[tt] Reuters: Climate change warms Arctic, cools Antarctica

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Climate change warms Arctic, cools Antarctica
http://uk.reuters.com/articlePrint?articleId=UKN0220811720080502
8.5.2

By Deborah Zabarenko, Environment Correspondent

WASHINGTON (Reuters) - The Arctic and Antarctica are poles apart
when it comes to the effects of human-fueled climate change,
scientists said on Friday: in the north, it is melting sea ice, but
in the south, it powers winds that chill things down.

The North and South poles are both subject to solar radiation and
rising levels of climate-warming greenhouse gases, the researchers
said in a telephone briefing. But Antarctica is also affected by an
ozone hole hovering high above it during the austral summer.

"All the evidence points toward human-made effects playing a major
role in the changes that we see at both poles and evidence that
contradicts this is very hard to find," said Jennifer Francis, an
atmospheric scientist at Rutgers University in New Jersey.

An examination of many previous studies about polar climate, to be
published May 6 in the journal Eos, "further depletes the arsenal of
those who insist that human-caused climate change is nothing to
worry about," Francis said in a telephone briefing.

In the Arctic, Francis and co-authors of the research said, warming
spurred by human-generated carbon dioxide emissions has combined
with natural climate variations to create a "perfect Arctic storm"
that caused a dramatic disappearance of sea ice last year, a trend
likely to continue.

'NEW STATE'

"Natural climate variability and global warming were actually
working together and they've sent the Arctic into a new state for
the climate that has much less sea ice," said James Overland, an
oceanographer at the U.S. National Oceanic and Atmospheric
Administration. "There's very little chance for the climate to
return to the conditions of 20 years ago."

In Antarctica, the ozone hole adds a new factor to an already
complicated set of weather patterns, according to Gareth Marshall of
the British Antarctic Survey.

The changes in air pressure that go along with depleted
stratospheric ozone are responsible for an increase in the westerly
winds that whip around the Southern Ocean, at latitudes a bit north
of most of Antarctica.

These winds isolate much of the southern continent from some of the
impact of global warming, Marshall said. The exception is the
Antarctic Peninsula, which reaches northward toward South America.
There, the effects of warming have been dramatic, he said, because
the winds that protect the rest of Antarctica do not insulate the
peninsula.

The stratospheric ozone hole, caused by the ozone-depleting release
of chemicals found in refrigerants and hair sprays, is likely to
fully recover by 2070 as less of these chemicals are in use, as a
result of international agreements.

The ozone layer shields Earth from harmful solar radiation, but its
recovery is likely to open the way for warming in central
Antarctica, the scientists said.

(Editing by Patricia Zengerle)