Can we avoid increasing climate change without dramatically lowering atmospheric CO2 emissions from fossil fuel burning?
The answer is essentially no. If we decrease emissions of greenhouse gases like methane, nitrous oxide, or chlorofluorocarbons, their atmospheric burden, and thus their climate forcing, will decrease in one to several decades. However, the effect of CO2 emissions on the forcing of climate change is primarily dependent on the total amount emitted since the beginning of the industrial revolution. Roughly speaking, as long as we continue to emit CO2, its climate forcing will continue to increase, so that as time progresses its effect on climate forcing would gradually overwhelm the others more and more. Once CO2 has been emitted into the atmosphere, the carbon cycle will redistribute it between the atmosphere, oceans, and terrestrial biosphere, but it will not disappear from those systems for thousands of years. This fact explains why all future scenarios holding atmospheric CO2 constant at some specified level need to drive emissions gradually to zero. This will occur sooner if the level
