A new large-scale study of crevasses on the Greenland Ice Sheet shows that those cracks are widening faster as the climate warms, which is likely to speed ice loss and global sea level rise.

Crevasses are wedge-shaped fractures and cracks that open in glaciers where the ice begins to flow faster. They can grow to more than 300 feet wide, thousands of feet long and hundreds of feet deep. Water from melting snow on the surface can flow through crevasses all the way to the base of the ice, joining with other hidden streams to form a vast drainage system that affects how fast glaciers and ice sheets flow.

Greenland ice researchers expect that more crevasses will form in a warming world because “glaciers are accelerating in response to warmer ocean temperatures, and because meltwater filling crevasses can force fractures deeper into the ice,” he said. “However, until now we haven’t had the data to show where and how fast this is happening across the entirety of the Greenland Ice Sheet.”

Using three dimensional images of the crevasses enabled the researchers to get the most accurate estimate of their total volume to date. The results show that crevasses grew significantly wider between 2016 and 2021.

“And they grow pretty much in lockstep with increased discharge” of icebergs and meltwater into the ocean, Chudley said. “That makes sense, right? Because the glaciers are speeding up because of influence from the warming ocean. As they speed up, they flow faster.”

Ice at the surface of glaciers generally flows faster than at their bases, which are slowed by friction with the surface they travel on. The difference in speeds cause the fissures, he explained. . . .In 2020, researchers calculated that Greenland’s ice sheet annually loses about 9 billion tons of water every hour.

The total annual freshwater flow off Greenland is about equal to the annual flow of the Amazon River, at about 1,000 gigatons per year, said Ken Mankoff, a researcher with the Geological Survey of Denmark and Greenland who led the comprehensive 2020 study tracking discharge from Greenland from 1986 to 2020. If all its ice melts, it would raise sea level by about 23 feet (7 meters).

A complete meltdown is projected to take thousands of years, but there is a lot of scientific evidence from periods of rapid climate warming in the not-so-distant geological past that show pulses of rapid global ice melt, with sea levels sometimes rising in surges of up to 13 feet (4 meters) per century. At the current rate of melting, Greenland’s ice could contribute about 3 feet (1 meter) of sea level rise by 2100.