In addition to the temperature, the team reconstructed the melt production of the ice sheet. Melting has increased substantially in Greenland since the 2000s and now significantly contributes to global sea-level rise. “We were amazed to see how closely temperatures inland are connected to Greenland-wide meltwater drainage – which, after all, occurs in low-elevation areas along the rim of the ice sheet near the coast,” says Maria Hörhold.
In order to quantify this connection between temperatures in high-elevation parts and melting along the edges of the ice sheet, the authors used data from a regional climate model for the years 1871 to 2011 and satellite observations of ice-mass changes for the years 2002 to 2021 from the GRACE/GRACE-FO gravimetry missions. This allowed them to convert the temperature variations identified in the ice cores into melting rates and provide estimates for the past 1,000 years. This represents an important dataset for climate research: better understanding of the melt dynamics of the ice sheet in the past improves projections of related future sea-level rise; reduced uncertainties in projections is one step to help optimize adaptation measures.
Another exciting finding from the study: the climate of the Greenland Ice Sheet is largely decoupled from the rest of the Arctic. This could be shown in comparison with the Arctic-wide temperature reconstruction ‘Arctic 2k’. Although ‘Arctic 2k’ is an accurate representation of the circumpolar region, it does not reflect the conditions in central Greenland. “Our reconstruction now offers a robust representation of temperature evolution in central Greenland, which has proven to have a dynamic of its own,” says Prof. Thomas Laepple, AWI climate researcher and co-author of the study. “Actually, we had expected the time series to strongly covary with the warming of the Arctic region,” Laepple reports. But the authors have an explanation for these differences: the ice sheet is several kilometres thick; because of its height, Greenland is more affected by atmospheric circulation patterns than other parts of the Arctic. Temperature time series on the Arctic with regional resolution are needed, says Laepple, in order to reliably describe climate change in the Arctic.