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Volcano may have impact on weather world-wide


Knight Ridder Newspapers

Washington -- Atmospheric scientists around the globe are watching Mount Mayon erupt in the Philippines, because the volcano's plume has the potential to moderate weather worldwide.

If its eruptions intensify, experts say, the following winter would be warmer in much of the United States and the next two or three summers would be cooler. Historically, extreme climatic changes brought about by volcanoes have caused snow in New England in July and a dreary Swiss summer that inspired the creator of "Frankenstein."

Eruptions big enough to affect the climate significantly happen about once a decade. They spew millions of tons of sulfur dioxide into the upper atmosphere, which begins 10 miles above the Earth. The sulfur dioxide changes into sulfate aerosols, which are liquid particles that reflect sunlight and keep some of the warmth from reaching Earth's surface, experts say.

It's enough to put on hold but not reverse--the effects of global warming said Georgiy Stenchikov, a Rutgers University environmental sciences professor.

Eruptions also produce beautiful sunsets when aerosol particles refract the sunlight in brilliant hues.

Mount Mayon's eruptions aren't that powerful yet. But the potential and the probabilities are strong enough that scientists should be talking about it, Stenchikov said.

"Mount Mayon is a very rest less volcano, and it's (erupted) very regularly," said Stephen Self professor of volcanology at the University of Hawaii. "It's capable of having a fairly sizable eruption.

'There's plenty of magma and it could be coming out (still). This type of activity is very stop-start."

Has happened before

Mayon erupted with enough power to alter the climate in 1814 and again in 1897, according to Bob Tilling, a U.S. Geological survey volcanologist. Often, the biggest eruptions are the later ones. in 1991, Tilling noted, the Philippines' Mount Pinatubo first erupted on April l. Its major eruption--the one that last altered our weather--came on June 15. It's been almost nine years and the atmosphere only now is nearly empty of sun-blocking sulfite aerosols.

"We're at possibly the lowest aerosol levels in the stratosphere that we've seen." said NASA senior research scientist Larry Thomason. "It's the cleanest in the last 25 years." Mount Pinatubo had spewed 18 million to 30 million tons of sulfur dioxide into the stratosphere, experts said.

"It was so dense in the stratosphere we couldn't see through it all the time." Thomason said. Temperatures dropped about half a degree around the world. Due to varying thickness of aerosol levels it was even cooler and damper on the U.S. East coast. The effects lasted about three years. The biggest eruption measured, of the Indonesian volcano Tambora of 1815, produced "the year without a summer." That caused New England's summer snow and prompted morose writer Mary Wollstonecraft Shelley to create the classic, character Frankenstein.

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Posted by Anthony Benoit
Environmental Engineering Technology at Three Rivers