Climate change is increasing the frequency and temperature of extreme heat waves that affect millions of people in the United States. A new paper published in Proceedings of the National Academy of Sciences provides evidence that high temperatures increase the risk of heart attacks and deaths from heat waves. The study also highlights how a changing climate will make heat waves more deadly.
In order to determine if global warming is making heat waves more deadly, researchers analyzed data from past and future heat waves in a study called Heat Stress in a Changing Climate. The researchers looked at the number of people who died from heat waves from 1970-2019 in the United States. They also looked at changes in the length and intensity of heat waves.
They compared the number of heat-related deaths between 2000-2015 to the number between 2015-2019, when a heat wave hit the state of Washington. They found that heat stress increased by 11.8 percent in 2020, the year the heat wave hit Washington. This is greater than the 1.8 percent increase in heat-related deaths over the 10 years before the heat wave hit the area. During the heat wave, the number of deaths was nearly twice the number of deaths during the 10-year period before the heat wave (4,814 versus 2,814 deaths).
This finding is especially pronounced because the heat wave in Washington had a very high number of deaths (10,814), nearly triple the number of deaths from any other heat wave. The authors write that this is an indication that “the risks of heat-related death are likely to continue to increase as the number of heat-related deaths increases.”
The researchers also analyzed the length of the heat wave in Washington and found that, on average, a heat wave lasts four hours longer in a warmer climate than it did ten years ago. For 2020, the heat wave in Washington lasted 6 hours, or nearly four times as long as it did in 2000. A more recent study showed that the impact of a heat wave