Running out of time? The fate of endurance races

This year’s Western States Endurance Run, America’s greatest ultrarunning race, unfolded as it often does under brutal heat – temperatures throughout the second 50 miles hovered around 37 Celsius all day.

To prepare for these conditions, runners have increasingly found new and innovative ways to ‘heat adapt’ their bodies to the extreme environment (enjoy the videos on YouTube of runners cranking their home gyms to 40 Celsius and running uphill on treadmills in double down jackets). 

Completing the race will always be a remarkable feat of grit, but this year’s conditions also served as a stark reminder: rising temperatures are increasingly reshaping the very nature of ultrarunning.

Western States has always been known for its extreme conditions, a factor that attracts the world’s best athletes. Starting in the cool mountain air of Palisades ski resort on California’s Lake Tahoe, few can imagine what’s to come. The following 18,000 feet of ascent and descent into the brutal Sierra canyons turns the temperature into an unrelenting cauldron of fire.

This heat is intensifying. Studies show the frequency of U.S. heat domes has jumped nearly three‑fold since the 1950s, now made up to 150 times more likely due to human‑driven climate change. This year’s thermal onslaught echoes the broader trend: drought‑stricken landscapes, earlier snowmelt, and longer, hotter summers across the West coast of America.

But it’s not just the temperature. The course itself has faced disruption. In recent years, a combination of catastrophic wildfires and heavy rainstorms has battered the Western States Trail. After 2022’s Mosquito Fire tore through 12.4 miles of the canyons, volunteer teams and the US Forest Service raced to rebuild, leveraging private funding to prevent a race cancellation. That crisis has become a cautionary tale: with wildfires now doubling in frequency and annual burn area up eight‑fold since 1985 in the Western United States.

The interplay of extreme heat, wildfire risk, and erratic precipitation - ranging from scorching dry spells to post‑fire flash floods - is altering the fabric of this iconic race. Snowpack decline in the Sierra Nevada, driven by warming winters and earlier meltings, threatens summer water availability, a critical resource for aid stations and remote stretches of the course.

In response to these escalating threats, many elite ultrarunners are stepping up as vocal advocates for climate action, but if climate change continues unchecked, Western States could soon shift from a once-in-a-lifetime challenge to a fabled story of the past.