Warming climate forcing marathon changes to keep runners cool

Marathon runners across the United States are facing increasing challenges as the warming climate forces changes to keep them cool during races. Paul Grinvalds, a marathon veteran, admits that it's common for runners to persist in their goals even when conditions become dangerous. Marathon organizers are responding to these concerns by adjusting race dates, starting times, and offering options for participants to cut their runs short.

For instance, the Sioux Falls marathon moved from August to September the following year due to hot conditions.

In Los Angeles, race organizers allowed runners to stop after 18 miles and still receive a finisher's medal when warm conditions were forecasted. The Twin Cities Marathon delayed its 2023 race by two weeks after cancelling it the previous year due to hot weather. These adjustments are a result of the Earth's hottest year on record in 2024, with the World Meteorological Organization forecasting a global temperature rise of more than 1.5°C above pre-industrial levels between 2025 and 2030.

According to a study by Climate Central, by 2045, optimal running conditions for recreational runners would be less likely at 46 of the 51 US marathons analyzed. The study suggests that the likelihood of running in cooler temperatures will decrease significantly. Experts warn that the warming climate makes it increasingly difficult for people to engage in outdoor physical activities, pushing them towards indoor exercises or alternative forms of exercise.

Running a marathon in warm, humid conditions is particularly challenging due to the body's struggle to cool down and maintain blood flow to muscles. Chris Minson, a University of Oregon professor, explains that the optimum temperature for running a marathon is around 10°C. As temperatures rise, the body has to work harder to supply blood to muscles and regulate temperature, leading to increased energy expenditure and reduced performance.

Acclimatization to warm weather can help improve performance in the heat, but it may not be as effective as running in cooler conditions. Douglas Casa, a kinesiology professor, emphasizes the importance of adjusting race dates and times based on weather patterns. The Twin Cities Marathon's decision to delay its race is seen as prudent in light of the rising temperatures.