A glaciologist stumbled across a picture of a lake where no one expected it to be, launching a continent-wide search for lakes and streams of meltwater in icy Antarctica.
By Kate Wheeling
A section of the West Antarctic Ice Sheet with mountains as viewed from the window of a NASA Operation IceBridge airplane over Antarctica on October 31st, 2016. (Photo: Mario Tama/Getty Images)
Jonathan Kingslake was looking at images of Antarctica on Google Earth in 2010 when he spotted a lake where he never expected to see one—on the Nivlisen Ice Shelf in East Antarctica, which hasn’t experienced the same drastic warming as its western counterpart. Kingslake could clearly see channels carved into the ice where the water had drained out of the lake. That observation inspired a continent-wide study of such drainage systems, which, the authors report today in Nature, are larger and more widespread across Antarctica than previously thought.
These drainage systems could have huge effects on how Antarctic ice shelves fare in a changing climate, but our current models don’t really take surface water on the continent into account. That’s because—until now—most researchers thought that Antarctica was too cold and too flat to support the flow of water over long distances.
“I always tell my students they should spend a long time on Google Earth just exploring and cruising around because there’s always amazing things to be seen,” Kingslake says.
Indeed, using satellite images and high-resolution aerial photographs dating back to 1947, Kingslake and his colleagues identified nearly 700 drainage systems across the continent, transporting water up to 75 miles and feeding lakes that, in one case, grew to be almost 50 miles long. The latter lake in particularhas been forming on the Amery Ice Shelf largely unnoticed since at least 1973, according to Kingslake. “An 80-kilometer-long lake existing on the surface of the Earth without us really knowing about it is just itself incredible to me,” he says.
Photographs from as far back as 1947 on the Roi Baudouin Ice Shelf, for example, show some of the same channels and ponds that still persist today. “It just really drives home the fact that these aren’t a new thing; the only thing new is the fact that we didn’t know about them before,” Kingslake says. “These have been there for decades, and they haven’t changed very much as far as we can tell.” But that doesn’t mean climate change won’t affect these drainage systems in the future.
Most of these streams and ponds can be traced back to areas of Antarctica at higher elevations, where exposed rock and blue ice absorb more solar radiation, increasing air temperatures and melting rates; those rates are expected to increase across Antarctica by the end of the century, and no one knows what effect that might have on these streams and ponds. “A reasonable hypothesis might be that they will expand,” Kingslake says. “That’s what we’re going to test in the next stage of this work.” Then, an even more important question might be, what effect does that water have where it ends up?
Meltwater drains downhill toward the ice shelves, which extend out from the continent and float on the ocean surface. The water can flow into and widen existing fractures or crevices on the shelf and, eventually, cause it to collapse. “There’s been some pretty dramatic examples of that causing whole ice shelves to disintegrate, essentially, over only a few weeks,” Kingslake says.
But these drainage systems aren’t necessarily bad news for Antarctic ice shelves. In a separate study published today in Nature, Kingslake and his colleagues found that at least one drainage system actually made an ice shelf more stable by steering meltwater that might have otherwise enlarged crevices within the shelf to drain directly into the ocean. Melt rates are expected to increase across the continent by the end of the century, but that variability makes it hard to predict what effect that flowing water might have on the region—or around the world.
“I think, in the long run, this field of research will lead to improved sea level predictions,” Kingslake says, “but we’re at such an early stage, its impossible for us to say whether predictions of sea level rise will be increased or decreased by this observation.”