Marathons are terrible for the planet, presenting a climate dilemma for elite runners: to fly or not to fly?

• Ultramarathon runner Damian Hall cofounded Green Runners to promote a more climate-aware sport.
• Hall rarely flies to races and won't compete in the UTMB Mont-Blanc this year due to its sponsor.
• Marathons like London and Toronto are going green, but travel is still a big carbon footprint.

Some 50,000 runners from around the world will descend on New York City next month for the marathon.

Damian Hall won't be there. The UK-based runner is known for setting records in longer ultramarathons, including earlier this year when he won the 268-mile Spine Race. In fact, he's flying to fewer races these days to reduce his carbon footprint.

"This sport is incredible. It's life-changing. But it can also be terrible for the planet," said Hall, who cofounded Green Runners, a group that advocates for a more environmentally aware sport. Founded in 2022, the group has grown to 1,000 members.

A lot of sportswear, sneakers, and free T-shirts — many of which are made from oil and gas — get tossed out. So do single-use water cups along the race route. Corporate sponsors can be big polluters trying to "sports wash" their image. Runners fly around the world to the events and produce greenhouse-gas emissions. Travel is "the elephant in the room" that many race organizers are reluctant to confront, Hall said.

The Paris Marathon, which attracts 57,000 runners annually, has audited its carbon footprint for years and in 2019 reported that 94% of emissions are attributed to travel while only 6% are produced by the event logistics. That year, the marathon was promoted as the first to be "carbon neutral" because it purchased offsets from a Kenya-based project that provided families with baked-clay cook stoves to replace dirtier, wood-burning ones. The marathon is also focused on diverting waste from landfills and donating surplus clothes and food.

Similar steps have been taken by the organizers of other large races, including the TCS Toronto Waterfront Marathon earlier this month. The event had more than 25,000 runners — 2,000 of whom were from other countries. The event purchased carbon offsets to compensate for a portion of its overall emissions and achieved the highest rating from the Council for Responsible Sport. The third-party certifier awards points for sustainable practices related to food, merchandise, waste, and emissions.

"We attract thousands of international participants, and that's a huge part of our business," Jen Cerullo, the manager of events and environment, social, and governance at Canada Running Series, which plans the Toronto Marathon, told Insider. "Finding a way to reduce that impact without reducing the number of people coming into the race is a huge part of the conversation."

No marathon has gone as far as London, which is charging a 26 euro climate levy on runners from abroad to fund the marathon's efforts to slash emissions by 2030. The stakes are getting higher, with the climate crisis already impacting some races. The Twin Cities Marathon in October was canceled for the first time in its 40-year history due to record-breaking heat.

Hall said he doesn't want runners to have to give up their dreams. That's not fair, especially because just 100 fossil-fuel companies are mostly to blame for the climate crisis. Still, athletes and sports organizations can use their influence to educate the masses.

For his part, Hall won't run the UTMB Mont-Blanc because the sponsor is an automaker. He is vegan, joins climate protests, wrote a book on running and the planet, and takes trains to participate in races around Europe. However, he did fly to the US this year for the Barkley Marathons in Tennessee.

"I agonized over that flight, and I'm still not totally comfortable with it," Hall said. "But I also want to show that you don't have to be perfect."