Polar regions are critically important for the Earth's energy balance, as they normally reflect a large portion of incoming solar radiation due to their high albedo. Recent climate changes, including the spectacular retreat of Arctic sea ice, are changing this picture. Two studies recently published in Nature Communications and Nature Climate Change and coordinated at the Georges Lemaître Center for Earth and Climate Research (TECLIM/ELIC) of the Earth and Life Institute (ELI), offer new insights on this issue. In the first study, led by Prof. Hugues Goosse, a comprehensive review of relevant polar climate feedbacks was established. Feedbacks can either damp or amplify the response of the climate system to a perturbation, and are therefore crucial for long-term changes. The authors have proposed a novel and standardized way to quantify these feedbacks both in observational data sets and in climate models. The work will facilitate intercomparison of the feedbacks and contribute to a more process-oriented evaluation of climate models. In the second study, Dr. François Massonnet and his coauthors examined the Arctic sea ice response of 44 climate models to increasing greenhouse gas emissions, and found that the disagreement among those models was primarily due to the disagreement on how they simulated the current sea ice thickness. This finding provides clear guidance for the future development of observing systems in the High North, in order to evaluate the reliability of climate models for future projections."