Britney Schmidt and Peter Davis

If the Florida-size Thwaites Glacier should crumble into the Antarctic Ocean as the planet warms, it could mean a global sea-level rise of up to 2 ft., enough to wipe out many coastal cities. A major Antarctic field campaign spearheaded by Britney Schmidt of Cornell University and Peter Davis of the British Antarctic Survey offers essential insight into the consequential, and unstable, glacier. Using a hot-water drill and a camera-enabled underwater robot, they were able to look at the glacier’s underside to better understand how, and how fast, it was melting. Their research, published in Nature in February, revealed troubling footage of the glacier melting from the bottom up, and a more nuanced view of glacier de-formation. “When you don’t understand how a process is happening, you can’t hope to forecast it,” says Schmidt. “Observing Thwaites in detail gives us a chance to make better choices for our future based on what we know is happening today.”

Baker is TIME’s senior climate correspondent

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