[Mb-civic] Scientific American: Climate Model Predicts Greater Melting, Submerged Cities

[William Swiggard]

Climate Model Predicts Greater Melting, Submerged Cities 

Scientific American  |  March 24, 2006  |  Science News
       
Over the past 30 years, temperatures in the Arctic have been creeping 
up, rising half a degree Celsius with attendant increases in glacial 
melting and decreases in sea ice. Experts predict that at current levels 
of greenhouse gases--carbon dioxide alone is at 375 parts per 
million--the earth may warm by as much as five degrees Celsius, matching 
conditions roughly 130,000 years ago. Now a refined climate model is 
predicting, among other things, sea level rises of as much as 20 feet, 
according to research results published today in the journal Science.

Modeler Bette Otto-Bliesner of the National Center for Atmospheric 
Research in Boulder and paleoclimatologist Jonathan Overpeck of the 
University of Arizona matched results from the Community Climate System 
Model and climate records preserved in ice cores, exposed coral reefs, 
fossilized pollen and the chemical makeup of shells to determine the 
accuracy of the computer simulation. Roughly 130,000 years ago, the 
Arctic enjoyed higher levels of solar radiation, leading to increased 
warming in the summer and the retreat of glaciers worldwide. The model 
correctly predicted the extent of the resulting Arctic ice melt, enough 
to raise sea levels by roughly nine feet.

"Getting the past climate change correct in these models gives us more 
confidence in their ability to predict future climate change," 
Otto-Bliesner says. "These ice sheets have melted before and sea levels 
rose. The warmth needed isn't that much above present conditions."

But sea levels rose as much as 20 feet 130,000 years ago and Overpeck 
speculates that may have been the result of additional melting in 
Antarctica. After all, the ice there is not all landlocked; some rests 
in the ocean and a little warming in sea temperatures could melt it or 
pry it loose. And this time around, the warming is global, rather than 
concentrated in the Arctic. "In the Antarctic, all you have to do is 
break up the ice sheet and float it away and that would raise sea 
level," he says. "It's just like throwing a bunch of ice cubes into a 
full glass of water and watching the water spill over the top."

Such a sea level rise would permanently inundate low-lying lands like 
New Orleans, southern Florida, Bangladesh and the Netherlands. Already 
sea level rise has increased to an inch per decade, thanks to melting 
ice and warm water expansion, according to Overpeck. And evidence that 
the Arctic is exponentially warming continues to accumulate. Indeed, in 
another paper in the same issue of Science, Goran Ekstrom of Harvard 
University reported a marked increase in so-called glacial earthquakes 
(seismic events recorded throughout the world when Greenland's glaciers 
slip past rock) since 2002. In fact, last year alone saw twice as many 
quakes as in previous years, with most of that increase coming during 
the summer months.

"We need to start serious measures to reduce greenhouse gases within the 
next decade," Overpeck says. "If we don't do something soon, we're 
committed to [13 to 20 feet] of sea level rise in the future."

http://www.sciam.com/print_version.cfm?articleID=0007FA05-10BC-1423-90BC83414B7F0000
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.islandlists.com/pipermail/mb-civic/attachments/20060329/353ec4d6/attachment.htm