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- 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.
- This article is part of Insider's weekly newsletter on sustainability. Sign up here.
Some 50,000 runners from around the world will descend on New York City next month for the marathon.