Relatively
speaking CO2 is a relatively weak greenhouse gas when compared
to equal masses of halocarbons which are a factor of at least
103 times more effective. The problem arises as humans are
responsible for generating so much more of CO2 gas than any
other!
In absolute terms the increase in atmospheric CO2 has
been
much greater than that for any of the other greenhouse gases
(natural or synthetic); it has risen by close to 100 ppm since
pre-industrial times, while the CH4 level, for example, has
gone up by around 1000 ppb or just 1 ppm. |
A
Delicate Balance?
The whole Earth–atmosphere system is in a dynamic
steady state or equilibrium. Most (89%) of the outgoing
longwave radiation is absorbed and recycled by the atmosphere,
and ultimately re-emitted to space from higher, colder
levels. As a result, energy circulates within the system
at a higher rate than the rate of input or output at
the top of the atmosphere: this is why the Earth's surface
is warmer than it otherwise would be. But in a balanced
state, there is no net accumulation of energy in any
part of the system, and no net loss.
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