Green displacement of water

Discussion in 'General Science' started by loosewire, Oct 12, 2013.

  1. loosewire

    Thread Starter AAC Fanatic!

    Apr 25, 2008
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    The loss of whales....super cruise ships

    more or less.....thinking of water displacement.
    .
     
  2. WBahn

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    Yep. Conservation of ocean volume means that for every 200kton super cruise ship that is built a thousand 200ton blue whales must perish.
     
  3. THE_RB

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    Ahah! So THAT's why the oceans seem to be rising?

    Because we keep putting new supertankers in the ocean without killing off enough of those silly whales. ;)
     
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  4. tcmtech

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    Given the masses and volumes that the planets oceans equal even if every ship ever made was taken out sea levels would only change by a few tens of millionths of an inch over all. ;)

    We humans and our activities do not add up to anything close too what the media wants everyone to believe.

    To be honest even our most active efforts and resulting byproducts tend to still fall below the aggregate threshold values of averaged natural phenomena when measured as a whole over a period of time. :rolleyes:
     
  5. WBahn

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    Hmmm. Let's see if I agree with that. Using very rough numbers, the Earth is a sphere 4000 mi in diameter giving it a surface area of about 200 million square miles. About 75% of that is water, so call it 150 million square miles. The volume of water over that area to a depth of 1 one-millionth would be 350 million cubic feet. At 64 lb/cu-ft, that would be about 22,400 million pounds, which would be 10 million long tons. The largest ships in the world come in at over 500,000 long tons displacement, so that would be equivalent to 20 such ships. By comparison, the USS Enterprise is under 100,000 deadweight tonnage.

    So I don't know if I buy that a few 10s of millions of an inch of water would be more than all of the ship ever built, but I think it is reasonably plausible and probably very safe to say that 1 one-thousand of an inch definitely is, and with a good margin.

    So now turning from the safe technical discussion to the more borderline one.

    While I agree, that doesn't absolve us of a responsibility for reasonable and rational stewardship -- and I suspect you agree. The problem, of course, is that people differ greatly on what "reasonable and rational" entail. That there is so much inaccurate and out-of-context information bandied about just makes reaching any kind of an agreement on that all the difficult.

    Having said that, this can (and probably will) quickly deteriorate into a political discussion the kind of which is not allowed here, so expect the thread to get closed pretty quickly if (and when) it does.
     
  6. tcmtech

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    I will call your numbers close enough as well. What I remember reading could have been 100's of millionths of an inch of 10's of 100's of thousandths of an inch.

    A lot of rough math I find on the internet relating very large and very small numbers tends to not be written common ratios or units most engineers/scientists/physicists or common farmers and machinists would recognize.



    I for the most part agree entirely. I believe in doing good stewardship of resources. I just don't like lame weakly based political agendas as excuses for taking good money and resources from people with little to no provable or justifiable science to back it up. ;)

    Still doesnt mean I wont burn a tire or two in my boiler to keep my place warm though. :p
     
  7. loosewire

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    Apr 25, 2008
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    Why do we use the lack of knowledge to get a post shut down ,displacement has

    nothing to do with politics. The post has started in the right direction ,a few guys has

    caught on to what its all about. History of water ,lets stay on course.
     
  8. strantor

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    Those islands they built in Dubai caused us to lose 2ft of water front in Texas.

    /joke
     
  9. tcmtech

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    Interesting. I wonder how many other people are taking into account the filling in of sea space to build islands and the like? I didn't but I will now!

    Given a large project like that displaces millions of tons of water alone that does add up rather fast! :eek:
     
  10. poopscoop

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    Dec 12, 2012
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    Hmm... I wonder exactly how much all of the ships in the world affect sea level:

    http://what-if.xkcd.com/33/

    About six microns—slightly more than the diameter of a strand of spider silk.
     
  11. tcmtech

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    It really takes the fun out things when you start comparing what us humans really do amount to in comparison to what nature does doesn't it?

    We can barely account for theoretical microns in oceans thousands of feet to even miles deep. :rolleyes:
     
  12. justtrying

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    Mar 9, 2011
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    sorry, this is a bit off topic, but Aral Sea is my favorite example of what humans do to water.
     
  13. WBahn

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    We can certainly have significant impacts, particularly on the regional level.

    While the Aral Sea is always touted as having been the fourth largest lake in the work, it is seldom pointed out that this was because it was so shallow to begin with. Back then it had an area of about 26,000 mi^2 and a volume of 260 mi^3 for an average depth of only 50 ft. By contract, the "smaller" Lake Tanganyika at less than 13,000 mi^2 has 4500 mi^3 of water, or nearly 20 times the water with half the surface area.

    Given the extreme surface area to volume ratio, it's not surprising that the lake was able to evaporate so quickly.

    It also appears that the "irreparable damage" is getting a good start on being repaired. In just about a year after a dam was finished in 2005 fish stocks had returned to economically viable levels and the fishing industry was already operating and exporting fish. Of course, what caused it to deplenish so rapidly is the same thing that is allowing it to recover much more rapidly than predicted -- it's a shallow lake.

    One thing that I found in a few places, including Wikipedia, is that the water lost by the Aral Sea is claimed to be the equivalent of draining both Lake Erie and Lake Ontario. Now, Lake Erie is another very shallow lake with an area of under 10,000 mi^2 with a total water volume of 117 mi^3. But Lake Ontario, though even smaller in area at under 8,000 mi^2, has by itself right at 400 mi^3 of water. So how they came up with that claim, who knows.
     
  14. tcmtech

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    Locally we had a similar thing go on with our local man made state lake, Lake Sakakawea over the last two decades or so.

    At one point the lake was something like 45 feet below its normal level. All the experts said that it would take 20+ years to fill back up to near normal levels.

    Not to long after that prediction I got into scuba diving at the lake in 2009. The next year after that (2010) the one place we dived in had 30+ feet of water over where we had parked our vehicles and camped out the year before.

    The spring the year after that(2011) the lake went over the spillway for the first time which was something like 5 feet above normal levels and stayed that way for most of the remaining year.

    All said and done our lake recovery was entirely done by nature in ways and in time lines shorter than the experts ever dreamed of and to top it off the outflow of the Garrison Dam that makes the lake was over double what it highest had ever been some decades earlier. (2011 - 150,000 CFS Vs 1964 - 64,000 CFS)
     
  15. Brownout

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    The headwaters were diverted for farming, cutting off supply to the inland sea.

    The dam created a very small lake in the area that was once part of the sea. The remaining may never be restored.
     
  16. WBahn

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    I didn't say that the lake disappeared because of evaporation. I said that it disappeared more quickly than expected because of the large surface area per depth ratio resulting in a heightened sensitivity to evaparative effects.

    When they diverted the head waters they knew full well that the lake would eventually dry up.
     
  17. PaulL

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    Aug 13, 2013
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    The Dubai islands were built mostly from dredged up sand. The net effect is that the water level went down and Texas became slightly bigger.
     
  18. R!f@@

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    Apr 2, 2009
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    Loosie is concerned about whales or me ??

    I can't tell.
     
  19. t06afre

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    So it is not Loosewire taking a swim in the ocean. Well I guess I have to eat humble pie for breakfast, lunch and dinner now:eek:
     
  20. t06afre

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    He just want the ocean for him self and nothing else. Quite selfish I would say
     
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