The Most Valuable Polluter: the carbon cost of NBA games

Nearly 20,000 people can gather in one building for just three hours, yet the largest source of greenhouse gas emissions associated with the event never existed within the building at all. This is an odd reality of professional basketball games: the most environmentally costly component of an NBA game is not the dazzling scoreboard, the colorful lights of the arena, or even the players’ flights in luxury private jets. It is the crowd’s transport to and from the avenue that adds the biggest carbon footprint, which is a surprising revelation about the environmental effects of attending sporting events.

The Madison Square Garden, known for its extensive lighting systems and climate control, is the largest electrical consumer in the building. However, its carbon footprint is prominent in transportation. Fan transportation accounts for 65 to 80 percent of the event's total carbon footprint, whereas team transportation accounts for less than 5 percent. Such a drastic comparison indicates that the carbon footprint of separate trips far exceeds the overall impact of sports events. In other words, a fan who points out that the team’s air travel has a negative environmental impact might unknowingly contribute to more pollution by traveling alone to the arena by car.

That finding is particularly relevant in New York. Madison Square Garden seats approximately 19,800 spectators for basketball, and a sold-out Knicks home game draws tens of thousands of commuters in Midtown Manhattan within a narrow window of time. Even in a city with one of the world’s most extensive public transportation systems, the cumulative emissions from private vehicles and occasional air travel by visitors remain the largest contributor to an NBA game’s carbon footprint.

The arena, meanwhile, is still a significant contributor to carbon emissions, as a modern NBA venue relies on continuous lighting, climate control, and high-definition scoreboards. Large sports venues can consume between 10,000 and 20,000 kilowatt-hours of electricity on an event day, an amount comparable to the monthly electricity consumption of roughly 1,000 to 2,000 average American households.

Though waste is not necessarily the biggest environmental issue, it is the most easily identifiable and apparent one, as thousands of disposable beverage cups, food containers, napkins, and merchandise pile up in the course of one game. The NBA became aware of this situation and has thereby broadened its timelines with the help of NBA Green. This was the case at the March 2025 NBA All-Star Weekend, which, with the help of organizers who managed to send more than 16,5000 lbs of waste away from landfills, was still completely powered by renewable electricity. Beyond this single event, the organization also committed to a 50 percent cut in operational greenhouse gas emissions by 2030 as part of the United Nations Sport for Climate Action Framework.

For that reason, the environmental report of the NBA basketball game is not written under the basket. Rather, it starts hundreds of miles away on highways, where thousands of individual choices quietly create the carbon cost for the game. It’s true that arenas should enhance electricity efficiency, but reducing the carbon footprint of sports events also depends on fans’ individual choices, including transportation and waste.