Greenland’s ice sheet is melting and being replaced by vegetation, major satellite analysis shows

An estimated 11,000 square miles or 28,707 square kilometers of Greenland’s ice sheet and glaciers have melted over the past three decades, according to a major analysis of historical satellite records.

The total area of ​​ice loss is equivalent to the size of Albania and represents approximately 1.6% of Greenland’s total ice and glacier cover. Where there was once ice and snow, today there are barren rocks, wetlands and shrub areas.

A team of scientists from the University of Leeds, who tracked changes in Greenland between the 1980s and the 2010s, say warmer air temperatures are causing ice to retreat, impacting the temperature of the earth’s surface. , greenhouse gas emissions and landscape stability.

Permafrost – a permanently frozen layer beneath the Earth’s surface – is being ‘degraded’ by warming and, in some areas, scientists warn this could impact infrastructure, buildings and communities that exist above it. above.

Their results are published in a paper titled “Land cover changes across Greenland dominated by a doubling of vegetation in three decades” in the journal Scientific reports.

Impact of global warming

Greenland is part of the Arctic region. It is the largest island in the world, with an area of ​​approximately 836,330 square miles (2.1 million square kilometers). Most of the territory is covered in ice and glaciers and is home to almost 57,000 people.

Since the 1970s, the region has warmed twice as fast as the global average. In Greenland, average annual air temperatures between 2007 and 2012 were 3°C higher than the average from 1979 to 2000.

And researchers warn that more extreme temperatures are likely in the future.

Jonathan Carrivick, an earth scientist based at the School of the Environment in Leeds and one of the study’s authors, said: “Warmer temperatures are linked to the land cover changes we are seeing in the Greenland.

“By analyzing high-resolution satellite images, we were able to produce a detailed record of ongoing changes in land cover.”

Ice disappears to be replaced by bare rocks and shrubs

Ice loss was concentrated on the edges of current glaciers, but also in north and southwest Greenland. High levels of ice loss were also observed in localized areas in the west, northwest-central and southeast.

Over the three decades, the amount of land on which vegetation grows increased by 33,774 square miles (87,475 km2), more than doubling during the study period.

A pronounced increase in vegetation was observed in the southwest, east and northeast. The greatest increase in dense wetland vegetation occurred near Kangerlussuaq to the southwest and in isolated areas to the northeast.

The researchers’ analysis found that vegetation increased along a latitudinal gradient between 63° north and 69° north and declined north of it.

Carrivick said: “We have observed signs that the loss of ice is triggering other reactions that will lead to further loss of ice and further ‘greening’ of Greenland, where shrinking ice exposes bare rock which is then colonized by tundra and possibly by shrubs.

“At the same time, water released by melting ice displaces sediment and silt, eventually forming wetlands and marshes.”

Ice loss triggers additional warming

Ice loss affects Earth’s surface temperature because of albedo, which measures how reflective a surface is.

Snow and ice are good reflectors of solar energy hitting the Earth’s surface, helping to keep the Earth cooler. As the ice retreats, it exposes bedrock which absorbs more solar energy, increasing the temperature of the Earth’s surface.

Likewise, as ice melts, the amount of water in lakes increases. Water absorbs more solar energy than snow, which also increases the temperature of the earth’s surface.

Greenhouse gas emitter

The analysis shows that wetlands have almost quadrupled in Greenland, particularly in the east and northeast. Wetlands are a source of methane emissions.

In their paper, the researchers note: “Vegetation expansion, particularly in wetlands, indicates but also exacerbates permafrost thawing, active layer thickening and thus greenhouse gas emissions previously stored in these Arctic soils. »

The researchers also developed a model to predict areas of Greenland likely to experience “marked and accelerated” changes in the future.

Dr Michael Grimes, the lead author of the report who conducted the research as part of his PhD, added: “The expansion of vegetation, which occurs in tandem with the retreat of glaciers and the ice sheet, significantly changes the flow. of sediments and nutrients in coastal waters.

“These changes are crucial, particularly for indigenous populations whose traditional subsistence hunting practices depend on the stability of these delicate ecosystems.

“Furthermore, the loss of ice mass in Greenland is contributing substantially to global sea level rise, a trend that poses significant challenges now and in the future.”