Even a normal summer day can feel suffocating for athletes whose bodies are working at the threshold of their physical limits, like those competing this month in Rio.
But as our planet grows warmer over our lifetimes, the number of cities that will be cool enough to reasonably host the summer games is going to rapidly dwindle. And that doesn’t just mean Atlanta or L.A. According to an analysis published in The Lancet last week, The Last Summer Olympics? Climate change, health, and work outdoors, only three plausible host cities in the entire continent of North America may still be low risk by 2085 (or the summer games of 2088): San Francisco, Calgary, and Vancouver. There may be zero in Africa or Latin America, and only two in Asia (Bishkek, in Kyrgyzstan, and Ulaanbaatar, in Mongolia).
"Eventually, climate change gets so extreme that all bets are off," says lead author Kirk Smith, professor of global environmental health at the University of California, Berkeley. Smith’s research focuses on the impact of climate change and pollution in the developing world, but with Rio capturing the world’s attention this month, he and his co-authors saw an opportunity to contextualize climate change. "It’s very hard to talk about what’s happening late in the century," he explains. "But it occurred to me that we do have things, the Olympics being one of them, that we expect to continue. And that that provides a way to think about things that are 60 or 70 years away."
They picked 2085 as a target date and the marathon as their target event, reasoning that it’s the most physically challenging outdoor endurance event at the Olympics. They pegged a "high-risk" temperature for marathoners at about 82.5 degrees Fahrenheit (for comparison, the 2007 Chicago marathon was cancelled when heat-stricken runners overwhelmed hospitals when the temperatures reached the high 80s). Then, they analyzed the future weather of 700 possible host cities (only in the northern hemisphere, since it contains nine tenths of the world's population) based on two common climate prediction models, looking at the probability of summer temperatures rising above 82.5 degrees.
Of almost 600 cities analyzed outside of Europe, for example, only eight qualified as low risk in 2085. Western Europe fared a little better, with many northern European and Scandinavian cities remaining eligible. In the United States alone, only San Francisco would be suitable in 70 years. Go a little further into the future—say the 2100s—and the authors found the last four suitably low-risk host cities will be Belfast, Dublin, Edinburgh, and Glasgow.
It may simply be too hot to risk it elsewhere. Of course, that doesn't mean the Olympics will end—just that as our planet changes, human behavior will have to adapt. "You could run the entire Olympics indoors at night, but that wouldn’t be the Summer Olympics we think of," Smith says.
But what’s really scary about this research isn’t its impact on elite athletes. It’s the impact on the poor. Half the world’s population works outdoors, Smith points out, and they won’t benefit from the luxuries Olympic athletes will. With productivity on the line, few bosses will consider altering work patterns or letting laborers take breaks. Smith calls this a "pernicious impact" of climate change—a term used to describe the negative effect of adaptation to a changing climate.
Put more simply, at a certain point in the future, the weather will become so extreme that we won’t be able to adapt any further without changing our behavior. Or, as the authors put it: "Increasingly, people will face a choice between doing what they have done for millions of years—work hard outdoors essentially any time they wish—and being safe."