Radiative forcing measures the influence that climate-altering factors have on the energy balance of the Earth. Examples of factors that can alter the Earth’s energy balance include atmospheric concentrations of greenhouse gases, aerosols from volcanoes and air pollution, and the amount of solar radiation delivered to the Earth by the Sun.
In a state of equilibrium, solar radiation entering the atmosphere equals the radiation that leaves the atmosphere. Figure 1 illustrates this energy balance. The radiative forcing of a particular factor, such as atmospheric concentrations of carbon dioxide (CO2), is the change in the energy balance that results from a change in the factor, such as an increase in CO2 concentrations. When the radiative forcing of a factor is positive, increases in the factor cause warming of the atmosphere. In contrast, for a negative radiative forcing, increases in the factor ultimately cause cooling (Forster et al. 2007).
Adapted for eXtension.org by Michael Crimmins, University Arizona
Forster, P., et al. 2007. Changes in atmospheric constituents and in radiative forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Southwest Climate Change Network
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