Major Arctic sea ice melt is expected this summer

Randoph E. Schmid, Associated Press Yahoo News 2 May 08;

The Arctic will remain on thinning ice, and climate warming is expected to begin affecting the Antarctic also, scientists said Friday.

"The long-term prognosis is not very optimistic," atmospheric scientist Jennifer Francis of Rutgers University said at a briefing.

Last summer sea ice in the North shrank to a record low, a change many attribute to global warming.

But while solar radiation and amounts of greenhouse gases in the atmosphere are similar at the poles, to date the regions have responded differently, with little change in the South, explained oceanographer James Overland of the National Oceanic and Atmospheric Administration.

What researchers have concluded was happening, was that in the North, global warming and natural variability of climate were reinforcing one another, sending the Arctic into a new state with much less sea ice than in the past.

"And there is very little chance for the climate to return to the conditions of 20 years ago," he added.

On the other hand, Overland explained, the ozone hole in the Antarctic masked conditions there, keeping temperatures low in most of the continent other than the peninsula reaching toward South America.

"So there is a scientific reason for why we're not seeing large changes in the Antarctic like we're seeing in the Arctic," he said.

But, Overland added, as the ozone hole recovers in coming years, global warming will begin to affect the South Pole also.

The briefing covered data being reported in a paper scheduled for publication next week in Eos, a journal of the American Geophysical Union.

Overland said he used to be among those skeptical about the effects of global climate change. The new findings, which he termed "startling," were developed at a recent workshop, he said.

There is agreement between weather observations, the output of computer climate models and scientific expectations for what should happen, added Francis.

All the evidence points toward human-made changes at both poles, she said, a conclusion that "further depletes the arsenals of those who insist that human-caused climate change is nothing to worry about."

Climatologist Gareth Marshall of the British Antarctic Survey said that while the term global warming is widely used, things are more complicated at the regional level.

In the Antarctic, he explained, climate change strengthened winds blowing around the continent, helping trap colder air. But that will decrease in the future, allowing warmer conditions to begin, he said.

And, Marshall added, all studies now show that human activities are the drivers of climate change in the Antarctic.

Asked if this summer will match last year's record low sea ice in the North, Overland that is likely.

"The tea leaves point to a minimal amount of sea ice next September, that would be the same as we had last summer, 40 percent loss compared to 20 years ago," he said. Overland added that the winter freeze got a late start last fall.

Francis added: "Over this entire fall, winter and right up 'till today the ice concentration, the amount of ice that's floating around on the Arctic, has been below normal every single day."

"All arrows are pointing towards, certainly not a recovery, something like we had last summer and possibly worse," she said.

Climate change warms Arctic, cools Antarctica
Deborah Zabarenko, Reuters 2 May 08;

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)