20 years ago, on March 17, 2002, the German-American satellite mission GRACE was launched to measure the Earth's gravitational pull with extreme precision. Scientists at TU Dresden have been using this data from the very beginning. From small changes in the Earth's gravity, they determine mass changes in the ice sheets in Greenland and Antarctica. The Institute for Planetary Geodesy of the TU Dresden also provides data series of these ice mass changes on behalf of the European Space Agency ESA.

“GRACE” stands for “Gravity Recovery and Climate Experiment”. The GRACE mission ended in 2017 and has been continued since 2018 through the “GRACE Follow-On” mission. GRACE and GRACE Follow-On work on the same principle: twin satellites follow each other in orbit at a distance of about 200 km. The fluctuations in this distance are measured, with an accuracy of a thousandth of a millimeter. Since the fluctuations in this distance are caused by the irregularities of gravity, this can be determined down to the smallest details. The immediate measurements, so to speak the raw data, are processed by colleagues at the Helmholtz Center Potsdam German Research Center for Geosciences, among others, and thus provide the starting data for the analyzes of the Dresden geodesists.

From 2002 to 2021, the Greenland ice sheet lost around 5 trillion tons of mass, the Antarctic ice sheet was around 1800 billion tons. One billion tons corresponds to the mass of one cubic kilometer of water. The meltwater increases the volume of water in the ocean and is responsible for around a quarter of global sea-level rise.

Quotes:

Martin Horwath, Professor of Geodetic Earth System Research, explains:

"Measuring provides facts. Determining changes in ice mass using gravitational force is a unique method because we cannot really miss any changes. In connection with other satellite methods, e.g. measuring ice surface heights and flow velocities, this method provides a detailed picture of current changes in the ice sheets."

"The decrease in ice on the continents leads to an increase in the water masses of the oceans. And we can also measure this with the help of its gravitational effect."

“The resulting data series contain many years of developments in the evaluation methodology. And the results are freely accessible on our data portal, for students as well as for climate researchers.”

Contact:
Prof. Martin Horwath
Institute for Planetary Geodesy
phone +49-351-46337582