Oceans rise faster than expected as climate change exceeds grimmest models

[Louisiana1976]

Since the 1997 international accord to fight global warming, climate change has worsened and accelerated — beyond some of the grimmest of warnings made back then.

As the world has talked for a dozen years about what to do next, new ship passages opened through the once frozen summer sea ice of the Arctic. In Greenland and Antarctica, ice sheets have lost trillions of tons of ice. Mountain glaciers in Europe, South America, Asia and Africa are shrinking faster than before.

And it's not just the frozen parts of the world that have felt the heat in the dozen years leading up to next month's climate summit in Copenhagen:

_ The world's oceans have risen by about an inch and a half.

_Droughts and wildfires have turned more severe worldwide, from the U.S. West to Australia to the Sahel desert of North Africa.

_Species now in trouble because of changing climate include, not just the lumbering polar bear which has become a symbol of global warming, but also fragile butterflies, colorful frogs and entire stands of North American pine forests.

_Temperatures over the past 12 years are 0.4 of a degree warmer than the dozen years leading up to 1997.

snip

http://rawstory.com/2009/11/global-warming-sped-kyoto-scientists/

[ixion]

1. I guess the Oceans didn't get the "climate change is a hoax" memo

and I'm sure we'll just keep debating it's existence until we're all underwater.

[OKIsItJustMe]

2. In geologic time, it’s a fairly recent memo, and oceans (frankly) are not very quick on the uptake

Give ’em a few millennia, and I’m confident they’ll get with the program…

[Gregorian]

3. Exponential increase. Not to mention the addition of modernization of the remiander of the world.

It's not just increases in our emissions, but that of India and China. Massive increases on top of exponential population growth. And people have called me a pessimist over the years. Stop being so negative. Well, there are things that go through one's mind, like multiple modes of melting. I've watched ice melt. It takes a while to begin, but turns into an avalanche as convection conducts it's way in a dramatic and accelerating slop.

Here is why stabilization of population is the crucial solution. Let's just say that all of our technology does yield the ability to live the way we are, and decrease carbon emissions by 50%. Given population growth of even half of that which is happening, this only gives us several decades before we're right back in the same scene in which we find ourselves. Half the emissions, double the number of users, and we're still melting. On top of which carbon dioxide lingers in the atmosphere for about a century. That means that even if we stopped ALL combustive activity, we'd still be under this cloud for a long long time.

The hardest part for me is to think that all I am doing is screaming out on internet forums, and not doing something far more productive. But what can one do against the tide of billions of people who either don't know or don't care. Including myself! I'm also increasing the CO2 content via my modern lifestyle. Coffee doesn't roast itself. Cement takes huge amounts of energy to produce. Vegetables that aren't organic require fake nitrogen in the soil, which is produced in giant factories to the tune of 1% of our entire energy use. Which also are polluting our waterways.

I hate having to endure this period in human history.

[joshcryer]

4. Even population stablization doesn't fix it, we need a concerted effort to go to zero emissions.

If we don't go to zero emissions that resource drain we have currently gets compounded exponentially as sea levels rise and land must hold more people per square km.

[OKIsItJustMe]

7. You know, even if we went to zero emissions tomorrow, that’s still true…

Obviously, first we’re all going to have to stop breathing, and suppress our farts.

But seriously… the last time GHG levels were this high, we didn’t have ice caps…

[joshcryer]

8. If we stopped tomorrow we might be OK, but since ice melt is a feedback loop....

...we are pretty much screwed.

Our grandchildren anyhow.

[OKIsItJustMe]

9. I guess “screwed” is a relative term

I’m kinda worried that we’re screwed; but I may have a lower threshold than you…

[joshcryer]

10. I plan to live a really longtime so perhaps "we" does include me.

:(

[Dead_Parrot]

11. What we need is negative emissions

Get the Carbon out of the air and back into the ground. Relatively straightforward from a technical standpoint, but since it would require a lot of effort and money, I think I'll go with "Screwed" as well.

Hey ho. Fun while it lasted.

[OKIsItJustMe]

13. Which brings us back to GeoEngineering™…

'cause I don’t think we can do anything else fast enough.

I mean, please, by-all-means, let’s plant trees, and all of the other natural stuff. But…

[Dead_Parrot]

15. I was thinking of a more direct approach.

Take http://www.freepatentsonline.com/4282187.pdf as an example: You take some atmospheric CO² and hydrogen from electrolyzed water, and with some chemical jiggery-pokery and a big power source you get a stream of methanol. (which you could cook into DME or a host of other things if need be).

It's designed as a liquid fuel source, but if you stuffed the output pipe into Ghawar, Cantarell or East Texas you've got an instant terraforming machine. This particular plan is fairly old hat, but there are few newer designs kicking around and any biofuel should be able to do the same thing so long as the net emissions is <0.

Chemically, it's not that radical. We're been wrangling hydrocarbons for long time, albeit in the other direction, and we're pretty good at it. The downside is that we'd need to pay for the buggers to be built and maintained with no income generated (although I guess if you sold off some of the synfuel you might get the sums to balance).

[joshcryer]

17. If you tax carbon it could pay for it 1:1. Make the tax the cost to remove it.

Pow, we're on our way. Unfortunately there exist no realistic non-emission fuel source to power us after the fact, at least until well after 2050.

[Dead_Parrot]

19. Doesn't need to be zero-emission, though

So long as we can suck it out of the air faster than we're putting it it, we're winning: Base it on EROEI (Emissions Released Over Emissions Ingested ;) )

[OKIsItJustMe]

23. Who says it needs to be revenue neutral?

Seriously… If you’re worried about your grandchildren having to pay for it, ask yourself if they’d prefer to be in debt or dead…

[Dead_Parrot]

25. Problem is...

...the buggers holding all the money at the moment aren't that interested in anything that happens beyond the next quarterly report. :(

[joshcryer]

26. Hell, I'd rather we actually ban carbon emissions over a decade and spent 100 trillion...

...fixing the problem over the same time period.

A sixth of world GDP is not likely though.

[OKIsItJustMe]

22. Yeah, like I said, GeoEngineering™

This scheme seems about as good as some others I’ve seen.

I'm pretty well convinced that we don’t stand a chance without something like this.

[Dead_Parrot]

24. Think I was using a different definition

Yours is better. Point taken. :)

[OKIsItJustMe]

34. Here’s the definition of the National Academies from 1992

http://books.nap.edu/openbook.php?record_id=1605&page=433

In this chapter a number of "geoengineering" options are considered. These are options that would involve large-scale engineering of our environment in order to combat or counteract the effects of changes in atmospheric chemistry. Most of these options have to do with the possibility of compensating for a rise in global temperature, caused by an increase in greenhouse gases, by reflecting or scattering back a fraction of the incoming sunlight. Other geoengineering possibilities include reforesting the United States to increase the storage of carbon in vegetation, stimulating an increase in oceanic biomass as a means of increasing the storage and natural sequestering of carbon in the ocean, decreasing CO2 by direct absorption, and decreasing atmospheric halocarbons by direct destruction. It is important to recognize that we are at present involved in a large project of inadvertent "geoengineering" by altering atmospheric chemistry, and it does not seem inappropriate to inquire if there are countermeasures that might be implemented to address the adverse impacts.

Our current inadvertent project in "geoengineering" involves great uncertainty and great risk. Engineered countermeasures need to be evaluated but should not be implemented without broad understanding of the direct effects and the potential side effects, the ethical issues, and the risks. Some do have the merit of being within the range of current short-term experience, and others could be "turned off" if unintended effects occur.

Most of these ideas have been proposed before, and the relevant references are cited in the text. The panel here provides sketches of possible systems and rough estimates of the costs of implementing them.

The analyses in this chapter should be thought of as explorations of plausibility in the sense of providing preliminary answers to two questions and encouraging scrutiny of a third:

1. Does it appear feasible that engineered systems could actually mitigate the effects of greenhouse gases?


2. Does it appear that the proposed systems might be carried out by feasible technical means at reasonable costs?


3. Do the proposed systems have effects, besides the sought-after effects, that might be adverse, and can these be accepted or dealt with?

…

(I think it’s a helpful explanation.)

[GliderGuider]

35. When you say, "I'm pretty well convinced that we don’t stand a chance without something like this"

Do you mean "Our species will go extinct without it", or something short of that?

[OKIsItJustMe]

36. A good question, to which I wish I had an equally good answer

One of the possible outcomes I fear is extinction.

On the other hand (for example) a new “dark age” while “short of” extinction, is not much better in my mind.

[GliderGuider]

39. I've taken the extinction end-point out of my considerations.

After all, it's in the getting from here to there that all the experiential difficulties lie. If the process stops short of extinction, well, we've still gone through the same set of tribulations up to that point.

The questions everyone really wants to have answered are, "What will those tribulations be, and how miserable will they make me and my loved ones?" And the short answer is that there is no way of knowing. The range of possibilities stretches from "We buy new cars and everything continues on as before," to digging ourselves sleeping holes with sticks, and every possibility in between. There are very few intermediate points that can be absolutely ruled out, and the possibility of significant immiseration is non-zero, because that already exists over large swathes of the planet.

In the face of that much uncertainty, what do we do? This is what drives my argument against geo-engineering. We have no idea what kinds of misery we might face, so we have no idea what level of effort and risk is reasonable to prevent or mitigate it. Any benefit assessment requires us to know the sorts and degrees of risks we're trying to mitigate, and the extent to which the proposed technology will actually mitigate them. We also know that the level of risk from any significant geo-engineering effort is non-zero, so we'd better have a reasonably good confidence that the expected benefits are commensurate with that risk. I claim it is impossible to know any of these - either the risks we actually face from climate change, or the benefits and knock-on risks that might accrue from the mitigation technology. In the face of uncertainty this vast, the Precautionary Principle requires us to sit on our hands.

And even in the Dark Ages people were happy. It doesn't take that much to make us happy.

[OKIsItJustMe]

40. I agree that there is a wide (but rapidly narrowing) range of possibilities

For example:

• We’re probably committed to > 2°C of warming. So, what are the likely outcomes of that?
• We’re probably committed to some degree of mass extinction. What are the likely outcomes of that?
• Fossil fuels will “run out” (be less and less available) in the foreseeable future. What are the likely outcomes of that?

We’re told that without radical change we’re likely looking at as much as 6°C of warming, and yet, our CO₂ emissions are not just increasing, but increasing at accelerating rates.

I don’t see us suddenly committing to the kind of social changes that may be necessary to avert catastrophe (“social collapse” counts as a catastrophe in my book.) That’s why I’ve become resigned to GeoEngineering™ (as defined http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=218230&mesg_id=218456">here.)

[GliderGuider]

41. The problem as I see it that we may be able to predict an event, but not its impacts.

As you say,

* We’re probably committed to > 2°C of warming. So, what are the likely outcomes of that?
* We’re probably committed to some degree of mass extinction. What are the likely outcomes of that?
* Fossil fuels will “run out” (be less and less available) in the foreseeable future. What are the likely outcomes of that?

I maintain that we have no clue as to the outcomes of any of those. Certainly not in the detail necessary to do a risk-benefit analysis on a geo-engineering proposal.

Yes, we know that CO2 is going up and is taking the average temperature along for the ride. What will the outcome of the rising temperature be? We can only see the outcomes "through a glass, darkly."

Catastrophe, including social collapse, is only one of the possibilities. Assuming it has a high probability, and therefore justifies filling the oceans with iron filings, the stratosphere with sulfate aerosols and LEO with trillions of little silver needles is just not on for me.

On the other hand, I'm not terribly afraid of the "social collapse" boogeyman any more so my willingness to take such unconscionable risks is much lower.

BTW, your definition of geo-engineering includes this throwaway comment: "others could be "turned off" if unintended effects occur." Oh really? To me that reeks of yet more scientistic hubris. If one of these techniques caused a tipping point to be hit in a domain we didn't think it was affecting, how would even know we should turn it off? And if we did turn it off, how sure are we that we wouldn't run into some sort of hysteresis effect (like we're seeing now with CO2 and temperature)? To me the risk of social rupture is a lot less frightening than the gray goo images I get when I think about geo-engineering.

[OKIsItJustMe]

42. “others could be ‘turned off‘ if unintended effects occur.”

This does not refer to all forms of GeoEngineering. It may help assuage your fears about “yet more scientistic hubris,” to read further:
http://books.nap.edu/openbook.php?record_id=1605&page=434

…

If the theoretical analyses, experiments, and development work show that these mitigation ideas continue to have promise, the possibility of actual deployment would raise additional issues. The global climate and geophysical, geochemical, and biological systems under examination are all highly nonlinear systems involving the interaction of many complicated feedback systems. Such systems are likely to exhibit various forms of instability, including dynamic chaos, as well as various unintended side effects. These possibilities must be seriously considered before deployment of any mitigation system, and the risks involved weighed against alternatives to the proposed system.

Would attempts to mitigate greenhouse warming using one of these geoengineering systems result in putting a global system into some unintended and undesired state? Effects that have been suggested as possible results of greenhouse warming itself, and which might result from attempts to mitigate it, include a shift to a glacial state and major shifts in ocean currents.

Our current models and understanding of geophysical systems do not allow us to predict such effects. Our understanding and modeling have so far not even permitted us to make a map of the possible states of the system. We might require a different modeling approach even to be able to do so.

It can be argued that, in the face of such uncertainty, we should not consider "tinkering" with the only earth we have. However, we are not entirely without understanding of this matter. The principal characteristic of chaos instability, for example, is that the behavior of states with only slightly different initial conditions may be totally different. This is frequently expressed by the statement that "the alighting of a butterfly may change the future of the earth." However, in the sense that we know something of the effects of various kinds of events on parts of the geophysical system, we do know a good deal about this.

…

In many simple nonlinear systems the phenomenon of hysteresis is observed. In these cases, as some physical variable is changed, the system changes its state in a particular way, but if the same physical variable is then returned to its initial value, the system does not retrace the path; it changes state along a different path. Thus attempting mitigation by decreasing the quantity of greenhouse gases in the atmosphere could, in principle, lead the system into a region of instability even though increasing them had not done so. The problem we face is that, given that the climate system is nonlinear and that we do not understand its state space, all actions can potentially lead to instability, and even a small-scale action is not necessarily less likely to do so than a large-scale action. Because of the possible sensitivity of geophysical systems to chaotic instability, we must proceed with caution in any geoengineering effort. We have to compare the nature and size of proposed actions with what we know about what has already been observed to occur in the system as a result of similar stimuli to it. This gives us a way of testing proposed actions. We can also try to learn the structure of the state space of the geophysical system by theoretical, modeling, and simulation analysis combined with observation of the system and its history, perhaps using small stimulus experiments that we believe to be safe to add to our understanding. While geological history provides evidence of what appear to be major changes in state, there is a great deal of observed variation in the system and in stimuli to the system that do not appear to result in changes of state.

…

As for “unconscionable risks,” there are “unconscionable risks” involved in our current course of action/inaction. We are playing not just with the possible deaths of Billions of people, not just with possible extinction of our species, but the possible extinction of many other species as well. As a “deep ecologist,” don”t you find this to be an “unconscionable risk?”

Your vision of a happy future “dark age,” I fear is as dangerous a form of denial as the denial of “climate change” itself.

[hunter]

57. Making coal seems a pretty good deal too...

CO₂ + H₂ ---> (chemical magic) ---> C_XH + O₂

But it ain't gonna happen.

[Odin2005]

63. My idea, have little solar-powered nano-bots convert CO2 into O2 and pure carbon.

The pure carbon can be diamond, nano-tubes, bucky-balls, whatever one needs for building materials.

[Gregorian]

14. If we don't get a quick handle on population growth, all of the rest is futile.

It's all based on the number of users. Unfortunately this is one thing almost no one either wants to see, or doesn't see. It's the one part of the equation that cannot be changed quickly. That is why it is so much more important than anything else.

[joshcryer]

16. Unfortunately the best method for population ceasation is a higher standard of living.

It works wonders in the developed world, to the point that population growth is negative.

[Gregorian]

20. Absolutely. By unfortunate, I suppose you mean higher carbon footprint.

It really is a dilemma. I see parallels between the ecology and politics. If only we had been more vigilant and responsible in the past, then today we wouldn't be facing such drastic decisions.

There is nothing wrong with a high standard of living. That has been our goal since we arrived on this planet. But now the curves have crossed. And with these numbers, no amount of trying will achieve a standard that we had in recent days gone by. I've purchased a number of ranches and farms over the years. When I think back on the huge dairy barn I owned, I could see that in 1890 we had electricity and streams full of fish. Civil rights sucked. But we had sustainable living. Ah, the stories I could tell about what was and when it died. Old locals telling their life stories. Just after world war two was when things began to decline.

We can't magically make the population decrease over night. We need to get renewable energy conversion immediately, but we must get people to see the massive power of population. It's deceptive as a mortgage. The old penny a day trick for 30 days. Doubling. If I hadn't spent nearly twenty years searching for beauty and silence and finding only ruination, I'd be less inclined to discuss population. But we've managed to trample every inch of this continent in just a hundred years.

[joshcryer]

27. Indeed, though theoreticallly a proper high level society need no carbon footprint.

And it seems that the USA is the only OECD country to reduce its emissions in the coming years, the rest are still having to play catch up over a long period of time.

[The2ndWheel]

38. Which is why immigration is high in the developed world

Our organizations and institutions need more people. What happens to a corporation that loses customers? What happens to a government with fewer tax payers? They go out of business, and they fall apart.

[JohnWxy]

5. recommended. People don't realize that it's very difficult to gauge the RATE of acceleration of GW.

AS you gather more data to get a better 'fix' on it, GW has moved ahead of your estimate, good as your data was when you measured it. And you need more data points to get an accurate 'fix' on an accelerating phenomenon.

[joshcryer]

6. Hansen said years ago that sea ice melt was going to smack us in the face.

The guy has been dead fucking on for almost 30 years and still people pretend as if it's no big deal.

Scientific reticence and sea level rise

http://pubs.giss.nasa.gov/docs/2007/2007_Hansen.pdf

[Bigmack]

12. And like I keep saying,

melting the Greenland ice sheet could have an impact on the circulation of the thermohaline current....causing..... Ms Bigmack

[joshcryer]

18. That produces a local effect, though. Europe gets colder, no more fine wines.

I doubt it would result in a global ice age as is suggested by some.

[Bigmack]

21. I agree...no GLOBAL

ice age....but Europe COULD well be significantly cooler, and the loss of fine wines! Now THAT'S a SERIOUS potential problem. At least two buck chuck will still be available.....Ms Bigmack

[Nederland]

31. Really hard to say

The volume of water from melting Greenland ice amounts to around 0.025% of the total volume of water in the thermohaline current. It is very difficult to say what effect that small a percentage will have on the current. It very well could have no effect at all.

[Nederland]

28. What a lousy article

It doesn't explain the rate of change very well at all. It really needs to explain how much the rate of ocean rise has changed over the 12 year period. By itself, the fact that the oceans have risen an inch and a half over 12 years is not very alarming. After all, if the rate is constant that means a mere ~12 inch rise by 2100--hardly anything concerning. What it really needs to explain is how much of that rise happened in the last say, the last two or three years. Anyone know the answer?

[joshcryer]

29. Search for the scientists' names.

This guy was not mentioned in the article but has done some research: http://www.phys.uu.nl/~broeke/

Another author not mentioned in this (admittedly poorly written article): http://www.csr.utexas.edu/personal/chen/publication.html

The latter guys paper is not even yet available on Nature that I can find, so here's an article: http://www.bloomberg.com/apps/news?pid=20601082&sid=atJRfSKS0cOA

You can find the information, it's just not easily found because journalists suck. They could at the bare minimum give out the DOI for the papers in question, but that'd be too difficult.

One thing I dislike about the article is that they mentioned that the Colorado water reserves were tapped in 2007. Since then we have had a very wet season, around the same we had in 2000. So that is skewing the information a bit there. But journalism works this way, unfortunately.

[Nederland]

30. Thanks

I did a little research myself and found this:




In Context: http://sealevel.colorado.edu/

Unfortunately, these measurements make it look like sea level rise has been pretty constant, not rising at an increased rate. If anything, the last few years make it look like things are slowing down.

[joshcryer]

32. You have to look at that graph in context. The 08 series is La Nina, it should be much lower.

Look at how the graph goes up and down, for each series of La Nina and El Nino. From 06 to 09 the lower bound is not as different, so we can expect the 2010-2011 series to be much higher than the trends before it. Just to illustrate most clearly, 1998 is the famous "hottest year on record," it was also one hell of a crazy El Nino. Sea level rise was epic when that happened. It took almost a year and a half for it to remotely recover. Is 2010 another year where an El Nino releases a lot of heat? Let's hope not. And let's hope the solar minimum we are experiencing stays that way.

I, unfortunately, can find none of the papers mentioned in the article, so I don't know where their conclusions are coming from.

The sea rise people mentioned in the article:

Andrew Weaver: http://climate.uvic.ca/people/weaver/weaver-publications.html

Michael Zemp: http://www.geo.unizh.ch/~mzemp/

[joshcryer]

33. I think when scientists say "accelerated" they mean from past or known model predictions.

So, for example, with the antarctic acceleration, it was thought that Antarctica was mostly stable, but it turns out to have accelerated past the models that we had built:

A second technology, interferometric synthetic aperture radar (InSAR) indicates that over the past decade, glacial mass discharge exceeds model predictions of snow accumulation. By this method, Antarctic ice loss is estimated to have increased 75% from 1996 to 2006, with 19692 Gt lost in 2006 alone4.

From: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo694.html

It obviously took time for us to gather the data, and process it. It's going to be interesting to see what the data tells us in the coming decade.

[OKIsItJustMe]

37. Please note that sea level rise is not uniform

http://tidesandcurrents.noaa.gov/sltrends/sltrends.shtml

[Howzit]

43. Then it isn't simply due to more melt water? NT

[joshcryer]

44. Thermal expansion.

[OKIsItJustMe]

48. There are other factors as well

Like evaporation rates, currents, the number (and volume) of rivers flowing in… “sea level” is not a world-wide constant, so why would we expect “sea level rise” to be?

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=218230&mesg_id=218692

[Nederland]

45. In the short run and for small increases, yes

In the long run obviously, sea level increases will all be the same.

[joshcryer]

46. If future flow increases, as is being observed, the baseline changes.

So that graph you showed will have a baseline on a completely different trajectory.

[OKIsItJustMe]

47. No, that doesn't necessarily follow, although it might seem to be “common sense”

http://www.news.utoronto.ca/science-and-technology/university-of-toronto-geophysicists-predict-amplification-of-sealevel-rise-1.html

University of Toronto geophysicists predict amplification of sea-level rise in North America following collapse of West Antarctic Ice Sheet

Friday, February 6, 2009

By Sean Bettam

University of Toronto geophysicists have shown that should the West Antarctic Ice Sheet collapse and melt in a warming world - as many scientists are concerned it will - it is the coastlines of North America and of nations in the southern Indian Ocean that will face the greatest threats from rising sea levels.

"There is widespread concern that the West Antarctic Ice Sheet may be prone to collapse, resulting in a rise in global sea levels," said geophysicist Jerry Mitrovica, who, along with physics graduate student Natalya Gomez and Oregon State University geoscientist Peter Clark, are the authors of a new study to be published in the Feb. 6 issue of Science magazine. "We´ve been able to calculate that not only will the rise in sea levels at most coastal sites be significantly higher than previously expected, but that the sea-level change will be highly variable around the globe," Gomez added.

…

The notion of a constant "sea level" is actually misleading. Consider, "sea level" at the Pacific Ocean end of the Panama Canal is about 20cm higher than "sea level" at the Atlantic Ocean end.
http://www.pol.ac.uk/psmsl/puscience/#3


Compare these records:



It appears that "sea level" is rising faster in Washington, D.C. than in Portland, ME.

Meanwhile sea level is actually falling at Skagway, AK.

[Nederland]

49. That makes no sense whatsoever

I understand that sea level in one place is not the same as in another place due to different gravitational effects and density differences--but how can the rise be different? It defies physics, doesn't it?

[Dead_Parrot]

50. It's just the way the effects add up

Using exaggerated figures to make the point...
Let's say you add 1m to sea level globally from melting ice. In warm areas, you'll get thermal expansion working on the extra 1m to turn it into 1.2m. If there's a spot where a current hits a land mass and rides up by a meter, adding 1m will make it ride up to 2m: If the local seascape can't cope with that much extra water flowing around the landmass, the ride up may be 2.5m. Add in thermal expansion and it's 2.8m, and so on.

As for Skagway, it's still undergoing isostatic rebound from the last ice age: The sea level isn't falling per se, it's just not rising as fast as the land (so far). So, a 1m rise in sea level is offset by a 1.1m rise in ground level, and the sea appears to lower by 0.1m. Some places, like the south coast of Britain, get the opposite effect: the land is getting lower from rebound, so a 1m sea level rise plus a 1m drop in ground level gives you a 2m rise locally. Same goes for a settling delta like New Orleans: Sinking land exaggerates the problem.

It must be a nightmare to model.

[OKIsItJustMe]

52. isostatic rebound

This is one of the reasons why North America will be more affected by a melting Antarctica. When you remove a whole lot of mass (in the form of ice) Antarctica (and the sea floor around it) will rise… displacing a bunch of sea water…

[Dead_Parrot]

53. Hmm. Not sure...

I know that some areas of fairly "high" continental shelf were exposed during the last ice age (Georges Bank, & Dogger Bank in the North sea spring to mind) because although they were somewhat depressed by ice, the difference was more than made up for by the low sea levels: This suggests (to me, at least) that the isostatic effects were comparatively small. Indeed, we might even find that the weight of the extra water sitting on top of the continental shelf has the opposite effect...

It's an intriguing thought, though. I'll poke it around a bit more and see what happens. :)

[OKIsItJustMe]

54. Start your poking here

http://www.news.utoronto.ca/science-and-technology/university-of-toronto-geophysicists-predict-amplification-of-sealevel-rise-1.html

…

"The typical estimate of the sea-level change is five metres, a value arrived at by taking the total volume of the West Antarctic Ice Sheet, converting it to water and spreading it evenly across the oceans, Mitrovica said. "However, this estimate is far too simplified because it ignores three significant effects:

1. when an ice sheet melts, its gravitational pull on the ocean is reduced and water moves away from it. The net effect is that the sea level actually falls within 2,000 km of a melting ice sheet and rises progressively further away from it. If the West Antarctic Ice Sheet collapses, sea level will fall close to the Antarctic and will rise much more than the expected estimate in the northern hemisphere because of this gravitational effect;

2. the depression in the Antarctic bedrock that currently sits under the weight of the ice sheet will become filled with water if the ice sheet collapses. However, the size of this hole will shrink as the region rebounds after the ice disappears, pushing some of the water out into the ocean and this effect will further contribute to the sea-level rise;

3. the melting of the West Antarctic Ice Sheet will actually cause the Earth´s rotation axis to shift rather dramatically - approximately 500 metres from its present position if the entire ice sheet melts. This shift will move water from the southern Atlantic and Pacific oceans northward toward North America and into the southern Indian Ocean.

…

[Dead_Parrot]

55. LOL. I just found that article...

Oh well. Not often I err on the side of optimism. :(

[Nihil]

56. Err ... what?

> 3. the melting of the West Antarctic Ice Sheet will actually cause the Earth´s
> rotation axis to shift rather dramatically - approximately 500 metres from its
> present position if the entire ice sheet melts. This shift will move water from
> the southern Atlantic and Pacific oceans northward toward North America and into
> the southern Indian Ocean.

:wtf:

I just checked the linked article to make sure you hadn't thrown that in as
a test to see if anyone was paying attention but that quote is genuine.

I find the scale of global energy systems to be pretty daunting at times
and, being a bear of little brain, I am sometimes overawed at things like
the wandering poles anyway (i.e., I know how far they are believed to have
meandered over the geological record) but I really don't like the idea that
as the current (geologically) rapid warming event is affecting the normal
motion of the rotational axis ...

:scared:

[joshcryer]

60. 30 gt of CO2 a year = massive fluxes in natural systems = holy crap.

The more I read about it the more daunting it is looking. We're in trouble for sure. Hopefully after the Copenhagen emissions are set I will know Excel enough to be able to make some nifty spreadsheets.

Playing with it now and the outcome we are expecting (from EIAs projected emissions) is 4-5C guaranteed. We cannot allow this to happen.

[joshcryer]

51. The thing is Nederland, the east ice sheet was not expected to melt until well after 2.0C.

It's melting now. That's a pretty big deal. I mean we have 5 years to go to *zero* emissions to prevent 2.0C. That's very very soon now. We have guaranteed ourselves 2.0C. Another 10 after that, we guarantee ourselves 3.0C. We really are going to be fucked here.

Clarification: East Antarctic ice sheet. Was thought to be able to be stable for quite some time. We are naive like that.

[Nederland]

58. I take away a different lesson

The lesson I get from all this is that our computer models suck. If we couldn't predict just a few years into the future to know that the east ice sheets would be melting now, how much confidence can you have in what the models say will be happening 50 years from now?

[joshcryer]

59. IPCC AR4 noted that our dynamical ice flow models were guesses.

We can't make models if we don't have data, and we really haven't had the data. The knowledge that the East Antarctic shelf is melting is very new. And it took a lot of analysis from satellites that weren't exactly designed to do that measurement.

[Nederland]

62. Good point

I just wonder what other "very new" knowledge will be revealed in the next decade.

[joshcryer]

65. I'm disappointed that that CO2 / temperature measuring satellite didn't make orbit.

When it crashed there was speculation in my circle of space enthusiasts that, given the problem was likely related to a false firing pyro, one of the more conservative engineers either consciously or unconsciously sabotaged it (by forgetting to remove the safety, etc).

They use pyros in space ships because they're extremely reliable, the odds of one not going is very low.

[Quantess]

61. Interesting thread.

[Odin2005]

64. And when the West Antarctic Ice Shelf goes...

:scared: