The world is adapting to extreme heat — but not nearly fast enough

This summer was more than uncomfortably hot — it was record-breaking, with many countries reporting their highest average temperatures yet. Western Europe, for example, sweated through five grueling heat waves this year that sucked moisture from the soil, turned vegetation into wildfire fuel, and shrank rivers until the fish ran out of water. Emergency rooms and ambulances were overwhelmed. Early estimates found that at least 35,000 excess deaths were recorded as temperatures soared — and that only accounts for the first four heat waves in about half of the continent.

But all this, the World Health Organization said, was just a “dress rehearsal.” The coming summers are bound to be even hotter. 

Two factors in particular could push global temperatures even higher in the coming years: El Niño and human-caused climate change. El Niño is a climate pattern that brings extra warmth around the globe every two to seven years. We’re in the early stages of the current cycle, which is on track to be the strongest in a millennium. 

And then there’s the problem of Earth’s atmosphere increasingly filling with heat-trapping greenhouse gases. Addressing climate change requires countries to drastically move away from burning fossil fuels and invest in alternative technologies, such as solar and wind power. In 2015, nearly every nation in the world entered a voluntary commitment to try to limit warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels, with a more ambitious target of 1.5 degrees C (2.7 degrees F). But a new United Nations report released last week found that we are certain to overshoot the latter goal within the next few years. This means that even more severe heat, drought, fire, sea level rise, and glacier loss is headed our way. 

As the effects of climate change and El Niño converge, scientists predict 2027 is very likely to be the hottest year ever recorded.

“There really is nowhere that is terribly well adapted to these very extreme events,” said Kristie Ebi, a lead author of the U.N. report and professor of global health at the University of Washington. Poor countries are the most vulnerable to climate change, but even wealthy countries are failing to adapt fast enough, the U.N. report found.

Some countries have found ways to reduce suffering and death from heat, even as the climate has warmed. After a 2003 heat wave claimed 70,000 lives across Europe, countries took steps to protect people, instituting early warning systems, establishing cooling centers, and helping hospitals prepare. France made an aggressive national plan that mandated air-conditioned rooms in nursing homes, instructed health workers to check in on older and frail people during extreme heat, and developed green spaces in cities to help cool them down. 

“A given heat wave is now actually much less deadly in France than it was before,” said Christopher Callahan, a climate scientist who studies heat, health, and economics at Indiana University. Still, the world is already at 1.4 degrees C of warming and counting, and scientists expect that at some point, “the heat waves will become so intense that they will sort of outstrip that adaptation progress,” he said. If countries continue to adapt to heat at the rate they have in recent decades, it would only prevent about 1 in 10 deaths that would be expected, according to one of his studies.

Ebi said that health officials have failed to keep up with the pace of change, such as more heat waves occurring outside of the traditional mid-May to mid-September season, and have overlooked extreme scenarios such as the record-breaking heat waves seen in Western Europe this summer. “The temperatures were just so high, much higher than the heat wave early warning systems were designed to manage,” Ebi said. 

The fact that the world is struggling to adapt to the amount of warming that’s already arrived is a troubling sign. Studies in recent years have suggested that the threshold at which heat becomes hazardous for the human body is lower than previously thought, with the danger zone starting with temperatures as low as 26 degrees C (79 F) when combined with high humidity. In addition to causing heat stroke, increased temperatures can put lethal amounts of stress on organs such as the heart, lungs, and kidneys.

“When 1.5 was decided, there was an assumption that 1.5 degrees C above preindustrial [temperatures] would be relatively safe,” Ebi said. “And I would say, today, that Europe does not think 1.4 degrees is relatively safe. For most of the U.S., it does not feel like 1.4 is relatively safe.”

So what will it mean for the world to overshoot its climate goals? The U.N. report warns that there “are no good outcomes above 1.5 degrees C” and the updated best-case scenario for global temperatures ends up peaking at 1.8 C. It lays out potential paths to slowly bring average temperatures back down to safer levels after that peak, but that wouldn’t necessarily mean a return to present-day conditions. At that point, it may be impossible for dead coral reefs to thrive again, or for all the melted ice to be refrozen. But it could still help with extreme heat.

To prepare for hotter conditions, Ebi said it’s important to “stress test” possible disaster scenarios, just as banks and militaries conjure worst-case scenarios to see how they’d play out and better prepare for them. Otherwise, communities will be forced to discover the devastating effects of extreme heat in real time, such as when Portland, Oregon, was struck with 116-degree F temperatures during the heat dome in June 2021. Under those unprecedented conditions, roads buckled, bridges warped, the power cables on the streetcar melted, and the light rail’s overhead copper wires expanded and sagged.

“There are a million different ways in which we can imagine making our society resilient to this kind of threat,” Callahan said, “and we just aren’t there yet.”