New satellite technology unveiled an alarming rate of ice loss in Greenland's ice sheet, revealing thinning over the past 13 years. Utilizing data from the European Space Agency's CryoSat-2 and NASA's ICESat-2 satellites, researchers mapped changes in the ice sheet's thickness with unprecedented accuracy.
According to a study published in Geophysical Research Letters, the Greenland ice sheet thinned by an average of 1.2 meters between 2010 and 2022, resulting in a total volume reduction of approximately 2,347 cubic kilometers. This volume is enough to fill Lake Victoria in Africa. The joint findings underscore the impact of climate change on one of the planet's largest ice masses.
"The agreement between CryoSat-2 and ICESat-2 confirms that combining satellite data yields a more reliable estimate of ice loss than either could achieve alone," said Nitin Ravinder, lead author of the study. He emphasized the importance of the satellite missions' complementary capabilities in enhancing the precision of ice sheet measurements.
The thinning occurred along the margins of the ice sheet, where reductions have been over five times greater than the average, reaching an average of 6.4 meters. Specifically, outlet glaciers such as Jakobshavn Isbræ and Zachariae Isstrøm have experienced thinning, losing up to 67 meters and 75 meters of ice thickness, respectively. These glaciers are among the fastest-retreating on the planet.
The data indicates that the largest changes in the Greenland ice sheet occurred in 2012 and 2019, years marked by exceptionally high summer temperatures. During these periods, the ice sheet lost more than 400 cubic kilometers of its volume annually. This rapid loss demonstrates the sensitivity of the ice sheet to rising temperatures and the accelerating effects of global warming.
The melting of Greenland's ice sheet not only contributes to global sea level rise but also affects ocean circulation and weather patterns across the planet. The influx of freshwater from the melting glaciers alters ocean currents, disrupting weather systems far beyond the Arctic region.
Thanks to the synchronization of CryoSat-2 and ICESat-2 since 2020, scientists can now collect radar and laser data almost simultaneously over the same regions. CryoSat-2 uses radar technology capable of penetrating clouds and measuring ice thickness even through snow cover, while ICESat-2 employs laser technology that offers surface-level precision but is hindered by cloudy conditions. The combination of these technologies enables researchers to measure changes in ice thickness with greater accuracy.
"We are very excited to have discovered that CryoSat-2 and ICESat-2 are in such close agreement," said Ravinder. "The complementarity of these two missions constitutes a strong motivation to combine the datasets in order to improve estimates of ice sheet volume and mass changes."
"It is great to see that the data from sister missions are providing a consistent picture of the changes going on in Greenland," said Thorsten Markus, project scientist for the ICESat-2 mission at NASA. "Understanding the similarities and differences between radar and lidar ice sheet height measurements allows us to fully exploit the complementary nature of those satellite missions."
The continuous monitoring provided by these satellites is crucial for accurately tracking the effects of climate warming and supporting adaptation efforts. Accurate measurements of the changing ice sheet are essential for preparing and adapting to the impacts of climate change, particularly for coastal communities threatened by rising sea levels.
The Greenland ice sheet began experiencing accelerated melting in the 1990s, with increases observed from the 2000s onward. Greenland, the 12th largest country on Earth, is predominantly covered by ice, with 80% of its surface encapsulated in a permanent ice sheet. The vast ice mass plays a role in maintaining cooler temperatures in the Arctic and regulating global sea levels.
Complete melting of the Greenland ice sheet could potentially raise global sea levels by about seven meters, submerging coastal areas and displacing millions of people worldwide. Additionally, the loss of ice disrupts local ecosystems, threatening species such as polar bears, seals, and walruses that rely on sea ice for their habitats.
Researchers from the UK Centre for Polar Observation and Modelling (CPOM) played a role in the study. CPOM utilizes satellite observations and numerical models to monitor changes in polar regions and predict the evolution of ice and oceans.