Greenland's "Dark Ice" This Summer Is Ominous

Dark colored ice in Greenland crisscrossed with
crevices. Melt water goes into the crevices
and can accelerate deterioration of the ice sheet.
Photo by Jason Box.  

If you've ever stepped outside into the winter sunshine after a snowstorm you know how blindingly bright it is out there.

The white snow reflects light, so it's glaring. The white snow reflects heat from the sun, too, and that helps keep things cold in the middle of January.

Greenland is a big ice sheet. Almost all of it is covered in thick, thick, thick ice all year.

That ice, although never pristinely white in the summer, reflects away the summer sun's heat, rather than absorbing it because the ice is very light colored.

At least it was. The ice sheet has been getting dirtier and darker in recent years and decades, and according to Eric Holthaus in Slate, this year the Greenland ice sheet is the darkest color it's ever been. Pictures of the ice sheet look like it's a giant version of a rotting snowbank at the last gasp of winter.

Dark, light, who cares? Well, YOU should. And everybody else, too. The dark ice in Greenland absorbs the sun's heat, a lot like a blacktop is a lot hotter in the summer than a patio painted white.

That means the ice up there was melting a lot faster than usual over this summer.  Fast melting is bad in Greenland. Unlike the Arctic Ocean, it's not floating ice. If ice floating on the ocean melts, the sea level won't rise, just like if the ice in your glass of gin and tonic melts. The glass won't get any fuller.

But if Greenland's ice melts, it runs off into the ocean, and contributes to sea level rise, perhaps the biggest threat from global warming. Since so much of the world's population lives in big cities on the coasts, it'll be tricky when the sea levels rise and flooding gets worse and worse.

Dark ice and a big crevice in Greenland
this past summer. Photo by Jason Box.  n

Do you move entire cities? Build multi-billion dollar sea walls and hope for the best? There's really no good options.

Already, American cities like Miami, Fla. and Norfolk, Va. are seeing the effects, and it might no be long before places like New York, Washington and Boston start to go under.

You want to keep Greenland's ice sheets bright and white, to slow the melting a bit.

A white Greenland won't solve the problem of rising sea levels, but anything to slow the process down helps.

Now what, though?  As I said, Greenland's ice was dark and yucky over the summer. There's a lot of theories why. The boreal forests of the Arctic way up north in Canada, Alaska and Siberia had more forest fires than ever before this summer, and in recent summers. 

(The Arctic is warming up, the snow is melting sooner the summers are hotter, so forest fires, in general are becoming more likely, and bigger. Arctic forest fires are burning at roughly twice the rate they were about a decade ago.)

Some of the soot from this year's northern forest fires landed on the Greenland ice sheet, so that helped make it darker.

You also get summer snowstorms in parts of Greenland to freshen up the ice and snow cover, and that didn't happen as much as usual this year. The dark stuff might also be partly composed of pollution and dust from places like here, and China, and God knows where else in the Northern Hemisphere. Maybe microbes are contributing.

A scientist named Jason Box is the main source for Slate's material on Dark Greenland. He's pretty strident in his public alarm over global warming. He's the guy who found himself in a bit of controversy in July when he Tweeted: "If even a small fraction of Arctic sea floor carbon is released to the atmosphere, we're f'd." 

So OK, Jason Box is blunt, and he probably pisses off people who aren't particularly concerned about global warming.  But from everything I read, his science is totally sound, so he's got cred.

It's not clear how to fix this, other than cooling the Earth, so we don't have so many Arctic forest fires, so Arctic summers are not hot, which would limit melting.