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\t\t\t\t\t\t20\/12\/2024<\/span> Global warming is driving the rapid melting of the Greenland Ice Sheet, contributing to global sea level rise and disrupting weather patterns worldwide. Because of this, precise measurements of its changing shape are of critical importance for adapting to climate change.<\/p>\n Now, scientists have delivered the first measurements of the Greenland Ice Sheet\u2019s changing shape using data from ESA’s CryoSat and NASA’s ICESat-2 ice missions.<\/p>\n<\/div>\n Although both satellites carry altimeters as their primary sensor, they make use of different technologies to collect their measurements. CryoSat uses a radar system to determine Earth\u2019s surface height, while ICESat-2 uses a laser system for the same task.<\/p>\n Although radar signals can pass through clouds, they also penetrate the ice sheet surface and have to be adjusted to compensate for this effect. Laser signals, on the other hand, reflect from the actual surface but cannot record when clouds are present. The missions are therefore highly complementary, and combining their measurements has been a holy grail for polar science.<\/p>\n A new study from scientists at the UK Centre for Polar Observation and Modelling (CPOM) and published today in Geophysical Research Letters<\/i>, shows that CryoSat and ICESat-2 measurements of Greenland Ice Sheet elevation change agree to within 3% of the changes taking place.<\/p>\n This confirms that both satellites can be combined to produce a more reliable estimate of ice loss than either could achieve alone. It also means that if one mission were to fail, the other could be relied upon to maintain our record of polar ice change.<\/p>\n Between 2010 and 2023, the Greenland Ice Sheet thinned by 1.2 m on average. However, much larger changes occurred across the ice sheet\u2019s ablation zone where summer melting exceeds winter snowfall; there, the average thinning amounted to 6.4 m.<\/p>\n<\/p><\/div>\n The most extreme thinning occurred at the ice sheets outlet glaciers. At Sermeq Kujalleq in west central Greenland (also known as Jakobshavn Isbr\u00e6), the peak thinning was 67 m, and Zachariae Isstr\u00f8m in the northeast the peak thinning was 75 m.<\/p>\n Altogether, the ice sheet shrank by 2347 cubic kilometres across the 13-year survey period \u2013 similar to the amount of water stored in Africa\u2019s Lake Victoria. The biggest changes occurred in 2012 and 2019, when the ice sheet shrank by more than 400 cubic kilometres because of extreme melting in those years.<\/p>\n Greenland\u2019s ice melting also has profound effects on global ocean circulation and weather patterns. These changes have far-reaching impacts on ecosystems and communities worldwide. The availability of accurate, up-to-date data on ice sheet changes will be critical in helping us to prepare for and adapt to the impacts of climate change.<\/p>\n \u201cWe are very excited to have discovered that CryoSat and ICESat-2 are in such close agreement,\u201d says lead author and CPOM researcher Nitin Ravinder. \u201cTheir complementary nature provides a strong motivation to combine the data sets to produce improved estimates of ice sheet volume and mass changes. As ice sheet mass loss is a key contributor to global sea level rise, this is incredibly useful for the scientific community and policymakers.\u201d<\/p>\n The study made use of four years of measurements from both missions, including those collected during the Cryo2ice campaign, a pioneering ESA-NASA partnership initiated in 2020. By adjusting CryoSat\u2019s orbit to synchronise with ICESat-2, ESA enabled the near-simultaneous collection of radar and laser data over the same regions.<\/p>\n This alignment allows scientists to measure snow depth from space, offering unprecedented accuracy in tracking sea and land ice thickness.<\/p>\n<\/p><\/div>\n Tommaso Parrinello, CryoSat Mission Manager at ESA, expressed optimism about the campaign\u2019s impact: \u201cCryoSat has provided an invaluable platform for understanding our planet\u2019s ice coverage over the past 14 years, but by aligning our data with ICESat-2, we\u2019ve opened new avenues for precision and insight.<\/p>\n \u201cThis collaboration represents an exciting step forward, not just in terms of technology but in how we can better serve scientists and policymakers who rely on our data to understand and mitigate climate impacts.\u201d<\/p>\n \u201cIt is great to see that the data from \u2018sister missions\u2019 are providing a consistent picture of the changes going on in Greenland,\u201d says Thorsten Markus, project scientist for the ICESat-2 mission at NASA.<\/p>\n \u201cUnderstanding the similarities and differences between radar and lidar ice sheet height measurements allow us to fully exploit the complementary nature of those satellite missions. Studies like this are critical to put a comprehensive time series of the ICESat, CryoSat-2, ICESat-2, and, in the future, CRISTAL missions together.\u201d<\/p>\n ESA\u2019s CryoSat continues to be instrumental in our understanding of climate related changes in polar ice, working alongside NASA\u2019s ICESat-2 to provide robust, accurate data on ice sheet changes. Together, these missions represent a significant step forward in monitoring polar ice loss and preparing for its global consequences.<\/p>\n<\/p><\/div>\n
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