There Greenlandlocated near the North Pole, is changing shape, size and geographical position. The earth’s crust that constitutes it is compressing in some areas and stretching in others, with the result that the island has become smaller overall. Besides, yes it is moved towards the north-west at the pace of about 2 cm per year over the last twenty years. The discovery was made by an international team led by researchers from the Technical University of Denmark (DTU), who published the study in the journal Journal of Geophysical Research: Solid Earth. Scientists analyzed data from one network of GPS stations distributed across Greenland, which have recorded the precise location of the island for decades. But what caused these transformations and movements? The person in charge is the current one climate change which determined the melting of icebut not only that: it also plays a role deglaciation occurred towards the end of the last ice age about 20,000 years ago. Knowing these variations is essential to understanding the consequences of global warmingbut also because they modify the reference points for the navigation.
How Greenland’s shape, size and location have changed
The researchers made the discovery by studying data from one network of 58 GPS stations present on the territory of Greenland, which have precisely detected all the movements of the island over the last twenty years. This data was integrated with the measurement of vertical lift of the crust and with the monitoring of horizontal deformations of the ground. The combination of all the data has made it possible to understand that the Earth’s crust under the ice of Greenland is being eroded lifting and at the same time he is suffering twisting, compression and stretching. The result is that overall the island has become smaller. Furthermore, it was discovered that the island has moved over the course of twenty years almost half a meter (to the tune of 2 cm per year) in north-west direction.
Causes and consequences of Greenland changes
The behaviors of the crust under Greenland are the answer to the melting of iceboth the current one due to climate change and the one that occurred approximately 20,000 years ago towards the end of the last ice age. With the melting of the ice, in addition to having a rise in sea level at a global level, in Greenland the weight exerted on the underlying earth’s crust decreases: the consequence is that the viscous material that makes up the earth’s mantle is redistributed and the crust floating on it rises under the area where the ice melts, while it lowers on the sides of this area. To better understand the phenomenon, just imagine the crust flexing like a trampoline when it is lightened. In fact, we are talking about post-glacial reboundongoing since the end of the last glaciation. This vertical movement allows the crust to reach an equilibrium condition by floating above the mantle. The lifting of Greenland was not the only consequence of the current and past melting. Its crust has also undergone a compression in correspondence with some areas and a elongation in others and it is slipped sideways because of slow flow of viscous mantle materials below.
Knowing these variations is essential to understand the consequences of global warming, but also for the detection and for the navigationsince they determine the movement of fixed reference points in Greenland.
