US Eastern Seaboard the spillway for a "slow wave" of melting Greenland glaciar water
July 8, 2008 10:28 AM   Subscribe

Melting Greenland glacier water forms a "slow wave" that stays in the Atlantic for at least 50 years before reaching the Pacific, according to a new study. The water piles up in the Atlantic. "It is often assumed that sea levels will rise instantaneously, but that is unlikely, given what we know about ocean dynamics." Fifty years after the meltwater is released from Greenland, sea-level rise could be 30 times greater around Greenland and down the eastern side of North America, including the Gulf of Mexico, than in the Pacific Ocean. Sea-level rises in Europe are around six times that of the Pacific, but only a fifth as great as on the opposite shore of the Atlantic.
posted by stbalbach (43 comments total) 10 users marked this as a favorite
 
30x greater on the Eastern Seaboard. And earlier in the article, "research has suggested that sea levels could rise by more than a metre". So are we talking tens of meters? Because the mean elevation of, say, Delaware is 18 meters...
posted by DU at 10:52 AM on July 8, 2008


Oh, wow... I never thought of that. I do oceanography for a living, and that's basic ocean physics; coriolis force confines water added at the edges of the ocean to the edge. So all of Greenland's water will end up flowing right down the coast! Oh, man, Florida's really in for it now...
posted by freedryk at 10:53 AM on July 8, 2008


Can we harvest energy off this slow wave?
posted by TwelveTwo at 11:05 AM on July 8, 2008 [1 favorite]


That's amazing and counterintuitive. Thanks for posting that.
posted by msalt at 11:13 AM on July 8, 2008


Is this where Fark would put an "Everyone Panic!" tagline?
posted by cjorgensen at 11:15 AM on July 8, 2008


"The thermal expansion of water as a result of global warming is already causing waters to rise around the world."

This line really made me wish I had my old textbooks around still. Had no idea.
posted by Shutter at 11:17 AM on July 8, 2008


I do oceanography for a living, and that's basic ocean physics; coriolis force confines water added at the edges of the ocean to the edge. So all of Greenland's water will end up flowing right down the coast! Oh, man, Florida's really in for it now...

Wouldn't the currents in the north Atlantic push this water down the European coast toward northern Africa, not down the CDN/US coast?

Fascinating and scary...
posted by Pantengliopoli at 11:29 AM on July 8, 2008


Wait, sorry -- I get it now. The coriolis forces creat those currents and the earth effectively moves "under" all that new water, piling it up on the Canadian/US side...
posted by Pantengliopoli at 11:31 AM on July 8, 2008


Ok, I just went and read the actual paper. It's a really cool model experiment that I wish I'd thought of--so obvious and so easy to do.

First off, the model experiment they ran isn't a prediction of future climate change; it's a simulation of the current changes in water level that have occurred over the last 50 years due to increased runoff from Greenland and Antarctica.

As of ~2000, they estimate sea level at New York is ~10 cm higher than it would have been without excess runoff. At Florida, it's ~7 cm higher. The west cost of Europe is much more uniform, and around 7cm. Atlantic Canada really feels it though: ~25 cm higher.

After 50 years the model is not even close to equilibrium, which isn't too surprising--they figure it takes about ~1000 years for a disturbance like this to fully spread throughout the oceans and settle down.

Interestingly, excess meltwater around Antarctica is essentially trapped along Antarctica's coast. I would have expected it to be able to jump to South America fairly easily, but it doesn't. It'll take forever for Antartica's meltwater to start affecting coastal sea levels, like a thousand years or so. Thank heaven for small blessings.

DU: We aren't talking tens of metres here, because Greenland isn't melting that fast. The amount the coastal sea level rises will depend on the balance between how fast the ice melts vs how fast the coastal waves can carry it away. The response is likely to be fairly linear, so even if Greenland's melt rate increases by a factor of 10, it will only result in about a metre of coastal sea level rise relative to the average ocean sea level. So if global sea level rose 1m, the coast might hit 2m. I think probably 1.2 or 1.3m is more reasonable.

TwelveTwo: Probably not.
posted by freedryk at 11:33 AM on July 8, 2008 [9 favorites]


Somebody get Keanu Reeves and Patrick Swayze on the phone, STAT!
posted by It's Raining Florence Henderson at 11:37 AM on July 8, 2008


Oh, and one last important point from the paper: they only figured in the effects of increased meltwater. There are many other things that affect sea level. For instance, Stammer notes that the decreased weight of ice on Greenland will cause the land underneath to rise, which will offset some of the sea level rise. So the actual amount of sea level rise is more complicated than this; this only calculates one part of the total sea level change.
posted by freedryk at 11:39 AM on July 8, 2008


Interesting. I wonder if this explains some of the odd data that came back from the 3,000 remote Argo drones a few months ago, showing no rise in sea level despite warmer ocean temperatures? I'm not sure about the distribution of the remotes, but I would assume they would have roughly equal spacing over the ocean surface: if few were at the peak of this slow wave, it would go some way towards explaining the apparent contradiction.
posted by Bora Horza Gobuchul at 11:39 AM on July 8, 2008


Wouldn't rising oceans have a cooling effect?
posted by Pollomacho at 11:54 AM on July 8, 2008


the decreased weight of ice on Greenland will cause the land underneath to rise

Please tell me that ice isn't a gigantic paperweight on Cthulhu or something.
posted by cowbellemoo at 11:54 AM on July 8, 2008 [7 favorites]


Surf's up!

Wait, why is everyone running away?
posted by Cool Papa Bell at 11:56 AM on July 8, 2008


Another unexpected side effect that another MeFite mentioned in one of our other threads: volcanoes.

"What the heck?" you might say. That was my reaction too. But the other poster pointed to a study showing that when the icecaps melt, we get a lot more volcanoes, presumably because the pressure that the ice exerts on the ground changes so much. The ground starts shifting, and we see volcanoes. Lots of them. The ash from the volcanoes, in prior epochs, then triggered small to medium ice ages.

We can be really sure we're changing the climate, but predicting just exactly how... well, that's difficult. We can't separate ourselves from the system and conduct experiments, and climate changes take decades or centuries, so isolating causes, effects, and eventual outcomes is really hard.

If changes happen slowly, I have great faith in our ability to adapt; adapting is what humans do. But if things happen fast enough, we may be unable to cope.

That's part of why trying to cut down CO2 emissions is so important. Even if it's too late to stop the eventual outcome, every year we buy is another year we can spend adapting ourselves. We'll need to constantly rejigger our distribution networks and areas of food production, and the slower that happens, the less painful it will be.
posted by Malor at 12:00 PM on July 8, 2008 [3 favorites]


Wouldn't rising oceans have a cooling effect?

Directly downstream from the melting ice I can see the just-above-freezing-temp new water cooling off the local area... exactly how local, I haven't a clue. The whole process of climate change is so complicated and filled with unexpected consequences (some mitigating the negative effects but not nearly enough), I have to train a skeptical eye on any explanation that's simple enough for me to understand.

The NWS has put off the start of the BIG HEAT WAVE in California for another day. It's still such an inexact science.

But when I hear denialists claim that the forecasts for warming aren't any better than the forecasts of "a new ice age" in the 1970s, I ask them if there is ANY science that isn't giving better answers now than 30 years ago. (That particular claim just stuck in my craw - thanks for letting me refute it here)
posted by wendell at 12:09 PM on July 8, 2008


So, the Atlantic would be... higher than the Pacific? Deeper maybe? This is a strange and interesting concept.
posted by quin at 12:50 PM on July 8, 2008


quin: The two are at different levels already, hence the need for locks on the Panama Canal. Otherwise, they could just build a big ditch and lets boats freely go both ways.
posted by ewagoner at 1:11 PM on July 8, 2008 [1 favorite]


Pollomacho-probably the opposite. Oceans have the lowest albedo (they absorb the most heat) of any feature on earth's surface, and ice has the greatest albedo (absorbs the least heat). So melting ice removes the most reflective feature, and replaces it with the most absorptive feature. Not all that favorable.
posted by HighTechUnderpants at 1:16 PM on July 8, 2008


I was thinking in terms of increased evaporation and moisture in the air, and the higher amount of cloud cover, but I see your point HighTech.
posted by Pollomacho at 1:24 PM on July 8, 2008


coriolis force confines water added at the edges of the ocean to the edge

Sorry if this is common knowledge and I am just ignorant, but does that mean that the oceans are in effect funnel shaped? Higer on the edges than in the center?

There is, I would imagine, an impressive amount of runoff into the oceans every year, but if that stays at the edges, then the oceans would be pretty concave indeed.
posted by Ynoxas at 1:31 PM on July 8, 2008


The two are at different levels already, hence the need for locks on the Panama Canal. Otherwise, they could just build a big ditch and lets boats freely go both ways.

True or not, that's not the reason for the locks on the Panama Canal.
posted by peeedro at 1:36 PM on July 8, 2008


peeedro: Oh, crap. You're of course right, and that's another memory from elementary school education I can safely forget. The difference between Atlantic and Pacific levels is a mere 20cm.
posted by ewagoner at 1:47 PM on July 8, 2008


There is, I would imagine, an impressive amount of runoff into the oceans every year, but if that stays at the edges, then the oceans would be pretty concave indeed.

You probably understand this better than you think you do. When you fill up a bucket with a hose what shape does the water form? Is it flat all the way across the surface or is it deeper at the edges?
posted by Pollomacho at 1:48 PM on July 8, 2008


But how fast is the Greenland ice actually melting? Very slowly, right? Like over a thousand years it'll be gone?
posted by Kraftmatic Adjustable Cheese at 2:01 PM on July 8, 2008


Another expected effect of the Greenland freshwater runoff into the north atlantic: Fresh coldwater will head south and if considerable enough, stop the gulf stream.
At which point Euro winters will be considerably harsher than they've been in the last 200 or so years.
posted by Fupped Duck at 2:13 PM on July 8, 2008


Can we harvest energy off this slow wave?

Wave power in general is an emerging technology--not without challenges, but looking more and more like it's feasible. However, this particular wave represents only a tiny tiny fraction of all available wave energy in the ocean, and in any case ordinary faster waves are better as an energy souce than a "slow wave" such as this one.

It's kind of like asking if we can harness energy from starlight1--while it might be theoretically possible, it would produce so little energy compared to sunlight, which is only beginning to be tapped anyway, that it's not worth bothering with.

1The common definition of starlight, which excludes sunlight.
posted by DevilsAdvocate at 2:56 PM on July 8, 2008


quin: The two are at different levels already, hence the need for locks on the Panama Canal. Otherwise, they could just build a big ditch and lets boats freely go both ways.

The locks are there to transport the ships over the the elevation gain on the land. If they were to build a big ditch, it'd have to be a couple hundred feet deep. It'd be a canyon more than a ditch.

The big lakes the canals use are 50 to 100 feet above sea level.
posted by five fresh fish at 5:15 PM on July 8, 2008


Stammer notes that the decreased weight of ice on Greenland will cause the land underneath to rise, which will offset some of the sea level rise.

Seems to me this would have the opposite effect: the seabeds attached to Greenland will rise, too, reducing the ocean's volume, and thus increasing the sea level.
posted by five fresh fish at 5:16 PM on July 8, 2008


cjorgensen writes "Is this where Fark would put an 'Everyone Panic!' tagline?"

No, no. The "Florida" tag would win!
posted by orthogonality at 5:33 PM on July 8, 2008


the seabeds attached to Greenland will rise, too

The ice is on the land, pushing down there, not over the seabed.
posted by stbalbach at 5:36 PM on July 8, 2008


The NWS has put off the start of the BIG HEAT WAVE in California for another day. It's still such an inexact science.

Wait! This isn't the Big Heat Wave right now? Becuase it is freaking hot.
posted by fshgrl at 5:52 PM on July 8, 2008


stbalbach: Uh-huh. And so Greenland is going to what, separate from the seabed and start floating? If the above-water part of Greenland rises, so will the surrounding coastline.
posted by five fresh fish at 6:54 PM on July 8, 2008


Yeah maybe a couple miles out or something on that scale. Landmass is not like a mattress where pressing down on one spot causes huge swaths to go down. It's more like a foam mattress, where pressing down in a spot mostly effects only that spot.
posted by stbalbach at 7:10 PM on July 8, 2008


More like a Simmons Beautyrest, then?
posted by five fresh fish at 8:22 PM on July 8, 2008


"What the heck?" you might say. That was my reaction too. But the other poster pointed to a study showing that when the icecaps melt, we get a lot more volcanoes, presumably because the pressure that the ice exerts on the ground changes so much. The ground starts shifting, and we see volcanoes. Lots of them. The ash from the volcanoes, in prior epochs, then triggered small to medium ice ages.

We can be really sure we're changing the climate, but predicting just exactly how... well, that's difficult. We can't separate ourselves from the system and conduct experiments, and climate changes take decades or centuries, so isolating causes, effects, and eventual outcomes is really hard.

If changes happen slowly, I have great faith in our ability to adapt; adapting is what humans do. But if things happen fast enough, we may be unable to cope.

That's part of why trying to cut down CO2 emissions is so important. Even if it's too late to stop the eventual outcome, every year we buy is another year we can spend adapting ourselves.


Your second (bolded) claim doesn't follow from your first.

The earth is roughly in whatever state it is now. There is some probability that it will get much warmer soon, some probability that it will stay mostly the same, and some probability that it will get much cooler soon. What will happen? We know that there is a LOT more energy going into the global climate system now, causing local and global climate change. I'd guess that the probability that things are going to stay mostly the same is very low. I'd give equal odds to both the hot and cold scenarios.

The obvious, linear models suggest more heat and an overall higher temperature. As you suggest, factors like more volcanoes could swing the needle around to very cold. If we can slow CO2 and other greenhouse gas production quickly enough, then we should - but can we? Have we already put too much into the atmosphere? If so, and we are too far gone into the hot zone that all the ice is going to melt and the volcanoes are about to crank up, then we may need to keep CO2 production going to keep us warm once those volcanoes get going.

It isn't at all clear that there is any meaningful difference between action and inaction, other than the cost of doing stuff. It is clear that things are going to change, but probably not in an obvious way.
posted by b1tr0t at 9:13 PM on July 8, 2008


That's a good point, bitrot. That said, we know that CO2 closely correlates with high temperatures, and while there may be systems that will react and drop temperatures again, we don't know what they are or how they work. Pinning our hopes on systems we don't even know for sure exist seems foolish to me. Doing the best we can to limit the impact we have would appear the wisest course, unless and until we know otherwise.

If we end up needing to release lots of carbon or methane into the air, I'm sure we can do it extremely quickly. Removing them, on the other hand, will be slow, difficult, and expensive.
posted by Malor at 10:36 PM on July 8, 2008


Oh, things are going to change in very obvious ways. Recent Greenland ice cores indicate that the climate flip-flopped over the course of a few years toward the end of the last ice age.
posted by five fresh fish at 10:38 PM on July 8, 2008


Pollomacho, water vapor is actually the most powerful greenhouse gas. Unlike dust from volcanoes, more water in the air would mean more heat.
posted by vira at 12:39 AM on July 9, 2008


I'd give equal odds to both the hot and cold scenarios.

lol - volcanoes are the new sun spot, a "bloggers favorite" contrary position.

water vapor is actually the most powerful greenhouse gas

Luckily it has an extremely short life in the atmosphere, measured in days and weeks instead of years and decades for other GHGs. On the other hand warmer air holds more moisture (humidity), so as things warm up the amount moisture increases. There is also a cooling effect from clouds and evaporation.
posted by stbalbach at 5:29 AM on July 9, 2008


Now I'm just playing devils advocate because I don't know much about this and I'm asking to allow those with more knowledge to shoot holes in my arguments, but wouldn't increased cloud cover add to the dimming of the Earth and thus cooling? Would added moisture in the air mix with carbon in the air and form higer levels of carbonic acid precipitation but less atmospheric carbon (sort of a bath for the air)?
posted by Pollomacho at 6:04 AM on July 9, 2008


Pollomacho, yeah all those things, it's a complex science. The mistake is to put too much emphasis on any one thing, they have to be examined individually and then come up with a whole pictures, that is what the IPPC did. The IPCC summary report goes into the different forcings (postitive and negative) of the many variables.
posted by stbalbach at 8:20 AM on July 9, 2008


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