As I ran the Austin Marathon recently, I thought about how this ancient ritual of traversing 26.2 miles brings communities together, promotes volunteerism and inspires people to root for complete strangers. Marathons are a celebration of human endurance and perseverance, but as an M.S. in Sustainability Science graduate, I couldn’t help but wonder: What is the environmental cost of this massive event?

Thousands of paper cups and tiny plastic gel packs littered the streets, discarded by runners hydrating and sugaring up on the go. Medals, made of metal and ribbon, were handed out to every finisher—not to mention the overstock. The sheer amount of single-use materials—from bibs and timing chips to the plastic-wrapped recovery snacks and thermal blankets—raised questions about the sustainability of the sport. Were the benefits of closing down city streets, reducing vehicular emissions for the day and encouraging an active lifestyle enough to counterbalance the waste generated? Or is a marathon, by its nature, an event that leaves an outsized environmental footprint?

The sustainability of marathons is a growing topic of concern. Some races have made strides in reducing their impact: switching to compostable cups, using recyclable bibs, sourcing medals from sustainable materials and even planting trees to make the race carbon neutral.

But before detailing all the proposed solutions, it’s important to grasp the scale of the issue. The New York City marathon alone collects roughly 38 tons of discarded clothing as runners shed their layers during the race. More strikingly, the event also generates around 54.3 kilotons of carbon emissions (according to one analysis)—the equivalent of a Boeing 747 making 424 transatlantic flights from NYC to London.

To address these challenges, some races have explored alternative hydration solutions, like personal refillable bottles or innovative biodegradable pods made from seaweed, such as the Ooho pods introduced at the 2019 London Marathon. While promising, these solutions have yet to see widespread adoption across the marathon circuit, largely due to logistical challenges and cost concerns.

Beyond hydration, other races have implemented creative sustainability efforts. The Boston Marathon recently introduced medals made from recycled steel and ribbons sourced from repurposed plastic bottles. The Toronto Waterfront Marathon’s Impact Bib program funds a sustainability charity in lieu of a race day shirt, and the Bath Marathon is planting one tree for every 20 registrants on a grove they own, each year adding more trees to further the goal of a carbon-neutral race. Some races, like the NYC Marathon, have swapped out the traditional disposable thermal blankets for reusable post-race ponchos, helping to cut down on single-use waste while providing runners with a lasting keepsake.

Despite these efforts, the reality remains that a single-day event requires extensive resources. Marathons necessitate thousands of volunteers, generate tons of trash and often rely on corporate sponsorships that come with promotional materials and branding-heavy giveaways—many of which are not sustainable. Even when sustainability is a stated goal, race organizers must balance financial constraints, logistical challenges and the expectations of participants and spectators.

This wasn’t my first marathon. I had the pleasure of competing in the 50th annual NYC marathon and still have the reusable post-race poncho they gave all the finishers. I wanted my second marathon in my new hometown to be about something bigger than myself. I started a fundraiser, got the attention of the local media and was able to raise a meaningful amount of funds for a nonprofit I’ve always supported. I truly believe that if I had created the fundraiser without the marathon, the outcome wouldn’t have been the same. There’s something about the nature of endurance challenges that compels people to champion a cause, whether it’s through cheering on runners, volunteering or donating to charities linked to the event.

When someone says they are training for a marathon, the response is usually a variation of something positive. People may be impressed, they may have questions or they may have their own race or endurance stories that they suddenly want to share. This is because marathons bring all kinds of individuals together. Running is one of the most natural human activities—we learn to run when we’re around two years old. To have an endurance sport built around something so fundamental is, by nature, a unifying activity that transcends political beliefs, racial backgrounds and socioeconomic differences.

But making race day sustainable will only be a priority to a subset of participants and spectators. While some runners may actively seek out eco-conscious races or opt to carry their own hydration, others simply focus on the personal challenge of completing the race. That means the responsibility largely falls on race organizers, city officials and sponsors to implement greener practices without disrupting the experience for runners.

And yet, there is something enduring about the time-honored tradition of marathons, rooted in history and human resilience. As I eye a third marathon in the not-so-distant future, my hope is to see even more sustainability efforts integrated into its organization. Organizers, sponsors and runners all have a role to play in making race day more environmentally friendly. The future of marathons isn’t just about pushing human limits—it’s about doing so in a way that respects the planet, ensuring that these incredible feats of endurance leave a lasting positive impact on both the people who run them and the planet that supports them.

Daryush Nourbaha, a graduate of Columbia’s M.S. in Science in Sustainability Science program, is an environment, health, safety and sustainability manager at Collins Aerospace. He lives in Austin, TX, with his wife, two daughters, and their dog, Zoë. 

Views and opinions expressed here are those of the authors, and do not necessarily reflect the official position of the Columbia Climate School, Earth Institute or Columbia University.