The loss of ice on the surface of Greenland is one of the most important phenomena associated with climate change observed in recent decades on our planet. Recent studies indicate that in the last 40 years some 28,700 square kilometers of permanent ice have been lost (a surface equivalent to the Community of Valencia, which has 23,255 km²) on this Arctic island of 2.16 million km² (four times the surface of Spain).
An investigation based on the review of satellite images between the years 1980 and 2010 has now delved into the calculation of this thawing process, paying special attention to how the surface is stripped of its traditional white mantle. In many cases, the first period after the thaw is the vision of a rocky surface, sand and mud; but in the medium term, the white turns green due to the appearance of vegetation, according to the results of this work that is presented this Tuesday, February 13, in an article published in the journal Scientific Reports. “Where there was ice and snow before, there are now rocks, arid areas, wetlands and scattered bushes,” summarizes the information note released by the University of Leeds (United Kingdom), to which the main authors of the new study belong.
The most important figure from this research is that, in three decades, the area covered by vegetation has doubled in Greenland, reaching a total of 87,475 km².
The authors of the review of satellite images and climate data from this three-decade period highlight that warmer air temperatures are causing the ice to retreat, which in turn is having an impact on Earth’s surface temperature. , greenhouse gas emissions and landscape stability.
For one thing, permafrost, a permanently frozen layer beneath the surface, is being “degraded” by warming and, in some areas, scientists warn it could have an impact on the infrastructure, buildings and communities that exist above it. she. But this is not the only and most serious problem of melting ice.
Greenland is part of the Arctic region and 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. Researchers warn that this trend is likely to continue and lead to more extreme temperatures in the future.
Jonathan Carrivick, an earth scientist at the University of Leeds’ School of Environment and one of the authors of the study, points out that, in addition to the warming processes that are best known (such as the increase in greenhouse gases), ” warmer temperatures are related to the changes in land cover that we are seeing in Greenland.” The study now presented has precisely this objective, according to Professor Carrivick: “By analyzing high-resolution satellite images, we have been able to produce a detailed record of the land cover changes that are occurring.
The images show that in many cases the ice disappears, revealing bare rocks and bushes. Ice loss was concentrated at the edges of today’s glaciers, but also in the north and southwest of Greenland. There were also high levels of ice loss in localized areas in the West, Midwest and Southeast, the authors note.
The greatest increase in dense wetland vegetation occurred in the vicinity of Kangerlussuaq in the southwest and in isolated areas in the northeast. The researchers’ analysis revealed that vegetation had increased along a latitudinal gradient between 63 degrees north and 69 degrees north and had decreased north of it.
Jonathan Carrivick explains that there have been “signs that the loss of ice is triggering other reactions that will result in further ice loss and “further greening of Greenland,” where the shrinking ice exposes bare rocks that then They are colonized by tundra and eventually shrubs.
“At the same time, the water released by melting ice moves sediments and silt, and that eventually forms wetlands and swamps,” indicates this co-author of the study in a note released by the University of Leeds.
The loss of ice affects the temperatures of the Earth’s surface due to albedo, that is, the disappearance of white surface layers reduces the albedo (ability to reflect solar rays), the Earth absorbs more heat and temperatures rise, which in turn causes greater melting of the ice; a totally negative spiral or chain effect.
Snow and ice are good reflectors of the sun’s energy that reaches our planet and this helps keep the Earth colder. As the ice retreats, it exposes bedrock that absorbs more solar energy, raising the temperature of the Earth’s surface. Similarly, as ice melts, the amount of water in lakes increases. Water absorbs more solar energy than snow and this also increases the temperature of the Earth’s surface.
The analysis shows a nearly quadrupling of wetlands across Greenland, particularly in the east and northeast. Wetlands are a source of methane emissions. In the paper now being published, the researchers noted: “The expansion of vegetation and especially in wetland areas indicates, but also exacerbates, the thawing of permafrost, the thickening of the active layer and, therefore, emissions of greenhouse gases previously stored in these Arctic soils.
The researchers also developed a model to predict those areas of Greenland that are likely to experience “marked and accelerated” changes in the future. Professor Michael Grimes, lead author of the report who carried out the research as part of his PhD, adds: “Vegetation expansion, occurring alongside retreating glaciers and ice sheets, is significantly altering the flow of water. sediments and nutrients into coastal waters: “These changes are critical, particularly for indigenous populations whose traditional subsistence hunting practices depend on the stability of these delicate ecosystems. “In addition, the loss of ice mass in Greenland contributes substantially to global sea level rise, a trend that poses important challenges both now and in the future,” highlights the University of Leeds.
