Strong ocean currents are eroding the ice beneath West Antarctica’s Pine Island Glacier, accelerating its melting.
According to one estimate, the total collapse of Pine Island Glacier and its tributaries could raise sea level by 24 cm. Global sea levels are currently rising at about three mm a year.
The glacier is currently sliding into the sea at a clip of four km a year while its ice shelf is melting at about 80 cubic km a year, 50 percent faster than it was in the early 1990s, says a new study.
The glacier, among other ice streams in Antarctica, is being closely watched for its potential to redraw coastlines worldwide.
The researchers say that a growing cavity beneath the ice shelf has allowed more warm water to melt the ice — a process that feeds back into the ongoing rise in global sea levels, reports the journal Nature Geoscience.
“More warm water from the deep ocean is entering the cavity beneath the ice shelf, and it is warmest where the ice is thickest,” said Columbia University’s Lamont-Doherty Earth Observatory oceanographer Stan Jacobs, who led the study.
The researchers found that in 15 years, melting beneath the ice shelf had risen by about 50 percent. Although regional ocean temperatures had also warmed slightly, by 0.2 degrees Celsius or so, that was not enough to account for the jump, according to a Columbia statement.
The local geology offered one explanation. On the same cruise, a group led by Adrian Jenkins, a researcher at British Antarctic Survey and study co-author, sent a robot submarine beneath the ice shelf, revealing an underwater ridge.
Researchers also directly observed, near the southern edge of Pine Island Glacier, the strength of the melting process as they watched frigid, sea water appear to boil on the surface like a kettle on the stove.