In June of 2021, British Columbia, Canada, had temperatures surpassing [1] 49.4 C. It was a “statistically ‘impossible’” record, according to environmental scientist Robert Rohde. This heatwave struck an even broader region including British Columbia, as temperatures for the Pacific Northwest were 17 degrees above average for the last week of June. Around 600 excess deaths were recorded in the region, with at least 200 of them directly attributed to the extreme heat. Meanwhile, temperatures in Death Valley, California hit 54.4 C, closest to the hottest ever measured temperature on Earth.

There is no doubt that we are living in a warming world. Of the top ten hottest years on record, seven have occurred since 2010, making last decade the hottest ever recorded. The heatwaves aren’t just getting hotter—they’re also becoming more frequent, with American cities experiencing three times more heat waves per year compared to the 1960s.

Climate change poses a multitude of risks to society, from inflaming conflict over scarce resources to exacerbating natural disasters like wildfires, drought, and storms. The 2020 wildfires in Australia, which occurred after a record-breaking [2] November heatwave, burned up to 100,000 square kilometers. In the summer of 2021, the US, Greece, Turkey, Italy, and Russia all struggled with their own record-breaking wildfires.

Not to mention, our bodies are not equipped to handle extreme heat. We can survive in temperatures above 37 C, the approximate internal temperature of the human body, by sweating. In dry air, sweat evaporates quickly and effectively cools down our bodies, keeping us from overheating. However, our natural defenses against high temperatures diminish as humidity rises, and climate change has caused more humid heat waves. High levels of humidity in the atmosphere limit its capacity to evaporate sweat, causing the body to get hotter and hotter.

It’s critical to remember that extreme temperatures threaten more than just humans. In June 2021, as temperatures soared in the American Pacific Northwest, billions of clams, mussels, oysters, barnacles, and other shellfish were literally cooked alive in their shells. Similarly, during the 2015 Indian heatwave, over 5 million chickens died due to the soaring temperatures in the southern state of Telangana. That led to food shortages and dramatic short-term inflation of prices for eggs and chicken. Heat waves that cause mass deaths of animals—not to mention human casualties—can have a knock-on effect [3] where an entire ecosystem or economy is destabilized.

How can we reduce the risks of extreme heat? One of the most important tasks is upgrading at-risk cities with new technologies to lower temperatures so that those places remain livable, even during heatwaves.

One heat mitigation strategy involves making buildings and surfaces in cities more reflective by painting roofs with special white paints. This reduces the amount of heat buildings absorb from the sun. Trials in India have shown that a white roof can reduce a building’s temperature by 2 C without using additional energy.

Natural vegetation in cities provides a cooling effect as well: plants evaporate water, provide shade, and filter polluted air. One Japanese researcher, Miyawaki Akira, has created a method for engineering sustainable urban forests that require almost no upkeep after the first three years. In Chennai, India, there are now over 25 Miyawaki forests designed to lower ambient temperature. Belgium, France, and Holland are all planting their own Miyawaki forests, in the hopes of keeping cities from becoming too hot.

While the risks of extreme heat are concerning, they seem, for now, controllable. As communities around the world look for ways to stay cool, and global leaders meet hoping to hash out a deal to prevent further climate change, how will you stay cool?