http://www.physorg.com/news10143.html Less sunlight reaching the Earth's surface has not translated into cooler temperatures, according to a team of solar physicists at New Jersey Institute of Technology. The scientists, who monitor the Earth's reflectance by measuring what is known as the moon's earthshine, have observed that the amount of light reflected by Earth -- its albedo -- has increased since 2000. The result has been less sunlight reaching the Earth's surface.
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The just-released update of the 20-year sequence of ISCCP satellite cloud data shows that during the first 15 years of observations, the percent difference between high lying and low-lying clouds remained steady at 7-8 percent. But in the last five years, for some unknown reason, the difference has almost doubled to 13 percent. The ISCCP data is a careful compilation of cloud observations covering the entire Earth from a range of meteorological satellites.
"That increase in the difference signals a relative decrease in the cooling effect of clouds," said Goode. "Thus, the rising reflectance of the Earth has not led to a reversal of global warming from the increase in sunlight being reflected back into space." What has happened is that the low, cooling clouds have decreased during the most recent years, while high, warming clouds have increased even more. Thus, the cloud data also reveal an increase in total cloud amount during 2000-2004. That increase is consistent with the earlier earthshine result of growing reflectance throughout that period.
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The earthshine studied by Goode and his colleagues can be seen as a ghostly glow associated with the moon's "dark side" -- or the portion of the lunar disk not lit by the Sun. The cloudier the Earth, the brighter the earthshine. "The phenomenon of earthshine was first observed by Leonardo DaVinci," said Goode.
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