19 June 2018: Cities and partners have issued a joint technical report, highlighting data analyses and case studies developed by the Urban Climate Change Research Network (UCCRN). It calls attention to urbanization trends, particularly in Asia and Africa, and illustrates the breadth and magnitude of climate change impacts on cities.

The first global-scale assessment of its kind, the report titled, ‘The Future We Don’t Want: How Climate Change Could Impact the World’s Greatest Cities,’ reviews both direct and indirect climate change impacts across six themes: 1) heat extremes; 2) heat extremes and poverty; 3) water availability; 4) food security; 5) sea level rise and coastal flooding; and 6) sea level rise and energy systems. The report notes that cities will most commonly encounter and have to manage risks in these areas.

The analysis compares numbers of people who currently face threats in each area to those estimated in the 2050s. It shows that by mid-century, climate change could pose an existential threat to people in cities around the world, noting that global average temperatures are already 1°C higher than preindustrial levels.

Rising sea levels threaten not only the 800 million people living in 570 cities, but also their power supplies.

To generate the report, the research team reviewed global data for the six themes, and contextualized such data through city-level case studies spanning multiple regions, including Africa, Asia, Europe, Latin America and the Caribbean (LAC) and Northern America. Researchers mapped, layered and examined the data using a geographic information system (GIS) database. The data were gathered from 2,586 cities with a total estimated population of over 1.4 billion people, which is expected to exceed 3.5 billion by 2050.

Key findings estimate that by 2050, over 1.6 billion urban dwellers in 970 cities will regularly experience heat extremes, a 700% increase compared to today. At the same time, the report finds that up to 650 million people across 500 cities will be at risk of water shortages. It notes that these impacts will disproportionately impact poor residents. The publication warns that rising sea levels threaten not only the 800 million people living in 570 cities, but also their power supplies. The report estimates that power plants capable of generating nearly 183,000 megawatts (MW) of electricity, enough energy to power nearly 90% of homes in the US, will be vulnerable by 2050.

The authors call for bold climate action at the city level not only because urban areas consume two thirds of the planet’s energy and produce nearly three quarters of all greenhouse gas (GHG) emissions, but also because urban decision makers such as mayors “are directly accountable to their constituents.” With the implications for cities made clear, the report demonstrates where and how local leaders can take action.

While case studies provide estimates as to changes in specific cities’ temperature and precipitation, as well as projected vulnerability, trends and impacts, they also highlight responses and potential solutions. The city examples showcase institutional reforms (SDG target 13.3), policy coherence (SDG target 17.14), action plans (SDG target 11.b) and investments in infrastructure (multiple targets under SDGs 7 and 9), mapping efforts and grassroots interventions as means of mitigating climate impacts in cities. While the initiatives link directly to specific SDGs and targets, their contributions to mitigating the effects of climate change span the breadth of the 2030 Agenda for Sustainable Development, impacting on health (SDG 3), economic growth (SDG 8), and food and nutrition (SDG 2), among others.

Research for The Future We Don’t Want project was conducted by C40 Cities, Global Covenant of Mayors for Climate & Energy, UCCRN and Acclimatise. [The Future We Don’t Want Homepage] [The Future We Don’t Want Technical Report] [C40 Press Release]