A rapid shift in ocean currents could imperil the world’s largest ice shelf

The Ross Ice Shelf was expected to stabilize major coastal glaciers well into the future

A massive ice cliff towers over a boat sailing in ice-encrusted waters in the background

The front cliff of the Ross Ice Shelf towers high above the 6,000-ton icebreaker, the Nathaniel B. Palmer, in the background. But 90 percent of its thickness lies underwater.

Michael Van Woert, NESDIS/NOAA

Antarctica’s largest ice shelf, buttressing a dozen major glaciers and slowing their flow into the ocean, may be surprisingly sensitive to warming.