Since 1979, global heat waves have moved 20 percent slower — meaning more people are staying in the heat longer — and occurred 67 percent more frequently, according to a study in the journal Science Advances published Friday.

The study found that the highest temperatures in heat waves are higher than 40 years ago, and the areas exposed to heat have become larger.

The study also revealed that heat waves have been getting worse for some time, but that these waves have become more comprehensive and intensely concentrated, not only in terms of temperatures and regions, but also in terms of their duration and movement across the continents, according to climate scientists Wei Zhang from Utah State University and Gabriel Lau from the University of California. Preston.

From 1979 to 1983, global heat waves lasted an average of about 8 days, but by 2016 to 2020, they had lasted up to 12 days, according to the study.

Eurasia was the hardest hit and the longest exposed to persistent heat waves.

Heat waves slowed down for the longest period in Africa, while North America and Australia witnessed the largest increases in temperatures and the largest extension of areas hit by heat waves, according to the study.

“This study sends a clear warning that climate change is increasing the risk of heat waves in more ways than one,” said Michael Weiner, a climate scientist at Lawrence Berkeley National Laboratory, who was not involved in the study.

Scientists say that just like in an oven, when heat waves last longer, the inside cooks more, and in this case, the inside becomes humans.

"These heat waves are moving much slower and slower, which basically means that there is a heat wave out there and these heat waves could last longer in the region. The negative impacts on our human society will be enormous and increasing over the years," said Zhang of the University of Utah.

The team ran computer simulations that showed this change was due to greenhouse emissions from burning coal, oil and natural gas. The study found the footprint of climate change by simulating a world with no greenhouse gas emissions and concluded that it could not lead to the worsening heat waves observed in the past 45 years.

The study also looks at changing weather patterns that spread heat waves. Atmospheric waves that drive weather systems, such as jet streams, are getting weaker, so they don't move heat waves as quickly — from west to east on most but not all continents, Zhang said.

This shows “how heat waves develop in three dimensions and move regionally and across continents rather than looking at temperatures at individual locations,” said Cathy Jacobs, a climate scientist at the University of Arizona, who was not involved in the study.

“One of the direct consequences of global warming is an increase in heat waves,” said Jennifer Francis, a scientist at the Woodwell Center for Climate Research, who was not involved in the study. “These results put a big exclamation mark on that fact.”