A study on “THE CRYOSPHERE” He identified the point of no return beyond which the glacial cap of Greenland would dissolve irreversibly, raising the seven -meter sea level. This collapse could take place if the global temperature increased by 3.4 ° C compared to pre -industrial levels, an imminent milestone
The glacial cap of Greenland: a giant in decline
With an extension of over 1.7 million square kilometers, the glacial cap of Greenland, island located between the Atlantic Ocean and theArcticrepresents the second largest ice depot on the earth. In fact, it houses about seven percent of global fresh water.
However, this gigantic tank is gradually disappearing: from the 80s to today, it has lost more than a trillion of ice tons, and the melting speed has increased by six times in the last decade.
Currently, it is estimated that every hour about thirty million tons of ice disperse at sea. This dissolution Massive is not only a phenomenon limited to the Arctic, but a catalyst for profound changes that influence the entire terrestrial climatic system.
The raising of sea level, direct consequence of the fusion of the cap, threatens millions of people who live in coastal cities and in the low islands. The fresh water of Greenland, pouring into the ocean, modifies its salinity and alters the delicate balance of marine currents.
The risk of a upheaval of the Southern Atlantic circulationthe great current that transports the heat to Europe and other regions of the globe, becomes more and more concrete. His weakening could translate into western Europe in western Europe, more intense tropical cyclones in the Atlantic and a drastic change in the regimes of monsical rains, with devastating effects on agriculture and food safety of entire populations.
The point of no return: the threshold of 3.4 ° C
The study led by dr. Michele Petrini del Norce Norwegian Research Centers and of the Bjerknes Centre for Climate ResearchIn Bergen, Norway, it took advanced climatic models to simulate the behavior of the cap in different environmental conditions. The results show that when the loss of ice reaches sixty percent of the mass budget compared to the pre -industrial era, Greenland enters an accelerated and irreversible dissolution phase.
If greenhouse gas emissions continue to grow without control, the final collapse point could be reached by the end of the century. With global temperatures above 3.4 ° C compared to the pre -industrial era, the fate of Greenland would be marked. The complete melting of the cap would take place in a period between eight thousand and forty thousand years, but its initial effects would already be perceptible within a few decades.
The mechanism of dissolution: an irreversible domino effect
The loss of ice in Greenland does not follow a linear trend, but is guided by a series of concatenated processes that amplify the phenomenon with a waterfall dynamic.
The isostatic rise of the soil, one of these factors, occurs when the weight of the ice is reduced and the terrestrial crust below tends to rise. However, if the dissolution rate is too quick, the ground cannot compensate for the movement, making the cap unstable and further accelerating the merger.
The Albedo effect, another decisive element, plays a key role in heating the Arctic region. The ice, being white, reflects a large amount of sun radiation in space, helping to keep temperatures low. With the reduction of glacial coverage, the exposed surface becomes darker, absorbing greater heat and feeding a vicious circle that accelerates heating and merger. This process is particularly evident in southern Greenland, where the increase in temperature has already transformed large portions of the cap into a mosaic of ice and uncovered soil.
Change in ocean currents also significantly affects the stability of the cap. The entry of enormous quantities of fresh water in the surrounding seas reduces the density of surface waters and slows down the transport of heat from tropical areas to the north. The result is a localized cooling which, paradoxically, can lead to more intense snowfalls in some areas of Greenland, while in others it accelerates the dissolution process with the formation of glacial lakes and deep fractures in the cap.
Western Greenland: a fragile bulwark
According to climatic simulations, western Greenland represents a critical area for the survival of the cap. Until this portion remains anchored to a coastal area with high altitude, ice leaks in the North and South are contained.
However, if the western cap loses contact with the coast and begins to withdraw towards the hinterland, the entire glacial structure could collapse, leading to the loss of over eighty percent of its mass.
The paleoclimatic reconstructions suggest that, during the last interglacial, the maintenance of the ice in this region prevented a total merger of the cap. Today, this same mechanism could offer a last hope to slow down the dissolution process, but only on condition that global temperatures do not exceed the critical threshold identified by scientists.