A new study confirms the existence of deep sea channels that help eat away at the Totten Ice Shelf from beneath.
By Nathan Collins
A variety of ice types off the coast of East Antarctica. (Photo: Wikimedia Commons)
The fact that Antarctic ice is melting away should come as no surprise, but the problem may be more widespread than previously thought. While most of the concern has focused on the West Antarctic Ice Sheet, new research confirms that relatively warm ocean water is melting East Antarctica’s Totten Glacier from below, thanks in large part to a recently discovered tunnel buried deep in the ice.
The Totten Ice Shelf—the part of the glacier that’s floating over the ocean—is particularly important because it’s the main thing keeping an enormous amount of ice from flowing into the sea. If the ice shelf were to melt away, it could unleash enough ice to raise sea levels by about 3.5 meters, or 11.5 feet, an amount comparable to melting in the West Antarctic Ice Sheet, researchers led by Stephen Rintoul note today in Science Advances.
Yet it was unclear whether the TIS was in as much danger as the WAIS, which sits over a deep trough in the bedrock below. When the WAIS ice shelf is healthy, it stops relatively warm ocean water from getting in and melting the shelf from beneath. But when the glacier starts to retreat, it sits higher in the water, allowing that warm ocean water in, ultimately accelerating the loss of ice.
Last year, researchers reported they’d found such a cavity underneath the TIS using radar and other measurements, but it remained unknown whether ocean water was making it into the cavity—and that’s where Rintoul and his team come in. It’s ordinarily very difficult to approach the TIS, but a shift in the weather allowed the researchers to get up close and take a series of measurements, including detailed temperature profiles and new seafloor maps.
That data revealed two channels—one 1,097-meter deep and roughly four kilometers wide—through the ice front, positioned more or less right in front of the cavity discovered last year. Temperature measurements indicated that a layer of relatively warm water, known as modified Circumpolar Deep Water, was flowing into that channel at a speed upwards of eight inches per second—which, given the size of the channel, adds up to a flow of around 58 million gallons per second.
In other words, everything is in place for rapid melting from below.
“Our observations confirm the existence of a pathway allowing for [warm ocean water to enter] the TIS cavity, highlighting variation in ocean-driven basal melt as a plausible mechanism to explain past and projected changes in the TIS and the ice sheet it buttresses,” the team writes.