Greenland's glaciers losing ice faster this year than last year, which was record-setting itself

Dec 15, 2008

Researchers watching the loss of ice flowing out from the giant island of Greenland say that the amount of ice lost this summer is nearly three times what was lost one year ago.

The loss of floating ice in 2008 pouring from Greenland's glaciers would cover an area twice the size of Manhattan Island in the U.S., they said.

Jason Box, an associate professor of geography at Ohio State, said that the loss of ice since the year 2000 is 355.4 square miles (920.5 square kilometers), or more than 10 times the size of Manhattan.

"We now know that the climate doesn't have to warm any more for Greenland to continue losing ice," Box said. "It has probably passed the point where it could maintain the mass of ice that we remember.

"But that doesn't mean that Greenland's ice will all disappear. It's likely that it will probably adjust to a new 'equilibrium' but before it reaches the equilibrium, it will shed a lot more ice.

"Greenland is deglaciating and actually has been doing so for most of the past half-century."

Box, a researcher with Ohio State's Byrd Polar Research Center, along with graduate students Russell Benson and David Decker, presented their findings at the annual meeting of the American Geophysical Union in San Francisco.

The research team has been monitoring satellite images of Greenland to gauge just how much ice flows from landlocked glaciers towards the ocean to form floating ice shelves. Eventually, large pieces of these ice shelves will break off into the sea, speeding up the flow of more glacial ice to add to the shelves.

Warming of the climate around Greenland is believed to have added to the increased flow of ice outward from the mainland via these huge glaciers.

Using daily images from instruments called MODIS (Moderate Resolution Imaging Spectroradiometer) aboard two of NASA's satellites, Box and his team are able to monitor changes in 32 of the largest glaciers along Greenland's coast.

They determined that during the summer of 2006-2007, the floating ice shelves at the seaward end of those glaciers had diminished by 24.29 square miles (62.9 square kilometers. But one year later -- the summer of 2007-2008 – the ice loss had nearly tripled to nearly 71 square miles (183.8 square kilometers). Much of this additional loss is from a single large floating ice tongue called the Petermann glacier

Late this summer, the Ohio State researchers were able to watch as a massive 11-square-mile (29-square kilometer) chunk broke off from the tongue of the massive Petermann Glacier in Northern Greenland. At the time, they also noted that a massive crack further up the ice shelf suggested an even larger piece of ice would soon crack off.

Box said that some findings may have confused the public's views of what is happening around Greenland. "For example, we know that snowfall rates have increased recently in this region," he said, "but that hasn't been enough to compensate for the increased melt rate of the ice that we're seeing now."

Source: Ohio State University

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User comments : 19

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agg
3.3 / 5 (7) Dec 15, 2008

Where is glacial ice increasing?
wfl
3.3 / 5 (7) Dec 15, 2008
So what!
Lord_jag
2.7 / 5 (7) Dec 15, 2008
So... why isn't New York under water yet???
Velanarris
3.3 / 5 (7) Dec 15, 2008
This is an article from about 4 months ago recycled. Speaking about the 08 ice loss in august compared to the 07 ice loss in august.

Old news.
MikeB
2.7 / 5 (7) Dec 15, 2008
"Greenland is deglaciating and actually has been doing so for most of the past half-century."

However Glacier Girl a WWII P-38 was recovered from Greenland in 1992. This airplane along with the rest of the group was found under 268 feet of ice.

Read the story here:

http://p38assn.or...very.htm
Quantum_Conundrum
3 / 5 (8) Dec 15, 2008
However Glacier Girl a WWII P-38 was recovered from Greenland in 1992. This airplane along with the rest of the group was found under 268 feet of ice.


In other words, somebody is a damned liar. The glacier would have needed to build by 268 feet over the past half century.
MikeB
2.7 / 5 (7) Dec 15, 2008
The story in my last comment includes the fact that Glacier Girl sat there for 50 years from 1942 til 1992. In that time period the ice piled up over her as high as a 27 story building. That is over five feet of ice buildup every year for fifty years in a time when the Earth was warming. I wonder what will happen as Greenland enters a cooling trend.
thermodynamics
3.5 / 5 (6) Dec 15, 2008
OK, lets talk about science for a bit. MikeB talked about how Glacier Girl was buried under 268 feet of ice and a bunch of the readers thought that meant the ice got that much thicker. That is not necessarily the case. Here is how it works. A glacier is always being snowed on. The snow builds up over time. However, an ice sheet is not a rigid piece of metal. Instead, it flows. As it flows it thins and stretches. The key is the balance between the snow that is building up and the flow that is stretching it. If there is more snow than stretch the glacier gets thicker. If there is more stretch than snow it gets thinner (there is also melt and flow under the glacier, but lets keep it simple). So, it is quite possible for a plane to be buried deeply in a glacier that is thinning. In this case the measurements indicate that the glacier is getting thinner. Other measurements (using gravity measurements from space) indicate these same glaciers are losing mass. In some cases there are a few glaciers in Antarctica that are gaining mass (though most throughout the world are losing their mass). A view that finding a plane buried in the glacier negates the fact that a glacier can be losing ice shows that someone doesn't understand how glaciers work.
MikeB
3 / 5 (4) Dec 16, 2008
How Glaciers Flow

- Glaciers flow under the force of gravity as snow accumulates on the upper parts of the glacier and wants to move down slope.
- The snow compresses to become ice and flows through the glacier into the ablation zone where it is lost.
Accumulation Zone
The area where inputs occur into a glacier system. This usually occurs near the top of the glacier or ice sheet and such inputs to the system include snowfall, wind blown snow, rain and avalanches.
Ablation Zone
The region in which more mass is lost than gained in a glacier system. This usually occurs at the end and sides of the glacier. Forms of losses include wind ablation, avalanching, iceberg calving and melting.
Internal Deformation
Ice deforms under its own weight due to gravity and the movements of tiny ice crystals. This causes the glacier to flow.

No thinning, no thickening, Glacier Girl was found in the same position relative to the rest of the squadron that she was in fifty years previously.
MikeB
2.3 / 5 (3) Dec 16, 2008
When their is insufficient accumulation of snow, a glacier does not continue to flow, it recedes.
Glaciers don't stretch.
Thanks,
Mike
thermodynamics
3.8 / 5 (4) Dec 16, 2008
When their is insufficient accumulation of snow, a glacier does not continue to flow, it recedes.
Glaciers don't stretch.
Thanks,
Mike


Mike:

Glaciers move under plastic deformation. What happens is that the pressure increases as the snow falls on it and it squeezes out through any way it can get to lower levels. It is similar to any fluid flow and the loss of mass takes place at the exit of the glacier to the ocean (usually). As the force is released by the calving off of sections of glacier at the ocean more flows down from the heights. Lets think about the process for a minute. If, as you seem to think, all of the snow coming down on an artifact (such as an airplane) only makes the glacier thicker, then what stops the glacier from becoming infinitely thick? The answer is that it deforms to flow towards lower levels. As it flows it takes on the contours of the land it is flowing over. The total mass of ice is what is important when we talk about a glacier growing or losing mass. As the ice flows toward the sea it tends to spread out (most of the time) and thin. There are instances where it is caught in a narrow opening and it can thicken but the mass flowing (less that ablated as you pointed out) stays the same as it moves to the sea. The glaciers do stretch (deform) as a plastic substance. To think they don't means you don't understand how ice moves. There was an experiment done on an alpine glacier in the 1800s that showed how a glacier flowed by driving stakes into it in a line to see if it showed fluid behavior. It did. It showed more motion in the center than toward the edges (due to friction). The glacier is a fluid driven by gravity and the fact that an airplane is 268 feet deep does not mean it is gaining (or losing) mass. That has to be calculated using other means. To make the assumption that because anything is buried in the snow that the glacier is growing is incorrect.
Velanarris
4 / 5 (4) Dec 16, 2008
The fact that no one has addressed that glaciers also sublimate under periods of low precipitation throws the whole glacial shrinking issue into propaganda land.
MikeB
3 / 5 (4) Dec 16, 2008
So, I guess what you are saying, Therm, is that the squadron of planes sank through 268 feet of solid ice all to the same level and position as they were before?
Or are you saying that the glacier thinned and dropped the planes into a crevasse, also all into the same position, and then this crevasse of solid ice closed around them without caucing major damage to them?
Just wondering.
Mike
thermodynamics
3.3 / 5 (3) Dec 16, 2008
MikeB: I am saying that the planes were covered with 268 feet of ice in the form of compacted snow over the years. Just as anything sitting on a glacier with snow falling would. As glaciers do, this one is flowing. The flow moves the glaciers and the planes toward the ocean. During the flow the glacier deforms to follow the terrain and changes shape as it needs to as it flows. This is plastic deformation. The glacier is losing ice (and everything it carries) where it meets the ocean. Eventually the planes would have been dumped into the ocean after, probably, being covered by even more ice. The point is that you cannot tell how much mass the glacier is gaining or losing by how deep it is in the glacier. You can only tell how long it has been there (that is why they core glaciers to get an idea of how old they are and what atmospheric conditions were at the various levels. Other techniques must be used to tell if the glacier is gaining or losing mass.
lengould100
1.8 / 5 (5) Dec 16, 2008
You guys should stop the religion and read thermodynamics posts again. Its called science, eg. using only facts to arrive at conclusions.
Velanarris
5 / 5 (3) Dec 16, 2008
MikeB: I am saying that the planes were covered with 268 feet of ice in the form of compacted snow over the years. Just as anything sitting on a glacier with snow falling would. As glaciers do, this one is flowing. The flow moves the glaciers and the planes toward the ocean. During the flow the glacier deforms to follow the terrain and changes shape as it needs to as it flows. This is plastic deformation. The glacier is losing ice (and everything it carries) where it meets the ocean. Eventually the planes would have been dumped into the ocean after, probably, being covered by even more ice. The point is that you cannot tell how much mass the glacier is gaining or losing by how deep it is in the glacier. You can only tell how long it has been there (that is why they core glaciers to get an idea of how old they are and what atmospheric conditions were at the various levels. Other techniques must be used to tell if the glacier is gaining or losing mass.
Thermo, that is very accurate in most cases however, not all glaciers actually flow into the sea, or into a warmer zone. Ignoring sublimation is tantamount to ignoring ice loss through natural means.
MikeB
3.7 / 5 (3) Dec 16, 2008
"MikeB: I am saying that the planes were covered with 268 feet of ice in the form of compacted snow over the years. Just as anything sitting on a glacier with snow falling would. As glaciers do, this one is flowing. The flow moves the glaciers and the planes toward the ocean."

So in the fifty years there was an accumulation of 268' of ice over the planes. That's exactly what I thought happened. Of course you realize that this solid plastic-like ice was formed by the compression of the snow. Because of this there had to be approximately 670' of snow which fell in the accumulation zone over the 50 year time period. That is approximately 13' of snow per year from 1942 to 1992, a time period when we saw the greatest growth of industry and CO2 in the history of this Earth. Also you are correct the glacier moved these planes about three miles along it's course.

This seems to be a long way of saying exactly what I did in my first comment. Which was:

"However Glacier Girl a WWII P-38 was recovered from Greenland in 1992. This airplane along with the rest of the group was found under 268 feet of ice."

Please provide evidence that this particular glacier is losing mass. I would like to see the last 50 years of satellite data... it doesn't exist.
yor_on
not rated yet Apr 04, 2009
Ice is a fluid :)
It's not tungsten, and it moves, it melts and refreezes, inside itself it has bubbles of flowing water that goes a long way to explain its plasticity. Although being buried under 268 feet of ice do seem somewhat drastic, I expect there to be other explanations than that our satellites are wrong.
yor_on
not rated yet Apr 04, 2009
Looking at it again I saw that this glacier wandered about a 100 feet a year "They were able to pinpoint its location because of discoveries by previous expeditions and precise calculations of the glacier's movement. (It drifts about 100 feet toward the ocean each year.)"

If you treat ice as a slow fluid and see it moving over obstacles I would assume that it works somewhat like a wave that is pressed up by the bottom coming up. And as water has different layers of density so might Ice have when in motion. Take some good jelly, put a object in it a little bit (snow/ice covering) then use a wall behind it to move the jelly as a whole over an uneven bottom. it's the simplest analogy I could come up with, but I think it would work to create similar effects.

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