The Heat Is Online

Feedback loop darkens Greenland's reflective surface

Greenland's ice melt accelerating as surface darkens, raising sea levels

Winnowing away of the ice, exacerbated by soot blown on to the ice from wildfires, means Greenland’s ice sheet is stuck in a ‘feedback loop’

The Guardian (U.K.), March 4, 2016

Greenland’s vast ice sheet is in the grip of a dramatic “feedback loop” where the surface has been getting darker and less reflective of the sun, helping accelerate the melting of ice and fuelling sea level rises, new research has found.

The snowy surface of Greenland started becoming significantly less reflective of solar radiation from around 1996, the analysis found, with the ice absorbing 2% more solar energy per decade from this point. At the same time, summer near-surface temperatures in Greenland have increased at a rate of around 0.74C per decade, causing the ice to melt.

This winnowing away of the ice, exacerbated by soot blown on to the ice from wildfires, means that Greenland’s ice is stuck in what is known as a “feedback loop” that will make it ever more vulnerable to warming global temperatures. The study predicts that the ice surface reflectivity, or albedo, will drop by 10% or more by the end of the century, which will trigger further melting.

“It’s melting cannibalism, basically – it’s melting that’s feeding itself,” said lead author Marco Tedesco, of Columbia University’s Lamont-Doherty Earth Observatory. “Rising temperatures are promoting more melting, and that melting is reducing albedo, which in turn is increasing melting.