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

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Russell Glacier and proglacial area, near Kangerlussuaq, West Greenland. Credit: Jonathan Kerwick

An estimated 11,000 square miles, or 28,707 square kilometers, of the Greenland 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 about 1.6% of Greenland’s total ice and glacier cover. Where there once was snow and ice, there are now barren rocks, wetlands and areas of bush.

A team of scientists from the University of Leeds, who have tracked changes in Greenland from the 1980s to the 2010s, say warmer air temperatures are causing the ice to retreat, which in turn is affecting land surface temperatures. Used to be. , greenhouse gas emissions and landscape sustainability.

Permafrost—a permanently frozen layer beneath the Earth’s surface—is being “destroyed” by heat and in some areas, scientists warn it could have an impact on the infrastructure, buildings and communities above it. .

their test result An article titled “Land cover change in Greenland is dominated by the doubling of vegetation in three decades” is published in the journal scientific report,

effect of global warming

Greenland is part of the Arctic region. It is the largest island in the world, measuring approximately 836,330 square miles (2.1 million square km) in size. Most of the land is covered with snow and glaciers and it is home to about 57,000 people.

The region has been warming at twice the global average rate since the 1970s. In Greenland, the average annual air temperature between 2007 and 2012 was 3 °C higher than the average from 1979 to 2000.

And researchers warn that even greater temperature increases are likely in the future.

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

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

The snow disappears and is replaced by bare rocks and bushes

Ice loss was concentrated around the edges of present-day glaciers, but also in the north and southwest of Greenland. Local areas in the west, central-northwest, and southeast also experienced high levels of snow loss.

Over three decades, the amount of land with vegetation growing on it increased by 33,774 square miles (87,475 square km), more than doubling over the study period.

A clear increase in vegetation was observed in the south-west, east and north-east. The greatest increase in dense wetland vegetation occurred in the southwest around Kangerlussuaq and in isolated areas in the northeast.

Analysis conducted by the researchers showed that vegetation increased along the latitudinal gradient between 63°N and 69°N and declined further north.

“We see signs that ice loss is triggering other reactions that will result in further ice loss and the ‘greening’ of Greenland, where the shrinking ice exposes bare rock that will later turn into tundra,” Kervik said. Colonized by and eventually become shrubs.

“At the same time, water from melting ice is moving sediment and silt, and that ultimately creates wetlands and fenlands.”

Greenland's ice sheet is melting and being replaced by vegetation

Comparison between land cover classification at 30 m resolution for the late 1980s and late 2010s shows that greenness is increasing as vegetation coverage expands, especially in the south-west and north-east. . Credit: University of Leeds

Heat increases due to loss of ice

The loss of ice affects land surface temperatures due to albedo, which is a measure of how reflective a surface is.

Snow and ice are good reflectors of the sun’s energy striking the Earth’s surface and help keep the Earth cool. As the ice retreats, it exposes bedrock that absorbs more solar energy, increasing the land surface temperature.

Similarly, as snow melts, the amount of water in lakes increases. Water absorbs more solar energy than ice and this also increases the temperature of the land surface.

greenhouse gas emitters

The analysis shows that wetlands have almost quadrupled across Greenland, especially in the east and north-east. Wetlands are a source of methane emissions.

Writing in the paper, the researchers said, “The expansion of vegetation and permafrost thaw, especially in wetland areas, indicates a thickening of the active layer and thus emissions of greenhouse gases already stored in these Arctic soils, but also increases Is.”

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

Dr Michael Grimes, lead author of the report, who conducted the research as part of his PhD, said: “The expansion of vegetation, occurring simultaneously with the retreat of glaciers and ice sheets, is driving significant changes in flow. ” Sediment and nutrient concentrations in coastal waters.

“These changes are significant, especially for indigenous populations whose traditional subsistence hunting practices depend on the sustainability of these fragile ecosystems.

“In addition, the loss of ice mass in Greenland is a significant contributor to global sea level rise, a trend that poses significant challenges both now and in the future.”

more information:
A doubling of vegetation in three decades led to changes in land cover in Greenland, scientific report (2024). DOI: 10.1038/s41598-024-52124-1

Provided by the University of Leeds


Citation: Greenland ice sheet is melting and being replaced by vegetation, major satellite analysis shows (2024, February 13) 13 February 2024 https://phys.org/news/2024-02-greenland- Retrieved from ice-sheet-vegetation-major.html

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