Two of the UK’s leading mayors are calling for urgent action to prepare for mass migration to cities due to the climate emergency, as a major report into the issue launches at the UN headquarters in New York on Wednesday. Mass migration to some of the world’s cities due to the climate emergency is already under way and the World Bank has estimated that unless significant action is taken, 216 million people could be on the move by 2050. In 2020, 30 million people were displaced due to the climate crisis, and 70% of people internally displaced due to the climate crisis are living in urban areas. The World Bank predicts that more than 1 billion people are at risk of being driven from their homes for climate-related reasons. The report, launched during UN Migration Week, uses several countries in Latin America as case studies for what is happening to cities as a result of the climate emergency, and makes recommendations to ameliorate the gloomy projections about the impact of climate emergency-linked migration across the world. The London mayor, Sadiq Khan, and the Bristol mayor, Marvin Rees, are key players in efforts to tackle climate emergency-related migration to their own and other cities due to climate change. Khan is chair of C40 Cities, a global network of almost 100 world leading cities dedicated to combating the climate crisis and the devastating human cost of forced and unmanaged migration to cities caused by the climate crisis. Rees is one of nine mayors around the world in the Global Mayors’ Taskforce on Migration The taskforce includes mayors from Lima to Los Angeles, and from Barcelona to Bristol. The report, which will be launched at the UN headquarters with president of the general assembly, Abdulla Shahid, and secretary general, António Guterres, has been produced by researchers at Columbia and New York City universities and has been commissioned by the Mayors Migration Council, working with the UN. Khan told the Guardian: “Cities are leading the way in tackling the climate emergency. As chair of C40, one of my priorities is taking urgent action to address the causes and devastating human cost of forced migration created by the climate emergency. “By tackling the climate crisis we can avoid the worst impacts of climate change while creating new growth and jobs opportunities in our cities. In London I am working towards doubling the size of London’s green economy by 2030. All over the world, people are already being forced to move due to the climate crisis. Mayors are taking urgent action to address these issues, but we cannot do it alone. Cities need more funding and powers from national governments to urgently address the climate emergency at a local level.” Rees added: “Cities hold the key to tackling climate change, with over half the world’s population living in densely populated urban areas. This percentage will grow as cities will also house the majority of those forced to migrate because of climate change in their home countries. It’s therefore imperative that Bristol, alongside other cities in developed nations, show leadership in how to minimise the long-term need for climate displacement. At the same time we recognise that migrants are an asset to our cities and can aid our inclusive green transition by bringing diverse skills and experience.” He called for city mayors to push for the investment needed to futureproof services and infrastructure so that cities can be prepared for climate emergency-related migration in future years. The report, Climate Migration in Mexican and Central American Cities, makes global recommendations for new projects in cities to tackle the climate emergency, which include migrants as part of the solution to greening economies and making them more sustainable. It also calls for city governments to become more involved in shaping policy on climate migration. Early planning and local investment in cities could change the new migration from a crisis into an opportunity, says the report. “Our hope is that this work highlights the clear and immediate urgency for driving national and international investment to city governments and local communities as first responders to climate migration,” it adds.