Like many of its inhabitants, the Earth is getting thicker around the middle — that’s what a new study out this week says. The increased bulge is due to the melting of the Greenland and Antarctic ice sheets.
The Earth was never perfectly round to begin with, due to its spin. Just as an ice skater’s skirt flutters up and away from her skates during her pirouette, water on Earth is more concentrated at the equator than at the poles.
As recently as 22,000 years ago, several miles of ice covered much of the northern hemisphere. Since the downward pressure of land-based ice has reduced as the ice melted, the land underneath has “rebounded” causing the Earth to become more spherical, said Steve Nerem, an aerospace engineer at the University of Colorado at Boulder and coauthor of a new analysis of the Earth’s bulge.
“It’s a bit like a sponge, and it takes a while to come back to its original shape,” Nerem said.
Scientists had observed the bulge shrinking for years, but then something changed. Around the middle of the 1990s, they noticed that the trend reversed and the Earth was getting fatter, like a ball squeezed at the top and bottom — but until recently they didn’t have the tools to understand why.
More here Earth is getting fatter.