If the Hardiest Species Are Boiled Alive, What Happens to Humans?

The June heat wave caused billions of deaths.

Christopher Harley / University of British Columbia; The Atlantic

For years, Sandra Emry, a researcher at the University of British Columbia, in Vancouver, has been studying the potential impact of future heat waves on rockweed, a species of brown alga that provides a habitat for marine life on both coasts of North America. To simulate a June heat wave in the year 2060 or 2080 in the Strait of Georgia, between Vancouver Island and the British Columbia mainland, she typically drags patio heaters down to the shore, warming the air around a patch of rockweed to 95 degrees Fahrenheit in order to see how the alga reacts.

This summer, she didn’t need the heaters. On June 28, her thermal-imaging camera showed the temperature nearing 125 degrees. Over the course of a four-day heat wave, dense beds of rockweed died, as did many of the nearby mussels, chitons, limpets, and other intertidal species. “The stench was awful. I never expected to see such a major die-off,” Emry told me. She didn’t think temperatures would get that high this soon.

Billions of mussels, clams, oysters, barnacles, sea stars, and other intertidal species died during the late-June heat wave in the Pacific Northwest, Christopher Harley, a zoology professor at the University of British Columbia, told me last week. Yes, that’s billions, plural. What I call “extreme, extreme heat events”—because the term extreme events doesn’t quite cover the dire situation—not only kill people; they kill plants and animals. In changing our planet’s climate, we’re permanently altering the natural world that is our life-support system. And we’re seeing this happen in real time.

Diptych of dead crab and mussels
(Christopher Harley / University of British Columbia)

Harley, who is investigating the extent of the June die-off, has learned from marine scientists at various institutions that an estimated 100 million barnacles died on a 1,000-yard stretch of shore near White Rock, British Columbia. While not all sites are as bad as White Rock, large numbers of dead marine animals have been found along much of the Salish Sea shoreline, from Olympia, Washington, to Campbell River, British Columbia. The situation is so alarming that Harley said it could lead to the collapse of the region’s maritime ecosystem.

This kind of destruction is so notable because rockweed, mussels, and other intertidal species are incredibly tough and used to wide swings in temperature. They spend 12 hours under the cold waters of the northern Pacific Ocean and then, at low tide, 12 hours exposed to the air and hot sun. Only an extreme, extreme event could kill them. This massive die-off may result in a radically different shoreline ecology, one without the thick carpet of mussels and rockweed that has lined much of the Salish Sea shore since the last Ice Age.

Many land-based species have also died from the heat. I’ve read numerous reports of flightless nestlings, including hawks and terns, throwing themselves out of nests and off rooftops, risking death and injury to avoid being cooked alive. The California Department of Fish and Wildlife has warned that nearly all endangered young salmon in the Sacramento River could die. Officials in Washington State also say that salmon in the Columbia and Snake Rivers are at risk. Overheated bears have been seen wading into backyard pools and ignoring swimmers at Lake Tahoe in order to get some cool relief.

Every living thing has its “Goldilocks zone”: a not-too-hot, not-too-cold temperature range. For tropical corals, such as those in the 1,400-mile-long Great Barrier Reef, ocean temperatures need to be between 71 and 85 degrees. If water temperatures reach 90 degrees, as they have in recent years, the reefs bleach and die. Other species like the water cold. Young salmon don’t do well in water above 68 degrees, and some Arctic seabirds show heat stress at 70 degrees. The Arctic is warming nearly three times faster than anywhere else. A heat wave in June 2020 pushed temperatures in one of the coldest places on Earth, Verkhoyansk, Siberia, from its typical 68 degrees to near 100.

Some birds and mammals have coping mechanisms for a drastic change in temperature. They generally deal with the heat by reducing their activity, including eating, and by panting to try to cool themselves. Fish, including salmon, need to consume more oxygen in warmer water; however, warm water holds less oxygen, adding additional stress that makes them more susceptible to disease.

Thermal camera shows temperature measured on shore
(University of British Columbia)

We’re only going to see more of this stress on our ecosystem. A comprehensive global assessment that measured heat waves from 1950 to 2000 found that their frequency, duration, and cumulative heat had increased significantly. In the Middle East and much of Africa, the number of heat waves, and their intensity, has increased by a whopping 50 percent every decade. In other parts of the world, the increase has varied from 10 to 30 percent per decade. While the impacts of drought have received much attention, heat waves are now considered a “major global threat” to plants, animals, and ecosystems globally. Scientific research into heat waves has exploded in the past decade: 1,400 studies have been published in the past six months alone.

Climate scientists are sounding the alarm loudly, urging the world to take action now in order to, as one scientist put it, “prevent the worst outcomes of global warming.” If billions of some of the toughest species on the planet dying is not the worst outcome, I’m sure we don’t want to see what is.

Climate, nature, and humanity’s well-being and survival are deeply interconnected. As the marine biologist and National Geographic explorer in residence Enric Sala told me, “Every morsel of food, every sip of water, the air we breathe is the result of work done by other species. Nature gives us everything we need to survive. Without them, there is no us.”