By Maddie Stone
In 1908, Ernest Shackleton’s legendary Nimrod team was making its way toward the South Pole when the men were startled by something unexpected: The sound of liquid water, roaring across the frozen wasteland toward the sea. One hundred and nine years later, scientists can confirm that this sound, described by one early explorer as “odd after the usual Antarctic silence” was not a trick of the mens’ imaginations, nor was it a fluke. Hundreds of individual waterways gush across our planet’s ice-covered continent in the summertime, and they have been doing so for decades.
An enormous waterfall at the Nansen Ice Shelf channels summertime meltwater into the ocean, a process that seemingly protects the shelf from collapse. Image courtesy of Jonathan Kingslake
A new analysis led by scientists at Columbia University’s Lamont-Doherty Earth Observatory is the first to reveal a vast network of drainage basins, including streams, channels, ponds and even waterfalls, dispersed across the continent of Antarctica. Although individual drainage basins have been documented on Antarctica for a years — and several have been studied in detail — the first wide-scale survey shows just how extensively Earth’s frozen continent bleeds in the summertime.
“There were a few hints of streams here and there, but we had no idea they were quite so widespread, or quite so large, or that they persisted for so long,” Jonathan Kingslake, a glaciologist at Columbia University and lead author on the study published this week in Nature, told Gizmodo. “The big question for me is, given predictions of how much Antarctica is going to warm, the amount of meltwater is going to double this century. If that occurs, will [these]drainage systems deliver water to places that can cause [ice sheet]collapse?”
That’s a serious concern, but it’s not the only possibility raised by the new work. In a companion study also published this week in Nature, glaciologist Robin Bell, along with Kingslake and others, explore how drainage networks might actually be helping the Nansen Ice Shelf, a site traversed by Shackleton’s Nimrod expedition, and a few years later by the Northern Party team of Captain Robert Falcon Scott’s British Antarctic Expedition, hold itself together. There, rivers along with a roaring, 122m-wide waterfall pump excess water off the icy shelf and into the ocean.
“Ice sheet models now just assume water ponds and damage the ice shelves,” Bell told Gizmodo. “We have shown that water can move,” perhaps, out of harm’s way.
The complex physics governing the flow of ice and water off Antarctica may sound arcane, but it has major consequences when you consider that the entire continent contains enough frozen water to raise global sea levels by 61m, putting coastal cities like Miami and New York deep underwater. But before we can predict how meltwater will impact Antarctic ice sheets in a warming world, we need more data on how widespread it is on the continent, today. To that end, Kingslake and his colleagues turned to Landsat satellite records and aerial photographs, using these two datasets to build a first-of-its-kind record of the continent’s drainage networks, extending all the way back to 1947.
Their analysis revealed widespread systems of streams, rivers and ponds — roughly 700 in total — mostly rimming the fringes of the Antarctic ice sheet, but in some cases, extending deep into the interior. While these features are ephemeral, spreading like weeds in the warm summer months, many seem to have existed on and off for nearly a century.
“Amazingly, we saw features in aerial photography from the 1940s very reminiscent of features we saw later in satellite images,” Kingslake said. “I think it’s remarkable that two years after World War II, people were flying around Antarctica taking photos of these features.”
But World War II pilots weren’t the first humans to notice Antarctica’s mysterious, icy rivers. As Bell discovered when she was compiling records for the Nansen Ice Shelf study, early Antarctic explorers were aware of the phenomena, too.
“I was trying to determine if there was evidence for change and realised that both the Nimrod and Scott’s northern party had crossed the Nansen [in the early 1900s],” Bell told Gizmodo, explaining how she travelled to the the Scott Polar Research Institute in England to review the journal records of the Northern Party. “It was something to hold the hand written notes of these scientists who studied the Nansen over 100 years ago,” she said…Continue Reading →