It seems the more details we get about global warming, the more pessimistic the predictions. This is not strictly true, for example some studies show that the oceans have greater capacity than we thought to absorb carbon-dioxide and buffer the greenhouse effect. Still, the overall impression is that with each new study, the possibility for faster and more devastating effects from global warming increases. Case in point, a new study based on Earth’s geological record, that compares the rise in sea level during inter-glacial warming periods, and the warming trends we are seeing now.

A new analysis of the geological record of the Earth’s sea level, carried out by scientists at Princeton and Harvard universities and published in the Dec. 16 issue of Nature, employs a novel statistical approach that reveals the planet’s polar ice sheets are vulnerable to large-scale melting even under moderate global warming scenarios. Such melting would lead to a large and relatively rapid rise in global sea level.
 
According to the analysis, an additional 2 degrees of global warming could commit the planet to 6 to 9 meters (20 to 30 feet) of long-term sea level rise. This rise would inundate low-lying coastal areas where hundreds of millions of people now reside. It would permanently submerge New Orleans and other parts of southern Louisiana, much of southern Florida and other parts of the U.S. East Coast, much of Bangladesh, and most of the Netherlands, unless unprecedented and expensive coastal protection were undertaken. And while the researchers’ findings indicate that such a rise would likely take centuries to complete, if emissions of greenhouse gases are not abated, the planet could be committed during this century to a level of warming sufficient to trigger this outcome.
[Source: EurekAlert]

 
This study adds to the picture presented by the IPCC (Intergovernmental Panel on Climate Change) 2007 report by including the melting of polar and Greenland ice-sheets. It shows that sea levels and the rate of change were underestimated.