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Archive for February 5th, 2008

Scientists identify ‘tipping points’ of climate change

Posted by mhudema on February 5, 2008

By Steve Connor, Science Editor

Tuesday, 5 February 2008

http://www.independent.co.uk/environment/climate-change/scientists-identify-tipping-points-of-climate-change-778027.html?service=Print

A major international investigation by dozens of leading climate scientists has found that the “tipping points” for all nine scenarios – such as the melting of the Arctic sea ice or the disappearance of the Amazon rainforest – could occur within the next 100 years.

The scientists warn that climate change is likely to result in sudden and dramatic changes to some of the major geophysical elements of the Earth if global average temperatures continue to rise as a result of the predicted increase in emissions of man-made greenhouse gases.

Most and probably all of the nine scenarios are likely to be irreversible on a human timescale once they pass a certain threshold of change, and the widespread effects of the transition to the new state will be felt for generations to come, the scientists said.

“Society may be lulled into a false sense of security by smooth projections of global change. Our synthesis of present knowledge suggests that a variety of tipping elements could reach their critical point within this century under anthropogenic [man-made] climate change,” they report in the journal Proceedings of the National Academy of Sciences.

The study came out of a 2005 meeting of 36 leading climate scientists who drew on the expertise of a further 52 specialists. It is believed to be the first time that scientists have attempted to assess the risks of what they have termed “tipping elements” in the Earth’s climate system.

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Arctic summers ice-free ‘by 2013’

Posted by mhudema on February 5, 2008

Arctic summers ice-free ‘by 2013’

http://news.bbc.co.uk/2/hi/science/nature/7139797.stm

By Jonathan Amos
Science reporter, BBC News, San Francisco

Arctic summer melting in 2007 set new records

More details

Scientists in the US have presented one of the most dramatic forecasts yet for the disappearance of Arctic sea ice.

Their latest modelling studies indicate northern polar waters could be ice-free in summers within just 5-6 years.

Professor Wieslaw Maslowski told an American Geophysical Union meeting that previous projections had underestimated the processes now driving ice loss.

Summer melting this year reduced the ice cover to 4.13 million sq km, the smallest ever extent in modern times.

Remarkably, this stunning low point was not even incorporated into the model runs of Professor Maslowski and his team, which used data sets from 1979 to 2004 to constrain their future projections.

In the end, it will just melt away quite suddenly

Professor Peter Wadhams

“Our projection of 2013 for the removal of ice in summer is not accounting for the last two minima, in 2005 and 2007,” the researcher from the Naval Postgraduate School, Monterey, California, explained to the BBC.

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