Warming climate forcing marathon changes to keep runners cool

Marathon runners often push through heat, even when temperatures exceed 16 degrees Celsius, as their bodies struggle to cool down during exertion. Paul Grinvalds, a veteran marathoner, acknowledged this stubbornness, stating that many runners will still attempt their goals despite the heat, which is an unwise choice given the likely painful and dangerous experience.

Climate change, primarily due to the burning of fossil fuels like coal and gasoline, is causing global temperatures to rise. Marathon organizers are facing the challenge of keeping races cool as a result. To address this issue, some have shifted race dates to earlier in the year or provided participants with the option to cut races short.

For example, the Sioux Falls, South Dakota marathon moved its event from August to September in 2024, after canceling the 2024 race due to hot conditions. Other races have also adjusted start times to cooler mornings or offered participants the choice of a shorter route.

In Los Angeles, race organizers allowed runners to stop after 18 miles and still receive a finisher's medal during warm conditions in March. However, this move sparked some online criticism. The Twin Cities Marathon, which was initially canceled in 2023 due to unfavorable weather, was eventually postponed by a couple of weeks after an analysis showed that later start dates would likely provide better conditions.

The analysis revealed that a 39-degree (4C) start is preferable to a 70-degree (21C) start, even if the latter brings snow.

The World Meteorological Organization predicts that Earth's average global temperature will likely rise by more than 1.5C between 2025 and 2030 compared to the 1800s. This warming trend is making conditions more challenging for most marathons. According to a study by the climate research group Climate Central, optimal conditions for recreational runners (6-7C) would be less likely at 46 of the 51 US marathons analyzed by 2045.

The ability to exercise outdoors and reap the benefits of physical activity is being threatened by climate change, according to Andy Pershing, a climate researcher who led the Climate Central study. Experts, such as Jessica Murfree of the University of North Carolina-Chapel Hill, say that marathon organizers, as well as those overseeing other endurance events, must consider changing event dates, times, and implementing additional safety measures as the climate continues to warm and become more unpredictable.