Northern Hemisphere extreme snowfall changes are studied using the Large ENsemble TIme Slice (LENTIS) model. Extreme snowfall frequency and amount are projected to increase more strongly than light snowfall in several regions. The sign and magnitude of change depend on the regions present-day seasonal mean climatological temperature. While light and extreme snowfall are projected to decline significantly, particularly in maritime and mid-latitude regions near the melting point, increases are expected in high-latitude maritime, select high-altitude and continental areas. Compared to light snowfall, extreme snowfall only begins to decline at seasonal mean temperatures roughly 7 °C higher. Consequently, increases in light snowfall are limited to the coldest regions, whereas increases in extremes already occur in relatively warmer, yet still freezing regions. In sufficiently cold regions, warming enhances extreme event frequency (up to 278%) and amount (up to 271%) more strongly than light snowfall (up to 101% and 152%). Regions near the melting point are thermodynamically controlled due to climate warming, while colder regions are likely influenced by both thermodynamic warming and dynamical circulation changes, evident for Greenland. Extreme Greenland snowfall is found to be associated with a sea level pressure anomaly dipole between Greenland and Northern Europe, promoting warm moist Atlantic air advection. Using the Greenland Oscillation Index (GOI) – which measures the strength of the dipole – it is found that increases in extreme snowfall events are linked to a higher frequency of favorable circulation patterns with above-median GOI, particularly over Eastern, Central and Northern Greenland.

While adapting to future sea-level rise (SLR) and its hazards and impacts is a multidisciplinary challenge, the interaction of scientists across different research fields, and with practitioners, is limited. To stimulate collaboration and develop a common research agenda, a workshop held in June 2024 gathered 22 scientists and policymakers working in the Netherlands. Participants discussed the interacting uncertainties across three different research fields: sea-level projections, hazards and impacts, and adaptation. Here, we present our view on the most important uncertainties within each field and the feasibility of managing and reducing those uncertainties. We find that enhanced collaboration is urgently needed to prioritize uncertainty reductions, manage expectations and increase the relevance of science to adaptation planning. Furthermore, we argue that in the coming decades, significant uncertainties will remain or newly arise in each research field and that rapidly accelerating SLR will remain a possibility. Therefore, we recommend investigating the extent to which early warning systems can help policymakers as a tool to make timely decisions under remaining uncertainties, in both the Netherlands and other coastal areas. Crucially, this will require viewing SLR, its hazards and impacts, and adaptation as a whole.