Shrinking Margins of Greenland: At Least 200 Coastal Glaciers Have Retreated Over the Past 20 Years
A recent study of Greenland’s ice sheet found that glaciers are retreating in nearly every sector of the island, while also undergoing other physical changes. Some of those changes are causing the rerouting of freshwater rivers beneath the ice.
In a study led by Twila Moon of the National Snow and Ice Data Center, researchers took a detailed look at physical changes to 225 of Greenland’s ocean-terminating glaciers—narrow fingers of ice that flow from the ice sheet interior to the ocean. They found that none of those glaciers has substantially advanced since the year 2000, and 200 of them have retreated.
The map at the top of this page shows measurements of ice velocity across Greenland as measured by satellites. The data were compiled through the Inter-mission Time Series of Land Ice Velocity and Elevation project (ITS_LIVE), which brings together observations of glaciers collected by multiple Landsat satellites between 1985 and 2015 into a single dataset open to scientists and the public.
About 80 percent of Greenland is blanketed by an ice sheet, also known as a continental glacier, that reaches a thickness of up to 3 kilometers (2 miles). As glaciers flow toward the sea, they are usually replenished by new snowfall on the interior of the ice sheet that gets compacted into ice. Multiple studies have shown that the balance between glacier melting and replenishment is changing, as is the rate of iceberg calving. Due to rising air and ocean temperatures, the ice sheet is losing mass at an accelerating rate and additional meltwater is flowing into the sea.
“The coastal environment in Greenland is undergoing a major transformation,” said Alex Gardner, a snow and ice scientist at NASA’s Jet Propulsion Laboratory and co-author of the study. “We are already seeing new sections of the ocean and fjords opening up as the ice sheet retreats, and now we have evidence of changes to these freshwater flows. So losing ice is not just about changing sea level, it’s also about reshaping Greenland’s coastline and altering the coastal ecology.”