Slide 23: The effects of current radiative forcings
Contemporary society has introduced many forcing factors into the environment. Climatologists' understanding of the various forcing factors varies, as shown in this diagram. What is certain is that the warming effect of anthropogenic greenhouse gas emissions far outweighs most other radiative forcings. As you can see on the left, stratospheric ozone generally provides a cooling effect by absorbing UV radiation, whilst it has a considerably larger warming effect where it is found in the troposphere as a result of human activities. It is assumed that most aerosols mostly produce cooling effects in the atmosphere by reflecting solar radiation. And important exception to this rule is the action of black carbon soot, which tends rather to absorb most light, and re-radiate it as infra-red radiation into the atmosphere. The action of other forcing factors is very poorly understood, and so it is very hard to say with any certainty what effect they have on global temperatures.