http://www.nytimes.com/2004/05/13/science/13DARK.htmlGlobe Grows Darker as Sunshine Diminishes 10% to 37%
Defying expectation and easy explanation, hundreds of instruments around the world recorded a drop in sunshine reaching the surface of Earth, as much as 10 percent from the late 1950's to the early 90's, or 2 percent to 3 percent a decade. In some regions like Asia, the United States and Europe, the drop was even steeper. In Hong Kong, sunlight decreased 37 percent.
Yet the dimming trend — noticed by a handful of scientists 20 years ago but dismissed then as unbelievable — is attracting wide attention. Research on dimming and its implications for weather, water supplies and agriculture will be presented next week in Montreal at a joint meeting of American and Canadian geological groups.
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Dr. James E. Hansen, director of the NASA Goddard Institute for Space Studies in Manhattan, said that scientists had long known that pollution particles reflected some sunlight, but that they were now realizing the magnitude of the effect.
"It's occurred over a long time period," Dr. Hansen said. "So it's not something that, perhaps, jumps out at you as a person in the street. But it's a large effect."
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