Why heat waves are getting worse and more dangerous

An urgent Excessive Heat Watch warning from a regional National Weather Service office affected by the week-long heat wave in mid June, 2024.An urgent Excessive Heat Watch warning from a regional National Weather Service office affected by the week-long heat wave in mid June, 2024. (Photoillustration: NOAA and George Thomas Jr.)

The June 2024 heat wave threatening 135 million Americans is illustrative of the increasing danger and implications of rising greenhouse gas emissions.

As another heat wave settles in place across much of the U.S., other life-threatening heat waves around the world this year may not have made your local news:

Our climate emergency is why heat waves are worse

The 10 hottest years since 1850 have all occurred in the past decade, with 2023 topping the list. As greenhouse gas emissions continue to rise, acting as a thickening, heat-trapping blanket smothering Earth, “heat waves have increased in frequency, intensity, and duration, notably across many parts of the world in the past decades,” according to a comprehensive research study recently published in Science Advances.

A world map plotted with color blocks depicting percentiles of global average land and ocean temperatures for the full year 2023. Color blocks depict increasing warmth, from dark blue (record-coldest area) to dark red (record-warmest area) and spanning areas in between that were "much cooler than average" through "much warmer than average."

A world map plotted with color blocks depicting percentiles of global average land and ocean temperatures for the full year 2023. Color blocks depict increasing warmth, from dark blue (record-coldest area) to dark red (record-warmest area) and spanning areas in between that were “much cooler than average” through “much warmer than average.” (Image credit: NOAA NCEI)

While heat waves are naturally occurring and affected by natural climate variability, the researchers said, anthropogenic forcing — in other words, humans burning fossil fuels — is “the main driver” of this troubling heat wave trend.

And as the world continues to warm, more moisture gets absorbed into the atmosphere, which can increase humid conditions during heat waves in some locations, exacerbating their impact.

The results suggest “longer-lived, longer-traveling, and slower-moving contiguous heat waves will cause more devastating impacts on human health and the environment in the future if greenhouse gas emissions keep rising and no effective measures are taken immediately.”

Leonardo DiCaprio and Jennifer Lawrence in a scene from "Don't Look Up," the 2021 disaster film in which they play two scientists who have difficulty making politicians and vacuous talkshow hosts comprehend the severity of an approaching comet's impending doom.

Leonardo DiCaprio and Jennifer Lawrence in a scene from “Don’t Look Up,” the 2021 disaster film in which they play two scientists who have difficulty making politicians and vacuous talkshow hosts comprehend the severity of an approaching comet’s impending doom. (Image: Hyperobject Industries and Bluegrass Films)

The researchers conclude, “Our findings provide important implications for the adaption and mitigation of globally connected extreme heat waves.” However, like all scientists who are ignored in the beginning of every disaster movie, as the memes go, as well as the veritable plethora of warnings from climate scientists since the 1980s, for how much longer will such warnings about the climate emergency be summarily dismissed by world leaders?

Related: Political will all we need to avert climate catastrophe