Figure ASatellite images from 2022 (Main image) and 1999 (Figure A) capture the retreat of Zachariae Isstrom, a glacier in northeast Greenland, as icebergs broke off its edge over the course of 23 years. In a recent study in Nature, researchers from NASA's Jet Propulsion Laboratory in Southern California calculated that Zachariae lost an estimated 176 billion tons (160 billion metric tons) of ice in the period between 1985 and 2022. That was the greatest mass lost for the period of any of the 207 glaciers analyzed in the paper.
The earlier image was taken by the Enhanced Thematic Mapper Plus on the Landsat 7 satellite on Aug. 5, 1999, while the later image was captured by the Operational Land Imager on the Landsat 8 satellite on Aug. 22, 2022.
Figure B is an annotated version of the 2022 image.
Figure BFigure C is an annotated version of the 1999 image.
Figure CThe study took a comprehensive look at glacial retreat around the edges of the entire Greenland Ice Sheet from 1985 to 2022 and found that 179 glaciers retreated significantly since 1985, 27 held steady, and just one advanced slightly.
The study found that overall the ice sheet shed about 1,140 billion tons (1,034 billion metric tons) of ice from 1985 to 2022, one-fifth more mass than previously estimated, as icebergs fell into the ocean at an accelerating rate.
Most of the ice loss came from below sea level, in fjords on Greenland's periphery. Once occupied by ancient glacial ice, many of these deep coastal valleys have filled with seawater – meaning the ice that broke off made little net contribution to sea level. But the loss likely accelerated the movement of ice flowing down from higher elevations, which in turn added to sea level rise. It also added previously unaccounted-for fresh water to the North Atlantic Ocean, which could have impacts on global ocean currents.
