The climate emergency is one of the world’s greatest challenges – rising sea levels, increasing resource scarcity, acute desertification and greater frequency and severity of extreme weather events are having complex and cascading impacts across the globe. One significant impact is on human mobility.

Although global attention is often paid to international, cross-border movements, far more people are moving within the boundaries of their own countries. Despite this, national governments are lagging in responding to the urgency of climate migration. Currently only 20% of the state pledges to the 2015 Paris Climate Agreement reference human mobility. And while many international frameworks and agreements recognise the importance of acknowledging the role of climate in affecting migration and displacement patterns, there is no commonly agreed legal definition for those displaced by climate change. Cities are on the front lines, experiencing the myriad effects of a changing climate while being at the centre of every aspect of human mobility related to climate change.

This paper is the culmination of the efforts in 2020 and 2021 of the C40 Cities-Mayors’ Migration Council partnership. It seeks to provide cities and climate change and migration practitioners with a clearer understanding of how these complex dynamics play out; to elevate best practices from around the globe; and to be a resource for advocacy efforts to influence decision-making and leverage national and international bodies to provide the financial, policy, data and capacity-building support necessary for cities to continue leading the way in responding to the intersection of climate change and migration.