The climate crisis has made heat waves more likely and more intense around the world. In the northern hemisphere, the record-breaking temperatures are putting millions of people in danger. During the last months, recurring heatwaves have been affecting Central and Western Europe, causing wildfires, evacuations, and heat-related deaths. In the United States, local leaders are also urging caution, while densely populated cities in Asia are announcing strategies for coping with the extreme temperatures.
Cities are on the front lines of this public health emergency. People living in urban areas are among the hardest hit when heatwaves happen, partly because of urban heat islands. This is a phenomenon that occurs when cities replace the natural land cover with dense concentrations of surfaces that absorb and retain heat, like pavements and buildings. Heat risk levels also vary by neighborhood, with less affluent and historically marginalized sectors being the most affected due to the density of the population, limited access to cooling systems, and the limited availability of green urban spaces.