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Global Warming & rising sea level

Discussion in 'General Yachting Discussion' started by OutMyWindow, Aug 18, 2007.

  1. NYCAP123

    NYCAP123 Senior Member

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    I don't think more battling experts have anything to do with it except to extend debate to forestall action.
  2. AMG

    AMG YF Moderator

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    Is that your conclusion after seeing this debate?
  3. brian eiland

    brian eiland Senior Member

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    Methane Hydrates

    Sorry gentlemen for not following this subject with deserved respect for quite a while. I did get this bit of info in my mail recently from another forum, and if I remember correctly there was mention of this in the film "CRUDE" that I referenced here;
    http://www.yachtforums.com/forums/general-yachting-discussion/8587-crude-oil-absolute-must-see-program.html
    I remember being quite surprised by the amounts of this substance existing, and the harmful (almost catastrophic) effect it could produce.
  4. AMG

    AMG YF Moderator

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  5. catmando

    catmando Senior Member

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    ^^^I can just hear the howls of laughter coming from the MMGW deniers when they read this.
  6. K1W1

    K1W1 Senior Member

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    Does anyone really seriously believe this guy thought it would be balmy and sunny at this time of year in DC?
  7. AMG

    AMG YF Moderator

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    Many sceptics to the CO2-hypothesis thinks he is pushing to keep momentum. Lately it is said that the Brown Cloud of Asia contributes to half the warming earlier blamed on CO2. Also to the melting of glaciers due to the soot. It is probably because of this Hansen is now after coal, as it is part of this problem, together with particles from burning fields and wood-burning stoves.

    So if I simplify. The warming we have seen over the last century is about 0.7°C and half of this was contributed to anthropogenic sources like change of land use and burning fossil fuel, perhaps 0.2° - 0.3° was blamed on CO2 alone. With half of that explained with the brown cloud it should remain about 0.1° of warming from CO2.

    Considering the negative logarithmic effect of added CO2, many scientists says there is virtually impossible to reach the alarming figures Hansen use to claim.
  8. brian eiland

    brian eiland Senior Member

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    Washington weather

    You are right, it was a cold day here in Washington yesterday. Perhaps he should have poseponed his trip till this weekend....we are expected 60 F by Sat
  9. brian eiland

    brian eiland Senior Member

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    Hydrates again, and Anoxic Oceans from CO2 levels

    Another thing you might want to look at is methane release from gas hydrates on the ocean floor. There have been several recent reports of major releases off the coast of Siberia. If I recall correctly, gas hydrates store their gas within ice structures. When these ice structures melt, the gas is released.

    So, a very large potential release may be waiting in the background for "forcing" from other phenomena which elevate temperatures. More positive feedback, that is.

    A tangentially related subject is the incidence of major extinctions on our little mudball. A phenomena we seem hell-bent on reproducing. The last one about 65 million years ago is pretty much agreed to have happened as a result of a hit from an asteroid or some such object. But let me quote at length from a recent Scientific American article:

    *Ghastly Greenhouse*
    http://www.sciam.com/article.cfm?id=impact-from-the-deep

    About half a decade ago small groups of geologists began to team up with organic chemists to study environmental conditions at critical times in the earth's history. Their work involved extracting organic residues from ancient strata in search of chemical "fossils" known as biomarkers. Some organisms leave behind tough organic molecules that survive the decay of their bodies and become entombed in sedimentary rocks. These biomarkers can serve as evidence of long-dead life-forms that usually do not leave any skeletal fossils. Various kinds of microbes, for example, leave behind traces of the distinctive lipids present in their cell membranes--traces that show up in new forms of mass spectrometry, a technique that sorts molecules by mass.

    This biomarker research was first conducted on rocks predating the history of animals and plants, in part to determine when and under what conditions life first emerged on the earth. But within the past few years scientists began sampling the mass extinction boundaries. And to the great surprise of those doing this work, data from the periods of mass extinction, other than the K/T event, suggested that the world's oceans have more than once reverted to the extremely low oxygen conditions, known as anoxia, that were common before plants and animals became abundant.

    Among the biomarkers uncovered were the remains of large numbers of tiny photosynthetic green sulfur bacteria. Today these microbes are found, along with their cousins, photosynthetic purple sulfur bacteria, living in anoxic marine environments such as the depths of stagnant lakes and the Black Sea, and they are pretty noxious characters. For energy, they oxidize hydrogen sulfide (H2S) gas, a poison to most other forms of life, and convert it into sulfur. Thus, their abundance at the extinction boundaries opened the way for a new interpretation of the cause of mass extinctions.

    Scientists have long known that oxygen levels were lower than today around periods of mass extinction, although the reason was never adequately identified. Large-scale volcanic activity, also associated with most of the mass extinctions, could have raised CO2 levels in the atmosphere, reducing oxygen and leading to intense global warming--long an alternative theory to the impacts; however, the changes wrought by volcanism could not necessarily explain the massive marine extinctions of the end Permian. Nor could volcanoes account for plant deaths on land, because vegetation would thrive on increased CO2 and could probably survive the warming.

    But the biomarkers in the oceanic sediments from the latest part of the Permian, and from the latest Triassic rocks as well, yielded chemical evidence of an ocean-wide bloom of the H2S-consuming bacteria. Because these microbes can live only in an oxygen-free environment but need sunlight for their photosynthesis, their presence in strata representing shallow marine settings is itself a marker indicating that even the surface of the oceans at the end of the Permian was without oxygen but was enriched in H2S.

    In today's oceans, oxygen is present in essentially equal concentrations from top to bottom because it dissolves from the atmosphere into the water and is carried downward by ocean circulation. Only under unusual circumstances, such as those that exist in the Black Sea, do anoxic conditions below the surface permit a wide variety of oxygen-hating organisms to thrive in the water column. Those deep-dwelling anaerobic microbes churn out copious amounts of hydrogen sulfide, which also dissolves into the seawater. As its concentration builds, the H2S diffuses upward, where it encounters oxygen diffusing downward. So long as their balance remains undisturbed, the oxygenated and hydrogen sulfide-saturated waters stay separated, and their interface, known as the chemocline, is stable. Typically the green and purple sulfur bacteria live in that chemocline, enjoying the supply of H2S from below and sunlight from above.

    Yet calculations by geoscientists Lee R. Kump and Michael A. Arthur of Pennsylvania State University have shown that if oxygen levels drop in the oceans, conditions begin to favor the deep-sea anaerobic bacteria, which proliferate and produce greater amounts of hydrogen sulfide. In their models, if the deepwater H2S concentrations were to increase beyond a critical threshold during such an interval of oceanic anoxia, then the chemocline separating the H2S-rich deepwater from oxygenated surface water could have floated up to the top abruptly. The horrific result would be great bubbles of toxic H2S gas erupting into the atmosphere.

    Their studies indicate that enough H2S was produced by such ocean upwellings at the end of the Permian to cause extinctions both on land and in the sea. And this strangling gas would not have been the only killer. Models by Alexander Pavlov of the University of Arizona show that the H2S would also have attacked the planet's ozone shield, an atmospheric layer that protects life from the sun's ultraviolet (UV) radiation. Evidence that such a disruption of the ozone layer did happen at the end of the Permian exists in fossil spores from Greenland, which display deformities known to result from extended exposure to high UV levels. Today we can also see that underneath "holes" in the ozone shield, especially in the Antarctic, the biomass of phytoplankton rapidly decreases. And if the base of the food chain is destroyed, it is not long until the organisms higher up are in desperate straits as well.

    Kump and Arthur estimate that the amount of H2S gas entering the late Permian atmosphere from the oceans was more than 2,000 times the small amount given off by volcanoes today. Enough of the toxic gas would have permeated the atmosphere to have killed both plants and animals--particularly because the lethality of H2S increases with temperature. And several large and small mass extinctions seem to have occurred during short intervals of global warming. That is where the ancient volcanic activity may have come in.

    Around the time of multiple mass extinctions, major volcanic events are known to have extruded thousands of square kilometers of lava onto the land or the seafloor. A by-product of this tremendous volcanic outpouring would have been enormous volumes of carbon dioxide and methane entering the atmosphere, which would have caused rapid global warming. During the latest Permian and Triassic as well as in the early Jurassic, middle Cretaceous and late Paleocene, among other periods, the carbon-isotope record confirms that CO2 concentrations skyrocketed immediately before the start of the extinctions and then stayed high for hundreds of thousands to a few million years.

    But the most critical factor seems to have been the oceans. Heating makes it harder for water to absorb oxygen from the atmosphere; thus, if ancient volcanism raised CO2 and lowered the amount of oxygen in the atmosphere, and global warming made it more difficult for the remaining oxygen to penetrate the oceans, conditions would have become amenable for the deep sea anaerobic bacteria to generate massive upwellings of H2S. Oxygen breathing ocean life would have been hit first and hardest, whereas the photosynthetic green and purple H2S-consuming bacteria would have been able to thrive at the surface of the anoxic ocean. As the H2S gas choked creatures on land and eroded the planet's protective shield, virtually no form of life on the earth was safe.

    Kump's hypothesis of planetary killing provides a link between marine and terrestrial extinctions at the end of the Permian and explains how volcanism and increased CO2 could have triggered both. It also resolves strange findings of sulfur at all end Permian sites. A poisoned ocean and atmosphere would account for the very slow recovery of life after that mass extinction as well.

    Finally, this proposed sequence of events pertains not only to the end of the Permian. A minor extinction at the end of the Paleocene epoch 54 million years ago was already--presciently--attributed to an interval of oceanic anoxia somehow triggered by short-term global warming. Biomarkers and geologic evidence of anoxic oceans suggest that is also what may have occurred at the end Triassic, middle Cretaceous and late Devonian, making such extreme greenhouse-effect extinctions possibly a recurring phenomenon in the earth's history.

    Most troubling, however, is the question of whether our species has anything to fear from this mechanism in the future: If it happened before, could it happen again? Although estimates of the rates at which carbon dioxide entered the atmosphere during each of the ancient extinctions are still uncertain, the ultimate levels at which the mass deaths took place are known. The so-called thermal extinction at the end of the Paleocene began when atmospheric CO2 was just under 1,000 parts per million (ppm). At the end of the Triassic, CO2 was just above 1,000 ppm. Today with CO2 around 385 ppm, it seems we are still safe.

    But with atmospheric carbon climbing at an annual rate of 2 ppm and expected to accelerate to 3 ppm, levels could approach 900 ppm by the end of the nextcentury, and conditions that bring about the beginnings of ocean anoxia may be in place. How soon after that could there be a new greenhouse extinction? That is something our society should never find out.

    If you search on "dead zones" you will find that they are already increasing world wide. Is this a marker? And the authors above comment that we are "still safe" at 385 ppm CO2. Most of us watching the Global Warming issue for the last several years have marveled at how many times we have heard something like
    "Scientists are amazed at how fast . . ." something is occurring. That may be because most of the models predicting the future of this phenomenon are using linear functions, and to my mind they should be exponential. It's that positive feedback thing you know. And there is a huge difference in the time estimate between the two.
  10. AMG

    AMG YF Moderator

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    And what if the feedback is negative..?
  11. brian eiland

    brian eiland Senior Member

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    The Carbon Loop and Ocean Anoxia

    This anoxic ocean event was discussed in this film....referenced here:

    The Carbon Loop
    http://www.yachtforums.com/forums/69609-post55.html
    "Imagine an ocean that is losing much of its sea-life, and then an anoxic event that pushes it into greater stagnation....Ocean Stagnation, it has occurred before. (1hr:02 minutes of the film)"
  12. brian eiland

    brian eiland Senior Member

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  13. AMG

    AMG YF Moderator

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  14. StarDecky

    StarDecky New Member

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    Methane hydrates at the ocean floor (Clathrates) could be a good source fuel energy and carbon for new hulls. One cubic foot of the stuff could be profitable. Also read the hydrates could be at fault for sinking some ships.?
  15. NYCAP123

    NYCAP123 Senior Member

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  16. AMG

    AMG YF Moderator

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  17. NYCAP123

    NYCAP123 Senior Member

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    You're kidding right? You did catch the last sentence: "This needs to be further explored, as it is likely to have an impact on predictions of future sea-ice distribution." That means that this is no news at all. And BTW, where was Florida "between ~8500 and 6000 years ago, when the limit of year-round sea ice at the coast of Greenland was located ~1000 kilometers to the north of its present position.", and what was the average temperature. May have been a few sunburns back then if there was a piece of land to stand on. Seems to me we should want to do anything in our power not to contribute to us getting to that point one day sooner than nature planned. In fact we might even want to do whatever we can to slow the natural process. Unless of course there's money to be made by not.
  18. AMG

    AMG YF Moderator

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    There is not much we can do to stop the next ice age...
  19. NYCAP123

    NYCAP123 Senior Member

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    That will long be preceeded by global flooding, the tropics being uninhabitable due to heat, and storms like we've never imagined. And there's much we can do not to help it along.
  20. AMG

    AMG YF Moderator

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    How much will the oceans rise if all the arctic sea ice melts? How much heat will that chilled water create? How about zero on both questions?