GLACIAL SPEED: Greenland may get much of the scientific attention but it is smaller glaciers such as the Columbia Glacier in Alaska pictured here that are already contributing to sea level rise--and will continue to do so in future.
Image: Courtesy of W.T. Pfeffer, INSTAAR/University of Colorado
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Greenland, the world's largest island, holds enough ice to raise global sea levels by 23 feet (seven meters). Add the ice sheets of Antarctica and the oceans would deepen more than 200 feet (60 meters). Satellite measurements from space and speed measurements on land confirm that Greenland's glaciers are melting and on the move. And although the picture is less clear in Antarctica, the global warming seems to be having an impact there, too.
So the question is: How much—and how soon—will sea level rise?
New research from glaciologist Tad Pfeffer of the University of Colorado at Boulder and colleagues published in Science attempts to better estimate the possible sea level rise over the next century by measuring the speed at which the world's glaciers—in Greenland and Antarctica but also the many mountain ice sheets throughout the globe—are actually speeding to the sea as well as how swiftly they may melt.
"What would the flow velocities of the ocean-ending outlet glaciers have to be," if Greenland alone was to raise sea level by just six feet (two meters)? "The answer turned out to be huge: about 49 kilometers [30 miles] per year, 70 times faster than those glaciers move today," Pfeffer says, "and three times faster than we've ever observed an outlet glacier to move."
Given that Greenland's glaciers are not presently moving anywhere close to that pace—Kangerdlugssuaq Glacier, the fastest, reached speeds above nine miles (14 kilometers) per year in 2005—the researchers also looked at ice that could contribute from the rest of the world. Assuming that the largest remaining ice shelves in East Antarctica—Filchner-Ronne and Ross—will remain intact, sea level rise from all other melting ice and the expansion of seawater as the weather gets warmer over the next century would be somewhere between 2.6 feet (0.8 meter) and six feet (two meters)—or nearly twice as much as projected last year by the U.N. Intergovernmental Panel on Climate Change (IPCC).
This does not take into account how much sea level might swell from the metldown of the numerous small glaciers in Alaska, Argentina, Canada and Russia, which already contribute 60 percent of sea level rise from glacial melt. (In fact, Pfeffer notes that they are melting faster and therefore adding to sea levels more rapidly than Greenland and Antarctica combined currently do.) Nor is it clear whether something might suddenly occur to change that upper estimate. "If those two big ice shelves [in Antarctica] go out, then it's an entirely different situation," Pfeffer says. "But there's no good evidence that that's going to happen over the next century."
Ancient melting events suggest that glaciers can disappear in a hurry, however, and raise sea levels by more than half an inch a year. The Laurentide ice sheet that stretched as far south as New York State and Ohio some 20,000 years ago had retreated to eastern Canada, just across the water from Greenland, by roughly 11,000 years ago thanks to increased sunlight (due to the periodic wobble in Earth's axis known as precession). It then completely disappeared by 6,800 years ago in two geologically rapid bursts, shedding enough ice to raise sea levels by as much as four feet (1.3 meters) per century, according to research published this week in Nature Geoscience.
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43 Comments
Add CommentIs anyone tracking the expansion of the globe and the raising sea levels.
Reply | Report Abuse | Link to thisWith the additional land form Earthquakes and Volcanos. Who's winning
unica4wireless: Volcanoes add no mass to earth, they get their mass from inside the globe and that is just "recycled crust material", the only new mass earth receives is from meteors and meteorites that hit us. And from that over 70% ought to hit seas and oceans (which cover about that percent of the earth). The net result of volcanoes/earthquakes and meteors/meteorites ought to be nil with regard to the rising sea levels.
Reply | Report Abuse | Link to thisGood article. I am curious about the reason that scientists and science writers do not use metric measures exclusively in their articles. Especially the ones written in U. S. seem to not only write in customary units with metric in () but sometimes switch or intersperse units throughout the article.
Reply | Report Abuse | Link to thisIt could be easier to read if one set of units were used the entire article.
There seems to be something wrong with your math. There are 92 years until 2100. 7cm * 92 = 6.44m, 13cm * 92 = 11.96m. So we're talking between 6 and 12 metres of sea level rise by 2100. Either that, or your yearly figures are wrong.
Reply | Report Abuse | Link to thistoo bad for New Orleans... looks like it is only going to get worse for that city... why are we continuing to rebuild it if they are going to loose... last time i checked man never won a battle against Mother Nature
Reply | Report Abuse | Link to thisWhat's an order of magnitude when politics are involved anyway?
Reply | Report Abuse | Link to thisScience always and again oversimplifies reality to the point where the conclusions of scientists meet with the embarrassing credulity of science fans. It's just another fantasy religion, science. This "science" is a belief in a fantasy, because it's so far from anything that should be considered truth.
Reply | Report Abuse | Link to thisAccording to the grand scheme of the analysis presented here, sediments washing into the oceans since the beginning of time should have raised sea levels to the point where there'd be nothing but fish living on the planet.
Reality is infinitely complex.
And that termed "science" by comparison is infinitely inadequate to describe reality.
Science is but a tool of politicians and other such liars.
Don Robertson
Wow, sounds like its time to buy some property in the mountains!
Reply | Report Abuse | Link to thisJiff
www.anonymize.us.tc/
People, Really now. Are we just getting more and more gullible. If the glaciers do melt, the sea level wont rise. "huh What how lies" But the truth is you can carry out this yourself. Get up go the the kitchen grab some ice put it in a bowl. Now fill the bowl of ice to the tip, very edge, with water. Leave it to sit, then go back later and find the overflowing bowl, the truth is you wont. Forget the big myth and hype about rising sea levels.
Reply | Report Abuse | Link to thisHmmm. This all seems very suspect to me. In order to raise sea level by one inch, 9,137 cubic kilometers (km�) of water must be added to the oceans. That means that one gigatonne of ice (which has a volume greater than 1 km�) must melt and flow into the ocean, or must calve from a land-borne glacier and land in the ocean. So, in order to get 2.6 feet of sea level rise, 285,074 km� of water must be added to the oceans. That's a lot of water. If you had an ice sheet 100m thick, that would cover a land area of 2,850,740 square km. Greenland has a land area of about 2.1 square km. So if Greenland were entirely covered by 100m of ice, and all of it melted at once, you would still not get the 2.6 feet sea level rise posited in the article. And that doesn't take into account sea water loss to evaporation and ice accumulation, as is taking place in Antarctica. I don't know the specifics, but I think someone is cooking the books here.
Reply | Report Abuse | Link to thisThis ice is on an island, NOT already floating :(
Reply | Report Abuse | Link to thisThe ice you're referring to in your example is already in the water. The ice mentioned in the article is out of the water, on land.
Reply | Report Abuse | Link to thisGreenland contains an ice sheet that covers 1.7 million square kilometers (656,300 square miles) - an area nearly the size of Mexico - and is as much as three kilometers (1.86 miles) thick in places.
Reply | Report Abuse | Link to thisExcept there is the problem in the article with this comment:
Reply | Report Abuse | Link to thisAdd the ice sheets of Antarctica and the oceans would
deepen more than 200 feet (60 meters).
Antarctica, yes. The oceans, no. This is a disappointing comment to find in an article on sciam.com.
As for Antarctica, it has a huge bowl in it that would retain some significant portion (though not a majority) of the melt even allowing for some rise in the land as it sheds the burden of ice.
While it seems nothing ever gets done by government to address problems for which it must play a part unless the problems have been elevated to a pending disaster or some other crisis, the exaggerated claims for every conceivable problem means everything is a crisis, leaving no room for setting priorities and greatly hindering the already limited ability to develop good policy. Moreover, the inflated partisanship to which we are subject today over relatively minor political differences ensures not just indifference, but outright hostility to anything perceived to be akin to little boys crying, "wolf!"
Yes, I misread the comment I quoted above and projected my own biases onto it. Please disregard it as yet more tripe spewed onto the Internet.
Reply | Report Abuse | Link to thisDoes anyone ever bother to think about how the rising sea levels will affect the current glaciers or sea ice? I mean, ice floats, duh.. If the water goes up 6", then the ice would rise a further 6" off the ground, or whatever its sitting on. This will create new stress points where the ice is attached to land or other ice masses at. Might this not cause the current ice sheets to break up even faster than they normally would? This would give the ice somewhere to float away to, and free up space for more ice to flow into.
Reply | Report Abuse | Link to thisOh and spike, your comment would be correct, if the only ice we were talking about was the ice currently in the water. The fact is that the ice people are worried about is the ice thats sitting on land, which will melt, or flow into the oceans thereby raising the water level. If you want to demonstrate this effect, fill a bowl up with water, then dump a bunch of ice cubes into it..
the comment about the ICE in a bowl does have credibility to it... but the original one is debunking the Myth that a former VP (gore) has stated over and over... showing how politics is used and how naive they are when it comes to actually checking their facts. because the first situation is the one Gore puts forward the second one is the correct one for what happens when Greenland melts.
Reply | Report Abuse | Link to thisthough i would also like to point out that when all this extra water/ice gets into the Ocean no one knows what will happen because we do not have direct observations of what will happen. (ice/sediment cores are not direct measurements how ever much people would like them to be) we have only collected direct measurements for 300 years or so but modern measurements for only about 50 years. and let us remember that the world has been around for 4 billion... so our models are only so so.
situations like what the move "day after tomorrow" puts forward are possible though i do not believe it would be anywhere near the scale the movie puts forward... cause that is Hollywood's over dramatized version of reality.
Good article.The rapid melting of the Greenland and the rise in the sea level is indeed a major challenge for the glaciologists,environmentalists and green activists.Melting of the ice sheets of Greenland is a result of global Warming and rapid increase in the carbon emission by the rich countriies.Let's unite and work together to save Greenland from Global Warming.
Reply | Report Abuse | Link to thisThe article is revealing and it shows how much of water is contained in the glaciers. It ought to correlate the rise of sea level due to global warming rate as well and state how the solar energy fluctuations will compound the whole thing.
Reply | Report Abuse | Link to thisCan someone explain how antarctica is melting when the highest tempiture on record is -13.6C or 7.5 F WELL BELOW FREEZING
Reply | Report Abuse | Link to thissteellatter: Because the melting goes on in the coastal areas which gets above freezing temperatures in the summer. Wikipedia has an excellent article on the subject with further reading as well; http://en.wikipedia.org/wiki/Climate_of_Antarctica
Reply | Report Abuse | Link to thisSediments washing into the ocean are just a reflection of erosion on land. Erosion is offset by the mountain-building effects of plate tectonics and volcanoes. That's driven by the internal heat of the earth. Uranium in the core cooks off slowly, releasing heat. For the last few billion years, it's been roughly a tie-as erosion eats away at the continents, other forces build them up.
Reply | Report Abuse | Link to thisAll of this happens much more slowly than icecap melting would go, if it were to happen. Over the next few centuries, whatever happens with sea level will happen mainly as a result of what happens to the icecaps of Greenland and Antarctica.
The ice sheet of Greenland averages deeper than 100 meters. It's not that complicated. Give the people doing the arithmetic a little credit, OK?
Reply | Report Abuse | Link to thisWhat bunk. A few things these researchers left out, how much of that water will be absorbed, yes absorbed by the coastline soil because it does absorb moisture. How much will be in the air as vapor from the supposed increase in temperatures? since higher temperatures will also equate to a higher moisture content in the atmosphere? How about inland lakes and rainfall? They will go up. So their research only makes sense if the ice melts and the soil absorbs no water and there is no increase in humidity.
Reply | Report Abuse | Link to this@ NotLikely,
Reply | Report Abuse | Link to thisYou are correct to say "if Greenland were entirely covered by 100m of ice, and all of it melted at once you would still not get the 2.6 feet sea level rise". But since the island is 80% covered and the ice averages 1,500m in depth, your calculation is somewhat beside the point.
Your observation that you "don't know the specifics" is also correct.
As soon as the Hollywooden idols start selling their beachfront property in Malibu ... I will 'believe' in the efficacy of this IPCC 'political -science'. At the expressed rates of innundation ... it won't be longer than 10 years before the FOR SALE signs are posted.
Reply | Report Abuse | Link to thisHow shameful that this nonsense passes for 'science'
Hey spike - you're correct as far as ocean ice is concerned. However, the melting of land-based ice (e.g., ice that's not floating in the water, but supported by land) will raise water levels.
Reply | Report Abuse | Link to thisI think Spike's forgetting the difference between landborn glaciers and floating sea ice. He's correct in that the latter is already compensated for in global sea level and won't contribute to a rise if and when it melts, but ice that's currently lying on land will, ie. that portion of glaciers which hasn't yet flowed to the sea and isn't being supported by it, and the main mass of icecap ice on Greenland and Antarctica.
Reply | Report Abuse | Link to thisWe still use the measurements of inches, feet and miles in the U.S. If the article was written only in "meters", etc., many of the people reading it would have no frame of reference for the amount being discussed.
Reply | Report Abuse | Link to thisOK, let's see if this arithmetic works:
Reply | Report Abuse | Link to thisall oceans surface area = 360 M sq km
surface area of Greenland = 2.1 M sq km
1 m rise in oceans = all of Greenland at 171 m thick melting completely
Global Warming vs Climate Variation vs Aquifer Depletion
Reply | Report Abuse | Link to thisMy thought is that, it is possible, we are in the midst of human induced "global warming" at the same time as natural "climate variation" is warming up the planet for a double wammy. Conservation, by itself, will not be enough. I don't know if this idea is correct, but it seems to be prudent that governments around the world employ an arsenal of programs to meet the potential impact of the melting of the polar ice caps. This would include solar power, wind power, tidal power, nuclear power, limits on fossil fuels and limits on population growth. It would also include river diversion.
At the same time, it is being reported that, around the world, aquifers are being depleted to meet the needs agriculture for the growing human population. I have never read, in any study relating the models used to predict the rise in sea levels due to the melting of the ice caps, the possibility of diverting rivers from flowing into the oceans to flow into the interior so that sea levels will not rise as quickly.
From the engineering point of view, how much water in the past has been diverted from flowing to the oceans and what is the corresponding impact on sea levels? We should not try to argue whether water diversion is good or bad. Just the fact please! Is it one inch or one foot or ten feet? What is the total capacity of all the aquifers around the world to absorb water and relate that to sea levels? Will it make a difference? From an engineering point of view, even if you find that the impact on sea levels in not that great, it would be important because it answers a question that has not been asked before. From the political point of view, you can still discuss the politics of diversion of rivers that cross borders.
From the political point of view, who stands to gain and who stands to lose from diverting rivers from the ocean? From an engineering point of view, what impact will it have on the environment? A few years ago, I read that diverting the largest river which flows into Hudson's Bay would eliminate the annual winter freezing, because fresh water floats on salt water and icebergs form. With no fresh water flowing into Hudson's Bay, it would be ice free all year and huge new fishery would be created to feed the world. Why hasn't this even been considered at the political level? Could Canada claim that fishery is in Canadian waters and limit it to Canadian companies? Would other countries object?
Forty years ago, an American plan (NAWAPA) was proposed to divert the mighty Canadian Mackenzie River, which flows into the Arctic Ocean, south to the United States to replenish the huge Ogallala aquifer.
(Arctic wild idea preserved - http://www.workingforchange.com/article.cfm?ItemID=11874 ).
All Canadians thought that the plan was nuts! Americans can't steal our water. We would rather piss it into the ocean. What would have been the impact on ocean levels if this plan had been approved 40 years ago? Politically, why was there opposition to the plan, and would there be the same opposition today?
There are also plans to divert Russian rivers that flow into the Arctic so they can irrigate Central Asia and replenish the Aral Sea. Russian nationalists oppose this plan.
(Arctic to Aral - http://ecoworld.com/Home/Articles2.cfm?TID=378)
The question that I would like answered is this:
Do these models of rising sea levels address the possibility of diverting rivers that flow into the oceans so that they can irrigate deserts, steppes, and replenish the aquifers that are currently being depleted? If they don't, then it indicates a bias that climate researchers have against engineering our way out of the impending global warming crisis in favour of a passive conservation approach.
Below is an example of the mindset of researchers in the field of global warming and water deficits. No mention of large scale river diversions
WATER DEFICITS GROWING IN MANY COUNTRIES
http://www.greatlakesdirectory.org/zarticles/080902_water_shortages.htm
"The two keys to stabilising aquifers are raising water prices and stabilising population. The first step is to eliminate the pervasive subsidies that create artificially low prices for water in so many countries. The next is to raise water prices to the point where they will reduce pumping to a sustainable level by raising water productivity and reducing water use in all segments of society. Low-income urban consumers can be protected with "lifeline rates" that provide for basic needs at an affordable price. Prices of underground water can be raised by installing meters on pumps and charging for water as Mexico has done or by auctioning permits to operate wells. Either way, water prices rise. "
ice in a bowl of water does not equate to the same thing. especially if the ice is sitting on a land mass and not atop of an ocean. so get beyond your 5th grade science level and realize that if you add water to water the levels will rise, same as 3 inches of rain will raise the level of a pond or lake.
Reply | Report Abuse | Link to thisTo spikef2163: Your experiment simulates sea ice, not land ice. A better experiment would be to place a rock inside a bowl of water, well above the water level and then put your ice on that.
Reply | Report Abuse | Link to thisTo NotLikely: Check you numbers, Greenland actually has a land area of about 2,166,086 square km of which 1,755,637 square km is ice-covered [google: greenland land.area]. The total ocean area is approx. 361 × 10^6 sqare km [wikipedia: ocean], the article talks about 2.8 inches of sea level rise from Greenland thawing, which is a reduction of the ice sheet of Greenland with approx. 15 meter.
Our modest input of CO2 won't change anything. So why bother ? We will have plenty of time to adjust. Even Noah had time to build an ark !
Reply | Report Abuse | Link to thisGabriel
this definately poses cause for concern but is the inforamtion presented a possible exaggeration- I must aggre that reality is complex.
Reply | Report Abuse | Link to thisThis is quite interesting, and I must agree that reality is very much so complex, so the question is how do we decifer what really is occuring?
Reply | Report Abuse | Link to thisI have heard about this in the past and I believe that it should be a growing concern. Greenhouse gases and climate change effects are creating a huge problem theses days not only for the sake of the melting waters but also Canada's Arctic soveriegnty (I just wrote a paper on that lol). But seriously if the waters rise enough (which still won't be for a long, long time) we could all drown or have to move to higher ground. We should be doing something to save the environment from pollution and/or even death. This just gives us one more reason.
Reply | Report Abuse | Link to thisDr. Nils-Axel M�rner has studied sea level and its effects on coastal areas for some 35 years. Recently retired as director of the Paleogeophysics and Geodynamics Department at Stockholm University, M�rner is past president (1999-2003) of the INQUA Commission on Sea Level Changes and Coastal Evolution, and leader of the Maldives Sea Level Project. The uncompromising verdict of Dr M�rner is that all this talk about the sea rising is nothing but a colossal scare story - Sea Levels Are Not Rising! Read more at http://www.climatejournal.org/climatenews00148.htm
Reply | Report Abuse | Link to thisSpike, Try filling half the bowl with dirt and the other with water. Then put ice on the dirt. Yes, when ice melts it will overflow. The melted water is extra. You are right that melting ice below the water line will reduce the sea level.
Reply | Report Abuse | Link to thisNot Likely, The ice sheet on greenland is thicker than the 100M you figured. A lot thicker. Sorry, but you might need the ark anyway.
So far this thread is addressing only part of the problem.
Reply | Report Abuse | Link to thisIce, whether on land or sea, reflects sunlight. When it melts, the earth absorbs more heat. Increased levels of CO2 in the atmosphere make heat harder to dissipate. Water expands when heated. The world's oceans will swell up and sea levels rise from heating alone. That's why even melting sea ice in the arctic will contribute to sea level rise.
um, spike, you are doing the wrong experiment. Ice in the water will not raise the water level because it is already IN the water. DUH.
Reply | Report Abuse | Link to thisGlaciers are not the same as sea ice, because they are above sea level and not in the water.
So, do this experiment. Get a bowl. Fill it to the rim with water. Then get a colander, a piece of screen, or something else with a hole in the bottom. Suspend the screen ABOVE the bowl and pile some ice on or in it so that the melting ice will drip into the water. Come back later and see what has happened.
For maximum educational value, set the bowl on the smooth level surface of your neatly made bed.
spikef2163 - you are doing the wrong experiment. Ice in a bowl of water will not raise the water level because it is already IN the water. Duh.
Reply | Report Abuse | Link to thisGlaciers are not in the ocean. They are ABOVE sea level, flowing down from the mountains toward the ocean. So, do this experiment. Get your bowl, fill it with water to the very brim. Then find a container such as a colander or a piece of screen that will allow the melting ice to drip through. Fill the colander with ice and suspend it above the bowl, so that the melting ice drips into the bowl. Come back later and see what has happened.
For maximum educational value, place the bowl and the suspended ice on the smooth level surface of your carefully made bed.
Sorry about the duplication. This newbie didn't understand how comments work.
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