What’s so bad about Carbon Dioxide?

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.

‘Global Warming’. An OpenLearn chunk used/reworked by permission of The Open University copyright © (2007).’ http://creativecommons.org/licenses/by-nc-sa/2.0/uk/