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Antarctic Ice Loss Big Enough To Cause Measurable Shift In Earth's Gravity
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.
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.
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Freezing water expands and takes up more volume which makes it less dense, yes, but it still has the same overall mass as when it was liquid. The idea here would be that the water runoff goes into the surrounding oceans, so mainland Antarctica would be losing overall mass.
The problem is that this is not intended or presented as a proof of climate change. It is merely measuring recent gravitational changes showing the affect of the reduction in ice. The article does pre-suppose that any melting of ice would be the result of climate change. You could certainly argue against that assumption.
But what you can't argue against is the fact that the ice is melting at all, although that doesn't stop some people here from cherry-picking one particular type of ice (sea ice), saying that it has expanded as if that is the complete argument against the total ice loss.
In complete denial of the FACT that Antarctic sea ice is at the HIGHEST LEVEL in decades, these Global warming cult members keep spreading the blatantly false propaganda.
Does the expansion of sea ice mean that the total volume of sea and land ice has gone up? Does it even mean that the volume of sea ice has gone up or is it just being spread thin?
You have cherry-picked a single variable that has gone up and ignored the bigger picture, and then made the outrageous claim that it is the people who actually measure the total ice that are spreading false propaganda.
Answer one question: has the volume of land ice gone up or down? If the answer is down, why is it so unimportant for you to mention this inconvenient fact?
On second thoughts, we can ask an even easier question. Has the total volume of ice gone up or down? According to the article, the gravitational measurements show that it has gone down. Why are you in complete denial of this FACT?
The cryosphere page at University of Illinois-Champagne shows that we are currently seeing more sea ice than the average, and the levels have been sharply rising the last few years.
It is the same effect: The ice on the land is melting and flowing into the sea where some of it re-freezes.
The area of ice is increasing, the mass of ice is decreasing.
In complete denial of the FACT that Antarctic sea ice is at the HIGHEST LEVEL in decades, these Global warming cult members keep spreading the blatantly false propaganda.
This would be wrong. It has been known from the older GRACE satellites that Antarctic Ice has been losing mass from the ice sheet.
In Antarctica the mass loss increased from 104 Gt/yr in 2002–2006 to 246 Gt/yr in 2006–2009, i.e., an acceleration of 26 ± 14 Gt/yr2 in 2002–2009. (Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE, I. Velicogna, Geophysical Research Letters, (2009))
You might be thinking of the Antarctic Sea Ice.
Now they are saying that if I don't drive a Prius, that the earths gravity will fail.
I don't think that that's what they're saying.
My reading of it is that they're saying that Antarctica and Greenland together are now losing 500 cubic kilometers of ice per year. They don't mention what will be the effect on that of you driving a prius, but I suspect not a lot.
This was measured using Gravity. I don't think that they say that gravity is failing.
Canada...had another record breaking hot summer, and expecting another winter with hardly any snow in the Vancouver region.
Really?
If I take a look at the measurements from EC, I see that most of the country was seasonal or far below seasonal. Including snowfalls in Alberta in June and August. In Southern Ontario where I live, it was on average of 3C lower than the seasonal averages, compared to ~3-6 years ago it was 5C lower. We still had ice on the great lakes in July, that hadn't been seen since the 1970's either. Of course it doesn't help that EC has been shutting down many of the weather stations that have been in use for awhile. And of course we can't forget that in much of the country our temperature records only start in the 1970's. So if you're going to claim "a record breaking hot summer" based on 30ish years of data, you're not doing yourself any favors.
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"is it possible that the ice has actually thickened and displaced more of the denser sea water?" -- not in this case. The geographic precision of these satellite gravity surveys and complementary ground and airborne surveys in the area constrain the loss of mass to ice over the land. In addition it is possible to estimate the change in ice mass on the land by other techniques and they are in agreement with the gravity. There is a good (but long) discussion of the recent observational techniques and results for the ice sheet mass balances in Greenland and Antarctica here: http://nsidc.org/cryosphere/so...