The report 'Water in a heated World' comes to the conclusion that national and international water policy must adapt to ongoing, accelerated changes in the global water cycle and respond to them quickly and comprehensively. The effects of climate change, the overexploitation of water resources, the unequal distribution of water, the loss of ecosystem services, and related health risks are increasingly leading to water emergencies. Recent examples include the declaration of a water emergency in Bogotá (Columbia) and Mexico-City due to water shortages, large-scale catastrophic flooding events in Central Asia, or the increasing pollution of water resources in many parts of Africa. The WBGU expects such regional water emergencies to occur more and more frequently, so we can now speak of a global pattern. We see this as a threat with a global dimension. In extreme cases, situations arise that are beyond the limits of controllability. They can lead to the destabilization of political, societal and ecological systems. Climate-change mitigation, the protection of ecosystems and a climate-resilient, socially balanced water management are the most important measures for preventing water emergencies. Water needs to be placed higher on the international political agenda.