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Iceland volcano unlikely to slow global warming: scientists

Global temperatures hit hottest March on record: US agency
Washington (AFP) April 15, 2010 - Global temperatures fueled by El Nino seasonal warming last month chalked up the hottest March on record, US weather monitors reported Thursday. "Warmer-than-normal conditions dominated the globe, especially in northern Africa, South Asia and Canada," the National Oceanic and Atmospheric Administration said in a statement. Combined global land and ocean average surface temperature for March 2010 was the warmest on record at 13.5 degrees Celsius (56.3 degrees Fahrenheit), which is 0.77 degrees Celsius above the 20th century average of 12.7 C, it said. Average ocean temperatures were the hottest for any March since record-keeping began in 1880, while the global land surface was the fourth warmest for any March on record, NOAA said, citing analysis from the National Climate Data Center.

It added that the January-March period was the planet's fourth warmest on record. The US agency cited two Asian examples of high March mercury: Tibet had its second warmest March since records began in 1951, it said citing the Beijing Climate Center, while Delhi, India had its own second warmest March since 1901 record-keeping, according to the India Meteorological Department. Cooler-than-normal temperatures prevailed in some locations, however, including Mongolia, eastern Russia, northern and western Europe, northern Australia, western Alaska and the southeastern United States, NOAA said. The agency also pointed to Arctic sea ice as a temperature indicator, and said this was the 17th consecutive March in which Arctic sea ice coverage was below average.

Last month's average coverage of 15.1 million square kilometers (5.8 million square miles) was 4.1 percent below the 1979-2000 average, the agency said. NOAA stressed that while El Nino, the weather anomaly which wreaks havoc on normal weather patterns from the western seaboard of Latin America to east Africa, weakened to a moderate strength in March, "it contributed significantly to the warmth in the tropical belt and the overall ocean temperature." El Nino was expected to maintain its influence in the northern hemisphere "at least through the spring," NOAA said. The record March temperatures are likely to be seen as evidence backing the case of those who believe climate change is an urgent crisis which must be addressed at the global level. The United Nations and several countries have called for a legally-binding agreement on climate change, but at a summit in Copenhagen in December states failed to agree on a deadline to reduce carbon emissions that cause global warming.
by Staff Writers
Paris (AFP) April 16, 2010
Big volcanic eruptions have had a cooling effect on Earth's climate, but the Icelandic event is too small to provide any such respite from manmade global warming, scientists said on Friday.

The benchmark cooling event of the past 20 years was in 1991, when Mount Pinatubo erupted in the Philippines.

It cooled Earth's surface by 0.5 degrees Celsius (0.9 degrees Fahrenheit) over the next year, enough to offset the impact of greenhouse gases from 1991 to 1993.

A smaller cooling episode occurred in 1980, when Mount St. Helens in the US state of Washington blew its top, an event that while impressive disgorged only a tenth of the material of Pinatubo.

The chill comes from a simple formula: The volcano spews out a huge amount of fine volcanic ash and sulphur dioxide, which are transported into the high altitude layer known as the stratosphere.

There, chemistry and physics combine, creating a fine layer of whitish particles that for months or years are blown around the Earth and reflect some of the Sun's rays rather than let the radiation reach the ground.

"Basically, it's like putting a reflector shield over the windscreen of your car -- you're stopping the inside of the atmosphere getting too warm," said Colin Macpherson of Durham University, northeastern England.

But he and others said the eruption at Iceland's Eyjafjallajokull glacier so far was too small, did not have sufficient sulphur content and its plume circulated at too low an altitude to make an impact.

Any effect will be "very insignificant," said Scylla Sillayo of the World Meteorological Organisation (WMO) in Geneva.

"At the moment, we are looking at something that's about 100 times smaller than Mount St. Helen's. At the scale it's at now, it's relatively unlikely that it will have any perceptible effect on climate," explained Kathryn Goodenough of the British Geological Survey (BGS).

Emmanuel Bocrie of the French weather service, Meteo France, added: "With Pinatubo, ash rose to 18,000 metres (58,500 feet), in the tropics.

"It's not at all the same situation in this case, where the plume is at an average of 6,000 metres (20,000 feet), with peaks of 11,000 metres (35,750 feet). In addition, this is in a zone of the atmosphere [the troposphere] where there are powerful winds, which have a huge dispersing effect."

The scientists said the Eyjafjallajokull eruption could have a regional effect on Europe's climate -- but only provided it went on for a matter of years.

"Back in the 1780s, a large eruption in southern Iceland went on for a couple of years and generated a lot of sulphur," said Macpherson.

"It caused a smog that was really rather nasty, there was a failure of crops as a result of acid rain, the air quality was really very poor. But that took the better part of two years to cause that kind of effect and certainly we are not looking at anything like that right now."

Another is a theory -- but no more than that -- that the present eruption could touch off a far larger, neighbouring volcano called Katla.

From 1821-1823, the present volcano erupted on and off, and at the end of the cycle, Katla erupted.

"People have suggested there may be links between them, through fissures, but it's important to emphasise there is no proof the one would trigger the other," Goodenough said.

Volcanic cooling is in any case only a temporary brake on the effects of manmade greenhouse gases, blamed for stoking dangerous change to the climate system.

Earth's surface temperature rose by 0.74 C (1.3 F) from 1906-2005, the UN's Intergovernmental Panel on Climate Change (IPCC) says. In the last half-century of that period, the warming doubled, to around 0.13 C (0.23 F) per decade.

Another downside is that the volcano material in the stratosphere damages Earth's ozone shield against ultraviolet radiation.




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