A team of scientists in Belgium has discovered a somewhat counterintuitive reason the Greenland ice sheet is melting at night...
The surprise culprit? Clouds.
Photo by Sy Clark/Flickr.
It may seem just ... kind of wrong to the many of us whose brains reflexively associate "clouds" with "chilly." If cloudy weather indeed equals cold weather, ice should ... stay frozen better on a cloudy day, right? According to this new study, however, increased cloud cover over the glacier actually accelerates the rate of melting.
Here's how it works, according to Kristof Van Tricht, University of Leuven professor and lead author on the paper:
"Over the entire Greenland ice sheet, clouds raise the temperature, which triggers additional meltwater runoff: 56 billion tons per year — a third more than clear skies. Contrary to what you would expect, this effect is not so much visible during the daytime melting process, but rather during the following night. A snowpack is like a frozen sponge that melts during the day. At night, clear skies make a large amount of meltwater in the sponge refreeze. When the sky is overcast, by contrast, the temperature remains too high and only some of the water refreezes. As a result, the sponge is saturated more quickly and excess meltwater drains away."
In other words...
The clouds basically act as a giant, celestial Snuggie for the glacier.
Overcast skies at night prevent heat — which builds up during the day while the sun is out — from escaping from the surface of the ice sheet. That heat makes it too warm for the water on the glacier's surface to refreeze when it's supposed to — and once the water drains off the glacier, it's lost forever.
Climate change is the elephant in the room here.
Of course, the results of the study would just be a cool, neat, "ain't science something" thing if the melting of the Greenland ice sheet didn't have the potential to cause seriously catastrophic problems for everyone on Earth.
At the current rate, Greenland is losing over 300 billion tons of ice a year. The consequences of the ensuing sea level rise are expected to include anything from increased flooding during storms to the evacuation of coastal cities — basically, nothing terribly desirable.
Researchers hope that identifying this new behavior will help them predict future melting events — and the overall rate of sea level swell — more effectively, rendering them better able to gird humanity's loins for the worst (or, at least, the not-so-good).
In the meantime, continuing to ratchet back all the carbon we're putting in the air will only help things for the better.
The major climate agreement signed in Paris last year is super ambitious with good reason: We need a super ambitious plan if we're going to have any hope of limiting the damage to our sea and sky that's already begun, and we need to make sure we stick to it.
That means electing politicians who not only believe that manmade climate change is a real thing, but are willing to take the necessary policy steps — de-incentivizing the burning of fossil fuels while investing in renewable energy — that will help us snuff it out for good.
That way, those bastard clouds can't threaten us anymore. ;)