The ice and snow cover that covers almost all of Greenland, the second largest in the world after Antarctica, has lost approximately 5,091 square kilometers of area since 1985, in a melting process that has accelerated since the 1990s. The volume of water dumped into the ocean as a result of this melting, despite being large, has so far had "a relatively small impact on the rise in sea level on a global scale."
However, what is most worrying in the short term is that the loss of ice in Greenland may be having negative implications on ocean circulation and, therefore, "altering the distribution of global thermal energy," according to data obtained with images of satellites and analysis of a study led by experts from NASA's Jet Propulsion Laboratory (JPL), whose results have been published in the journal Nature (January 17).
Ice sheets around the world have experienced retreat in recent decades, and the Greenland ice sheet in particular has experienced a period of accelerated mass loss since the 1990s, the team recalls in the introduction to the article. headed by Chad Greene, a glaciologist and remote sensing specialist at JPL.
Climate models anticipate with a high level of certainty that this ice loss in Greenland will continue, but research into how the ice sheet has previously retreated could offer insight into its future behavior.
Chad Greene and his colleagues used satellite images to establish 236,328 glacier terminal positions between 1985 and 2022. From this, the authors quantified the extent of calving (the process of ice breaking up at the end of a glacier) and changes in the edges of the ice sheet and, therefore, the total ice area lost, explains Nature in a summary note of the results of this study.
The authors found that the Greenland ice sheet had lost about 5,091 square kilometers of ice over the past four decades. More specifically, according to the analysis, the ice sheet has shrunk by an average of 218 square kilometers each year since January 2000. This area may seem relatively small (Greenland is 2.166 million km²) but it represents the loss of approximately 1,034 gigatonnes of ice and snow (1 gigaton is equal to 1 billion tons).
The authors point out that this melting retreat has not, for now, contributed substantially to sea level rise, but "it may play a role in ocean circulation patterns and how thermal energy is distributed across the planet." .
Greene and his co-authors also found that some of the Greenland Ice Sheet glaciers that experienced the largest difference between winter growth and summer retreat in a single year (including Jakobshavn Isbræ and Zachariæ Isstrøm) were also the glaciers that retreated the most. from 1985 to 2022. This indicates that the seasonal variability of glaciers could predict long-term retreat.
