Subglacial Antarctic Swamp Discovered Beneath Florida-sized Glacier

Deep beneath the Antarctic ice sheet lie lakes and streams of water, filtering through frigid glaciers. Now, scientists have detected a vast, subglacial water system beneath West Antarctica's Thwaites Glacier. The findings could have major implications for potential sea level rise.

Thwaites is a Florida-sized outlet glacier in the Amundsen Sea Embayment. The massive piece of ice is considered to be a key factor when it comes to global sea level rise. On its own, the glacier holds enough fresh water to raise oceans by about three feet--that's enough to swamp some coastal communities and cause serious threats to others.

In order to better understand the potential for this glacier to melt, the researchers used an innovation in airborne ice-penetrating radar analysis. This allowed them to view the subglacial water system and revealed that it consists of a swamp-like canal system that's several times as large as Florida's Everglades. This "swamp" beneath the glacier then shifts to a series of stream-like channels downstream as the glacier approaches the ocean.

"Looking from side angles, we found that distributed patches of water had a radar signature that was reliably distinct from stream-like channels," said Dusty Schroeder, one of the researchers, in a news release. This, in particular, was what allowed the scientists to distinguish the streams from the swamp-like area.

Swamps and streams have important and different implications for the movement of glacial ice. Swamps tend to lubricate the ice above them. Streams, in contrast, tend to cause the base of the ice between the streams, rather like how rain grooves on a tire can help prevent a car from hydroplaning on a wet road.

So what do the findings mean for the glacier? It shows that Thwaites Glacier is stable in the short term and is currently holding its position on the continent. That said, a large pile of ice that's built up in the transition zone could rapidly collapse if warming continues. This, in turn, could release the water into the sea.

"Like many systems, the ice can be stabilized until some external factor causes it to jump its stability point," said Don Blankenship, a co-author of the new study, in a news release. "We now understand both how the water system is organized and where that dynamic is playing itself out. Our challenge is to begin to understand the timing and processes that will be involved when that stability is breached."

The findings are published in the journal Proceedings of the National Academy of Sciences.