Dramatic Greenland Ice Sheet Melt This Week Actually Raises Sea Level

Via Rolling Stone/Getty Images: Melting ice this week in Greenland.

As expected, that heat wave in Europe last week moved into Greenland over the past couple of days, which is definitely not a good thing.

Temperatures there are 25 to 30 degrees above normal, with some low elevation places up there in Greenland reaching the 70s. In the middle and peak of the Greenland ice sheet, at an elevation of 10,551 feet,  it managed to get above freezing for 11 hours on Tuesday, which is extremely rare, the Washington Post reports. (In the height of summer, Summit, Greenland's normal high temperatures are just in the low teens, believe it or not.) 

The Greenland melt down this week could well be the worst in recorded history, probably besting the benchmark great melt of 2012. Rolling Stone reported that some melting occured on 87 percent of the Greenland ice sheet on Tuesday, before the peak of the heat wave.  By the way, I know Rolling Stone is primarily a music magazine, but they've gotten into some very good political and climate change reporting in recent years.

Before, say, the 1980s, it was very rare for most of the ice sheet to be melting simultaneously, though of course parts of it would experience some melting on the warmer days of summer. Still, the amount of ice lost on Greenland in the summer was always balanced by accumulations of new snow and ice during the winter.

Not any longer. Unlike ice in the Arctic ocean, which melts like ice cubes in a glass and doesn't affect sea levels, Greenlands meltwater runs off and contributes to global sea level rises.

Says Rolling Stone:  "This week alone, Greenland will lose about 50 billion tons of ice, enough for a permanent rise in global sea levels by about 0.1 mm"

Yes, that's only 0.004 of an inch, so that alone you won't notice. But as glaciers worldwide melt and Greenland continues to shed ice, and Antarctica begins to thaw, too, you can see how 0.0004 of an inch in a week can add up to a lot of sea level rise over the course of several decades.

There's more meltwater coming off of Greenland. The Washington Post said 197 billion tons of ice melted from Greenland and flowed into the ocean during the month of July.  

Of course in Greenland, like everywhere else, the warming won't be consistently this bad, and not every year will have such great melt downs. They're just becoming more frequent. In some years, like 2017 and 2018, Greenland experiences chilly summers, so on those occasions, there is very little net ice loss from the ice sheet, as the Category 6 blog notes.

But studies show that Greenland melts like the one in 2012 happen on average only once in 250 years, the Washington Post says. That another one is occuring now, just seven years later, is worrisome.

This much melt exposes older snow and ice to the sun. The older ice has bits of soot and dirt and such in it, so it's darker. That will draw in more of the sun's heat, and contribute to even more melting. That would happen before the melting season shuts down in the early autumn, or would happen again if this winter's new snow melts and exposes the old ice again.