Ice-Loss Moves Earth 250 Miles Down

Earth's mantle under Antarctica is moving at such a rapid rate it is changing the shape of the land, a new study published in the journal Earth and Planetary Science Letters  explained.

At the surface, Antarctica is a motionless and frozen landscape. Yet hundreds of miles down the Earth is moving at a rapid rate, an international research team, led by Newcastle Universityin the UK, has shown.

Previous studies have indicated that Earth is "rebounding" in response to the shrinking of the overlying ice sheet, a byproduct of climate change. Scientists believed this movement of the land was due to an instantaneous, elastic response followed by a very slow uplift over thousands of years.

But GPS data collected in this new study reveals that the land in this region is actually rising at a phenomenal rate of 15 millimeters a year. That is much greater than can be accounted for by the present-day elastic response alone.

"You would expect this rebound to happen over thousands of years and instead we have been able to measure it in just over a decade," lead researcher and PhD student Grace Nield said in a statement. "You can almost see it happening which is just incredible."

This study is the first to show how the mantle below Earth's crust in the Northern Antarctic Peninsula is flowing much faster than expected, most likely due to subtle changes in temperature or chemical composition.

Therefore, the mantle is "runnier" and can flow more easily, and so responds much more quickly to the lightening load happening hundreds of miles above it, changing the shape of the land.

This phenomenon is not a new development. Since 1995 several ice shelves in this Antarctic region have collapsed and triggered ice-mass unloading, causing the solid Earth to "bounce back."

"Seeing this sort of deformation of the Earth at such a rate is unprecedented in Antarctica. What is particularly interesting here is that we can actually see the impact that glacier thinning is having on the rocks 250 miles down," co-author Professor Peter Clarke concluded.