The Bib and the Boarding Pass
They were in the same plastic sleeve, the clear one they hand you at the expo with the safety pins and the sticker for your gear-check bag tucked inside. For months I’d kept the bib pinned to the corkboard above my desk, corral number printed in the bottom corner. The boarding pass only turned up now, folded in four against the medal ribbon: seat 15F, boarding at 6:10 a.m., a time that still reads to me like a provocation. Two sheets of paper from the same family. Each carries a number that, for one day, is yours alone, and a gate that shuts at a fixed hour without waiting for anyone.
I’d trained sixteen weeks for that marathon and packed it into a suitcase in a single evening. Race shoes wrapped in a paper bakery bag and stuffed into my carry-on, because of the whole trip the cargo hold was the one thing I didn’t trust. Gels counted twice. Singlet rolled tight as a cigar. At the gate, vending-machine coffee scalding my fingers, I started counting other people’s shoes. Towering midsoles, colors nobody would choose for the office, lean calves showing below the hem of their track pants. Half the plane was headed to my start line. We recognized each other without a word, with the slightly ridiculous complicity of people who know that in forty-eight hours they’ll suffer in exactly the same way, on the same asphalt, 1,200 miles from home.
For years I thought of that flight as a prologue. A piece of logistics, like picking up the bib or the plate of pasta the night before, something to get out of the way before the part that mattered. The race began at the gun. Everything else was transit, and nobody measured the transit.
What Tokyo and Valencia Measured
In February, the Tokyo Marathon Foundation published its emissions estimate for the 2026 race, built with the Japanese climate consultancy ASUENE as the first step of a three-year partnership. It’s a calculation made before the start, using data from the previous edition, when the field numbered around 38,000 runners, and the total the organizers give is 26,029 metric tons of carbon dioxide. The scope reaches well past what the Foundation itself produces: it also takes in the travel and consumption of everyone who runs, watches and works the race. According to the organizers, Tokyo is the first marathon in Japan to make the full picture of its emissions public.
Broken down, the line items make a lopsided shape. The organization’s direct emissions come to one metric ton; the electricity that keeps the event running, three. Travel by runners, spectators and staff reaches 23,017 metric tons, 88.4% of the total. Hotels stay under 3%.
There’s one line in that table I kept going back to. Under waste, the organizers also counted the clothes and shoes runners abandon at the start to keep the cold off: twelve metric tons, 0.05%. I thought of the shapeless sweatshirt I leave on the corral fence every time, bought at a thrift store for the sole purpose of being sacrificed, and the small pang of guilt as I pull it over my head when the announcer starts the countdown. In Tokyo’s ledger, that gesture is a figure lost somewhere past the decimal point.
In Valencia, the same math is done by GO2 by Global Omnium, whose ties to the marathon run in two directions: it measures the footprint as the organizers’ consultant and, for the third consecutive year, it’s the race’s dedicated sustainability sponsor. Worth keeping in mind as you read the numbers, and the organizers point out that the latest edition’s calculation was verified by an independent third party. The figures reported on the race website list 34,627 runners from 136 countries, 65% of them traveling from abroad, and 579 kilograms (about 1,280 pounds) of carbon dioxide equivalent per participant. More than 91% of that footprint, they write, is tied to runners reaching Valencia from all five continents. For the half marathon, the share climbs to nearly 95%.
Set side by side, the two measurements point the same way. The weight of a major international marathon lies in the road each runner travels to reach the start, far more than in the paper cups crackling underfoot at the mile 18 aid station. Valencia says so with very little hedging: the distance runners cover to get to the race is the main driver of its impact. And from five continents, that distance nearly always has wings.
The Light Run and the Heavy Trip
In Tokyo, the organizers also ran the numbers in reverse. Thirty-nine thousand runners covering 26.2 miles each add up to just over a million miles moved by legs alone, enough to circle the Earth some forty times. Covered in gasoline cars, they estimate, the same distance would produce around 230 metric tons of carbon dioxide. From there they draw their conclusion: running is, by its very nature, one of the lowest-impact ways a person can move.
I set those two numbers one over the other, 230 above 23,017, the way we stacked fractions in grade school. The trip people make to run Tokyo weighs about a hundred times the marathon itself, even if you picture the whole race driven by car.
Then I thought back to my own race. For three hours and forty minutes I moved on what I’d eaten: the pasta the night before, a banana at dawn, four gels torn open with my teeth between mile 9 and mile 22. A running body burns mostly itself and gives back heat, sweat, a crust of salt on the brim of a cap. I know of no more frugal engine. The real bill I’d run up two days earlier, at 33,000 feet, motionless, knees jammed against the seat in front.
The heaviest part of my marathon I did sitting down, seatbelt fastened, seat back in its full upright position.
The Japanese organizers draw a conclusion from this imbalance that struck me as honest. A marathon’s footprint depends on the choices of an enormous number of people, not only on whoever stages it, and decarbonizing a sporting event can’t stay their job alone. For the coming years they’re announcing work on mobility and offset programs. I read it in the same fall that some marathons are moving their dates and start times because of the heat, and the coincidence stays with me. Climate has walked into the race calendar through the front door. Now the people who put on these races are starting to tell us how much we weigh, too, just by getting there.
Where We Race, and Why
The destination marathon has its own sentimental economy, and I know it well. The week when an entire city belongs to the race, the expo, breakfast at the hotel with the bib already pinned to the shirt folded over the chair. The name of a capital added to the list, the medals hung in a row down the hallway. Some people collect the majors the way others collect continents, and more than once I’ve envied the ones who could tell the story of every single race.
None of this appears in the Tokyo and Valencia tables, and rightly so. An emissions audit has no column for a city seen at seven miles an hour, for cheering in a language you don’t speak and that, at mile 18, you understand perfectly. Those things remain true. So do the tons.
There’s an irony in these numbers that I can’t bring myself to find cruel. Valencia is among the races that draw the most runners from abroad, nearly two entrants in three, and it publishes the very figure that makes the price of that appeal visible. The organizations that need the runner who flies in from far away are the same ones now showing that runner what the trip weighs. It’s a kind of honesty rarer than it looks, and it leaves the decision where it has always been.
The faraway race was always my choice, and it carried a cost even when no one wrote it down. For years, before signing up, I asked myself whether I was ready, whether my work calendar would hold, whether my legs would reach the right date in one piece. Now I also ask myself why there, of all places. Sometimes the answer is a city I’ve wanted for years, or someone waiting for me at mile 25. Sometimes it’s just a nail in the hallway with nothing hanging on it yet.
A marathon has a single official distance, twenty-six miles and three hundred eighty-five yards, measured with a calibrated bicycle along the shortest route a runner could possibly take, so that no one runs a yard less. As of this year I know a second one. It starts at my front door, crosses two hours of sky, and no course certifier will ever sign off on it.
That one is ours to weigh.