The largest glacier in East Antarctica contains so much ice it could raise sea levels by at least 11 feet if it all melted — and research now shows the ice has been retreating because of warmer-than-usual waters brought on by strong winds.
Between 2001 and 2006, water just a couple of degrees warmer than usual caused ice in this region of Antarctica to flow toward the sea about 5 percent faster than usual, according to a study published today in Science Advances. That might not seem like much, but it actually means that ice was melting — in an area of Antarctica that’s largely been considered stable.
“East Antarctica is generally just untouched.”
Antarctica is changing: several massive icebergs have been breaking off the continent lately, one glacier has been cracking from the inside out, and rain has been observed over what’s technically an ice desert. But these changes have mostly occurred in Western Antarctica, an area that’s closer to the tip of South America and more susceptible to global warming. Western Antarctica is also much more studied, says Catherine Walker, a NASA postdoctoral fellow at the Jet Propulsion Laboratory. Because of its location, it’s easier to access by boat and planes, and the US has a research base there. In comparison, East Antarctica is much less studied. “Antarctica is isolated in itself but East Antarctica is generally just untouched,” Walker tells The Verge.
While West Antarctica has seen lots of changes, East Antarctica has generally been considered more stable, Walker says. But today’s study shows that that’s not the case: glaciers in this part of the continent are also experiencing melting. And with our planet warming up, things aren’t going to get better. “Up till now, we basically had a stationary ice sheet, and now it’s started to move,” says Walker, who was not involved in today’s research. The study adds to evidence that the Totten Glacier is “sort of the canary in the coal mine,” she says.
Totten is the biggest glacier in East Antarctica, says study co-author Chad Greene, a PhD student researching East Antartica at The University of Texas at Austin. And previous studies have shown that the glacier is melting from below: Totten, in fact, is rooted to ground rock deep below sea level, and that makes it vulnerable to warming ocean waters, Greene tells The Verge. The glacier is also holding back the vast Aurora Subglacial Basin, which is all underneath sea level. Totten is “serving as this little cork, I guess, or a plug to hold vast ice that’s just waiting to flow down,” Walker says. If all this ice melts, there’s the potential for many feet of sea level rise — so scientists have been trying to understand what’s happening at Totten.
For today’s study, Green and his colleagues analyzed satellite data and used models to answer that question. They found that between 2001 and 2006, the ice in the floating portion of the glacier, called the Totten Ice Shelf, was flowing faster toward the ocean. Even if we think of ice as something solid, in fact, ice flows in glaciers. Think of it as pancake batter that’s pilled up and spreads toward the edges under its own weight, Greene says. And how fast ice flows is a proxy for ice melting: if the ice is thinning, losing weight, it just flows faster. The reason for the speedup seems to be warmer-than-usual waters, which were carried from the deep ocean by strong westerly winds, according to the study.
The melting occurred where ice, bedrock, and the ocean meet, melting the glacier from below. It wasn’t constant, though: the ice slowed down again between 2006 and 2013, and might have picked up speed again after 2013, though more data is needed to actually confirm this, Greene says.
The findings don’t bode well for the future: climate change is expected to make those westerly winds that carry warm water from the deep ocean even stronger, and bring them closer to Antarctica itself. Ocean waters are also warming up overall, threatening to eat away at the ice. “You can melt ice a lot more quickly with warm water than you can with warm air,” Greene says. The glacier won’t collapse in our lifetime, he says, but understanding all the things at play that might cause the collapse is key to understand how high sea levels could rise.
A study published last month showed that strong winds and warmer than usual waters were also responsible for speeding up melting at four glaciers in Western Antarctica. Those glaciers though had the potential to raise sea levels by only a few millimeters. Totten could add more than 11 feet of water to the oceans, submerging cities like New York and Miami. It’d be “much more significant than we’ve ever seen in our lifetime,” Walker says.