NASA Satellite Measurements Show Unprecedented Greenland Ice Sheet Melt

NASA reports that measurements taken from orbiting satellites indicate the Greenland ice sheet underwent melting over a larger area than they've seen in 30 years of observations. On July 8, the satellites found evidence that about 40% of the ice sheet's surface had melted. Observations just four days later showed 97% of the surface had melted. "This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland's weather since the end of May. 'Each successive ridge has been stronger than the previous one,' said Mote. This latest heat dome started to move over Greenland on July 8, and then parked itself over the ice sheet about three days later. By July 16, it had begun to dissipate. Even the area around Summit Station in central Greenland, which at 2 miles above sea level is near the highest point of the ice sheet, showed signs of melting. Such pronounced melting at Summit and across the ice sheet has not occurred since 1889, according to ice cores analyzed by Kaitlin Keegan at Dartmouth College in Hanover, N.H. A National Oceanic and Atmospheric Administration weather station at Summit confirmed air temperatures hovered above or within a degree of freezing for several hours July 11-12." Photos also surfaced last week showing the Petermann Glacier in Greenland 'calving' — some very large chunks of it broke off and started to drift away.

Comments

I'm not going to panic just yet...

[oraclese]

At the risk of sounding like a denier, I'm not going to freak out just yet, since it says in the article (and partially in the summary) that this is believed to happen every 150 years or so, last time being 1889.

Re:I'm not going to panic just yet...

[dr2chase]

That, I'm pretty confident they have right. Big volcanos leave world-wide signatures in the ice, these can be cross-referenced to tree rings, varves (fucking spell-check, "varve" is a word, it's layers of mud at the bottom of lakes), sometimes even historical records.

(There, glaciology in three or fewer sentences :-)

Re:I'm not going to panic just yet...

[Rei]

To have to delve into this again: Both Greenland and Iceland have icy areas and "green" areas; Iceland has a larger percent of "green" areas to be sure, but that doesn't stop it from having the largest glacier in Europe and getting lots of snow every winter, nor does it mean that there aren't even forests (albeit stubby) in Greenland.

Iceland was named by Flóki Vilgerðarson, who witnessed drifting pack ice during his first winter in Barðaströnd in Vestfirðir (the West Fjörds), something unknown in southwestern Norway where he was from (to be fair, it's relatively rare in Iceland, too, but not nearly so rare as in southwestern Norway). Must have seemed crazy to him, to see the sea itself frozen.

Greenland was named (although not discovered), as mentioned, by Eiríkr (TH)órvaldsson (commonly known as Erik the Red). He landed in the southwest side of Greenland. Look at the southwest side of Greenland in Google Maps with the satellite layer on and tell me what you see. It's green. There are quite significant areas of non-glaciated land there, which is why that's where Greenland's population lives. Greenland, as a whole, was not "melted" then "frozen" and now "melting again" on the order of a thousand years; that area has been, in historic times, constantly ice free, while most of the island has, likewise, been constantly ice covered. There's been advance and retreat of glaciers, but nothing so dramatic as what people are talking about here.

As for "Grænland": first, think of what was known about Greenland before Eiríkr. It's said that on a very clear day you can see Greenland from certain parts of Vestfirðir, although I've never tried myself. It's about 300 kilometers. About 50% of days here during the summer in Reykjavík we can see details on Snæfell which I think is something like 150 kilometers away, so I wouldn't discount it. If you could see it, all you'd see was icy mountains. Then Gunnbjarnarsker (Grunnbjörn's Skerries) were discovered off the Greenland coast before Eiríkr, which Snæbjörn Galti tried (and horribly failed) to colonize. The east coast of Greenland and the straits are just too harsh. But, exiled from Iceland for three years for murder, Eiríkr sailed through icy seas, and along the frozen coasts of Greenland, and then discovered... well, green. And lots of it. So should it really be a surprise that he named it that? Yes, the saga says that he wanted to give it a good name to encourage colonists, but that wasn't unusual; to him, it compared similarly to Iceland. He wasn't calling a frozen rock "green" to trick people.

Atlantic Currents

[gznork26]

With that much fresh water being added to the North Atlantic, we ought to be talking about the health of the Atlantic Ocean currents that are energized by the temperature difference between equator and polar regions, and the deep water exchange, which is driven by the difference in salinization. Most important of these currents is the Gulf Stream. It stopped several hundred years ago, over the course of a single lifetime, and caused the Little Ice Age in Europe. I've already heard some reports about the speed of the current slowing. An awful lot depends on those currents, and we've heard nary a peep about the implications.

Re:Atlantic Currents

[phantomfive]

and we've heard nary a peep about the implications.

I don't know why you haven't heard a peep, scientists have taken this quite seriously and have done some research on the topic. The difficulty, of course, is good historical data is hard to find, and frankly, good measurements of the entire ocean are not easy to make even now.

In any case, the latest scientific research suggests little cause for alarm.