Change is constant and common on Earth through geological time. But in the icy polar regions, changes have been dramatic and rapid in recent decades. One example is northwest Greenland, where a lot has changed in 21 years.
The pair of images above shows part of Greenland along Melville Bay (a subsection of Baffin Bay) on September 3, 2000 and September 21, 2021. Images were acquired with the Enhanced Thematic Mapper Plus (ETM +) on Landsat 7 and the Operational terrestrial imager (OLI) on Satellite 8, respectively. (Note that Earth Observatory originally released a false-color version of the 2000 image. Both images above are in natural color and show a slightly larger view.)
The images show a coastal strip of 80 kilometers (50 miles). Like so many places on the outskirts of Greenland, a series of glaciers here transport ice from the interior of the island to the coast and out to the ocean. Most of these marine-terminated glaciers are retreating. Kjer and Hayes, the two main outlet glaciers above, also accelerate.
Note that in 2000, the Kjer Glacier was contiguous with a few rocky outcrops. These rocks helped strengthen the ice and slowed its flow to the ocean. Then in 2012, the glacier floats ice shelf disintegrates. The rocks have become self-contained islands, surrounded in the 2021 image by open water and a mixture of sea ice and icebergs, or mixture. Having lost contact with the rocks, the interior ice of the glacier can flow even faster to the ocean.
According to Alex Gardner, a snow and ice scientist at NASA’s Jet Propulsion Laboratory, the data from IT’S LIVE and the NASA MEASURES Program show that a year before the ice floe broke, the glacier flowed at an average speed of 1,200 meters per year. In 2018, the average glacier speed was over 4,000 meters per year.
“Kjer is experiencing an almost four-fold increase in ice flow due to the collapse of its floating ice shelf, possibly due to the melting of warmer ocean waters,” Gardner said. “This has led to an increased contribution of ice to the ocean and accelerated sea level rise.”
In the 1970s, the Greenland ice sheet gained about as much ice as it lost, a state of equilibrium that lasted until the mid-1990s when the loss of ice began. is accelerated. Between 2002 and 2021, Greenland lost about 280 gigatons of ice per year, adding 0.8 millimeters (0.03 inches) per year to global sea level rise.
Images from NASA’s Earth Observatory by Lauren Dauphin, using Landsat data from the United States Geological Survey. Kathryn Hansen story.