Antarctica’s lost so much ice it’s changed Earth’s gravity
Ice_loss_dips_gravity
A visualisation of satellite data, showing the gravity change over West Antarctica.

It sounds like something out of a science fiction film, but Antarctica has now lost so much ice it’s caused a noticeable shift in Earth’s gravity, the European Space Agency (ESA) announced last week.

“The loss of ice from West Antarctica between 2009 and 2012 caused a dip in the gravity field over the region,” the ESA wrote in a press release.

But while it sounds extreme, the change in gravity won’t affect us much - for example, if you were in Antarctica right now you wouldn’t actually feel any more “weightless” than you do anywhere else in the world. 

The biggest implication of the discovery, as Eric Holthaus from Slate.com and the climate desk over at Wired report, is that it confirms global warming is significantly changing the Antarctic.

Although we often think of gravity as a constant, the strength of gravitational force actually varies depending where on Earth’s surface you stand, and the density of the land (or ice) you’re standing on.

Over the past four years the ESA’s GOCE satellite measured Earth’s gravitational field in unprecedented detail, and revealed that there’s been a significant decrease over West Antarctica. The change was confirmed by lower resolution data from a US and German-run satellite called GRACE.

Although it's pretty grim news, it's not exactly surprising - earlier this year, an unrelated team concluded that major West Antarctic glaciers have now begun “unstoppable” collapse, and would lead to unpreventable sea level rise of several metres over the next several hundred years.

The ESA’s CryoSat satellite, which measures the altitude of regions on Earth, also recently revealed that the rate at which ice has been lost from the West Antarctic Ice Sheet has increased by a factor of three every year since 2009.

The ESA team is now hoping to scale up their investigation and map the change in gravity over the entire Antarctic continent, to better measure the impact climate change is having on the region, and help the world to better predict sea level rise.

Watch a visualisation of the change in gravity:

Sources: Wired, Slate.com