Austrian researchers use innovative satellites to measure the total amount of water on land, but also below the surface. The magnitude of the subterranean drought in Europe is so great that it is changing the total mass of our blue planet.
Europe has been facing a historic drought for several years: the global water table has been low since 2018, despite the few episodes of intense rainfall and flooding that several countries have experienced. After the dark years of 2018 and 2019 in terms of precipitation, there was no real improvement until the summer of 2022, which was characterized by a severe drought on 75% of the European continent.
Satellites estimate the total mass of the earth
A new generation of satellites makes it possible to accurately quantify the extent of drought at depth, and not just surface drought (also called agricultural drought), which improves slightly depending on weather conditions. These satellites, Tom and Jerry, are in orbit about 300 miles from Earth and are 125 miles apart. These two “back-to-back” satellites (hence their name) orbit the earth at a speed of 30,000 km/h. They do this 15 times a day around our planet’s orbit and can thus take a picture of the entire earth in one month.
The aim of these satellites is to analyze all changes in the total mass of the earth, which depends, among other things, on the groundwater level, but also on lakes, seas and oceans. In order to determine the development of the amount of water at depth, the researchers then have to subtract the snow, ice and, of course, water masses present on the surface. The totality of terrestrial water reserves is ultimately the addition of groundwater, glaciers, snow, soil moisture and bodies of water (lakes, rivers, etc.). By subtracting all other water masses from their calculations, scientists can determine the exact amount of groundwater that exists per region on Earth.
The deep dryness of the soil causes the mass of the earth to decrease
The effects of heavy precipitation also affect the Earth’s mass recorded by the satellites: this increases significantly when the Asian monsoon takes place. As well as the melting of the ice, which reduces the mass of the earth: between 200 and 300 gigatonnes of ice disappear from Greenland every year. The conclusions of Graz University of Technology (Austria) on Europe are alarming, especially for Central Europe. The water levels are extremely low in countries that were not previously considered dry areas: Germany and Austria in particular. This permanent deficit will lead to long-term water supply problems, the researchers conclude. This drop in groundwater levels is so significant at the European level that it is clearly reflected in the evolution of the Earth’s mass.
Calculations on the development of the Earth’s mass are initially time-consuming and require several months of work. But in the future, researchers believe real-time variations in Earth’s mass will be available.