The net flux of radiation in or out of a system. The five major greenhouse gases account for about 97% of the direct radiative forcing by long-lived gases. Interannual variations in the growth rate of radiative forcing due to CO2 are large, and probably related to natural phenomena such as volcanic eruptions and ENSO events, as well as to anthropogenic activity (Hoffman et al. (2006) Tellus B 58, 5). Precisely the same forcing can produce hugely divergent evolutions of the climate system given infinitesimally small differences in initial conditions (Washington (2000) PPG24, 4; E. N. Lorenz1963).
A forcing factor would therefore be a factor that affects forcing (for example, Cuffy and Vimeux (2001) Nature412), but Tooth (2008) PPG32, 1 lists climate, tectonics, and human activity as forcing factors in an arid geomorphology, and Burningham (2008) Geomorph. 97, 3–4 writes of sea-level rise as a forcing factor on estuaries. (The literature is littered with references to forcing factors—clearly the buzzwords—but the writers seem to mean major/dominating factors.) Coco and Murray (2007) Geomorph. 91, 3–4 go one further, and refer to a forcing template of spatial structures and geological constraints in the evolution of sand patterns.
Subjects: Earth Sciences and Geography.