The findings show that up to 8 million people are likely to move to the ten cities identified in the report by 2050 as a result of climate change alone, exacerbating existing trends of migration towards cities.

The first-of-its-kind analysis from C40 and the Mayors Migration Council studied the projected impact climate change on internal migration for ten cities across three continents: Bogota (Colombia), Curitiba, São Paulo, Rio de Janeiro, Salvador (Brazil), Amman (Jordan), Karachi (Pakistan), Dhaka (Bangladesh), Accra (Ghana) and Freetown (Sierra Leone). Despite their vast geographic and demographic differences, all ten will need to prepare to receive significant inward climate migration over the next 25 years.

While all cities in the research are projected to receive climate migrants, the intensity will vary in line with projected increases in global warming. In a scenario in which the world fails to meet the 2015 Paris Agreement targets of keeping global warming under 1.5^oC above pre-industrial levels:

• Karachi could receive as many as 2.3 million domestic climate migrants by 2050;
• cities like Bogotá, Rio de Janeiro and Karachi could see a threefold increase in the number of climate migrants compared with scenarios where Paris Agreement targets are met; and
• many cities including Freetown and Amman – as primary economic hubs for the country – are expected to receive at least half of all people moving due to climate change within the country.

This research has also, for the first time, looked into the type of climate impacts that will drive migrants to cities. These include reduced crop yields, sea levels rising, and extreme weather events such as floods and wildfires. Researchers found that in every country, multiple, overlapping climate factors, which put homes and livelihoods at risk, are the main drivers of climate migration to cities.

Migrants’ roles in green transition

Some 800 million jobs are at risk globally due to the impacts of climate change and unplanned green transitions. Globally, migrants are also playing an essential and under-recognised role in cities and sectors that are critical to the green transition, including construction, waste management and transport, but face challenges accessing opportunities and decent jobs. Meanwhile, no country has the domestic workforce ready to support its green transition efforts.

Additional research to be published later this month by C40 Cities, Emerson Collective’s Climate Migration Council (CMC), and the Mayors Migration Council in a new policy brief, shows migrants will bring essential skills to these ten cities, often in agriculture and primary industries that are key for adaptation, nature-based solutions and new urban bio-economies that many of the cities’ studied are already ramping up, as part of their climate action plans. It highlights more than 30 examples of city-led actions to drive the creation of good green jobs for all – including migrants and refugees – while developing a green, diverse and inclusive workforce.

Vittoria Zanuso, executive director of the Mayors Migration Council, said: “Whether supporting green microenterprises in Freetown or integrating migrant waste workers into co-operatives in Accra, city leaders show what inclusive climate action looks like in practice. City leadership can turn climate migration from a crisis into an opportunity.”

These findings clearly show that cities are central to managing new climate migration in a way that is beneficial to urban communities and economies and to transform global challenges into critical economic, environmental and social opportunities, but they need the right support and recognition to do so.

Executive director of C40 Cities Mark Watts said: “At C40, we see the crucial role cities are playing in addressing climate migration and supporting vulnerable communities.

“The innovative efforts taken by cities highlights the leadership at the local level, from integrating informal workers to providing vital services for migrants. Cities are on the front lines of the climate crisis and are bearing the brunt, and are working together to help solve it. We need national governments to do the same, because this is a global issue that nations can’t simply isolate themselves from. This is also a human issue, a matter of livelihoods, so we can’t delay. We need decisive action now.”

Marshall Fitz, managing director of immigration at Emerson Collective and advisor to the Climate Migration Council, said: “Migrants bring skills, expertise, and an entrepreneurial mindset to the communities they settle in, particularly in sectors that are critical to the green transition, including agriculture, construction, waste management, and more.

“Cities that invest in the creation of good green jobs can accelerate their energy transition by ensuring migrants are able to access those opportunities. This research shows that by welcoming migrants and investing in skills training for all workers, we can meet a number of critical objectives: provide economic empowerment to workers, help meet the goals of the Paris Agreement, and build more resilient and inclusive cities for all.”