Sunday, November 14, 2010

Less ice

The NY Times has a detailed article by Justin Gillis about the loss of ice from glaciers, principally in Greenland and the dearth of information about the ice loss as more and more satellites take the plunge. Be sure to check out the interactive graphics. An interesting bit of cleverness is described

Two seismologists, Meredith Nettles and Göran Ekström of Columbia University, discovered a few years ago that unusual earthquakes were emanating from the Greenland glaciers as they dumped the extra ice into the sea. “It’s remarkable that an iceberg can do this, but when that loss of ice occurs, it does generate a signal that sets up a vibration that you can record all across the globe,” Dr. Nettles said in an interview in Greenland.

Analyzing past records, they discovered that these quakes had increased severalfold from the level of the early 1990s, a sign of how fast the ice is changing.

There is just a bit of the usual he said she said, with John Christy doing the obligatory turn of someone who knows a bit about climate but nothing about glaciers saying don't worry, move on, while those who study glaciers
“As a scientist, you have to stick to what you know and what the evidence suggests,” said Gordon Hamilton, one of the researchers in the helicopter. “But the things I’ve seen in Greenland in the last five years are alarming. We see these ice sheets changing literally overnight.”
and sea level rise say worry a lot.

Climate scientists readily admit that the three-foot estimate could be wrong. Their understanding of the changes going on in the world’s land ice is still primitive. But, they say, it could just as easily be an underestimate as an overestimate. One of the deans of American coastal studies, Orrin H. Pilkey of Duke University, is advising coastal communities to plan for a rise of at least five feet by 2100.

“I think we need immediately to begin thinking about our coastal cities — how are we going to protect them?” said John A. Church, an Australian scientist who is a leading expert on sea level. “We can’t afford to protect everything. We will have to abandon some areas.”

So what we have is a lot of observations, models and understanding against one guys gut feeling. Whom should Eli believe, remember this is about betting the bunnies.


Anonymous said...

Those darn satellites sure are expensive--I don't think we can afford to keep putting 'em up there if they are going to wear out after five or ten years. Sounds like a good place to reduce the deficit.

evilPolysuperskeptic said...

Minor kvetch: I grimace when people use the term "literally" and clearly what the mean is the opposite "figuratively". Almost as evil as saying LOL if you didn't. ;)

"things I’ve seen in Greenland in the last five years are alarming. We see these ice sheets changing literally overnight.”

Anonymous said...

Arctic sea ice is going down way ahead of schedule (follow the volume). By and by a lot of summer heat will be freed from remelting the same thing over and over. What will it do then?

Pete Dunkelberg

J Bowers said...

"I don't think we can afford to keep putting 'em up there if they are going to wear out after five or ten years."

Hey, we could stop making books, too. Acquiring knowledge is such an inconvenience, especially the more misanthropic one is.

Rocco said...

evilPolysuperskeptic: What makes you think he didn't mean it literally?

Anonymous said...

We are so conservative in our estimates of sea level rise, with those conservative estimates being dismissed as alarmist it is inevitable that we are going to have one failed defence after another.

We are not good at preparatory adaptation. Robert Repetto did a piece "The Adaption Myth" sadly I think he will be proved correct.

The loss of satellite coverage only increases the odds that we will be caught by surprise. One day the tide will not go back out again.

Little Mouse.

PS Climate Progress also has a post today on the same issue.

Poly said...

Rocco, he is talking about the frequency of ice earthquakes (a measured seismic signal). They have been observed before. What is notable is the frequency of them increasing. And how he came to the realization was from prolonged study ("five years"). This is described in the article (even a bit in my quote).

Note: If you could remove one individual night from the events (or add one), it would not significantly change the long term process.

David B. Benson said...

It doesn't matter because by 2060 CE we all run out of food:
Romm's commentary about Dai on global drought

Anonymous said...

"he is talking about the frequency of ice earthquakes"

Actually he probably isn't, seeing as he is one of the researchers to spends every summer in the Arctic and probably sees day to day changes at the height of the melt season. His quote is from page two of the article where they discuss taking water temperature measurements from the open doorway of the helicopter.

Anonymous said...

When you get above the arctic circle you need to be precise with your definition of day and night. I don't think things change very much overnight. In fact things freeze up overnight. However, you might see massive changes in a single day if that day is about 2 months long.


Aaron said...

When I look at Greenland as a p-chem problem, I get a structure that collapses into a water/ice flow under its own weight sooner, rather than later. Am I wrong that moulins are the most interesting topic in the world? Why doesn’t every p-chem guy in the world spend all of his spare time perfecting his own model of moulins?

Where else does a p-chem guy have a chance to beat Cassandra at her own game?

Hank Roberts said...

I recall considerable doubt about moulins, e.g.

I've been finding drumlins and pingos very interesting. There have long been arguments in the science about how both structures form and whether from slow or fast changes. The implications vary.

blogosity at:

Aaron said...

The water falling through the moulins converts its potential energy to kinetic energy which is transfered by impact to the surrounding ice - warming the ice and cooling the falling water. How warm does Mario think water that has been flowing through ice will be? The ice will always contain less heat then the water, and heat will move from the water to the ice. The temperature of water at the bottom of the ice says nothing about energy that the water may have transferred to the ice. (Actually it says that the water transferred enough heat to the ice sheet that the ice around the moulin was heated to 0C. So now we have a column of ice, in the ice sheet that has been warmed to 0C. (For somebody looking at structural strength, that is very interesting.) Of course, such ice is weak, and the weight of the ice squeezes the moulin closed. (However, this working of the ice does adds energy to the ice, and does not cool the it.)

We are seeing moulins at 1500 m above sea level, that means the water is falling ~3 km to the bottom of the Jakobshavn fjord. Compare that to the 30 or 60 meters at Niagara Falls.

Robert said...

Somewhat related and somewhat not