Human-caused climate change, exacerbated by decades of racist policy, is causing life-threatening conditions in segregated communities in Florida and Arizona. That’s the headline finding of reporting by the Center for Public Integrity and Columbia Journalism Investigations, and published in partnership by Mother Jones, the Arizona Republic, and Orlando Sentinel. New data, including analysis never before possible with ZIP code-level resolution, show the neighborhoods with the highest rates of heat-related illnesses are also those with a history of racial segregation, and inequities are worsened by the heat.

In Arizona, Spanish speakers and migrant workers who only speak Indigenous languages are at heightened risk because they don’t have access to heat illness information, while farmworkers in Florida are especially vulnerable to the region’s high humidity, which when combined with the heat limits the body’s ability to cool down. Extreme heat and heatwaves are some of the clearest impacts of climate change on extreme weather and kill as many as 5,600 people living in the U.S. every year. (Both: Mother Jones; Arizona: Arizona Republic; Florida: Orlando Sentinel; Climate Signals background: Extreme heat and heatwaves)