos-
phere and climate. For example, if the temperature goes
up because CO
goes up, the amount of water vapor in the
atmosphere goes up too, just as vapor coming off a pond
increases as the temperature rises. Since water vapor itself
is a greenhouse gas, the temperature goes up still more.
His model did not include another feedback loop that
moves in the opposite direction, the effects of clouds. If
water vapor goes up, clouds would be expected to
increase. White clouds re
ect more of the incoming solar
radiation back into space before it gets to the ground than
