Human-induced climate change is causing dangerous and widespread disruption in nature and is affecting the lives of billions of people around the world, says this Intergovernmental Panel on Climate Change (IPCC) report. People and ecosystems least able to cope are being hardest hit. Increased heatwaves, droughts and floods are already exceeding plants and animals’ tolerance thresholds, driving mass mortalities in species such as trees and corals. These weather extremes are occurring simultaneously, causing cascading impacts that are increasingly difficult to manage. They have exposed millions of people to acute food and water insecurity, especially in Africa, Asia, Central and South America, on small islands and in the Arctic. To avoid mounting loss of life, biodiversity and infrastructure, urgent, ambitious, and accelerated action is required to adapt to climate change, at the same time as making rapid, deep cuts in greenhouse gas emissions.