If you thought this summer’s heat waves were bad, a new study has some disturbing news about dangerous heat in the future

29th August, 2022.      //   Climate Change  // 

EXPLAINER-HEAT-WAVE-copy-768x512

 

AS global temperatures rise, people in the tropics, including places like India and Africa’s Sahel region, will likely face dangerously hot conditions almost daily by the end of the century—even as the world reduces its greenhouse gas emissions, a new study shows.

 

The mid-latitudes, including the US, will also face increasing risks. There, the number of dangerously hot days, marked by temperatures and humidity high enough to cause heat exhaustion, is projected to double by the 2050s and continue to rise.

 

In the study, scientists looked at population growth, economic development patterns, energy choices and climate models to project how heat index levels—the combination of heat and humidity—will change over time. We asked University of Washington atmospheric scientist David Battisti, a co-author of the study, published August 25, 2022, to explain the findings and what they mean for humans around the world.

 

What does the new study tell us about heat waves in the future, and importantly the impact on people?

 

There are two sources of uncertainty when it comes to future temperature. One is how much carbon dioxide humans are going to emit—that depends on things like population, energy choices and how much the economy grows. The other is how much warming those greenhouse gas emissions will cause.

 

In both, scientists have a really good sense of the likelihood of various scenarios. For this study, we combined those estimates to get a likelihood in the future of having dangerous and life-threatening temperatures.

 

We looked at what these “dangerously high” and “extremely dangerous” levels on the heat index would mean for daily life in both the tropics and in the mid-latitudes.

 

“Dangerous” in this case refers to the likelihood of heat exhaustion. Heat exhaustion won’t kill you if you’re able to stop and slow down—it’s characterized by fatigue, nausea, a slowed heartbeat, possibly fainting. But you really can’t work under these conditions.

 

The heat index indicates when a person is likely to reach that threshold. The National Weather Service defines “dangerous” as a heat index of 103 F (39.4°C), and “extremely dangerous” as 125°F (51.7°C). If a person gets to “extremely dangerous” temperatures, that can lead to heat stroke. At that level, you have a few hours to get medical attention to cool your body down, or you die.

 

“Extremely dangerous” heat index conditions are almost unheard of today. They happen in a few locations near the Gulf of Oman, for example, for maybe a few days in a decade.

 

But the odds of the number of “dangerous” days are increasing as the planet warms. We’ll likely have about the same weather variability as today, but it’s all happening on top of a higher average temperature. So, the likelihood of extremely hot conditions increases.

  • Linkedin

  • Pinterest

  • Youtube