A new study is showing bad news from the Greenland and Antarctic ice sheets.

NASA data: Greenland, Antarctic ice melt worsening:

New satellite information shows that ice sheets in Greenland and western Antarctica continue to shrink faster than scientists thought and in some places are already in runaway melt mode.

British scientists for the first time calculated changes in the height of the vulnerable but massive ice sheets and found them especially worse at their edges. That’s where warmer water eats away from below. In some parts of Antarctica, ice sheets have been losing 30 feet a year in thickness since 2003, according to a paper published online Thursday in the journal Nature.

…

These new measurements, based on 50 million laser readings from a NASA satellite, confirm what some of the more pessimistic scientists thought: The melting along the crucial edges of the two major ice sheets is accelerating and is in a self-feeding loop. The more the ice melts, the more water surrounds and eats away at the remaining ice.

“To some extent it’s a runaway effect. The question is how far will it run?” said the study’s lead author, Hamish Pritchard of the British Antarctic Survey. “It’s more widespread than we previously thought.”

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The research found that 81 of the 111 Greenland glaciers surveyed are thinning at an accelerating, self-feeding pace.

The key problem is not heat in the air, but the water near the ice sheets, Pritchard said. The water is not just warmer but its circulation is also adding to the melt.

“It is alarming,” said Jason Box of Ohio State University, who also wasn’t part of the study.

Worsening data, including this report, keep proving “that we’re underestimating” how sensitive the ice sheets are to changes, he said.

The paper itself is here (paid access, sadly).

Once again: We’re still behind the curve in understanding how and how quickly the climate responds to a (geologically speaking) swift change, like increasing the atmospheric CO2 level from 270 to 380 ppm in a couple of centuries.


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