sea level rise

The fastest-melting Greenland glacier has made a temporary U-turn

Iceberg from the Jakobshavn Glacier in Disko Bay, Greenland.
Iceberg from the Jakobshavn Glacier is seen in Disko Bay, Greenland, in 2017. Photo: Andrew Freedman

The Jakobshavn Glacier in west-central Greenland, which has been the fastest-flowing and thinning glacier on the vast ice island during the past 20 years, has temporarily slowed its retreat and thickened in the past few years, scientists say.

The big picture: Using new, high-resolution data of ocean currents at and near the glacier's floating ice shelf, NASA researchers were able to show that an influx of cooler waters since 2016 has slowed — but not completely halted — Jakobshavn's rapid melt. The glacier is still adding to global sea level rise, since it continues to lose more ice to the ocean than it gains from snow accumulation, but at a slower rate.

A 1,000-foot tall chasm is found within a crucial Antarctic glacier

An inlet filled with sea ice around Venable Ice Shelf.
An inlet filled with sea ice around Venable Ice Shelf, as seen during an Operation IceBridge flight on Nov. 16, 2017. Photo: NASA/Nathan Kurtz.

Two important studies on Antarctic ice shed light on how much progress scientists are making to predict the continent's future, and how little we really know.

The threat: The first study, published on Jan. 30 in Science Advances, used synthetic aperture radar from satellites and aircraft to determine the motion and structure of the rapidly melting Thwaites Glacier in West Antarctica.