Global warming causing Greenland to rise - what are your thoughts?

Question

Global warming causing Greenland to rise - what are your thoughts?

Answer 1

Isostatic rebound is basic geology. Isostatic rebound is still occuring near Chicago. Your suggestion that the isostatic rebound is indicative of recent glacial melt in Greenland is unfounded IMO. Paul is correct that it would tend to make sea levels rise. What you are forgetting is that Greenland isn't rising straight up at the sea shore. What happens is the continental mass (including some land that is currently submerged) tends to rise. Obviously if the continent rose all things being equal, it would cause the sea level to rise because it would reduce the area of the ocean, albeit to a very small extent. That is the simplest way that I can think of to explain the concept .



You can think of it as Greenland rising is due to the continental mass floating on the mantle. As ice melted, it became lighter and moved upward. It isn't displacing less water in the ocean, it is displacing less plastic rock in mantle.



If you assume the water in an aquarium is rock on the upper mantle of the earth and a small two by four board floating in the tank is Greenland. If you have an ice cube on the 2X4, it sinks slightly. if you remove the ice cube, the 2X4 rises slightly. This is a simple mental model of how isostatic rebound occurs.

Answer 2

Disconcerting.



Hydrostatics imply that Greenland would tend to rise. I don't know whether the same would apply to the most northerly parts of Canada and Alaska. This rising is bound to displace ocean water and thus accelerate sea level rise.



Has the size of this potential effect been calculated, and added into the other terms in sea level rise, such as simple expansion, and water from glaciers?

Answer 3

With Earth Sciences, the simplest answer is usually correct. lol! Great question Dana, I love it when you get the denial crowd to do contortions to come up with an answer. As our understanding of how the Planet works becomes more holistic, the cause and effect of every action becomes more apparent and predictable. Unless of coarse you have a hidden agenda and the facts don't fit your fantasy.

Answer 4

Let me take an engineer's view of melting Greenland's Ice Sheets. You can look these numbers up on the internet and wade through the math yourself to check the calculations:



* Area of Greenland Ice: 1,710,000 square kilometers

* Thickness of Ice: 1.666 kilometers (average)

* Volume of Ice: 2,848,000 cubic kilometers

o (Source: Wikipedia)



If it all melted, worlds oceans would rise by:



* Area of world's oceans: 361,000,000 square kilometers (Wikipedia)

* Calculated sea level rise from melt: 7.26 meters (2.848 million cu-km of ice spread across 361 million sq-km of ocean, including the loss of volume from melting---ice shrinks when melted.)



Oh-oh, that looks like a real problem--it's nearly 24 feet of rise!!! But, hold on a minute: How long would it take to melt that much ice? That depends on how much ice there is and the physical properties of water, particularly the latent heat of fusion:



* Volume of Ice: 2,848,000 cubic kilometers

* Mass of Ice: 2,848,000,000,000,000,000 kilograms

* Heat of Fusion: 334 kiloJoules/kilogram (a physical property of water; this must be added to ice at 0 deg-C to cause the phase change to liquid water)

* Heat of Fusion Required for Melting:

o 951,519,000,000,000,000,000 kiloJoules = 15,849,000,000,000,000,000 kwh



(One kiloJoule is 1 kilowatt applied for 1 second, or a kilowatt-second or 0.0166 kilowatt-hours--the same unit as on your electric bill.)



That's a lot of energy and it must all come from somewhere. The sun is really the only source available. Barrow, Alaska, is at about the same latitude as the middle of Greenland. Solar radiation falling on Barrow averages about 2 kwh/square-meter/day (Funny; no one seems to know the insolation for Thule, Greenland.)

(Source: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/serve.cgi)



* Area of Greenland Ice: 1,710,000 square kilometers= 1,710,000,000,000 square meters

* Greenland Solar Radiation: 3,420,000,000,000 kwh/day



So if all the solar radiation that hits Greenland is totally devoted to melting ice (no reflection, no heating of air) , the time required is 4,637,000 days, (Heat of fusion required divided by the available average solar radiation).



That is a little over 12,700 years. And this is just to melt the ice that has already reached 0 deg-C; it takes more to raise the temperature from ambient to the melting point. (What's the average temperature of the ice today? I dunno...)



It's just an opinion, but this tells me that my distant great-great's will have plenty of time to move from their beach-front property---if a melt really does occur...



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That is a lot of isostatic rebound, if that's what it is. Do we have evidence of significant ice loss from Greenland and commensurate sea level rise? Actually no. We have some evidence in increased geothermal activity, which may be related -- or not. We have some suggestion of increased ice accumulation in central Greenland which might result in elastic deformation of the island (depression causing saucer uplift around the periphery). So much ice loss that all of Greenland is getting taller? Very, very doubtful...

Answer 5

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Greenland does not really exist--Al Gore made it up to become rich.

Answer 6

This is fairly standard science. The Canadian Shield down to the Great Lakes is still rising since the end of the last Ice Age. We think of the Earth as a solid chunk, but given the mass it's really more like Play Doh. It can be squeezed and bent quite a bit and it has a lot of rebound locked into it. As the article stated the area of the Greenland ice cap near the top still gets a lot of snow with not much decline noted, but along the edges the glaciers are losing ground fast...at least in terms of historical times. Relieved of this weight the 'rebound' is a natural process. In the area around the Great Lakes the rebound will probably empty most of the water out in a few million years. Lake Michigan will be the Michigan swamp. Something to look forward to.

Answer 7

The earth temperature is balanced by solar radiation (UV) emitted by the sun and infrared radiation that is reflected/released from the earth. These two lights will balance the earth temperature. However, there are the greenhouse gases. There are five major greenhouse gases; Nitrogen oxide (NOx), Carbon dioxide (CO2), water vapor, chlorofluorocarbon (CFC) and methane (CH4). These gases trap the infrared but still allow allow the UV to penetrate in. This imbalance of lights causes the earth temperature to rise, ie global warming. There are other causes of global warming but this is the strongest point I could think of. The effects of global warming is rising of sea level due to melting of ice in the Arctic which could lead to flooding. The ozone layer will also be depleted since the greenhouse gases will only let the UV light in. Apart from that is sudden changes in weather/extreme weather events because of the temperature rise.

Answer 8

I would think that's a rather premature conclusion..less sea rise..the land has been compressed, as the weight of ice is removed, the rebounding of land does not necessarily mean less displacement of water..it could have the opposite effect.

The land wants to "expand" taking up more volume., as well as whatever forces may be pushing from below. Are there major fault lines, and possible volcanic activity like in Iceland?And would the rebounding land have any effect on the rate of Greenland's glaciers calving and accelerating the flow of ice into the sea?



Things might get a lot more active and interesting geologically I suppose. Could we possibly see massive breaks or calving of ice?

Answer 9

Interesting ! Also interesting is how no mention is made in this report about any relationship to the Icelandic volcano. You would think with the proximity that there would be some kind of measureable connection... With all this acitivity in the northern Atlantic, these events create a somewhat ominous atmosphere for the rest of the world (no pun intended), don't they? Here's hoping a little volcanic ash induced winter comes a little earlier this year, to cool things off in the Arctic...

Answer 10

Just done some quick calculations and the rise of 25mm (1 inch) per year seems somewhat on the high side but not inconceivable.



Greenland is loosing ice mass at the rate of 400 billion tons per year or about 440 billion cubic metres. If this volume of ice were spread evenly over Greenland it would represent a layer 203mm (8 inches) thick.



With an annual ice loss of this order it would appear that observations of up to 25mm of elastic isostatic rebound might be stretching it a bit. I would suspect that the recent ice loss isn’t the only factor involved.



Although it’s 8,000 years since the demise of much of the glacial ice mass that once covered Greenland, the land is still recovering and ‘bouncing back’. The process of isostatic rebound has two stages – the first rapid stage is caused by the elasticity of the land mass reforming. The second stage is a much slower process, it occurs over many thousands of years and is caused by subterranean uplifting. This is the effect caused when the Earth’s mantle is no longer quite so compressed by the mass above it, this enables the mantle to slowly reoccupy the space from which it was originally squeezed; this exerts an upward force causing the land above to rise very slowly.



It’s quite probable that some of the recently observed rise is caused by the land recovering from the last ice-age, this could account for as much as 10mm of the recent rise.



What isn’t mentioned in the report is the extent of land mass that was observed to be rising at 25mm a year, it would be helpful to know this figure.



Given that post glacial rebound is a basic geological phenomenon then it’s only to be expected that Greenland will be rising. Any rise that occurs seaward of the mean high water spring (max tide limit) will contribute to global sea level rises.



Paul B enquired about the effect this would have on sea levels, on a global scale isostatic rebound is causing sea levels to rise by 0.1mm a year, thermal expansion of the seas and oceans accounts for 1.6mm and the burden of additional water from the melting of ice in the polar and mountain regions adds a further 1.5mm.



Mike mentioned the relationship between ice loss and land rise. The elastic rise is relatively proportionate to the mass of ice lost but the mantle uplifting decreases logarithmically.



Another point of Mike’s concerns the factors leading to the loss of ice. On the surface the primary reason for the decline in ice mass is due to increased atmospheric temperatures and insolation. Precipitation tends to fall as snow except around the periphery during the short summer season. Evapouration and humidity have only a slight effect as the requisite atmospheric conditions rarely present themselves.



There is increased melting within the ice mass itself and along the boundary between the land and ice. This is the consequence of surface meltwater entering moulins (sink holes) and percolating down through the ice, melting more ice as it goes. Ultimately this meltwater can reach the bedrock beneath the ice where further melting can occur.



However, it’s possible that the most important factor with regard to the amount of ice lost could be due to the accelerated advance of the glaciers. Indications are that the increased amount of water reaching the bedrock is acting as a lubricant. This is causing inverted glacial creep – ordinarily the central part of a glacier will advance quicker than the edges and base but we’re now observing faster movement at the base. In some places we’re observing accelerated basal sliding, where the whole glacier slides as one solid mass.



This increased flow means more ice is entering the seas and oceans and it’s here where most of the mass of ice is lost. In part due to the calving (shearing) of ice but mostly because the ocean water melts the ice below the waters surface and undercuts the glacier. In time the overhang becomes too great and it breaks off.

Answer 11

See, look what we all done know, More people die, 99% of us are burning garbage, Polluting lakes. The Environmentalists are try to convince people to help mother Earth, but almost all people think that Mother Earth is actually Mother "Russia" (Russia, dirtiest place on Earth). You know what, I've been trying to convince the costumers to stop throwing too much fish food to the lake full of fishes, 10.5% part of it is already polluted and people don't care about Mother Earth, They care about their family, love ones and their selves.



Guess what, we all can't change. Some of us only can... In the next ten years, we will be living on boats...in some areas... Some places are already flooded and some are underwater.



What the hell am I talking about? Just have fun while it lasts... Unless more and more environmentalists grow and grow till a 1 huge freaking family fit for a medium country and spread all over the world...



(I'm just a lil crazy today because I haven't slept yet...)

Answer 12

This is way too much relative rate of rise to be explained through Isostasy. I think that these guys had better talk to a Structural Geologist with training in rock mechanics and rheology, before making such unbelievable statements!

You are basically saying that removal of tens of feet of ice result in rebound within rigid and semi ductile crust of an inch every year? Not very likely. The Earth is not this elastic. It is not a spring! If there has been that kind of a rise, it is more likely that it is a response from early Holocene Melting where the removal was much more rapid than even the AGW folks can concoct.



EDIT:

For those that may want to see some actual science on Glacial rebound here is a paper from those "warming deniers" at the AGU...something called "Geophysical Research Letters"...I think they are a right wing think tank...maybe Creationists!



They may have a point though since I am old enough to remember thise massive glaciers on St. Catherine Street when I was a kid in Montreal. I see that their removal has caused about 3 times as much glacial rebound as Greenland according to Figure 1.



http://www.earth.northwestern.edu/people/seth/Texts/gpsgia.pdf

Answer 13

Thoughts:



1. Given that land can rise and fall on different parts of the Earth in the absence of ice seems to indicate that there are other reasons land can move like this. Has this research taken into account how an ice free Greenland would be responding? I would think that would be necessary to attribute any portion of land movement to ice loss.



2. They make an assumption that loss of ice is directly proportional to land rise (ie. the claim that accelerating land rise is caused by accelerating ice loss). Again, to make this claim 100% correct, they would have to eliminate any physical processes that may dictate that that the rate lessening of ice weight corresponds instantly to the rise of land. For example, in a shock and spring system, the increase or decrease of the load does not correspond to the instantaneous rise of fall of the system (that's the whole purpose of shock absorbers).



3. As well, although it is not specifically addressed in this report, and it may be in the actual study, but there is an assumption that ice loss is directly related to air temperature. I would submit that ice loss or gain is also related to other factor like precipitation, evaporation, humidity and geophysical processes occurring on the land under the ice.



Edit: 4. Have they found that the entire land mass of Greenland is rising, or that the overall average is a rise or that just the coast is rising? For example, an increase in ice mass in the center of Greenland could cause the outer edges to "bulge" (all else being equal).



I'm no geologist but I do have a science background and those are the thoughts that I have quickly come up with.

Answer 14

And what of Antarctica? It's rising too. In order for those landmasses to rise, other land masses must fall. And these events will cause more earthquakes and even volcanoes.

Answer 15

Sea levels measured around Greenland falling, final nail in global warming's coffin?



I'll see if I can get posted on WUWT.