Scientists have spotted a never-before-seen hole under the Antarctic ice.
The cavity is 984 feet tall and roughly two-thirds the size of Manhattan. It's a sign that this part of the Antarctic ice sheet is flattening faster than experts thought.
Antarctica is ringed by a skirt of ice sheets and floating ice shelves that provide a buffer between the ocean and the landlocked ice on the continent. These floating sheets act like a dam, as Ross Virginia, director of the Dartmouth College's Institute of Arctic Studies, previously told Business Insider. They prevent the continental ice from flowing into the ocean, where it eventually dumped, leading global sea levels to rise.
But as the ocean temperature increases, warmer water at the base of these ice sheets causes them to melt from below. That melting gives rise to cavities like this recently discovered gap.
"[The size of] A cavity under a glacier plays a major role in melting," said Pietro Milillo, an environmental engineer at NASA's Jet Propulsion Laboratory and lead author of the study, in a press release. "As more heat and water get under the glacier, it melts faster."
The findings are just one indicator of the complex pattern of retreat and ice melt taking place at Thwaites Glacier, the authors of the new study said. Sections of Thwaites Glacier are retreating by up to 2,625 feet per year.
When ice sheets melt from below, they lose structural integrity. If they disintegrate, a surge of continental ice could flow into the ocean ̵
Here's how scientists found the alarming cavity, and why Thwaites Glacier might be a one-way road to its demise.