Similar populations of seabed-rooted animals separated by 1,500 miles of ice, researchers say, could mean that the West Antarctic Ice Sheet was once a trans-Antarctic seaway. This surprising find has also led researchers to wonder if a warming planet could again cause the thick ice sheet to collapse and give way to a swath of open water. The team, which published their study in Global Change Biology, found similar but separated bryozoans--creatures also called moss animals--in both the Ross and Weddell Seas while conducting the Census of Antarctic Marine Life. Given that bryozoans don't move all that much, lead author David Barnes suggests that the isolated populations came from the same, connected habitat.

“Because the larvae of these animals sink and this stage of their life is short--and the adult form anchors itself to the sea bed--it’s very unlikely that they would have dispersed the long distances carried by ocean currents,” Barnes said. “Our conclusion is that the colonization of both these regions is a signal that both seas were connected by a trans-Antarctic sea way in the recent past.” [Wired]

If that's the case, Barnes says, this past disappearance of the mile-thick ice sheet, possibly as recently as 125,000 years ago, hints at the West Antarctic Ice Sheet's fragility. Calling the ice sheet Antarctica's "Achilles' Heel" in a press release, he says it might not withstand a warming planet.

"The most likely explanation of such similarity is that this ice sheet is much less stable than previously thought and has collapsed at some point in the recent past," he told Reuters. "And if the West Antarctic ice shelf has been lost in recent times we have to re-think the possibility of loss in future with climate change," he said. [Reuters]

Studying how Antarctica's geography has changed in the past may give researchers a better understanding of how sea levels will change if the sheet melts.

"[B]ecause any collapse will have implications for future sea level rise, it's important that scientists get a better understanding of big deglaciation events," Barnes said. Scientists estimate that a complete collapse of the West Antarctic Ice Sheet would raise global sea levels by around 11 to 16 feet (3.3 to 5 m). "This biological evidence is one of the novel ways that we look for clues that help us reconstruct Antarctica's ice sheet history," Barnes said. [Live Science]

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