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Sunday, November 7, 2010

Volcanoes Have Shifted Asian Rainfall



Large, explosive volcanoes such as Indonesia's Merapi (erupting here in 2006) have the potential to change weather patterns if their eruptions are big enough.
http://www.terradaily.com/reports/Volcanoes_Have_Shifted_Asian_Rainfall_999.html New York NY (SPX) Nov 08, 2010 Scientists have long known that large volcanic explosions can affect the weather by spewing particles that block solar energy and cool the air. Some suspect that extended "volcanic winters" from gigantic blowups helped kill off dinosaurs and Neanderthals. In the summer following Indonesia's 1815 Tambora eruption, frost wrecked crops as far off as New England, and the 1991 blowout of the Philippines' Mount Pinatubo lowered average global temperatures by 0.7 degrees F-enough to mask the effects of manmade greenhouse gases for a year or so.
Now, scientists have shown that eruptions also affect rainfall over the Asian monsoon region, where seasonal storms water crops for nearly half of earth's population.
Tree-ring researchers at Columbia University's Lamont-Doherty Earth Observatory showed that big eruptions tend to dry up much of central Asia, but bring more rain to southeast Asian countries including Vietnam, Laos, Cambodia, Thailand and Myanmar-the opposite of what many climate models predict. Their paper appears in an advance online version of the journal Geophysical Research Letters.
The growth rings of some tree species can be correlated with rainfall, and the observatory's Tree Ring Lab used rings from some 300 sites across Asia to measure the effects of 54 eruptions going back about 800 years.
The data came from Lamont's new 1,000-year tree-ring atlas of Asian weather, which has already produced evidence of long, devastating droughts; the researchers also have done a prior study of volcanic cooling in the tropics.
"We might think of the study of the solid earth and the atmosphere as two different things, but really everything in the system is interconnected," said Kevin Anchukaitis, the study's lead author. "Volcanoes can be important players in climate over time."
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