Arctic coasts are characterized by sea ice, permafrost and ground ice. This makes them particularly vulnerable to the effects of climate change, which is already accelerating rapid coastal erosion. The increasing warming is affecting coast stability, sediments, carbon storage, and nutrient mobilization. Understanding the correlation of these changes is essential to improve forecasts and adaptation strategies for Arctic coasts. In a special issue of the journal Nature Reviews Earth & Environment, researchers from the Alfred Wegener Institute describe the sensitivity of Arctic coasts to climate change and the challenges for humans and nature.