Antarctic ice shelf breaking apart from inside out

Pine Island Glacier, at the outer edge of West Antarctica, is the fastest melting glacier in the region. In 2015, a 583 square kilometre piece of it broke off.Now researchers are beginning to understand how this is happening.

More concerning, however, is the new study by researchers at Ohio State University suggests that this is likely to continue, which could cause sea levels to rise.

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The researchers discovered that the calving, or breakup, of the Pine Island Glacier began in 2013 after a rift formed at its base about 32 kilometres inland. The rift began to move upward over the following two years until it finally broke through the surface, causing the breakup.

This new finding suggests the ice shelf is breaking apart from the inside out. Typically melting occurs on the outer edges of glaciers as a result of relatively warmer waters. However, recently, scientists have suspected that warm water below the ice sheet is weakening glaciers, causing melting from below.

It's generally accepted that it's no longer a question of whether the West Antarctic Ice Sheet will melt, it's a question of when.- IanHowat,Ohio State University

Glaciers, such as Pine Island, keep inland ice from entering the ocean. But this new mechanism of melting could hasten further calving allowing significant water to flow into the oceans, raising sea levels by as much as three metres. The researchers believe that this could occur within the next 100 years, displacing 150 million people around the world.

"It's generally accepted that it's no longer a question of whether the West Antarctic Ice Sheet will melt, it's a question of when," the study's lead researcher, Ian Howat, associate professor of earth sciences at Ohio State said in a statement. "This kind of rifting behavior provides another mechanism for rapid retreat of these glaciers, adding to the probability that we may see significant collapse of West Antarctica in our lifetimes."