Nov 5 2001
From The Space Library
Researchers from NASA and the National Oceanic and Atmospheric Administration (NOAA) published research indicating that, during the 20th century, the world’s average temperatures had increased, and the United States’ average temperatures had declined. Using data from satellites and 7,200 weather stations worldwide, NASA and NOAA scientists had found that the global mean surface air temperature had increased by 1ºF (0.6ºC) during the 20th century. However, temperatures had not increased consistently but had undergone successive periods of warming (from 1900 to 1940), cooling (1940 to 1965), and warming again (1965 to 2000). The evidence also indicated that these temperature changes had not been uniform throughout Earth. For example, although the average surface air temperature in the United States had increased during the latter part of the 20th century, it had remained at a level comparable to average U.S. temperatures during the 193 0s. In addition, the researchers had discovered evidence that humans had influenced surface air temperatures on a local scale in large urban areas, suburbs, and even in small towns. However, the data also indicated that this effect had been of modest magnitude and might reflect problems with data measurement. (J. Hansen et al., “A Closer Look at United States and Global Surface Temperature Change,” Journal of Geophysical Research 106, no. D20 (2001): 23947–23963; NASA, “Satellites Shed Light On Warmer World,” news release 01-212, 5 November 2001.)
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