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Thursday, October 1, 2009

Stefan Rahmstorf, Pier Vellinga: No way to stop sea levels from rising

No way to stop sea levels from rising

by, 30 September 2009

At an Oxford University climate conference, experts announced that sea levels across the globe will almost inevitably rise more than 6 feet.

"The crux of the sea level issue is that it starts very slowly but once it gets going it is practically unstoppable," said Stefan Rahmstorf, a scientist at Germany's Potsdam Institute and a broadly respected sea level expert.
"There is no way I can see to stop this rise, even if we have gone to zero emissions."

According to Rahmstorf, the best outcome was that once temperatures finally adjust and become stable, sea levels would only rise steadily "for centuries to come," rather than gain momentum.

The majority of scientists anticipate at least a 2 degrees Celsius jump in temperatures because of man-made greenhouse gas emissions, if not more. Just this last century, the world has warmed by 0.7-0.8 degrees, reported Reuters.

Rahmstorf surmises that even if the world were to limit warming to 1.5 degrees, there would still be over a six-foot rise in sea levels over centuries, which would swallow some island nations.

His best estimate projects that there will be over a three-foot rise in sea levels this century, assuming it warms three degrees, and up to over sixteen meters over the next three centuries.

"There is nothing we can do to stop this unless we manage to cool the planet. That would require extracting the carbon dioxide from the atmosphere. There is no way of doing this on the sufficient scale known today," he said.

Scientists have explained that ice melting takes on a momentum of its own. For example, when there is less ice to reflect heat, the air becomes warmer and warms the surrounding areas, which in turn causes more ice to melt.

"Once the ice is on the move, it's like a tipping point which reinforces itself," said Wageningen University's Pier Vellinga, citing various research.

"Even if you reduce all the emissions in the world once this has started it may be unstoppable. I conclude that beyond 2 degrees global average temperature rise the probability of the Greenland ice sheet disintegrating is 50 percent or more."

"(That) will result in about 7 meters sea level rise, and the time frame is about 300-1,000 years."

Bangkok will host delegates from about 190 nations in an effort to speed up negotiations led by the U.N. to replace the Kyoto Protocol with a more stringent climate treaty.

The speakers in Oxford cited points in history to fortify their claims about rising sea levels. Three million years ago the planet was 2-3 degrees warmer and the sea 25-35 meters higher, and 122,000 years ago 2 degrees warmer and 10 meters higher, they said.

"What we now see in Greenland, Antarctica could be a temporary phenomena but it could also be the start of what we saw 122,000 years ago," said Vellinga.

The past century has seen seal levels rise almost eight inches and that effect was accelerating, speakers noted.
This rise was building on storms such as those found in the Philippines, although there is not enough proof to blame that single event on climate change, said Rahmstorf.

"Of course the flooding from a given storm event would be less severe if we hadn't added those extra centimeters."

Approximately 40 million people across the world currently reside in flood plains, said Southampton University's Robert Nicholls. That amounts to 0.6 percent of the global population and 5 percent of global wealth, because of valuable assets such as airports and power plants.

Rahmstorf expressed confidence that coastal protection could significantly reduce lost land and assets. Speakers estimated the cost of that to be anywhere from $72.85 billion per year by 2020 to up to $215 billion a year by 2100.


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