High-end Climate Change and Adaptation - Science for Adaptation Policy Brief #3

This policy brief examines potential impacts and adaptation challenges associated with high-end climate change scenarios in which global warming exceeds commonly expected levels by the end of the twenty-first century. Drawing on climate model projections and scientific studies, it describes how warming of about 4°C above pre-industrial levels could generate severe global impacts, including extreme human heat stress in tropical regions, increased drought and wildfire risk, major threats to food security, biodiversity loss and large increases in people exposed to coastal and river flooding. It notes that such warming remains within the range projected from current energy policy trajectories and that sea level rise may continue for centuries, potentially reaching several metres. The brief also assesses adaptation capacity, highlighting governance and economic barriers, limits to adaptation and the need for further research to reduce uncertainties and improve understanding of adaptation effectiveness.