Nasa launches satellite to precisely track how Earth's ice is melting

Every 91 days, the $1bn, decade-in-the-making creation will orbit over more than 1,000 paths. The satellite, about the size of a Smart car, will point six lasers at ice sheets in the Arctic and Antarctica. It will then calculate how long the beams take to bounce back. Nasa will be able to more accurately measure the heights of ice sheets and the thickness of remaining sea ice.

“With sea ice, we’ve been able to measure the extent (or area) really well since about 1980 … but what we haven’t been able to measure is the thickness,” said Tom Neumann, Nasa’s deputy project scientist for the mission. “Thickness is a key piece of the puzzle because thinner sea ice is broken up more easily by storms. It melts faster. So it gives you some insight into why the area is changing the way it is.”

Melting ice in Greenland and Antarctica has increased the global sea level more than a millimeter per year, a third of the overall increase, according to Nasa. Sea-level rise is getting faster, and seas could be several feet higher by the end of the century.