Only a few months ago, the U.N. Intergovernmental Panel on Climate Change (IPCC) forecast--using computer models--that the Arctic Ocean could be ice free as early as 2050. The new report, citing more up to date satellite measurements, says the computers are off by about 30 years.
This is a big deal, folks. The polar ice cap over the Arctic Ocean reflects an enormous amount of the sun's energy away from earth, whereas dark seas would absorb that sunlight, adding to the effects of global warming.
Melting the polar ice cap will not, in itself, raise sea levels to any significant degree, since the ice is already floating in the water. (Same as ice melting in a glass of water.)
The danger, however, is that melting of the Arctic Ocean will further raise temperatures up north, accelerating the already alarming decline of the Greenland Ice Cap, which WILL raise sea levels. Indeed, some experts believe that as the Greenland ice melts, the glacial ice cap begins to float on a lake of melt water, raising the possibility of large portions sliding off into the sea all at once.
Unfortunately, if the new report is correct, it's probably already too late to prevent the Arctic Ocean from melting. That doesn't mean we shouldn't start taking action on global warming--but it does mean that time is already running out rapidly, and therefore that we need to take more aggressive action to prevent longer term catastrophes.