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Earth Science

Global Warming 5 Million Years Ago In Antarctic Drastically Raised Sea Levels 437

Posted by samzenpus
from the how-deeps-the-water-momma? dept.
An anonymous reader writes "As temperatures rise, scientists continue to worry about the effects of melting Antarctic ice, which threatens to raise sea levels and swamp coastal communities. This event, though, isn't unprecedented. Researchers have uncovered evidence that reveals global warming five million years ago may have caused parts of Antarctica's ice sheets to melt, causing sea levels to rise by about 20 meters."
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Global Warming 5 Million Years Ago In Antarctic Drastically Raised Sea Levels

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  • More to the point... (Score:4, Informative)

    by Extremus (1043274) on Monday July 22, 2013 @12:37PM (#44352007)

    It is well known that sea levels have been going up and down throughout the ages. The question now is whether or not we are acelerating these variations and whether life can adapt to them fast enough.

    • by UnknowingFool (672806) on Monday July 22, 2013 @12:45PM (#44352117)
      This is the point most deniers seem to miss when they bring up past periods of climate change. Scientists have never said it didn't happen in the past. What they say is the rate of change is faster than they have seen and may be faster than species can adapt and humans are most likely the cause of the current change.
      • by i kan reed (749298) on Monday July 22, 2013 @01:06PM (#44352367) Homepage Journal

        Actually, it's not the rate of change, it's the rate of change of the rate of change that's scary.

      • by AmiMoJo (196126) *

        That and the pollution. In the past it didn't involve creating vast amounts of particulate matter or mountains of plastic.

        • Yeah, sure. All those volcanic eruptions and tons of dinosaur emitted methane had nothing to do with it.

          • by gtall (79522) on Monday July 22, 2013 @03:03PM (#44353725)

            Errr... the dino's farted out about 65 million years ago. My guess is their farts would have dissipated by 5 millions years ago seeing as methane has about a net lifetime of 8.4 years in the atmosphere.

            Don't let science blind you, just continue to use whatever you are using.

      • by flyneye (84093)

        Bigger better faster. Sadly the bigger better faster turned out to be alligators instead of Tyrannosaurs, so when I go to Outback Steakhouse I only get a dinky serving of gator bites instead of a whopping Tyrannosteak!
         

      • by catchblue22 (1004569) on Monday July 22, 2013 @01:59PM (#44353037) Homepage

        A couple of important points: Firstly, 5 million years ago, there weren't 7 billion people living on Earth, people whose food supply was dependent on an agricultural system tightly adapted to today's particular climatic conditons. I will always remember a lecture given by one of my geology professors. He drew a graph on the board, initially without a scale. On the left, the graph fluctuated wildly up and down, going from extreme highs to extreme lows. Then suddenly, the graph settled down to mild up and down variations, and became basically horizontal, continuing to the right. Then he labelled the axes. The vertical axis was local temperature for an area where most humans lived. The horizontal axis was time. The time when the temperature settled down to a relatively constant pattern was about 10 000 years ago, the time when the last ice age ended. Then he asked us what other important event occurred around 8000 to 10000 years ago. Of course, the answer was the dawn of human civilization. Human civilization appeared about 8000 years ago. Civilization can only exist because of agriculture. People begin to plant crops in one area. They grow more food than they can eat, so they can have more children. Not all members of society have to spend time farming; individuals can afford to spend time doing other things like making pottery to store extra food, building better houses, or posting on Slashdot.

        The problem for cities comes when the conditions that allowed successful agriculture change. Three or four years of failed crops caused by drought or heat or cold or surplus precipitation will exhaust all stored food. The residents of the cities will have to abandon their cities to begin hunting and gathering again, thus largely shattering any nascent civilization. The lesson from this is that human civilization was not simply the result of the triumph of human intelligence over nature. Civilization appeared 8000 years ago because the climate conditions favored it. During the last ice age, the conditions did not favor the development of cities. Even in areas that were not covered in ice, the climate conditions would have been highly variable thanks to the huge persistent ice sheets to the north. One day the air would come from the warm south, another day, the air would come from the cold northern ice sheets. These unstable conditions would have made sustained agriculture impossible.

        My second point is that the well known fact that the climate in the past has shifted from warm to cold to warm should not be comforting to us. In fact, it should be the opposite. The fact that the Earth's climate has shifted in the past indicates that our climate is highly sensitive to relatively small forcings. Tiny changes in the Earth's orbit that cause periodically the Northern hemisphere to get more sunlight, and then tens of thousands of years later less sunlight are thought to have forced the Earth into and then out of ice ages (Milankovic Cycles). The slow collision of the Indian sub-continent with Asia, and its resulting volcanism is thought to have caused a large spike in carbon dioxide concentrations, resulting in a climate where the conditions in the north were near tropical.

        The fact that the climate has shifted in the past due to relatively small changes indicates that "relatively small" changes wrought by humans, such as the removal of carbon from under the ground and the dumping of it into the atmosphere are capable of pushing our climate into a very different state, one that is likely to reduce human agricultural output by enough to make our current large scale civilization a dubious proposition.

      • by Ol Olsoc (1175323)

        Scientists have never said it didn't happen in the past.

        Not only that, but they have for a very long time said that it did happen

        But there is a time table for the deniers:

        Stage 1: Global warming is hogwash and liberal claptrap

        Stage 2: Look! There is one data point that doesn't correspond. Proof that Global warming is not real

        Stage 3: Well, there is such a thing as global warming, but humans don't cause it!

        Stage 4: Well, maybe humans had something to do with it. Butn not enough to mean anything

        Terminal Stage: Humans have caused Global warming, but we

    • by gmuslera (3436) on Monday July 22, 2013 @12:51PM (#44352181) Homepage Journal
      More than life, civilization, most of mankind and big cities are near sea level, and at coasts. And the crops that feeds most of them are not so far. Maybe if sea rises 20 meters in a century or two we could cope with that, but if time is much shorter it will be pretty bad. Also not sure how it would impact ocean's salinity and life that much water if happens fast, but if is affected you are cutting also sea food to that people.
      • More than life, civilization, most of mankind and big cities are near sea level, and at coasts. And the crops that feeds most of them are not so far.

        How wrong can you be grasshopper. Crops are grown along rivers, generally in flood plains. Now the rivers may rise, but that's not necessarily a bad thing for farmers.

        • by gmuslera (3436)
          You are right, is not common to see crops in ocean's coasts, close to coastal cities or not. The main vulnerability for crops, being "long term" investments, is extreme weather, like floods, hailstorms, ground frost or similar events, that could be more common or more unpredictable if the weather changes enough to rise 20 meters the sea level.
        • Take the central valley of California. It's all farms for many hundreds of miles, and it's all very close to sea level elevation. Yes it's inland -- but when the sea level rises the delta floods and it becomes an inland sea.
    • Jesus. Get a grip. (Score:5, Informative)

      by Jane Q. Public (1010737) on Monday July 22, 2013 @01:19PM (#44352523)
      According to IPCC's WORST-CASE estimates (from which they have recently backed off), sea levels were not projected to rise by more than about a meter over the next 100 years.

      I daresay we can adapt fast enough to that.
    • by sl4shd0rk (755837) on Monday July 22, 2013 @01:22PM (#44352549)

      whether life can adapt to them fast enough.

      Depends on the life which is trying to adapt. Sealife, in the instance of rising sea levels, probably has a better chance at adapting than air sucking land dwellers.

    • Re: (Score:2, Insightful)

      by gsgriffin (1195771)
      Would like to see the math here.

      I do know that when ice melts, it takes up less volume than liquid water. I also understand that Antarctica is large, but the oceans around the world are pretty big, too. You're trying to scare me into believing that a couple portions of Antarctica can produce enough water to raise the oceans around the world by 60 feet. Someone please tell me how much ice would have to be melted in order to do that and if Antarctica (even if completely melted) could do that. Seems a lit
      • by CrimsonAvenger (580665) on Monday July 22, 2013 @01:43PM (#44352823)

        Let's see....

        According to Google, Antarctica is ~14 million square km, and has an average of about 1.6 km of ice on top of it.

        So, call it 22.4 million cubic km of ice. With a density of about 0.92 g/cm^3. So ~20.6 million cubic km of water tied up in that ice sheet.

        Surface area of the planet is ~510 milllion square km.

        Which gives us ~40 meters of sea level rise as a MINIMUM if the entire ice sheet melts.

        Of course, it's not all expected to melt, but hey....

      • Re: (Score:3, Informative)

        by kedmison (554607)
        Think in 3D, not 2D.
        This article appears to reference a decent study http://www.bbc.co.uk/news/science-environment-21692423 [bbc.co.uk] According to it, the average depth of ice in the Antarctic is around 2126m, (~6975ft, or ~1.3 miles!) At that depth, it would take the ice contained under a 1 square yard area to cover a football field with over a foot of ice. (6875*3*3 = 62275 cubic ft, 360*160*1=57600 cubic feet)

        Oh yeah: that 2.1km average: it's apparently over a 12.295 million square kilometer area. 26.54 millio

        • by goltzc (1284524)

          Think in 3D, not 2D. This article appears to reference a decent study http://www.bbc.co.uk/news/science-environment-21692423 [bbc.co.uk] According to it, the average depth of ice in the Antarctic is around 2126m, (~6975ft, or ~1.3 miles!) At that depth, it would take the ice contained under a 1 square yard area to cover a football field with over a foot of ice. (6875*3*3 = 62275 cubic ft, 360*160*1=57600 cubic feet)

          Oh yeah: that 2.1km average: it's apparently over a 12.295 million square kilometer area. 26.54 million cubic _kilometers_ of ice. while we're at it: surface area of the planet: 510,072,000 sq km (wikipedia).

          So. simple math from there: 26,540,000/510,072,000 = 0.052km... or about 52m (170ft) for the planet if all ice in Antarctica melts. The article actually says potential equivalent of 58m, so an exercise to the reader to determine where the extra 6m comes from.. and how many cities that would affect.

          BTW: Highly recommend seeing the movie Chasing Ice http://www.chasingice.com/ [chasingice.com] for a view of how fast the glaciers are changing. Netflix carries it.

          Your not thinking fourth dimensionally!

    • by danbob999 (2490674) on Monday July 22, 2013 @01:47PM (#44352867)

      It is well known that sea levels have been going up and down throughout the ages. The question now is whether or not we are acelerating these variations and whether life can adapt to them fast enough.

      Life isn't threatened by anthropogenic global warming. Even the human specie, as a whole, isn't threatened. There is also a scientific consensus on the fact that global warming is happening and that we are responsible for it.

      The real question is whether the costs of reducing greenhouse gases emissions outweigh the costs of global warming. The answer is that it's globally cheaper to reduce greenhouse gases, however every single country or individual, by being selfish, has interest to let the others pay the bill.

      • Agreed, life is not threatened by this. And humanity will almost certainly survive.

        What would be lost is much of the Internet, many airports, most seaports, lots of railways, roads, pipelines, electric grids. Basically much of the infrastructure that supports what we call "civilization". As frail as that is, it is our species crowning achievement, and I for one do not want to see it damaged, let alone broken.

        Yeah, what we have done could probably be rebuilt. But I'd rather we tried not to go that way.

    • Of course life can adapt. Even humans can adapt. The question is how much will it cost to adapt, and how many will die who cannot.

      • You left out, who will pay the costs of adapting.

        Currently the industries that are generating vast wealth from the processes that release CO2 are using a portion of those immense financial resources in a public relations and political campaign to ensure that this cost does not come out of their revenue stream. The PR and political pay-off cost is a small fraction of what the cost of adaptation would be.

    • by Burz (138833)

      http://www.nasa.gov/topics/earth/features/rapid-change-feature.html [nasa.gov]

      If temperatures were to rise 2 degrees Celsius over pre-industrial times, global mean temperature would far exceed that of the Eemian, when sea level was four to six meters higher than today, Hansen said.

      "The paleoclimate record reveals a more sensitive climate than thought, even as of a few years ago. Limiting human-caused warming to 2 degrees is not sufficient," Hansen said. "It would be a prescription for disaster."

      -snip-

      The human-caused release of increased carbon dioxide into the atmosphere also presents climate scientists with something they've never seen in the 65 million year record of carbon dioxide levels – a drastic rate of increase that makes it difficult to predict how rapidly the Earth will respond. In periods when carbon dioxide has increased due to natural causes, the rate of increase averaged about .0001 parts per million per year – in other words, one hundred parts per million every million years. Fossil fuel burning is now causing carbon dioxide concentrations to increase at two parts per million per year.

      "Humans have overwhelmed the natural, slow changes that occur on geologic timescales," Hansen said.

      I think its both the rate and direction of temperature change that is so worrisome. Life on Earth today is adapted to multi-millennial oscillations between familiar "glacial cool" and "ice age" conditions, not the hothouse Earth. Even if most species could migrate much faster, [guardian.co.uk] its unlikely to be of much help.

    • by gtall (79522)

      Adapting fast enough is one problem. There is another problem. Suppose that the previous warming was not caused by CO2 but something else. Regardless of whether CO2 is causing our warming, the massive amount of CO2 we have pumped into the atmosphere is changing the ph of the ocean. The ocean is at the bottom of the food change, if we fuck that up, we're truly fucked. The ph is already screwing up the coral reefs.

    • by hey! (33014)

      Oh, there's no question *life* can adapt to these changes. The question is whether certain economies with enormous assets located in coastal regions can survive. 39% of Americans, for example, live in coastal counties. Although for political reasons that figure includes counties bordering the Great Lakes (America's "North Coast"), nonetheless the assets the US economy has enormous assets on the coast.

      Of course *rate* makes a big difference. The extreme upper level IPCC estimate for sea level rise by 210

  • FUD title (Score:4, Informative)

    by argStyopa (232550) on Monday July 22, 2013 @12:39PM (#44352039) Journal

    Or, we COULD say "Middle Miocene ice age 15 million years ago drastically lowered temperatures, lowered sea level 20m" as well, couldn't we?

    Then it warmed, and melted, and sea levels rose. (The subject of the OP.)

    Then it froze again, and sea levels dropped, since the last ice age ended only about 11,000 yrs ago.

    It's almost like this shit is cyclic.

    • by Antipater (2053064) on Monday July 22, 2013 @12:44PM (#44352115)

      It's almost like this shit is cyclic.

      Fortunately, this time we've invented magazines and toilet paper to cope with the problem.

    • Re: (Score:2, Insightful)

      by Waffle Iron (339739)

      It's almost like this shit is cyclic.

      That's right, it's just like a Ferris wheel.

      So let's say you want to jump off the ride when you're near the top. Go ahead, no problem! After all, the next cycle would bring you back down to the ground anyway. It's all the same.

    • by Nemyst (1383049)
      Oh it most certainly is cyclic. The question is whether what we're seeing right now is part of that cycle or not. Many think that it's too fast to be part of it, or at the very least that it's a combination of a cycle and something else (ie. humans).

      Plus, regardless of the cause, if things do indeed heat up so much so that water levels raise dramatically, we're in deep shit. Just look at how much of the population of the world lives on a coast.
    • There is great evidence that shows shifts in the centuries, too. I like to challenge people to go to California and look at a cross-section of a redwood or sequoia tree. Most of the state and national parks have a huge section (8-10' diameter) of an old tree. In some cases, it shows almost 2,000 of rings. If you ponder and consider what the ring sizes mean, you will see a hundred years (or so) of thick rings meaning good growth, certain climate, plenty of rain, etc... Then you will see a section of anoth
  • by bobbied (2522392) on Monday July 22, 2013 @12:39PM (#44352041)

    That was a long time before the bronze age.. Nobody was burning fossil fuels and dumping CO2 into the air. SO.... How does something like this happen? Can you believe there is some kind of natural process that we don't yet understand going on?

    Problem with all of this is that if the process cycles are in the millions of years, it's going to be impossible to really know if your models are accurate because you only have a few thousand years of recorded history to validate your models with. Plus, you don't know if the system has been disturbed by some outside forces, say a meteor strike (think meteor crater) or volcanic eruption.

    Interesting evidence guys, please keep looking into this..

    • by Robear (68955) on Monday July 22, 2013 @01:01PM (#44352325)

      Because there can't be both natural and man-made causes for warming and cooling? Really? That seems arbitrary, especially if it's just the argument from disbelief.

      We've got very good evidence that there are climate cycles, and very good evidence that we should be cooling right now, but we're not. We have very good evidence that we're warming specifically because of our own actions, and that's overwhelming the natural cycles, both in speed of change and intensity.

      If you are comfortable with natural cycles, then the physics of artificial change should not faze you, because the physics behind them is the same. If something can be changed by natural forces, then it can be affected by artificial ones of sufficient scale and intensity. Excluding the latter is simply ignoring evidence.

      • There are no 'artificial' causes of anything. We are all just as natural as any other life form.

        • So what? Do you propose we retire the word because of your extravagant reductionism?

          Any time a sentient, tool-using organism decides to create or build something, whether it be for survival or amusement or any other purpose, that is an act of an artificier [thefreedictionary.com] and the result is artificial [thefreedictionary.com]. The word just means "man-made." We are distinct from the rest of the world because we have skill in manipulating it; that is the meaning of the word. More importantly, however, and not entirely implied by the word itself, we

        • natÂuÂral
          Adjective
          "Existing in or caused by nature; not made or caused by humankind."
          http://lmgtfy.com/?q=define%3A+natural [lmgtfy.com]

          arÂtiÂfiÂcial
          Adjective
          "Made or produced by human beings rather than occurring naturally, typically as a copy of something natural: "artificial light"."
          http://lmgtfy.com/?q=define%3A+artificial [lmgtfy.com]

          First research what words actually mean. Only then try to tell others what they mean.

      • Re: (Score:2, Insightful)

        by argStyopa (232550)

        Except, essentially, is what you're saying is that
        a) cyclic thing happened many times before, yet
        b) THIS time it's "our" fault.

        Until you provide substantial proof that THIS cycle is substantially different than all the others, I refuse to panic.

    • by gmuslera (3436)

      There weren't humans 5m years ago, but around then emerged the very first hominids, in fact we could be here because that warming or what caused it, if it did the selective pressure that caused the most adapted to the new environment to survive.

      There are a lot of possible natural causes for global warmings and freezings, the actual problem is more centered on the speed of it, and if we are the cause this time. And maybe we won't be the best adapted for the new environment that we are creating.

    • by Type44Q (1233630)

      How does something like this happen?

      Asteroid impact or a supervolcano?

    • Re: (Score:3, Informative)

      by Anonymous Coward

      It's still surprising to me that no one has ever heard of Milankovitch cycles [wikipedia.org]. There are three cycles that all work to change the overall climate. There are meters of ice in various spots around the world, and they all have layers of trapped gas bubbles that are used as indicators for what the atmosphere must have been like during that time period. The problem is that as things get older, the ice is thinner and thinner, so the further back you look the less certainty you have. Overall though, it's still pre

    • by agenaud (538288)

      You read one article from your armchair and think, "hey good going, look into this"? There's been active research in climate cycles and mass extinction events since the 1800's.

      Some causes are the precession, solar output, and meteors as you mention. CO2 and temperature are co-dependent feedback variables. Raise CO2, temperature rises. Raise temperature, CO2 rises. (same in reverse and hense we see a very cyclical 100 000 year pattern). It doesn't matter what triggers it. By all evidence we are on the up slo

    • by amiga3D (567632)

      It is all irrelevant anyway. I fully believe it's getting warmer, the seas are rising, and man is a significant chunk of the cause. So what? The fact is that to make any real difference will require people to drastically change their lives and their standards of living. Even if we do so it may not make any difference. Even if you get everyone in the US on board that's just 300 million people. How about the third world that is just starting to develop? How will they bear the costs of reducing output o

  • Has anyone identified the high water mark? Apparently the continental shelf indicates the low mark - with all that extra land mass. This whole thing is cyclic, and we should not be surprised that it was a bad idea to build huge cities along the coastline of today. OK maybe surprised, but lets not pretend we can stop it.
  • by whitroth (9367) <whitroth@@@5-cent...us> on Monday July 22, 2013 @12:48PM (#44352157) Homepage

    How many thousands of years did it take for that warming... the equivalent of *one* century? But no, zillions of barrels of oil and coal, burned, can't *possibly* affect the whole world's climate, no, no....

                  mark

    • 40 years ago we were going into a deep freeze according to our climate "scientists"

      So you've only got 30-40 years to explain the sudden reversal in terms of human behavior.

      You don't have the whole of the industrial age because our course has recently reversed according to climate "scientists."

  • by sqrt(2) (786011) on Monday July 22, 2013 @01:14PM (#44352459) Journal

    Before anyone smugly proclaims that this proves humans aren't responsible for climate change, remember that it's possible for some phenomenon to have multiple causes. It's entirely possible for there to be both natural and man-made causes for variations in climate. Giving examples of natural causes doesn't do anything to weaken the argument against anthropogenic climate change in this epoch.

    If climate change is currently man-made, or partially man-made, or being made worse by human activity, then it's still worth bending every effort to slow or reverse it.

    • Re: (Score:2, Insightful)

      by UnknowingFool (672806)
      Well climate deniers often rely on faulty reasoning behind their arguments. (1) If climate change happened in the past, there is no way humans could have caused this one. (2) Since climate change happened in the past, there is no need to be concerned with this one. As you pointed out, the existence of climate change is not solely dependent on one cause. As for the second issue, mass extinctions that could be triggered by this climate change are a cause for concern unless humans plan on moving to another
    • Re: (Score:3, Insightful)

      by Anonymous Coward

      "If climate change is currently man-made, or partially man-made, or being made worse by human activity, then it's still worth bending every effort to slow or reverse it."

      No, it isnt.

    • Climatologists generally agree the natural trend was (relatively slowly) taking us into another ice age. I think this means the overall natural contribution to global warming is less than zero.

      What is also unnatural is the rate of warming, which appears to be orders of magnitude faster than anything since the dinosaurs were wiped out (not counting smaller variations less than 2C).

  • by Anonymous Coward

    As temperatures rise

    Temperature isn't rising.

    scientists continue to worry about the effects of melting Antarctic ice

    Scientists are presently worried about the credibility of their models, because reality has failed to comply.

    • Scientists aren't cherry picking data to make absurd claims like "temperature isn't rising". They are not dishonest cretins posting pre-canned bullshit anonymously on Internet forums.

  • The paper is about the melting of the Antarctic ice sheet, not about sea levels.

  • Good (Score:4, Funny)

    by PPH (736903) on Monday July 22, 2013 @02:05PM (#44353121)

    There are no socioeconomic problems that can't be solved by a good 20 meter rise in the sea level.

  • People need to remember that sea levels have risen about 130m in just the last 20000 years (and go up and down by that amount about every 100000 years).

    The article makes an interesting point, namely that there may be some additional sea level rise if temperatures go up again, but that's always been expected.

  • "I tell you what it is. It's your quote un-quote pollution control. I heard on talk radio you don't even need 'em. It's just the latest nazi government plot. Open your eyes, man, they're trying to control Global Warming. Get it Global. That's U.N. Commissars code for telling us what the temperature is gonna be in our outdoors. Let it warm up I say. See what Butchros Butchros Ghali Ghali thinks of that. We'll grow oranges in Alaska." - Dale Gribble

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