Estimated Climate Forcings Today Compared With 150 Years Ago
This graphic depicts changes in 12 climate "forcings" or factors that have contributed to climate change since 1850. These agents can be categorized into three areas: greenhouse gases, other man-made (anthropogenic) forcings, and natural forcings. The greenhouse gases consist of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and chlorofluorocarbons (CFCs). The other anthropogenic forcings consist of black carbon (soot, formed by incomplete combustion), reflective aerosols (tiny airborne particles that reflect sunlight back to space), soil or dust, land cover changes, and forced cloud changes. Natural forcings include changes of the sun's energy and changes of aerosols from volcanic eruptions.
Hansen, J.E., and Mki. Sato, Trends of measured climate forcing agents, Proc. Natl. Acad. Sci. 98, 14778-14783 (2001).