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Global Warming will step up after 2009 |
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Written by Deborah Zabarenko
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Thursday, 09 August 2007 |
Global warming is forecast to set in with a vengeance after 2009, with at
least half of the five following years expected to be hotter than 1998, the
warmest year on record, scientists reported on Thursday.
Climate experts have long predicted a general warming trend over the 21st
century spurred by the greenhouse effect, but this new study gets more specific
about what is likely to happen in the decade that started in 2005.
To make this kind of prediction, researchers at Britain's Met Office -- which
deals with meteorology -- made a computer model that takes into account such
natural phenomena as the El Nino pattern in the Pacific Ocean and other
fluctuations in ocean circulation and heat content.
A forecast of the next decade is particularly useful, because climate could be
dominated over this period by these natural changes, rather than human-caused
global warming, study author Douglas Smith said by telephone.
In research published in the journal Science, Smith and his colleagues predicted
that the next three or four years would show little warming despite an overall
forecast that saw warming over the decade.
"There is ... particular interest in the coming decade, which represents a key
planning horizon for infrastructure upgrades, insurance, energy policy and
business development," Smith and his co-authors noted.
The real heat will start after 2009, they said.
Until then, the natural forces will offset the expected warming caused by human
activities, such as the burning of fossil fuels, which releases the greenhouse
gas carbon dioxide.
"HINDCASTS" FOR THE FUTURE
"There is ... particular interest in the coming decade, which represents a key
planning horizon for infrastructure upgrades, insurance, energy policy and
business development," Smith and his co-authors noted.
To check their models, the scientists used a series of "hindcasts" -- forecasts
that look back in time -- going back to 1982, and compared what their models
predicted with what actually occurred.
Factoring in the natural variability of ocean currents and temperature
fluctuations yielded an accurate picture, the researchers found. This differed
from other models which mainly considered human-caused climate change.
"Over the 100-year timescale, the main change is going to come from greenhouse
gases that will dominate natural variability, but in the coming 10 years the
natural internal variability is comparable," Smith said.
In another climate change article in the online journal Science Express, U.S.
researchers reported that soot from industry and forest fires had a dramatic
impact on the Arctic climate, starting around the time of the Industrial
Revolution.
Industrial pollution brought a seven-fold increase in soot -- also known as
black carbon -- in Arctic snow during the late 19th and early 20th centuries,
scientists at the Desert Research Institute found.
Soot, mostly from burning coal, reduces the reflectivity of snow and ice,
letting Earth's surface absorb more solar energy and possibly resulting in
earlier snow melts and exposure of much darker underlying soil, rock and sea
ice. This in turn led to warming across much of the Arctic region.
At its height from 1906 to 1910, estimated warming from soot on Arctic snow was
eight times that of the pre-industrial era, the researchers said.
Source: Reuters
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