Science & Technology

Shrinking Margins of Greenland: At Least 200 Coastal Glaciers Have Retreated Over the Past 20 Years

1985 – 2015

A current research of Greenland’s ice sheet discovered that glaciers are retreating in almost each sector of the island, whereas additionally present process different bodily adjustments. Some of these adjustments are inflicting the rerouting of freshwater rivers beneath the ice.

In a study led by Twila Moon of the Nationwide Snow and Ice Knowledge Heart, researchers took an in depth have a look at bodily adjustments to 225 of Greenland’s ocean-terminating glaciers—slim fingers of ice that circulate from the ice sheet inside to the ocean. They discovered that none of these glaciers has considerably superior since the 12 months 2000, and 200 of them have retreated.

The map at the high of this web page exhibits measurements of ice velocity throughout Greenland as measured by satellites. The info have been compiled by means of the Inter-mission Time Collection of Land Ice Velocity and Elevation mission (ITS_LIVE), which brings collectively observations of glaciers collected by a number of Landsat satellites between 1985 and 2015 right into a single dataset open to scientists and the public.

About 80 % of Greenland is blanketed by an ice sheet, also called a continental glacier, that reaches a thickness of as much as 3 kilometers (2 miles). As glaciers circulate towards the sea, they’re normally replenished by new snowfall on the inside of the ice sheet that will get compacted into ice. A number of research have proven that the steadiness between glacier melting and replenishment is altering, as is the price of iceberg calving. As a consequence of rising air and ocean temperatures, the ice sheet is dropping mass at an accelerating price and extra meltwater is flowing into the sea.

“The coastal setting in Greenland is present process a serious transformation,” stated Alex Gardner, a snow and ice scientist at NASA’s Jet Propulsion Laboratory and co-author of the research. “We’re already seeing new sections of the ocean and fjords opening up as the ice sheet retreats, and now we now have proof of adjustments to those freshwater flows. So dropping ice is not only about altering sea stage, it’s additionally about reshaping Greenland’s shoreline and altering the coastal ecology.”

Although the findings by Moon, Gardner, and colleagues are in keeping with different Greenland observations, the new survey captures a development that has not been obvious in earlier work. As particular person glaciers retreat, they’re additionally altering in methods which might be doubtless rerouting freshwater flows beneath the ice. For instance, glaciers change in thickness not solely as hotter air melts ice off of their surfaces, but additionally as their circulate pace adjustments. Each situations can result in adjustments in the distribution of strain beneath the ice. This, in flip, can change the path of subglacial rivers, since water will all the time take the path of least resistance (lowest strain).

Citing earlier research on the ecology of Greenland, the authors word that freshwater rivers beneath the ice sheet ship vitamins to bays, deltas, and fjords round Greenland. As well as, the under-ice rivers enter the ocean the place the ice and bedrock meet, which is usually properly beneath the ocean’s floor. The comparatively buoyant freshwater rises, carrying nutrient-rich deep ocean water to the floor, the place the vitamins could be consumed by phytoplankton. Analysis has proven that glacial meltwater rivers instantly have an effect on the productiveness of phytoplankton, which function a basis of the marine meals chain. Mixed with the opening of new fjords and sections of ocean as glaciers and ice cabinets retreat, these adjustments quantity to a change of the native setting.

“The pace of ice loss in Greenland is beautiful,” stated Moon. “As the ice sheet edge responds to fast ice loss, the character and conduct of the system as a complete are altering, with the potential to affect ecosystems and individuals who rely on them.”

NASA Earth Observatory picture by Joshua Stevens, utilizing Landsat information from the U.S. Geological Survey and the Inter-mission Time Collection of Land Ice Velocity and Elevation (ITS_LIVE) mission at NASA/JPL-Caltech, and the Normal Bathymetric Chart of the Oceans (GEBCO). Story by Calla Cofield, Jet Propulsion Laboratory, with Mike Carlowicz.

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