With extreme heat waves in Europe, Asia, the United States and beyond, it’s clear climate change is making summers more dangerous and deadly. Urban areas are feeling the worst effects; a phenomenon known as the urban heat island effect. 2022 saw high temperatures in Kansas, Spain, Portugal, England (especially London), and India. But even within cities, the warming is not distributed evenly. During the Pacific Northwest heat dome of 2021, the region's most extreme heat wave ever, this temperature difference reached a staggering 25°F between neighborhoods in Portland, OR. And new research is illuminating how a century of racist housing policies known as redlining have contributed to this often deadly inequality. The 2022 heat waves are not single events. They are another data point during years of escalating extreme weather. Previously, the 2019 European heat wave, the 1980 US heat wave, 1995 Chicago heat wave and many more are part of this trend.