In this Climate Research (CR) Special, the Centre for Regional Change in the Earth System (CRES) brings together scientific expertise (ranging from climate to social sciences) with practitioners and stakeholders to present thematic research addressing gaps in (1) our understanding of climate-system behaviour at a regional scale and in particular at the upper fringes of current climate scenarios; (2) what the effects of such changes might be; and (3) potential adaptations. CRES has developed a broad set of tools related to climate adaptation; this includes improved regional climate and hydrological models, impact models, integrated assessment models, economic models, decision support tools and spatial planning tools. Through a coordinated research effort these tools were applied to provide new information on climate, hydrology, nutrient dynamics, ecosystem responses and economic risks. The studies in this CR Special highlight potential effects of extreme global warming with a focus on Denmark and northern Europe.