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"

[riverat1]

The weaker gravity is the reason space missions are launched from places that are close to the equator, Florida in the US and French Guiana for the ESA.

You'll notice that most space missions are launched toward the east as well. This is mainly because the rotational velocity of the Earth is greatest at the Equator (~1,040 mph or 1,674 km/h) which means less fuel is needed to reach orbital velocity. I doubt gravity has a lot to do with it but it probably helps a bit as well.

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:Chicken Little Global Warming nuts

[Gadget_Guy]

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?