Abstract

The 6 th Assessment Report cycle of the Intergovernmental Panel on Climate Change (AR6) comes at a precipitous moment in history. Human influence has warmed the planet, and widespread and rapid impacts are occurring to natural and human systems in all regions of the world. In response, immediate action is needed if there is to be any hope of limiting global warming to 1.5°C or well below 2°C below pre-industrial levels, as well as preparing for and adapting to current and future risks. The transformations needed in response to climate change will require decisive action in cities and urban areas. Cities and urban areas are a major source and driver of emissions; they are also crucial sites for system transitions in the near term and transformations over longer time frames.

This report distills the IPCC AR6 Working Group I report into accessible and targeted summaries for urban policymakers. It offers the most current and comprehensive scientific understanding of changes to the physical world as a result of human activities. Key findings on current and future changes in the climate and their implications for urban areas include: i) Human-induced climate change is affecting every region of the world, and even more the cities and urban areas therein; ii) In the coming decades, warming will continue to worsen, as will associated effects on cities such as drought, heavy rainfall, floods, extreme heat, storm surges, and cyclones; iii) Many cities and urban areas will also experience sea-level rise and associated coastal erosion, and more frequent coastal flooding; iv) Looking out to 2050, without immediate and deep reductions in emissions, global warming will exceed 2°C, exposing even more cities and people, infrastructure and ecosystems in them.