The members of the international research group led by Dániel Topál, an assistant research fellow at the ELKH Research Centre for Astronomy and Earth Sciences (CSFK), Institute for Geological and Geochemical Research, found that high-latitude winds play an essential role in driving the acceleration of Greenland ice loss. A study presenting the results was published in the prestigious international journal Nature Communications.
The Greenland ice sheet has lost ice mass at an accelerating rate over the past few decades, raising the global sea level, and this is expected to continue with ongoing human-driven climate change. Using a unique modelling approach, an international group of scientists found that wind changes observed between 1990 and 2012 explained over half of that portion of sea-level rise that is associated with Greenland mass loss. However, global climate models, which underestimate the recently observed Greenland melt increase suggest that the extra melt is overwhelmingly due to a generally warmer atmosphere arising from human-driven greenhouse gas warming and less associated with regional wind changes. This bias may severely limit the ability of models to make accurate predictions of future sea-level rises.
The surface temperature change (linear trend) in Greenland and its surroundings between 1990 and 2012 (when the strongest warming occurred in the last 40 years) obtained as a result of (a) the observed (Obs) and (b) the exclusively wind-driven model experiment (Exp). The dotted parts show statistically significant (p<0.05) trends. The model experiment reproduces the observed trends in about 50% on a regional average.
The authors analyze modern satellite observations and climate reanalysis datasets, together with historical climate records from ice cores and tree rings, which consistently show that large-scale atmospheric circulation and winds have played a key role in driving warming in and around Greenland over at least the past 400 years. The authors suggest that these winds are linked with decadal variability of tropical Pacific Ocean surface temperatures. However, many uncertainties remain, especially regarding tropical-Arctic linkages, and it is unclear whether the global climate models actually respond to tropical sea-surface temperature forcing in a similar way as seen in observations. The authors warn that, although climate models participating in the sixth phase of the Coupled Model Intercomparison Project (and in the IPCC’s Sixth Assessment Report, published in 2021) project faster and more widespread Greenland melting that the previous model generations (reported in the Fifth Assessment Report in 2013), without properly constraining the atmospheric circulation in climate models these projections should be treated with caution. The findings of the new study highlight an urgent need for improved understanding of the observed Greenland Ice Sheet climate changes. This will enable more effective adaptation and mitigation plans to address the challenging threat posed by the global sea-level rise.
The lead author of the study, Daniel Topál (CSFK Institute for Geological and Geochemical Research), said “A key research priority should focus on why models tend to overestimate the warming magnitude driven by anthropogenic forcing over some parts of the Arctic without suggesting any general atmospheric circulation change as observed from 2000. It is critical that we can accurately pinpoint how warming happens in terms of atmosphere, ice, and ocean interactions and processes. More detailed knowledge of driving factors will enable us to prepare for future scenarios of Greenland melting.”