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Posted at 11:00 AM ET, 07/12/2010

NASA eyeballs glacial melt in Greenland

By Andrew Freedman

* Several rain chances this week: Full Forecast *


Satellite images from DigitalGlobe, via NASA, showing the recent breakup of part of the Jakobsahvn Isbrae glacier.

The Jakobshavn Isbrae glacier, one of the largest glaciers in Greenland, swiftly lost a 2.7-square mile chunk of ice between July 6 and 7, NASA announced late last week. The ice loss pushed the point where the glacier meets the ocean, known as the "calving front," nearly one mile farther inland in a single day. According to the space agency, the new calving front location is the farthest inland on record.

Events such as this one are not unusual, but rarely do scientists see them unfold in near real-time. Researchers working with the space agency spotted the rapid ice loss using high-resolution satellite imagery. Two such images tell the story. In the first image (above), a rift, which looks like a narrow horizontal line indicated by the red arrow, can be seen developing in the glacier. In the next image, taken a day later, the ice below the rift has collapsed into the sea and the location of the calving front has retreated.

Why does this glacier matter to me, you ask?

The short answer: sea level, although this particular event won't raise the level of the Potomac or any other U.S. river anytime soon. Unlike the loss of sea ice, glacial melting causes sea level to increase, and the fate of glaciers like this one will play a key role in determining by how much sea level increases.

The Jakobshavn Isbrae is what is known as an outlet glacier, which the National Snow and Ice Data Center defines as "a valley glacier which drains an inland ice sheet or ice cap and flows through a gap in peripheral mountains." In other words, it serves as a drainage pipe from the land ice into the ocean. According to NASA, the Jakobshavn Isbrae, which is located in western Greenland at about 69 degrees north latitude, is the largest outlet glacier in Greenland, draining 6.5 percent of Greenland's ice sheet area.

Scientists at NASA, NOAA and other agencies are keeping close tabs on Greenland's ice due to its significant ramifications for global sea level rise. If the entire Greenland ice sheet were to melt (a process that would likely take several centuries to play out, even with more global warming than we've already seen), sea level would rise by as much as an estimated 23 feet globally. NASA reports that "as much as 10 percent of all ice lost from Greenland is coming through Jakobshavn, which is also believed to be the single largest contributor to sea level rise in the northern hemisphere."

Interestingly, this particular glacier has been retreating especially rapidly in recent years. As the below image shows, the ice front receded more 27 miles in 160 years, but in recent years the ice loss rate has increased, with six miles of retreat observed in just the past decade.


Location of the successive calving fronts of the Jakobshavn Isbrae glacier between 1851 and 2009. Credit: NASA. Enlarge image.

Recent studies have found that warming ocean temperatures may be responsible for much of the increased melting of Greenland's outlet glaciers, and this may be accelerating the melting of the larger Greenland ice sheet. For example, one study published in Nature Geoscience in February concluded that glaciers in west Greenland are melting 100 times faster at their undersea end points than on the surface.

This event would support the ocean-driven melt theory, according to a NASA ice specialist.

"While there have been ice breakouts of this magnitude from Jakonbshavn and other glaciers in the past, this event is unusual because it occurs on the heels of a warm winter that saw no sea ice form in the surrounding bay," said Thomas Wagner, cryospheric program scientist at NASA Headquarters, in a press release. "While the exact relationship between these events is being determined, it lends credence to the theory that warming of the oceans is responsible for the ice loss observed throughout Greenland and Antarctica."

By Andrew Freedman  | July 12, 2010; 11:00 AM ET
Categories:  Climate Change, Freedman, News & Notes, Science  
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Comments

(1) Some years ago, I read in the not-too-distance future, New York City's climate will be more like Savannah's (which would make Washington, D.C. more like Jacksonville... ugh!)

(2) The Earth may well be in a period of "natural" global warmup. But there's no question that fossil fuel emissions are contributing to the overheating. And until the ostriches get their heads out of the sand and start seriously addressing this, we may well be creating a catastrophe for future generations as in bye, bye Bangladesh, Bangkok, and Boca, and ta-ta Tampa.

Posted by: JerryFloyd1 | July 12, 2010 11:35 AM | Report abuse

Regardless of what exactly is causing the melt, we should not continue to build or expand metro areas directly on the coast. Sea levels are ever changing and have been both higher and lower. Over the next 80 years we must move inward.

Posted by: Ferrari5k | July 12, 2010 11:47 AM | Report abuse

Warm winter in Greenland???

I thought it was a blocking pattern up there, which was partially responsible for all our snow! If that's so, we D.C. snow lovers would like to see more of these "Greenland blocks" in future winters.

Perhaps the blocking ridge up there did result in milder temperatures than normal.

Posted by: Bombo47jea | July 12, 2010 12:57 PM | Report abuse

So I have attached a slide for you to glance at regarding Greenland weather during an NAO negative period like we often experienced this winter in the NW portion of the globe. It illustrates a mixed bag for Greenland itself. Hard to conclude temperatures and precipitation effects.. perhaps almost negligible.

Posted by: Camden-CapitalWeatherGang | July 12, 2010 1:30 PM | Report abuse

It appears that this process has been ongoing for far longer than any significant ghg emissions by mankind. It appears from the drawing (which should be quantified by the authors) that at least 1/2 of the glacial ice disappeared before 1931. It would be interesting if the rate of melt loss of ice were correlated with time and area. Since there has been no sea level rise in the arctic, in fact i beleive sea levels have declined in the arctic; an estimate of the volume of water from the loss of ice from this glacier would be of interest. Relating ice loss to time and mean annual temp would also prove interesting. I wonder why these questions are not asked by the authors of the study or by the news team covering these kinds of items. You know it is not rocket science only climatology - a little like astrology.

Posted by: mtreiber1 | July 12, 2010 1:34 PM | Report abuse

Bombo, the Greenland block served to keep Greenland very warm relative to climatology while helping force cold air southward towards the central and eastern U.S.

Posted by: SteveT-CapitalWeatherGang | July 12, 2010 3:17 PM | Report abuse

It is a leap to say that "[increased melting of Greenland's outlet glaciers] may be accelerating the melting of the larger Greenland ice sheet." They don't say how the increasing speed of the outlet glacier affects the interior glaciers (the ones that matter). Those interior glaciers move at about 10's of meters per year with no sign of acceleration. How are they going to accelerate?

The only way to guess at some sort of effect on the interior glaciers is to use a model such as Glimmer. The paper where they did that http://www.the-cryosphere-discuss.net/4/233/2010/tcd-4-233-2010.html uses a climate model that results in ridiculously high Greenland temperatures to melt a significant portion of the ice in 400 years. How high? They won't say so it's probably completely unrealistic.

The bottom line is it will take wildly high temperatures to turn the mainland glaciers into slush that will be able to flow into the outlet glaciers. Those outlet glaciers have accelerated but as a result of the end of the LIA, not manmade warming (see dates on picture posted above). There's no imminent or inevitable catastrophe here, just a very speculative model with really warm temperatures.

Posted by: eric654 | July 12, 2010 8:43 PM | Report abuse

Over a thousand years ago, my Viking ancestors colonized parts of Greenland during a relatively mild period. This was way before the advent of the internal combustion engine, so how do you know that the melting glaciers on Greenland are the results of human activity?

Posted by: VikingRider | July 12, 2010 9:29 PM | Report abuse

If humans could use nuclear weapons to turn most of the surface of the Earth into a radioactive dead zone, then it is by Man's calm hand that life persists at all on the planet.

Once a physical power exists, it is a conscious decision that prevents the usage of that power.

Just because we are too ignorant to understand how the apex predator determines the biosphere and what survives doesn't change the fact that we are the apex predator and we impact every living system on the planet by doing and NOT doing things every minute of our existance.

Not long ago we used to think the Moon was a God and an erupting Volcano the anger of our Lord.

The more ice you lose on the coast, the faster the ice above it will come down. Duh..

Posted by: ender3rd | July 13, 2010 8:17 AM | Report abuse

The Greenland ice sheets are not above anything. Part of the bases are below sea level and the rest are not very high above that. The only way they will start to move faster than their current negligible speed is if they soften into slush and that's only possible using a model with extremely high temperatures.

Posted by: eric654 | July 13, 2010 8:34 AM | Report abuse

First you say above nothing, then you say only part are below.

Then you say the only way for them to speed up is by much higher temps turning them to slush.

Of course you ignore the new area of research about catastrophic glacial lake drainage and the lifting of massive sheets by the lubrication at the base.

Or maybe a Winter of rain instead of snow or many other factors relevant yet not quite understood at this time.

Sure must be nice to already know all there is to know about the Arctic. What planet did you come from?

Posted by: ender3rd | July 13, 2010 9:20 AM | Report abuse

Please post a paper for lake drainage and/or base lubrication and I (and others I am sure) will be happy to read it. There are obviously lots of things I don't know and I like to argue the details because that's where I can most easily show that each proposed catastrophe really requires some sort of speculation. Again show me a paper and we'll see if it is a speculative stretch or not.

Posted by: eric654 | July 13, 2010 10:02 AM | Report abuse

Raise sea level one inch.

What is the measured lifting on all ice sheets that extend off the underlying sub-surface contact area into the ocean?

Zero to one inch in lift?

Based on the thickness of the sheet, one inch of sea level rise creates a rift proportionally inland.

Further the uplift of ice allows for an uplift in crust.

What impact does this have on volcanization?

Magma moving up at the bottom of the inland glaciers is quite enough heat to cause rapid deglaciation of a region.

Posted by: ender3rd | July 13, 2010 10:16 AM | Report abuse

Not enough physics for one day? Try this headline:

35,000 oil platforms in the Gulf depressurize the sub-ocean crust enough to sink New Orleans.

Don't need sea level rise when you are pumping the pressurized oil from beneath your feet.

See: Strawberry irrigation during winter freeze causes sinkhole development in Florida.

It's physics not climatology.

Posted by: ender3rd | July 13, 2010 10:53 AM | Report abuse

On the first theory, the outlet glaciers might possibly pivot zero to one inches, but that's just those (and I don't think they are rigid enough). The rest of the bowl of ice will stay where it is. Don't know about the magma impacts, but I'll look for some papers on it.

The second theory seems plausible, pumping anything out of the ground and not replacing it will have some sort of impact albeit localized.

Posted by: eric654 | July 13, 2010 5:09 PM | Report abuse

SIWOTI!
The Greenland ice sheet rises to over 3200 m (2 miles) above sea level.
The height of its base is irrelevant; the action isn't happening there.
It would take centuries to melt because there's so much of it.

Posted by: imback | July 13, 2010 8:33 PM | Report abuse

Above someone claimed action is at the base (lubrication, etc), later imback says it is elsewhere. But there are no details in either case to show what is really going on. Where is elsewhere? The surface? No, snow replaces melt. The edges? Yes, but just the outlet glaciers which will stabilize.

As for centuries, yes a good argument is putting it in the Sahara in the sun, it would take centuries to melt. But Greenland won't become the Sahara unless a very wildly warm model is used.

Posted by: eric654 | July 13, 2010 9:53 PM | Report abuse

eric654, I was correcting your disinformation that the Greenland ice sheets are not above anything. That's ludicrously false.

Posted by: imback | July 13, 2010 10:34 PM | Report abuse

imback, what I said is certainly not disinformation. The cross section http://www.geus.dk/viden_om/voii/ilulissat-uk/goii03_fig03_large_uk.jpg shows that the height you mention (2 miles high) is not relevant. The picture (from a Greenland melting is catastrophe website) expands the vertical by about 60 to 1. In other words, the Greenland ice is literally flatter than a pancake.

Look at the Glimmer model uses and you will see that the ice will have to turn into slush in order to flow to the ocean. That won't happen except with extremely warm model temperatures.

Posted by: eric654 | July 14, 2010 7:53 AM | Report abuse

Eric,

There you go again with your "only way" talk.

If the top is level and it sits 2 miles above sea level, the pressure it creates below is proportional to it's distance above sea level.

Physics is physics.

Volcanic activity beneath ice is one way to speed up melting at the bottom.

Warm air following the glacial lake drainage is another way to take heat from the surface and transfer it to the base.

I am not claiming that the ice will melt the day after tomorrow, just that there are many variables that can impact calving along the edges, and that small regional glacial collapse is all that would be required to start off another Younger-Dryas event.

And as large chunks drop off further inland, depressurization and lifting only make prediction more impossible.

So the real question is not when or why, but is the variable of human activity playing a part?

And the physics says yes. Drilling an ice core is a variable, running an ice breaker through a solid sheet is a variable, killing all the whales is another.

The apex predator designs his ecosystem often without understanding how.

Posted by: ender3rd | July 14, 2010 9:36 AM | Report abuse

--begin quote--
Since 1831, the glacier has retreated about 60km, as seen in the image above. About half of that occurred in the first 80 years (prior to 1931) and the other half has occurred in the last 80 years. The long term rate has not changed. As you can see, the retreat occurs in spurts, with quiesced periods in between.
--end quote--

Source of the above quote.

The industrial revolution didn't begin until the 1940's. What caused the melt prior to the 1940's? And if the long term rate of melt has remained basically the same since 1851, doesn't that fact alone disprove the fear mongering over this issue? If man and CO2 were to blame, wouldn't the rate of melt increased since 1940?

Mr. Q.

Posted by: Mr_Q | July 14, 2010 10:24 AM | Report abuse

"The industrial revolution didn't begin until the 1940's"

You might want to google "industrial revolution".

Posted by: Mujokan | July 14, 2010 10:45 AM | Report abuse

ender3rd, I'm not quite sure what argument you are making. I agree in general that mankind can do all sorts of bad things to the environment without knowing what he is doing. Specifics are important and your examples should be more detailed to be properly understood. For example, killing all the whales leads to what?

You seem to claim that 2 miles of ice creates lots of pressure which if relieved would lead to volcanic activity. Did I get that right? The answer is simple, the 2 miles is not diminishing, not moving over 10's of meters per year and not accelerating. The retreat of the outlet glaciers has not resulted in any geophysical consequences.

Another claim is "small regional glacial collapse is all that would be required to start off another Younger-Dryas event" That is quite outlandish in several respects, first there is no such small regional glacier that would do that, second that there are none that are collapsing and third that it would cause a Younger-Dryas event (which may be caused by a large meteor impact).

Posted by: eric654 | July 14, 2010 10:49 AM | Report abuse

Killing all the whales leads to an increase in available whale food. Whale food is microscopic and by it's massive bloom, changes oxygen content and the CO2 cycle.

Runoff fertilizer creates dead zones. Dead zones change the CO2 cycle.

What we need to agree on is that the Earth hypothetically was once covered in ice, Snoball Earth. Another time it was ice free and crocs and dinos roamed the Arctic.

These two scenartios are logical outcomes of messing with natural variability. You can't know for certain, but ice sheet stability would reduce variability.

The thickness of the Greenland sheet is still being determined as are the rates of increase and decline.

When the facts are still being collected, would you agree that intentionally changing CO2 cycles, ocean chemistry, land use and species migration/evolution is ill advised?

It's great to speculate that our actions have minimal impact up until the point we see major impact like in the Gulf.

Combine natural ocean warming with runoff fertilization, oil spills, marsh drainage, river channeling, over-fishing of top predators and you end up with coastal regions in economic collapse.

In a world of 6 billion, increasing the per capita energy and protein consumption while watching shifting species migration and human swarming, you end up with the obvious outcome, massive population decline.

This is our future. We are laying the groundwork as we talk.

Posted by: ender3rd | July 14, 2010 11:10 AM | Report abuse

Question: "When the facts are still being collected, would you agree that intentionally changing CO2 cycles, ocean chemistry, land use and species migration/evolution is ill advised?"

Yes. As I always say here, specific details matter. We should all specifically do things to minimize our intentional uses of resources. The changes in the commons (e.g. CO2 in the air) have to be carefully examined and weighed. That's what I always try to do here.

The political solutions are going to be very polarizing (e.g. government control of energy industry). I also believe that economic growth has been the greatest protector of the environment, on a per capita basis, than any other factor. People will strongly disagree with that, but limiting economic growth is not going to win many political points among the vast majority of Americans. However, expanding government basic R&D for alternatives will result in economic growth whereas taxing refineries will do the opposite.

Posted by: eric654 | July 14, 2010 12:04 PM | Report abuse

Limiting economic growth is well underway.

It all started back when America was cheated away from mass transit and the highway system dropped like a bomb on Hiroshima.

Ever since our growth has been limited by gas and coal combustion. When you use the military to support a private global enterprise, you are limiting your economic capability.

These limitations have severly crippled our ability to diversify our energy infrastructure and has reduced our exports to pallets of 100 dollar bills.

My father retired from GE and collected a pension for 30 more years.

How many current employees have the same opportunity?

Military world domination for oil worked well for the post WWII workforce, today it is our Achilles Heal.

So much of what we inhereted is unsustainable that only a radical shift will keep us from total economic irrelevancy.

Is that the position you want America to be in when some global catastrophy rears it's ugly head?

At least we are smart enough to know that historical changes in biodiversity were so catastrophic from natural variabilty, that adding our own human variabilty isn't a good idea.

It's just that we don't have the collective capacity to give a damn enough to get off the oil teat.

Posted by: ender3rd | July 14, 2010 1:22 PM | Report abuse

Economics is quite complicated. On a worldwide basis, opportunities are growing, so you might not get a nice pension from GE, but a lot of people in developing countries will make a living instead of starving like they did when GE gave out those pensions to Americans.

The way to handle catastrophe is a robust economy. One part of that is savings which is really deferred consumption. The conservation of resources like oil or the use of alternatives is effectively deferred consumption on a regional or national level. So you have a point there. I always think of Alaska as a strategic petroleum reserve. Perhaps we will never need to use it.

Another part of economic robustness comes from production and trade. It takes a while to ramp up productive capacity if, for example, a hurricane hits. In that case we have to trade for stuff we need. We can spend our savings at that point. If it's all debt or pallets of 100 dollar bills, that's a completely different problem, namely the weakening of the dollar and overuse of cheap Fed credit for economic manipulation or wartime priorities.

The final point is, as I always say, what are the specific problems. More CO2 in the air is not a problem. More CO2 causing warming is potentially a problem, but one that needs to be analyzed. More CO2 causing acidification is potentially a problem but needs to be carefully analyzed. Every single potential problem needs to be examined in detail. Otherwise we will solve imaginary problems and create real ones.

Posted by: eric654 | July 14, 2010 2:05 PM | Report abuse

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