Volcano not yet big enough to have 'global effect': experts

[Guest guest]

Volcano not yet big enough to have 'global effect': experts

Alister Doyle, Reuters Published: Thursday, April 15, 2010

OSLO -- A vast cloud from an intensifying volcanic eruption in Iceland is too

small so far to slow global warming as happened in 1991 with the explosion of

Mount Pinatubo in the Philippines, experts say.

Cataclysmic eruptions, led by Pinatubo and Mount Chichon in Mexico in 1982 in

the 20th century, spewed so much debris into the upper atmosphere that they

cooled the planet for months, briefly offsetting the effect of industrial

heat-trapping gases.

" This is not like Pinatubo. So far the scale is not big enough to have a global

effect, " said Hans Olav Hygen, a climate researcher at the Norwegian

Meteorological Institute.

The eruption under the Eyjafjallajokull glacier -- 10 times more powerful than

another nearby last month -- threw up a 6 kilometre cloud of ash and closed down

air traffic across northern Europe.

" At the moment this is a relatively small eruption, not as big as some in the

past from Iceland, " said Colin Macpherson, a geologist at the University of

Durham in England. Experts were monitoring to see possible impacts of ash on

health.

A poison cloud from the eruption of Iceland's Laki volcano in 1783-84 killed

thousands of people across Europe and undermined farm output by spewing an

estimated 120 million tonnes of sulphur dioxide into the air, he said.

That amount of sulphur dioxide was three times European industrial output in

2006, he said.

Volcanic sulphur gases ejected high into the stratosphere and swept around the

globe in the jetstream can linger for 12 to 14 months and dim sunlight,

according to the U.N. panel of climate scientists.

Heavier ash generally falls back to Earth -- where it can cause respiratory

problems -- within 3 months.

Some experts advocate the deliberate injection of sulphur dioxide in the

stratosphere in a " geo-engineering " short cut to slow global warming and offset

more floods, heatwaves, droughts, and rising sea levels.

That option has become attractive for some after a U.N. climate summit in

Copenhagen in December failed to produce a binding global deal to cut emissions

of greenhouse gases. Others say the risks are too big -- ranging from

disruptions of weather patterns to acid rain.

" Pinatubo was the last major event. The levels of aerosols in the upper

atmosphere have been fairly low of late, " said Geoff Dollard, practice leader on

air quality at the AEA consultancy which advises the British government.

" Generally there's a cooling effect from aerosols, " he said. This is a lightish

dust. We are keeping an eye on it " for possible threats to health. Dust in the

air is nothing new -- storms from the Sahara can bring an orange-ish dust to

northern Europe.

On an index of climate change since 1980 run by the International

Geosphere-Biosphere Programme, conditions got worse every year except 1982, 1992

and 1996. It links the dips to volcanic fallout from Chichon, Pinatubo and

Monserrat in 1996.

http://www.nationalpost.com/most-popular/story.html?id=2910621