May 28 2004
From The Space Library
A group of scientists led by Enric Pallé of the New Jersey Institute of Technology published research indicating that, since 1999, the amount of sunlight reaching Earth's surface had declined. Analyzing NASA's data on cloud cover, along with data from Earth-based telescopes, the team had calculated how much sunlight Earth reflected to the Moon, using the results to determine the amount of sunlight that reached Earth. They reported that the amount of sunlight reaching Earth's surface had begun to increase in the mid-1980s, but had started to decline in the early 1990s, a trend that the team attributed to the increasing pollution of Earth's air. The air pollution had reduced the amount of sunlight reaching Earth's surface and had increased the amount of water droplets condensing in the atmosphere, thereby increasing the amount of cloud cover blocking sunlight. (Enric Pallé et al., “Changes in Earth's Reflectance over the Past Two Decades,” Science 304, no. 5676 (28 May 2004): 1299-1301; Kenneth Chang, “After a Period of Brightness, Earth Dims, Researchers Say,” New York Times, 28 May 2004.
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