Melting raises fears about Antarctica glacier collapse

Scientists have warned that one of the most significant glaciers in Antarctica is at serious risk of collapse because of being loosened by warmer temperatures in the surrounding seas, with the potential for globally significant consequences.

The Thwaites Glacier, also known as the Doomsday glacier because of the impact its melting would have, flows into the Amundsen sea off western Antarctica and is around the same size as Great Britain or Florida.

Opinion on its longevity is divided, but at a meeting of the American Geophysical Union on Monday, some delegates suggested it could have as little as five years left before the continued erosion of its ice from beneath would lead to a greater rate of fracturing higher up, which could result in a serious raising of global sea levels.

"There is going to be dramatic change in the front of the glacier, probably in less than a decade. Both published and unpublished studies point in that direction," glaciologist Ted Scambos from the International Thwaites Glacier Collaboration told the BBC. "This will accelerate the pace (of Thwaites) and widen, effectively, the dangerous part of the glacier."

The website Science News quoted him as saying carbon dioxide emissions were significantly to blame.

"We're watching a world that's doing things we haven't really seen before, because we're pushing on the climate extremely rapidly with carbon dioxide emissions … it's daunting," Scambos explained.

Another glaciologist, Erin Pettit from Oregon State University, told United States broadcasting network CNBC that rising sea levels were a near inevitability and the focus should now turn to how to manage their environmental impact.

"We are already on track for sea level rise in the next several decades that will impact coastal communities worldwide," Pettit said. "We can't reverse this sea level rise, so we need to consider how to mitigate it and protect our coastal communities now."

According to Scambos, Thwaites is the widest glacier in the world, and over the last 30 years, it has doubled the outflow speed of the water it has released. It holds enough water to raise global sea levels by more than 60 centimeters, and were it to be significantly damaged, it could also impact on other surrounding glaciers, compounding the problem.

The website of scientific journal Science says diagonal fractures have been spotted spanning nearly the entire length of the glacier's ice shelf, adding to fears about its stability.

Scientist from the British Antarctic Survey have been part of a team using hot water to drill access holes into the ocean cavity, hundreds of meters below the ice shelf, to assess conditions within.

It reported that the water in the area known as the grounding zone, where the glacier lifts off the sea bed, was uncharacteristically warm, and also salty, two factors which are regarded as likely to increase the chances of significant melting from below the surface.