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Earth

Antarctic Ice Loss Big Enough To Cause Measurable Shift In Earth's Gravity 232

An anonymous reader writes: Contrary to what we were sometimes taught in high school physics, the Earth's gravity is not constant. It actually shows slight variations on different parts of the Earth's surface, and the variations correlate with the density of the material on that surface. The European Space Agency has been measuring gravity for four years, mapping these variations and recording the changes those variations have undergone. Its data indicates "a significant decrease [in gravity] in the region of Antarctica where land ice is melting fastest. Further analysis is, of course, planned so that the whole of Antarctica can be taken into account and "the clearest picture yet of the pace of global warming" can be determined on that continent.
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Antarctic Ice Loss Big Enough To Cause Measurable Shift In Earth's Gravity

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  • by UnknownSoldier ( 67820 ) on Wednesday October 01, 2014 @12:20AM (#48033149)

    http://en.wikipedia.org/wiki/F... [wikipedia.org]
    http://en.wikipedia.org/wiki/F... [wikipedia.org]

    The Gutenberg Discontinuity, is the boundary, as detected by changes in seismic waves, between the Earth's lower mantle and the outer core about 1800 miles below the surface. It is also called the core-mantle boundary.
    http://en.wikipedia.org/wiki/M... [wikipedia.org]

  • by aepervius ( 535155 ) on Wednesday October 01, 2014 @12:21AM (#48033155)
    I can't speak for all country, but in France you are taught 1) that gravity constant used varies and we get the values at equators, pole, (iirc 9.78 to 9.83 while we used 9.81) and our lattitude, altitude

    2) but afterward to make it simpler we always assume it is a constant because we do not have the math tool to integrate with g(r,theta, rho) over complex surface.

    At no point we were taught that gravity is a constant. What we were taught is to use it as constant in simplified problems. That is a difference. I would wagger it is the samer in the country of the submitter, only he missed the important semantic difference.
    • by timeOday ( 582209 ) on Wednesday October 01, 2014 @12:50AM (#48033323)
      More fundamentally, ALL equations are only approximations. They are just models of reality that fit well enough to suit the purposes, or as well as we can currently measure. The Laws of Physics are our current understanding of the truth, not the truth itself.
      • Re: (Score:2, Offtopic)

        by phantomfive ( 622387 )

        More fundamentally, ALL equations are only approximations.

        There's truth and falseness in every sentence.....including this one.

    • by PolygamousRanchKid ( 1290638 ) on Wednesday October 01, 2014 @02:04AM (#48033579)

      but in France

      We've discussed these issues in France for Google and Amazon already. If gravity is doing business in France, gravity is subject to the laws of France. The French government can tax gravity to pay for subsidies of other weaker forces in France.

    • by Yoda222 ( 943886 )

      The "gravity constant" that you are describing is the gravity acceleration at the earth surface due to the earth (where you may or may not have subtracted the centripetal acceleration due to the earth rotation) which changes with the position on earth mainly due to the fact that the distance from the surface to the center of the earth is changing (due to flattened at the poles and bulges at the equator). So this is more a change with location than a change with time. The ESA studies is more about the measur

  • We have to tear down all buildings, as they're slanted now.

    On the bright side, perhaps the tower of Pisa will one day be straight again.

  • "Scientists are now armed with the most accurate gravity model ever produced."

    Unfortunately "global warming" has become politicized to the extent that it's really hard to follow the science and technology being discussed. For me the original article is about measurement and our ability to detect minute changes in gravity. There is no "global threat" from the ebbs of gravity. But the scientists behind the satellite gravity monitoring probably figured that introducing the findings with "reveals" and rel

    • You aren't quite right that the satellite gravity scientists are just using climate as a "hook" to display their techniques. A major reason for the launch of these very precise gravity satellites is to use gravity to monitor the movement of water (not just ice) in and around the Earth. Hence the name of the GRACE satellite -- Gravity Recovery and Climate Experiment. The NASA GRACE fact sheet is at -- http://earthobservatory.nasa.g... [nasa.gov] with more details.

  • Seriously, just like China's massive earthquake caused by their dams and reservoirs, the loss of land ice will very likely cause a major Antarctica earthquake. Upon happening, that will likely crack open a number of glaciers.
  • "Contrary to what we were sometimes taught in high school physics, the Earth's gravity is not constant."

    I began my education in 1961. That's pretty far back, I guess. I learned a little about gravity before I left elementary school. Then, a bit more in junior high school. Junior high didn't teach me that gravity is constant on the earth's surface. I was exposed to the idea that gravity varies from one place to another, and we were taught that our weight might vary by a couple of pounds depending where

  • Its the Global Warming diet. Weight loss is guaranteed!
  • Because this is clearly inferior. Play with it a bit. Play spot the warming.

    https://www.climate.gov/news-f... [climate.gov]

    Note:

    1) 1998 - 2015
    2) 1880 - 2015
    3) 1978 - 1998
    4) 1947 - 1957 - this is when all that sea ice grew.[1]

    Odd is was so cold at a time of peak smog.[2]

    [1]"In the early 1920s and 1930s, temperatures were high, similar to that of the present, and this affected the glacial melt. At the time many glaciers underwent a melt similar or even higher than what we have seen in the last ten years. When it became co

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