As climate change warms the planet, summer heat waves become increasingly dangerous.
In the summer of 1995, a heat wave in Chicago killed over 700 people. A 2003 heat wave in Europe killed tens of thousands of people. The majority of Earth’s population lives in cities, where heat waves are amplified by the “urban heat island” effect. Buildings and pavement absorb and store extra heat, making cities hotter than the surrounding area. The frequency of extreme heat has been increasing across the Northern Hemisphere, and upcoming warming is expected to make it worse.
Warmer air can also hold more moisture, so humidity often increases as heat does. This added humidity will make it even more uncomfortable and dangerous to work outside in summer months and is expected to cost billions of dollars in lost wages.
To counter extreme heat, many turn to indoor air conditioning. But air conditioners are a driver of climate change—they release more heat-trapping carbon emissions into the atmosphere. Many U.S. cities are taking simple but effective measures to adapt to this new reality, including developing better publicity for heat wave forecasts, more neighbor-to-neighbor check-ins for vulnerable people, and opening public cooling centers for those without air conditioning.