Climate Greenland's ice is melting by almost 200 cubic kilometers every year
The Greenland ice sheet shrank by an average of 196 cubic kilometers per year between September 2010 and August 2022. The annual amount of melting fluctuated between 4 and 464 cubic kilometers.
25.12.2024, 07:30
25.12.2024, 08:10
SDA
This was reported by a research group led by Nitin Ravinder from the University of Leeds in the journal "Geophysical Research Letters". The Greenland ice sheet is the second largest ice sheet on Earth after the Antarctic ice sheet. For the first time, the scientists compared altitude measurements from the CryoSat-2 satellite missions of the European Space Agency Esa and ICESat-2 of the US space agency NASA.
Measurements using two different methods
CryoSat-2 uses radar to measure the height of the ice on the Greenland ice sheet, while ICE-Sat-2 uses lasers. Radar has the advantage that it penetrates through clouds, meaning that it can also be used when the sky is cloudy.
However, the radar frequencies used penetrate up to ten meters into snow surfaces, meaning that the measurement is relatively inaccurate and must be improved by correction calculations. The laser, on the other hand, measures the snow and ice surface quite precisely - but only when the sky is almost cloudless. Since the launch of the ICESat-2 mission in 2018, both systems have been measuring in parallel.
Ravinder and colleagues found that the measurements with the two technologies differed only slightly: In the inner area of the ice sheet, they were only 0.2 centimetres apart per year. In the melting zone at the edge of the ice sheet, where there is a greater dynamic of ice gain in winter and ice loss in summer, the difference was 3.3 centimetres per year.
Overall, the differences account for only around six percent of the observed trend. "We are very pleased with the discovery that CryoSat-2 and ICESat-2 are in such close agreement," emphasized Ravinder.
Water loss almost corresponds to the volume of Lake Victoria
Based on the measurement data from the two satellite systems, the researchers determined an average reduction in ice height of 11.6 centimetres per year across the entire ice sheet from 2018 to 2022. However, this melting was very unevenly distributed: In the large inner area it was only 6.3 centimetres, in the marginal areas 54.3 centimetres, i.e. around nine times as much.
For the period 2010 to 2022, the scientists calculated an average annual ice loss of 79 cubic kilometers in the inner area and 117 cubic kilometers in the peripheral areas.
This total of 196 cubic kilometers per year results in a volume loss of 2352 cubic kilometers for the entire study period. This is almost equivalent to the volume of water in Africa's largest lake, Lake Victoria, with a volume of 2760 cubic kilometers.
According to a study from 2023, the melting Greenland ice has led to a rise in global sea levels of 13.6 millimetres since 1992. According to Esa data, a complete melting of this ice sheet would cause sea levels to rise by around seven meters.
