A new report has detailed the social and economic effects of climate-driven extreme heat through the prism of 12 cities, spanning six continents and covering an urban population of more than 123m.
The report ‘Hot Cities, Chilled Economies: Impacts of Extreme Heat on Global Cities’ produced by Adrienne Arsht-Rockefeller Foundation Resilience Center says that climate-driven heat is changing the way we live and work. Extreme heat currently kills more people worldwide than any other climate-driven disaster.
The 12 cities included in the study were Athens, Bangkok, Buenos Aires, Dhaka, Freetown, London, Los Angeles, Miami, Monterrey, New Delhi, Santiago and Sydney.
The report reveals that the danger posed by extreme heat in urban centres - particularly in the global south - defies overestimation. By 2050, more than 970 cities will experience average summertime highs of 35°C (95°F) - nearly triple the 354 cities that already do. The urban population exposed to these sky-high temperatures will increase by 800%, reaching 1.6bn by 2050.
Dense concentrations of buildings and paved surfaces absorb and amplify heat - especially in areas with little tree cover or green space - creating heat islands where poor and minority neighbourhoods often bear the brunt of broiling temperatures.
Heat reduces labour productivity in a wide range of ways. Losses from heat-related reductions in worker productivity are high and mounting. In an average year, these losses total $44bn across the twelve cities in 2020 and the amount will rise to $84bn by 2050 without action to reduce emissions.
Losses as a proportion of total output are high across the board, ranging from 0.1% in Santiago to 8.3% in Dhaka. To put the figures into a global context, estimated economic losses from all natural catastrophes were valued at around 0.3% of the world’s output in 2021.
In addition to the $44bn, losses to productivity also affect sales, income, and real estate tax revenues: as losses grow, they will increasingly constrain cities’ fiscal room for investment in public services.
These reductions in worker productivity may affect workers’ incomes. The effects are even more direct for hourly or informal workers who are paid only when they work and may face increasing work stoppages or choices between working in dangerous heat conditions or having no income.
Cities in the global South face greater, more rapidly increasing impacts. These cities tend to have hotter and more humid climates, meaning they face a greater challenge from heat, and their more labour-intensive economies and lower access to active cooling technologies mean they are more vulnerable to heat.