Climate Change Slows Heat Waves, Exposing Humans To Extreme Temperature Longer

Climate change is slowing heat waves, exposing humanity to severe temperatures for longer periods of time than previously, according to a new study.

Heat Waves Lasted For 12 Days

While prior studies have revealed that climate change is driving heat waves to become longer, more frequent, and more violent, a new study took a different approach, characterizing heat waves as unique weather patterns that move along air currents, just like storms.

According to a study published in Science Advances, global heat waves have moved 20% slower since 1979, allowing more people to stay hot for longer periods of time. They have also occurred 67% more frequently.

The study discovered that the maximum temperatures in heat waves are higher than 40 years ago, and the region under a heat dome is greater.

Heat waves have previously been shown to worsen, but this study is more comprehensive and focuses heavily on not only temperature and area but also how long the high heat lasts and how it travels across continents, according to study co-authors and climate scientists Wei Zhang of Utah State University and Gabriel Lau of Princeton University.

Global heat waves lasted an average of eight days from 1979 to 1983, but by 2016 to 2020, they had increased to 12 days.

"Those heat waves are traveling slower and so slower so that basically means that ... there's a heat wave sitting there and those heat waves could stay longer in the region," said Zhang.

The researchers divided the planet into three-dimensional grid cells and characterized heat waves as million-square-kilometer areas when temperatures exceeded the 95th percentile of the local historical maximum temperature.

They then tracked their movements over time to establish how quickly the hot air was traveling.

The study found that Eurasia was particularly heavily hit by long-lasting heat waves. Heat waves slowed the most in Africa, whereas North America and Australia experienced the greatest rises in total magnitude, which measures temperature and area.

"This paper sends a clear warning that climate change makes heat waves yet more dangerous in more ways than one," said Lawrence Berkeley National Lab climate scientist Michael Wehner, who wasn't part of the research.

Heat-Trapping Pollutants

The researchers also used computer models to show that the change was caused by heat-trapping pollutants from coal, oil, and natural gas combustion.

The study discovered climate change's fingerprint by simulating a world without greenhouse gas emissions and concluded that it could not explain the worsening heat waves witnessed over the last 45 years.

The study also investigates the changes in weather patterns that cause heat waves. Atmospheric waves that move weather systems, such as the jet stream, are diminishing, causing heat waves to move slower - west to east on most but not all continents.

They also utilized climate models to see what the consequences would have been if human-caused climate change hadn't occurred, and they discovered that manmade influences played a significant role.

"One of the most direct consequences of global warming is increasing heat waves. These results put a large exclamation point on that fact," said Woodwell Climate Research Center scientist Jennifer Francis.