Green Greenland

Earth’s second largest ice sheet is melting at an extreme rate

The Greenland ice sheet is the second largest ice sheet on Earth after the Antarctic ice sheet.

(Bild: AP)

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 four and 464 cubic kilometers.

For the study, the scientists compared altitude measurements from the European Space Agency's (ESA) CryoSat-2 and the US space agency NASA's ICESat-2 satellite missions for the first time.

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.

Ravinder and his 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 centimeters apart per year. In the melting zone at the edge of the ice sheet, the difference was 3.3 centimetres per year.

(Bild: AP)

However, the radar frequencies used penetrate up to ten meters into snow surfaces, so 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. 

The Greenland ice sheet is the second largest ice sheet on Earth after the Antarctic ice sheet.

(Bild: AP)

Overall, the differences only account for around six percent of the observed trend.

Reduction in ice height by 11.6 centimetres
Researchers used the measurement data from the two satellite systems to determine 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.

Further findings:

• For the period 2010 to 2022, scientists calculated an average annual ice loss of 79 cubic kilometers in the inner area and 117 cubic kilometers in the marginal areas.

• This total of 196 cubic kilometers per year results in a volume loss of 2,352 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 2,760 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.