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.

Comments

"Contrary to what we were sometimes taught"

[aepervius]

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.

Re:"Contrary to what we were sometimes taught"

[pepty]

Actually, the reason why space missions are launched from places closer to the equator is that missions are cheaper there: money near the equator is moving at a higher percentage of escape velocity than money at the poles. That's why the tax havens are frequently in those latitudes.

Re:The last sentence in the summary...

[Gadget_Guy]

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.

Re:Whoah, wait a minute...

[riverat1]

The article barks at the wrong tree. The cryosphere page at University of Illinois-Champagne shows that we are currently seeing 1.3 million sq. km more sea ice than the average, and the levels have been sharply rising the last few years.

There is a fine balance between trying to increase awareness and being a downright propagandist. Unfortunately, this article doesn't help the cause. This is exactly the kind of thing that make people believe environmentalists are exaggerating and grasping at straws.

Wired: Stop. You are not helping.

Before you go on you really should learn the difference between ice sheets, ice shelves and sea ice. They are not the same thing. Talking about sea ice in response to this article about the West Antarctic Ice Sheet is a non-sequitur.