BACK List of illustrations HOME
The Discovery of Global Warming November 2009
A century of average surface temperatures of the Northern Hemisphere, looking back from 1980. (Shown as differences in °C from the 1946-60 mean.) Decades later, scientists concluded that the drop after 1940 was largely due to a rise in industrial pollution, which blocked some sunlight, and that the decline was not seen in the Southern Hemisphere. For a graph of temperatures into the 21st century click here. From P. D. Jones et al., Monthly Weather Review 110 (1982), p. 67, reproduced by permission American Meteorological Society.