In Antarctica the researchers identified 85 subglacial lakes So far unknown, located some kilometers below the surface of the glacial cap. The discovery was possible thanks to the data collected in ten years by Cryosat satellite of ESA. These lakes they fill themselves of water from the merger of the ice above and they dry up in a cyclical waymaking the height of the surface of the cap vary, and for this they are said “active“. The satellite is able to detect these variations and therefore to monitor the filling and emptying cycles of the lakes over time. The lakes just discovered are added to those already known, leading to 231 The number of antarctic active subglacial lakes. Knowing what happens under the surface of the ice in depth is very difficult, so the role of satellites is essential to better understand the Polar ice dynamics and its effects onSea level raising.
The discovery of the 85 new lakes under the ice of Antarctica
There Cryosat Missionwhich is part of the future ESA program, was launched in 2010 and collects data relating to sea ice thickness polar and at variations in height of the caps Glacial above Greenland and Antarctica. To do this, use a Radar altimeterwhich also detects small changes in height. The data obtained from the satellite Between 2010 and 2020 they served researchers to identify the presence of 85 active subglacial lakes to kilometers deep under Antarctic ice, in contact with the rocky substrate. Cyclically these lakes are filled with water coming from the melting of the ice above and then empty influencing the height of the cap at the local level. With this discovery, i Active subglacial lakes known in Antarctica have become 231: This means that the amount of water that they periodically release into the surrounding ocean is significant and could also compromise the stability of the cap. In the future it will be necessary monitor their filling and drainage cycles To understand how to influence theSea level raising. It will be a huge step forward since, as Sally Wilson, main author of the study, says, “the numerical models that we currently use to project the contribution of entire glacial caps to the rise in sea level do not include subglacial hydrology”.
How the subglacial lakes hidden under the guall of Antarctica are formed
The melting water that feeds the subglacial lakes is formed by the ice present at the base of the Antarctic cap mainly due to the heat of the rockspartly dating back to the formation of the earth and partly deriving from the decay of the radioactive isotopes present in the earth’s crust. The heat that produces water from Antarctic ice also comes from heating for friction caused by the slipping of the ice on the rocky substrate. Also theenormous pressure Exercised by the above cap has a role, because it lowers the casting point of the ice to its base. This derived water can accumulate on the surface of the substrate below the cap and originate lakes circular or elongated. Antarctic subglacial lakes In total there are 766but many are stableThat is, they do not fill and empty cyclically. The others are active and water flows from them periodically, facilitating and also accelerating ice sliding above in the ocean. To fill and empty, active lakes can take months or years. The largest known subglacial lake is the Vostok lakein Eastern Antarctive: about 230 km long and has an area of about 10,000 km2, contains a volume of water equal to approximately 5000 km3. Even if it is believed that it is stable, if they dry up it could have a huge impact on the stability of the cap, the ocean circulation, on the sea level and on the marine habitats.
