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Huge Canyon Discovered Under Greenland Ice

timothy posted about a year ago | from the earth-the-present-frontier dept.

Earth 137

cold fjord writes with this news, straight from the BBC: "One of the biggest canyons in the world has been found beneath the ice sheet that smothers most of Greenland. The canyon — which is 800km long and up to 800m deep — was carved out by a great river more than four million years ago ... It was discovered by accident as scientists researching climate change mapped Greenland's bedrock by radar. The British Antarctic Survey said it was remarkable to find so huge a geographical feature previously unseen. The hidden valley is longer than the Grand Canyon in Arizona. ... The ice sheet, up to 3km (2 miles) thick, is now so heavy that it makes the island sag in the middle (central Greenland was previously about 500m above sea level, now it is 200m below sea level)."

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So just wondering... (4, Interesting)

Daetrin (576516) | about a year ago | (#44710539)

In theory, if all the ice on Greenland melted, how long would it take Greenland to spring back up again? I'm presuming it wouldn't be instantaneous or even noticeable to a human on Greenland at the time (well, aside from the earthquakes that would almost certainly accompany such an event,) but are we talking years, decades, centuries, or longer?

Re:So just wondering... (-1, Offtopic)

MacroSlopp (1662147) | about a year ago | (#44710569)

It won't be noticeable to humans...
They won't exist by the time it get's that warm.

Re:So just wondering... (-1, Redundant)

Daetrin (576516) | about a year ago | (#44710691)

Congratulations on failing to read the question and failing to provide an answer! It's been awhile since i've seen such a succinct double fail! I am interested in the plain and simple "what if [xkcd.com] " of "what if the ice wasn't there, what would happen?" Which is why i specified "in theory" when i asked the question. I really have no interest in whatever personal boogeyman of science or politics or theology or whatever it is you're trying to derail the conversation with.

Re:So just wondering... (4, Informative)

K. S. Kyosuke (729550) | about a year ago | (#44710751)

By "spring up", you mean floating the crust higher on the mantle? I thought that the north of Europe was even now still rising after the last Ice Age, and that's been quite some time.

Re:So just wondering... (-1)

Anonymous Coward | about a year ago | (#44710785)

Congratulations on failing to read the question and failing to provide an answer! It's been awhile since i've seen such a succinct double fail! I am interested in the plain and simple "what if [xkcd.com] " of "what if the ice wasn't there, what would happen?" Which is why i specified "in theory" when i asked the question. I really have no interest in whatever personal boogeyman of science or politics or theology or whatever it is you're trying to derail the conversation with.

It appears to be bog-standard leftwing misanthropy.

Re:So just wondering... (2)

mark-t (151149) | about a year ago | (#44710823)

Why do you figure that the earth will not be inhabitable by humans? Consider that before the last major ice-age, the world was much warmer than it is now....

Re:So just wondering... (1)

jovius (974690) | about a year ago | (#44713935)

At least it'll be less habitable, because the climate change at hand is a whole lot faster than what it has naturally been. The planet tries to accommodate the relatively quick input of energy (coming from the suddenly enhanced greenhouse effect and deforestation...), and in the process goes to extremes more often than before. The cycles in the past hundreds of thousands of years have been relatively stable and changes have been taking place in thousands of years. We are in the middle of a balance seeking process, and the new balance is unknown. The historical oscillations have been perturbed.

What comes to to the original question the land in Finland rises 3 - 9 mm per year for example (although this may not all be from recovering from the ice age). The rise has even changed the direction of river flows. Islands of one archipelago gain new area about 1 km^2 per year. The total land area gains 7 km^2 year. 12000 years ago Finland was buried under 2 - 3 kilometers of ice.

Re:So just wondering... (1)

evilmidnightbomber77 (2891503) | about a year ago | (#44714233)

It will be habitable for some number. It sure as hell won't be inhabitable by 7 billion humans though.

Re:So just wondering... (1)

khallow (566160) | about a year ago | (#44712025)

Why wouldn't humans exist? We're not talking of conditions that would kill humans after all. Just merely warm enough to melt ice on Greenland.

Re:So just wondering... (-1)

Anonymous Coward | about a year ago | (#44712059)

get is? get was? something belongs to a "get"?

Re:So just wondering... (0)

Anonymous Coward | about a year ago | (#44713595)

Why did you use an apostrophe in the word "gets"?

Re:So just wondering... (5, Informative)

necro81 (917438) | about a year ago | (#44710753)

Centuries to millennia. Geologists are able to measure the ongoing rebound [wikipedia.org] of North America from the retreat of the glaciers from the last ice age.

Re:So just wondering... (4, Informative)

Anonymous Coward | about a year ago | (#44710817)

Millennia. The post-glacial rebound [wikipedia.org] is still happening in North America from the last ice age [wikipedia.org] , and that was 10,000 years ago. The New Madrid Seismic Zone [wikipedia.org] is still active today, and experts agree that it has the potential to produce another very powerful earthquake.

Re:So just wondering... (2, Interesting)

Anonymous Coward | about a year ago | (#44710819)

Some places in Sweden are raising with 9mm/year so it could probably be noticed by humans over a lifetime.

Re:So just wondering... (1)

NatasRevol (731260) | about a year ago | (#44711603)

Noticeable is an understatement

That's 35 inches in 100 years.

I hope it's even!

Re:So just wondering... (1)

jopsen (885607) | about a year ago | (#44711693)

Noticeable is an understatement

That's 35 inches in 100 years.

I hope it's even!

Or 9mm per year, 9cm per 10 years, 0.90m per 100 years, to be exact...

Re:So just wondering... (1)

NatasRevol (731260) | about a year ago | (#44711753)

I doubt the 9mm is exact, so your precision is ... not.

Re:So just wondering... (3, Informative)

PurpleAlien (797797) | about a year ago | (#44712483)

High Coast (Sweden) and Kvarken Archipelago (Finland)

"The geomorphology of the region is largely shaped by the combined processes of glaciation, glacial retreat and the emergence of new land from the sea which continues today at a rate of 0.9 m per century."

Source: http://whc.unesco.org/en/list/898 [unesco.org]

Re:So just wondering... (1)

mevets (322601) | about a year ago | (#44713313)

9mm/yr after how many years?
The shape of the curve is probably more interesting; as the awkwardly phrased wikipedia page attests:
----
Studies have shown that the uplift has taken place in two distinct stages. The initial uplift following deglaciation was almost immediate due to the elastic response of the crust as the ice load was removed. After this elastic phase, uplift proceeded by slow viscous flow so the rate of uplift decreased exponentially after that.
-----
I think it would be quite observable.

Re:So just wondering... (1)

Anonymous Coward | about a year ago | (#44710865)

Michigan and Upper New York are still rebounding from the last ice age.
It will take a while. Today, typical uplift rates are of the order of 1 cm/year or less.
http://en.wikipedia.org/wiki/Post-glacial_rebound

Re:So just wondering... (0)

Anonymous Coward | about a year ago | (#44710953)

that would explain the weight loss i experience, yes i measure my weight loss at that scale you insensitive clod

Re:So just wondering... (5, Informative)

icebike (68054) | about a year ago | (#44710927)

In theory, if all the ice on Greenland melted, how long would it take Greenland to spring back up again? I'm presuming it wouldn't be instantaneous or even noticeable to a human on Greenland at the time (well, aside from the earthquakes that would almost certainly accompany such an event,) but are we talking years, decades, centuries, or longer?

It would be noticeable by humans over their life span.

You see this (in smaller scale) in places in Alaska where receding ice caps and the glaciers that flow from them slowly recede up the valleys and vegetation changes appear in the wake.

You also see the river flowing from the glaciers cutting deeper channels to the ocean. The glaciers flowed directly to the ocean earlier, now the glacier's nose is several miles upstream. The river channels "grow" high banks as you travel away from the glacier toward the ocean. This is a sign of uplifting land, (there are no longer and deposited soils being laid down in the area, yet the river banks grow steeper, and the river surface is within a few feet of mean high tide over the years.

Its not much, but you can see it over a period of 30 or 40 years if you are observant. Surveyors can measure it these days (even without GPS), relative to mean high-tide in those places where survey markers were installed decades ago.

Re:So just wondering... (1)

X-Ray Artist (1784416) | about a year ago | (#44711567)

I was hoping there would be a decent answer to this question. I was curious about the answer and this explains it best to me.

Re:So just wondering... (2)

Tastecicles (1153671) | about a year ago | (#44710949)

dunno, but there is a seesaw effect still in play in Western Europe; the most dramatic effect is seen along the length of mainland Britain. While Scotland is still rising after spending a while under a couple miles of ice, the South of England is sinking as it was largely ice-free during the last big freeze. The phenomenon is slow, it's taking a few thousand years for a complete oscillation, but geological evidence suggests that prior to the last ice age, the North Sea was bone dry (being several hundred metres above sea level!). It won't be very many hundreds of years before Loch Ness is physically isolated from the sea at either end and becomes a fully enclosed high saltwater lake!

Re:So just wondering... (1)

mrbester (200927) | about a year ago | (#44711431)

The south of England, particularly the Weald and south coast from Dover to Selsey, was under the sea until the Cenozoic era, hence the chalk downs and cliffs made of crushed fossilised prehistoric sea shells. To say there must have been a few of them is an understatement; Beachy Head is 513ft high. And that's after tens of millions of years of erosion.

Re:So just wondering... (0)

Anonymous Coward | about a year ago | (#44711119)

It would probably take at least tens to hundreds of thousands of years, given that in locations such as Canada and northern Europe that formerly had several kilometres of glacial ice on them are still rising today due to isostatic rebound [wikipedia.org] . The ice was thickest in these areas about 100000 years ago and most of it had melted away by about 10000 years ago, but it's still rising. Total rise is on the order of several tens of metres [uwgb.edu] depending upon location. Along Hudson's Bay (northern Canada) there are raised beaches all over the place on the land, marking the former location of the shorelines.

Re:So just wondering... (1)

hydrofix (1253498) | about a year ago | (#44711289)

During the last ice age up to only 15,000 years ago, the whole of Scandinavia was covered under a very heavy glacial mass, causing the earth's crust to deform. In these areas, the earth is currently raising or rebounding [wikipedia.org] at a rate of about 3-5 millimeters per year, or up to 10 inch (25 cm) in half a century (50 years). Such changes are indeed quite visible during a human life. An elderly person might recognize that a shore where he or she used to spend time as a child has visibly changed as if by a permanent low tide during their lifetime.

Re:So just wondering... (1)

riverat1 (1048260) | about a year ago | (#44713025)

The Canadian Shield is still rising from the end of the last glaciation around 12,000 years ago. Lake Champlain used to be part of the Champlain Sea [wikipedia.org] until isostatic rebound caused it to rise above sea level around 10,000 years ago.

I think I know what it is (4, Interesting)

50000BTU_barbecue (588132) | about a year ago | (#44710551)

Is it where the Wunderland Treatymaker was test fired?

Re:I think I know what it is (0)

Anonymous Coward | about a year ago | (#44710645)

Is it where the Wunderland Treatymaker was test fired?

Bonus points for Larry Niven reference!

Al Gore, you're wanted on line 1... (2)

themushroom (197365) | about a year ago | (#44710555)

Now's the time when climate change could do some good... RAISE GREENLAND! Make it green land!

Re:Al Gore, you're wanted on line 1... (2)

Kjella (173770) | about a year ago | (#44711425)

And only 1031 years after it was named so in order to trick people into immigrating there, better late than never I guess.

Sooo, 4 mya Greenland wasn't ice-covered? (0)

Anonymous Coward | about a year ago | (#44710589)

I guess the Earth must have been warmer, from all the mammoths driving SUVs.

Please don't post stories about "Global Warming" (-1, Troll)

Finallyjoined!!! (1158431) | about a year ago | (#44710597)

on /.

You'll have all the weirdos calling by; claiming that eating toasted bread kills hedgehogs

Re:Please don't post stories about "Global Warming (-1)

Anonymous Coward | about a year ago | (#44710813)

Why would a slashdotter make a post about global warming when it's obvious that the underground canyon was excavated by aliens many eons ago? Haven't you seen the surface entrance [imageshack.us] to the subterranean alien base in Google Earth (of course, the US government has pressured Google into removing from their image database)?

Re:Please don't post stories about "Global Warming (-1)

Anonymous Coward | about a year ago | (#44710875)

Actually the article could have been written about my ex-girlfriend. Cavernous and saggy while not as pretty as Greenland.

Ha ha, I can see I've been modded as a Troll (0)

Finallyjoined!!! (1158431) | about a year ago | (#44711291)

How ironic.

Re:Ha ha, I can see I've been modded as a Troll (0)

Anonymous Coward | about a year ago | (#44712237)

Well, you said to look out for weirdos talking about toasted bread killing hedgehogs, so we modded down everyone talking about such crazy things.

All can be fixed.... (4, Funny)

pollarda (632730) | about a year ago | (#44710603)

With a little global warming one of the world's greatest landmarks could be recovered, the sag in central Greenland would be fixed and a new source of income for Greenland could be tapped as tourists flock to this new "Grand Canyon" to go hiking, fishing, and camping.

Re:All can be fixed.... (3, Funny)

Anonymous Coward | about a year ago | (#44710773)

Based on my own experience, once there's sagging in the middle it never goes away no much how hard you try to burn off the weight.

Re:All can be fixed.... (1)

Impy the Impiuos Imp (442658) | about a year ago | (#44710871)

And the rest of Canada, Alaska, and Siberia. By that time we will have robots serving us sp it's all irrelevant. Bring on the robots as fast as possible.

Re:All can be fixed.... (0)

Anonymous Coward | about a year ago | (#44711045)

By the time that happened there would be no tourists! For the automation and "free markets" have left the plebs too poor to go on something they think was a myth once called vacation or retirement.

Only a few highly specialized and born wealthy humans remain with their automaton workforce running bellow capacity for there was no customers nor capital system implemented that could buy their cheap to manufacture and as expensive as possible to sell products.

Re:All can be fixed.... (0, Offtopic)

ChrisMaple (607946) | about a year ago | (#44712419)

It's astonishing how quickly opponents of capitalism and freedom contradict themselves. If goods are cheap to manufacture, The manufacturer maximizes profits by changing the selling price in a series of decrements, in each decrement making new profits by selling to people unwilling to buy at the old price. Inevitably the price falls to a small multiple of the cost of manufacture, where most people who are interested can buy. For the rich owner of the means of production to fail to do so would mean that he is too stupid to maximize his profits.

Historically, the concept of retirement for most people is a new thing, which has developed as the wealth made possible by capitalism has accumulated. Before that, people worked until they died.

More info (3, Informative)

cold fjord (826450) | about a year ago | (#44710611)

Giant Canyon Discovered Under Greenland Ice Sheet [nationalgeographic.com]

While flying over the ice sheet, scientists over the past three decades have measured the depths of the canyon using a radar system that operates at frequencies transparent to radio waves—from around 50 megahertz to 500 megahertz. A pulse of energy is sent down to penetrate through the ice, bounce off the bedrock, and travel back to the radar system. (Also read: "'Shocking' Greenland Ice Melt: Global Warming or Just Heat Wave?")

'Grand Canyon' of Greenland Discovered Under Ice Sheet [livescience.com]

Re:More info (1)

JWW (79176) | about a year ago | (#44710821)

frequencies transparent to radio waves

What the heck??

Re:More info (1)

cold fjord (826450) | about a year ago | (#44710901)

No doubt that is referring to radar frequencies which will penetrate the ice.

Re:More info (0)

Anonymous Coward | about a year ago | (#44711401)

Ice is fairly transparent to certain frequencies of radio waves, as are most materials to varying degrees. Why do you think that wifi and cellphone signals can travel through walls? For conventional radar use in the atmosphere (say, for tracking planes) you're only interested in the "hard" returns/reflections from the very first interface between the air and some other material, but nothing stops you from continuing to record radio signals after the first reflection to see if there are any reflections from "deeper" interfaces further away. The same techniques can be used to actively scan through walls, or in this case through kilometres of glacial ice to see the reflection off bedrock. Ice is transparent enough that you can see a long way down, and the contrast between ice and bedrock is strong, so it shows up well. The same technique can be used on ordinary ground (ground penetrating radar [wikipedia.org] ), but the depths aren't as good due to greater attenuation in typical ground materials rather than ice, especially if liquid water or other conductive material is present. In mathematical principle it's a similar technique as is used for medical ultrasound images or seismic images except that instead of using sound waves you are using radio waves, and the reflections therefore come back a LOT faster (close to the speed of light).

You want to know something *really* cool? You can even do it from orbit, around another planet [nasa.gov] .

Re:More info (1)

HornWumpus (783565) | about a year ago | (#44712251)

Duh. He was ripping on the reporters English and lack of understanding.

Why is it (1)

nayrbn (2704751) | about a year ago | (#44710631)

that Greenland is called Green again?

Re:Why is it (5, Informative)

Ioldanach (88584) | about a year ago | (#44710765)

that Greenland is called Green again?

Propaganda. Erik the Red named it that in 985 AD to get people to colonize it with him.

Re:Why is it (1, Interesting)

Anonymous Coward | about a year ago | (#44710849)

And despite what you've been taught, it was a successful farming colony until the climate cooled and the route north of Great Britain became too hazardous.

Re:Why is it (1)

riverat1 (1048260) | about a year ago | (#44713893)

I think you'd have to say it was a marginal farming colony. I've never heard any indication they had enough surplus to export.

Re:Why is it (1)

CanHasDIY (1672858) | about a year ago | (#44710913)

I had always heard that the residents of Iceland named it, in order to trick Viking raiding parties.

No citation, pure heresay.

Re:Why is it (0)

Anonymous Coward | about a year ago | (#44711299)

That's the explanation that I was taught in school in Social Studies.

Re:Why is it (0)

Anonymous Coward | about a year ago | (#44710987)

We did a quick survey on Slashdot, and found:

1) Naming it that way is definitely the result of a false flag operation and/or extraordiary rendition.
2) Sweden named it that to appease their masters in the US government.
3) NSA! PRISM!
4) It was named that way to confuse the US military's drone program, as the pilots will see icy terrain and assume it can't be Greenland.
5) Naming it this way is a clear and unambiguous violation of human rights, and was probably done by your typical cop.
6) Steve Jobs never would have named it Greenland, and this is a clear signal that Tim Cook taking over at Apple is a death knell for the company.
7) Steve Jobs named it Greenland, in a clear attempt to claim that he invented the color Green, and the concept of 'dry land.'
8) Steve Ballmer named it, and is sending a Microsoft employee to take over the government, in a clear attempt to destroy its economic value.
9) Elon Musk once slept there, and Elon Musk invented every piece of 'green' technology known to man, so it's only natural that a site of such historic significance would be given this name.
10) Timothy's an idiot.

Unfortunately, each answer has received 10% of the vote, so there's no clear winner. But it's DEFINITELY one of those reasons - here on Slashdot, these are the only reasons things happen!

How much does flow direction matter? (0)

Anonymous Coward | about a year ago | (#44710655)

How much does flow direction on a large land mass matter for climate? They say the river flowed north. There's something I've never thought about before. If the river flowed north, the glaciers probably flow north too (obviously much more slowly). That means that as the glaciers grew, more and more fresh water got pushed north where it would stay cold. Within certain limits, would this lead to a feedback effect?

How stable is the north-south aspect here? Could Greenland's continental divide by "tilted" by a large seismic or volcanic event? If it's just a subtle gradient, the pressure of the ice pushing the island down could have tilted the flow towards the south at times, throwing cold water into the north atlantic.

In general, what role does the direction of flow over land plan in our climate? What would things be like if most of the Mississippi valley drained into Hudson Bay?

lol (1)

slashmydots (2189826) | about a year ago | (#44710687)

Well, I'm sure the hardcore LARPers are packing their bags already because that sounds so RPG/D&D cliche to me. Get your authentic adventuring rowboat and let's go!

Science schmience (3, Funny)

Alsee (515537) | about a year ago | (#44710713)

was carved out by a great river more than four million years ago

More lies straight from the pits of hell.
Obviously this super-canyon was carved during Noah's flood.
Another Win for Flood geology!

-

Re:Science schmience (3, Funny)

cold fjord (826450) | about a year ago | (#44710999)

It will be funny till they find Noah's Ark.

Re:Science schmience (-1)

PRMan (959735) | about a year ago | (#44711135)

Considering the "Little Grand Canyon" was formed near Mt. St. Helens in mere days, it's something to consider:

"About 100 feet deep and somewhat wider, it is about 1/40th the scale of the mighty Grand Canyon. This canyon was formed in one day from a mudflow."

http://www.answersingenesis.org/articles/2000/05/17/helens-evidence-for-genesis [answersingenesis.org]

Observable science for the win!

Re:Science schmience (4, Informative)

MightyMartian (840721) | about a year ago | (#44711305)

http://www.chem.tufts.edu/science/franksteiger/grandcyn.htm [tufts.edu]

AiG's claim was long ago debunked. At this point, the Weekly World News is probably a more reliable source of information than the lying mentally ill nutbars who write for AiG.

Re:Science schmience (1)

Anonymous Coward | about a year ago | (#44711363)

Please don't conflate mentally ill with stupid.

Re:Science schmience (1)

three333 (453814) | about a year ago | (#44711741)

Pits of hell melt ice,
Plus too many syllables.
Worst haiku ever.

I'm down-voting every global warming denier (-1)

Anonymous Coward | about a year ago | (#44710747)

...we don't need anymore ignorance through politics on here. This is supposed to be a science forum.

So how would this change GW models? (1)

HighOrbit (631451) | about a year ago | (#44710767)

I've read and heard that the salinity of the ocean drives a large part of the currents. The entire premiss of the over-the-top disater film "Day after Tomorrow" was that warming would dump fresh water into the N. Atlantic shutting down the salinity driven currents (that draw the warm Gulf steam northward and thereby warm the N hemisphere) leading to a deep freeze in the N Hemisphere. Granted that was a bit of far fetched fiction. But does knowing that ice-melt will follow the canyon and dump into the relatively self-contained arctic instead of the N. Atlantic change real-word global-warming models?

Re:So how would this change GW models? (0)

Anonymous Coward | about a year ago | (#44710967)

The movie may be somewhat nuts, but the salinity driven currents have been shut down in the past, but probably not on too short of timescales. But in what way would some canyon buried under the ice have anything to do with which way ice-melt flows?

Re:So how would this change GW models? (0)

Anonymous Coward | about a year ago | (#44711315)

Good question.

Accident? (3, Insightful)

TechyImmigrant (175943) | about a year ago | (#44710769)

> It was discovered by accident as scientists researching climate change mapped Greenland's bedrock by radar.

If you discover a canyon while scanning the bedrock with radar, that isn't an 'accidental' discovery. An accidental discovery is when you're looking for a dropped contact lens and come across a canyon instead.

Re:Accident? (0)

Anonymous Coward | about a year ago | (#44710869)

Exactly.

Re:Accident? (0)

Anonymous Coward | about a year ago | (#44710969)

If you discover a canyon while scanning the bedrock with radar, that isn't an 'accidental' discovery. An accidental discovery is when you're looking for a dropped contact lens and come across a canyon instead.

Yes, I think you might call it "unexpected", because they didn't expect such a big canyon, but they sure as hell didn't find it by accident. Lots of work and planning over many decades went into mapping this canyon.

Re:Accident? (2)

TechyImmigrant (175943) | about a year ago | (#44711127)

This year I accidentally arranged 100,000ish logic gates into a functioning circuit for use in microprocessor products made by my employer, by using the design tools and design processes available to me.

Re:Accident? (2)

LynnwoodRooster (966895) | about a year ago | (#44713217)

This year I accidentally arranged 100,000ish logic gates into a functioning circuit for use in microprocessor products made by my employer, by using the design tools and design processes available to me.

Quick, buy a lottery ticket! Your luck may run out!

How accurate is the sea level rise figure? (2, Interesting)

Ioldanach (88584) | about a year ago | (#44710847)

"If the Greenland ice sheet melts completely it will raise global sea level by 7 metres and swamp many major cities" (article)

Does this account for what would happen when Greenland floats back up?

Re:How accurate is the sea level rise figure? (1)

shadowofwind (1209890) | about a year ago | (#44711007)

You're joking? Or assuming that the compression of Greenland is mainly water being squeezed out and not rock being compressed?

Re:How accurate is the sea level rise figure? (2)

Ioldanach (88584) | about a year ago | (#44711061)

If an area the size of Greenland is depressed 300 meters, I'd wonder if it is deformation of the Earth's crust and the whole thing could be pushed back up by internal pressures when the weight is gone. Not assuming anything, just wondering if that could happen and what the impact on sea levels would be if it did.

Re:How accurate is the sea level rise figure? (2)

ChrisMaple (607946) | about a year ago | (#44712541)

The rock and magma displaced when Greenland sank might (more or less) return from wherever it went. If that area were below the seabed immediately surrounding Greenland, the ocean in that area would get slightly deeper, partially counteracting the increased ocean level (probably about 1/3 in the long term.) However, islands near Greenland might sink along with the ocean floor.

On the other hand, if the ocean floor near Greenland is relatively still, the closest islands might rise along with Greenland.

I can imagine other mechanisms and affects, so it's by no means clear what will happen.

Re:How accurate is the sea level rise figure? (-1)

Anonymous Coward | about a year ago | (#44711035)

LOL. These are climate "scientists", they have no fucking idea and even if they did know, they would probably conspire to hide the evidence as they have done with the widespread global cooling trend [climatedepot.com] .

Re:How accurate is the sea level rise figure? (-1, Troll)

flyingfsck (986395) | about a year ago | (#44711079)

Ssssssh, don't confuse the global warmers with weird facts.

Re:How accurate is the sea level rise figure? (0)

Anonymous Coward | about a year ago | (#44711201)

No, just the ice. But the effect of the rising land surface would be small on a global scale and would only slightly affect the sea level by comparison, because the volume of Greenland's bedrock surface below sea level is much smaller than the volume of melting ice above sea level. The effect of the isostatic adjustment would be a slight increase in sea level as the land rebounded and displaced the water formerly occupying the areas that were below sea level. It would also take tens to hundreds of thousands of years to occur, so its effect is pretty long-term compared to the melting.

Re:How accurate is the sea level rise figure? (4, Informative)

mrvan (973822) | about a year ago | (#44711275)

The sea level rises because the stuff covering Greenland is ice. When it melts it flows into the ocean, raising sea levels. Greenland is around 2M km2, and the ice sheet is around 2km thick, so we're talking about 4 million cubic kilometers of water. Earth has around 361 sq kilometers of water, so spreading the water around the earth gives around 10 meters of ice on each meter of water, or around 9 meters of water. In other words, (1) greenland is huge, and (2) the sea level rise is purely ice flowing into sea and has nothing to do with geological changes.

Greenland rebounding does absolutely nothing because the "extra" volume is not taken out of the ocean. The water doesn't suddenly jump back up on the land.

(arctic ice melting does not affect sea levels because the weight of the ice is already displacing water. Antarctic ice and glaciers on land are in the same situation as greenland ice)

Re:How accurate is the sea level rise figure? (1)

dkf (304284) | about a year ago | (#44711503)

Greenland rebounding does absolutely nothing because the "extra" volume is not taken out of the ocean. The water doesn't suddenly jump back up on the land.

Not true. You can get shifting in the surrounding rock as things move around, though the effects are complex. There's also the differences due to the change of the local gravity field; all that ice has a lot of mass and does currently attract plenty of seawater to it.

I have no idea what the relative sizes of these effects are likely to be.

Re:How accurate is the sea level rise figure? (2)

Kjella (173770) | about a year ago | (#44712595)

Not true. You can get shifting in the surrounding rock as things move around, though the effects are complex.

It's earth's crust rising out of the mantle, if anything the surrounding seabed will rise slightly with it, certainly not the other way around.

There's also the differences due to the change of the local gravity field; all that ice has a lot of mass and does currently attract plenty of seawater to it.

Extremely minimal, even if you have 2km sideways pull from the ice there's 6400km of downwards pull towards the center of the earth so water doesn't gather much Heavy mineral deposits or a thick crust directly under the water is different, that adds more compression without trying to counteract the sideways forces.

Re:How accurate is the sea level rise figure? (1)

Nidi62 (1525137) | about a year ago | (#44712457)

Don't forget to take this canyon into account. When all the ice melts, the water will just fill up the canyon instead of all of it going into the ocean. Maybe I should set up a bottling plant there. A bunch of people will pay good money to drink "pure glacier water". I'll be rich :)

Re:How accurate is the sea level rise figure? (1)

Thomasje (709120) | about a year ago | (#44712639)

Greenland rebounding does absolutely nothing because the "extra" volume is not taken out of the ocean. The water doesn't suddenly jump back up on the land.

It is true that Greenland rebounding won't affect sea level, but not for the reason parent seems to imply. The real reason is that when a land mass is pressed downwards by an ice sheet, it sinks because it displaces material in the mantle. That mantle material is squeezed out sideways, and ends up raising adjacent land masses or ocean floor.

When the ice sheet melts, the displaced mantle flows back, the depressed land rebounds, and the raised adjacent land or ocean floor sinks back.

This effect is currently causing the Netherlands to sink at a rate of about five millimeters per year, while Scandinavia is rising at a similar rate. The rebound from the last glacial, in other words, is still ongoing, and quite significant. (Having to raise sea dikes by half a meter over a century, even without global warming induced sea level rise, is a pain in the ass and not something you can just ignore...)

If Greenland losing its ice and rising causes no dry land to sink but only ocean floor, that floor sinkage will compensate for some of the sea level rise, but not quickly enough to help us save our coastal lands and cities.

Re:How accurate is the sea level rise figure? (1)

riverat1 (1048260) | about a year ago | (#44713945)

Mod parent up. I was going to post the same thing. You can see the effect in North America because land north of New Jersey on the East Coast is still rising from the end of the last glaciation while south of NJ land is sinking in a seesaw effect.

Re:How accurate is the sea level rise figure? (0)

Anonymous Coward | about a year ago | (#44713387)

I think the argument is that the additional water on top of the oceanic plates pushes those plates lower and magma pressure in turn pushes continental plates up (which are also lighter with the water).

Of course this is on a geological time scale though, so you'll have to turn SimEarth up to max speed to see the effect.

Re:How accurate is the sea level rise figure? (0)

Anonymous Coward | about a year ago | (#44711313)

"If the Greenland ice sheet melts completely it will raise global sea level by 7 metres and swamp many major cities" (article) Does this account for what would happen when Greenland floats back up?

Wow. Your post really got the attention of the nutters. Rebound [wikipedia.org] is a very slow process taking hundreds of thousands of years. Parts of North America and much of Antarctica are still rebounding from the last glaciation.

Re:How accurate is the sea level rise figure? (1)

cusco (717999) | about a year ago | (#44711483)

No, nor for when Antarctica rebounds. It's such a slow process that i don't think it will make much difference unless you're looking at it on a time scale of centuries.

So what? (1)

AndyKron (937105) | about a year ago | (#44710903)

Who cares? Someone will just come along and fuck it up.

3km thick (1)

agm (467017) | about a year ago | (#44711025)

I find the idea of ice 3km thick to be mind boggling!

Re:3km thick (1)

TechyImmigrant (175943) | about a year ago | (#44711925)

Who on Earth could make enough gin to balance out that much ice?

Re:3km thick (1)

riverat1 (1048260) | about a year ago | (#44713969)

That's nothing. On Antarctica the ice is up to 4.8 km thick.

Huh. (1)

Type44Q (1233630) | about a year ago | (#44711167)

Huge Canyon Discovered Under Greenland Ice

And to think: they didn't even need to roll it in flour.

cha-ching...

"The British Antarctic Survey said...." (0)

Anonymous Coward | about a year ago | (#44711257)

"Ummmmm.... Are we lost?"

Wrong pole, I know, but (1)

kruach aum (1934852) | about a year ago | (#44711327)

I hope to Cthulhu this means we'll discover shoggoths next.

Re:Wrong pole, I know, but (1)

nextekcarl (1402899) | about a year ago | (#44712125)

Maybe HPL should have started his stories out with a variation of the standard crime re-enactment disclaimer: "Some names and places have been changed to protect the sane."

Crayon? (2)

steelfood (895457) | about a year ago | (#44711629)

First time I saw the title, I read it as "Huge Crayon Discovered Under Greenland Ice"

Giant, ancient river delta means lots of oil (2, Interesting)

Anonymous Coward | about a year ago | (#44711723)

If there is a giant, ancient river bed across Greenland, that means it has a delta where it dumped into the ocean at its discharge end a long time ago. Find that ancient delta and drill for oil "downstream" of it. Petroleum, is primarily formed from zooplankton and algae getting buried under sedimentary rock for ages, and this process happened greatest where ancient river deltas (and even present deltas) are found.

Marianas Trench (0)

Anonymous Coward | about a year ago | (#44712011)

I wonder how that compares with the Marianas Trench, if that could be considered a canyon.

Length doesn't mean anything... (-1)

Anonymous Coward | about a year ago | (#44712077)

If you can't go deep

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