Arctic ice may vanish due to warming

A new study using satellite measurements has revealed that thick Arctic sea ice older than nine years, had all but disappeared by 2007, because of global warming. 

According to a report in Discovery News , this older ice is giving way to thinner ice which is only two or three years old. In fact, the new ice now accounts for 58 percent of the ice cover - up from 35 percent in the mid-1980s. 

"The thinning is consistent with long-term warming," said ice researcher James Maslanik of the University of Colorado in Boulder. 

The thinner ice that's now dominating the Arctic is more vulnerable to ridging - the crumpling into ridged rafts of ice - or melting, said the report. 

Either way, there will be more open water, which can absorb summer sunlight and warm up the Arctic even further, the report added. 

The key to the new sea ice measurements is data from the laser altimeter onboard NASA's Ice, Cloud and Elevation Satellite (ICE-Sat). 

Using the altimeter data to measure the different heights of ice floating above the water, the researchers could distinguish between older, thicker perennial ice and younger, thinner perennial ice. 

According to the report, the researchers then applied the new information to almost three decades of data from satellite imagery and drifting buoys, which had been used to estimate ice age. The result was a record of differently aged perennial ice volumes going back to the early 1980s. 
Using the new techniques, the researchers were also able to better calculate the sea ice volume in addition to how much area the sea ice is covering. 

Both are critical numbers for deciphering how the Arctic Ocean is responding to global warming.

Source:Climate Ark
Date:2008-1-21