Greenland, the sand of the glaciers puts the island in front of a climatic dilemma

There sand it is both an abundant and a rare commodity. The Earth has vast deserts consisting mainly of this material, which however is not the same for which the so-called sand mafias are willing to carry out massacres. The particular variety that criminals desperately try to get their hands on is a fundamental ingredient of concrete used for buildings and infrastructure, the production of which is increased exponentially in recent decades, with a significant impact on the climate: the sector today is in fact responsible for8 percent of global carbon dioxide emissions (CO₂).

But the sand is also at the center of an unusual story. Climate change is destroying the Greenland ice sheet, producing an extraordinary amount of melt water, as melted ice is called (even if we somehow managed to stop emissions today, the melting of Greenland could contribute to a significant rise in sea level). By a strange twist of fate, Melt water contains the type of sand suitable for making concrete, a process that generates additional heating and increases melting. Large plumes of glacial sediments are created along the coast of Greenland they are actually adding land on the edge of the island. Despite being big alone three times Texasthe ice cap of the Greenland produces the8 percent of suspended river sediments that flow into the oceans.

The country now he will have to understand whether greater exploitation of this precious and abundant resource is sustainable from an environmental, social and economic point of view. “It is a rather controversial issue: we are saying that Greenland can benefit from climate change – explains Mette Bendixen, geographer at McGill University, Canada -. Contrary to most other areas of the Arctic coast, Greenland it is not eroding. On the contrary, it expands, because the ice sheet is melting. We can therefore think of the ice cap as a tap that releases not only the water, but also all the sediments“.

A special sand

Effectively, these sediments are truly special. Desert sand, in the Sahara for example, is not suitable for the production of concrete because it is too rounded and uniform. Over the millennia, winds move the grains, polishing them. Producing concrete with this type of sand would be “almost like building with marbles – explains Bendixen -; we need more angular, not rounded particles. And this type of material is exactly what you get from rivers, for example, or from material deposited by glaciers“.

Rubbing against the ground, the Greenland ice sheet – which covers 1.8 million square kilometers and has a thickness that can reach 3200 meters – creates sediments, including sand, fine silt and larger gravel fragments. When the ice melts, the streams of water carry all the debris to the sea, further eroding the landscape. Compared to the Sahara, where the sand spends thousands of years rolling around in the desert, the particles that detach from Greenland are more recent. Are also more angular and have a more varied shape. Instead of acting like marbles, they fit together like pieces of a puzzle, one optimal characteristic for the production of concrete.