Six massive glaciers in West Antarctica are moving faster than they did 40 years ago, causing more ice to discharge into the ocean and global sea level to rise, according to the latest research.
The amount of ice draining collectively from those half-dozen glaciers increased by 77 percent from 1973 to 2013, scientists report this month in Geophysical Research Letters, a journal of the American Geophysical Union. Pine Island Glacier, the most active of the studied glaciers, has accelerated by 75 percent in 40 years, according to the paper. Thwaites Glacier, the widest glacier, started to accelerate in 2006, following a decade of stability.
The study is the first to look at the ice coming off the six most active West Antarctic glaciers over such an extended time period, said Jeremie Mouginot, a glaciologist at University of California-Irvine (UC-Irvine) who co-authored the paper. Almost 10 percent of the world’s sea-level rise per year comes from these six glaciers, he said.
The amount of ice released by these six glaciers each year is comparable to the amount of ice draining from the entire Greenland Ice Sheet annually, Mouginot said. If melted completely, the glaciers’ disappearance would raise sea levels 4 feet (1.2m), according to co-author and UC-Irvine Professor Eric Rignot.
Mouginot and his colleagues used satellite data to look at sequential images of the glaciers from 1973 to 2013. The scientists then calculated how fast the ice was moving by tracking surface features, such as cracks in the ice, to determine the distance the glaciers traveled from month to month and year to year.
“This paper is important in showing that a glacier can actually ‘feel’ what is happening far downstream of itself,” said Thomas. “It means that if you disturb the ice sheet near the coast, the glaciers will feel the push and rapidly respond hundreds of kilometers inland.” This finding suggests that glacier acceleration models may need to be reevaluated.