ABSTRACT
The earth’s climate is fundamentally driven by the balance between incoming solar radiation and outgoing infrared radiation (see greenhouse effect). Radiative forcing is derived from anthropogenic greenhouse gas emissions and other factors that force the radiation balance away from its natural state.1 It is expressed in global annual average Watts per square meter (Wm-2). In effect it is a measure of “how far out of balance” the atmosphere currently is. If net radiative forcing is positive, the earth’s system is absorbing more energy than would normally be the case, leading to global warming. Conversely, if radiative forcing is negative, the earth absorbs less energy than normal, resulting in global cooling. At present, radiative forcing stands at +1.6 Wm-2, indicating a net warming effect.
