When the FIFA World Cup hits North America in June 2026, 48 teams and millions of sports fans will be traveling among venues spread across Canada, the United States and Mexico.

It's a dramatic expansion - 16 more teams will be playing than in recent years, with a jump from 64 to 104 matches. The tournament, whether you call it soccer or football, is projected to bring in over US$10 billion in revenue. But the expansion will also mean a lot more travel and other activities that contribute to climate change.

The environmental impacts of giant sporting events like the World Cup create a complex paradox for an industry grappling with its future in a warming world.

Sports are undeniably experiencing the effects of climate change. Rising global temperatures are putting athletes' health at risk during summer heat waves and shortening winter sports seasons. Many of the 2026 World Cup venues often see heat waves in June and early July, when the tournament is scheduled.

There is a divide over how sports should respond.

Some athletes are speaking out for more sustainable choices and have called on lawmakers to take steps to limit climate-warming emissions. At the same time, the sport industry is growing and facing a constant push to increase revenue. The NCAA is also considering expanding its March Madness basketball tournaments from 68 teams currently to as many as 76.

Estimates for the 2026 World Cup show what large tournament expansions can mean for the climate. A report from Scientists for Global Responsibility estimates that the expanded World Cup could generate over 9 million metric tons of carbon dioxide equivalent, nearly double the average of the past four World Cups.

This massive increase - and the increase that would come if the NCAA basketball tournaments also expand - would primarily be driven by air travel as fans and players fly among event cities that are thousands of miles apart.

Sports are big business, and adding more matches to events like the World Cup and NCAA tournaments will likely lead to larger media rights contracts and greater gate receipts from more fans attending the events, boosting revenues. These are powerful financial incentives.

In the NCAA's case, there is another reason to consider a larger tournament: The House v. NCAA settlement opened the door for college athletic departments to share revenue with athletes, which will significantly increase costs for many college programs. More teams would mean more television revenue and, crucially, more revenue to be distributed to member NCAA institutions and their athletic conferences.

The inherent conflict between maximizing profit through growth and minimizing environmental footprint presents a dilemma for sports.

Several sport organizations have promised to reduce their impact on the climate, including signing up for initiatives like the United Nations Sports for Climate Action Framework.

However, as sports tournaments and exhibition games expand, it can become increasingly hard for sports organizations to meet their climate commitments. In some cases, groups making sustainability commitments have been accused of greenwashing, suggesting the goals are more about public relations than making genuine, measurable changes.

For example, FIFA's early claims that it would hold a "fully carbon-neutral" World Cup in Qatar in 2022 were challenged by a group of European countries that accused soccer's world governing body of underestimating emissions. The Swiss Fairness Commission, which monitors fairness in advertising, considered the complaints and determined that FIFA's claims could not be substantiated.

Aviation is often the biggest driver of emissions. A study that colleagues and I conducted on the NCAA men's basketball tournament found about 80% of its emissions were connected to travel. And that was after the NCAA began using the pod system, which is designed to keep teams closer to home for the first and second rounds.

Some academics, observing the rising emissions trend, have called for radical solutions like the end of commercialized sports or drastically limiting who can attend sporting events, with a focus on fans from the region.

These solutions are frankly not practical, in my view, nor do they align with other positive developments. The growing popularity of women's sports shows the challenge in limiting sports events - more games expands participation but adds to the industry's overall footprint.

Further compounding the challenges of reducing environmental impact is the amount of fan travel, which is outside the direct control of the sports organization or event organizers.

Many fans will follow their teams long distances, especially for mega-events like the World Cup or the NCAA tournament. During the men's World Cup in Russia in 2018, more than 840,000 fans traveled from other countries. The top countries by number of fans, after Russia, were China, the U.S., Mexico and Argentina.

There is an argument that distributed sporting events like March Madness or the World Cup can be better in some ways for local environments because they don't overwhelm a single city. However, merely spreading the impact does not necessarily reduce it, particularly when considering the effects on climate change.

Sport organizations and event planners can take steps to be more sustainable and also encourage more sustainable choices among fans. Fans can reduce their environmental impact in a variety of ways. For example:

Avoid taking airplanes for shorter distances, such as between FIFA venues in Philadelphia, New York and Boston, and carpool or take Amtrak instead. Planes can be more efficient for long distances, but air travel is still a major contributing factor to emissions.

While in a host city, use mass transit or rent electric vehicles or bicycles for local travel.

Consider sustainable accommodations, such as short-term rentals that might have a smaller environmental footprint than a hotel. Or stay at a certified green hotel that makes an effort to be more efficient in its use of water and energy.

Engage in sustainable pregame and postgame activities, such as choosing local, sustainable food options, and minimize waste.

You can also pay to offset carbon emissions for attending different sporting events, much like concertgoers do when they attend musical festivals. While critics question offsets' true environmental benefit, they do represent people's growing awareness of their environmental footprint.

Through all these options, it's clear that sports face a significant challenge in addressing their environmental impacts and encouraging fans to be more sustainable, while simultaneously trying to meet ambitious business and environmental targets.

In my view, a sustainable path forward will require strategic, yet genuine, commitment by the sports industry and its fans, and a willingness to prioritize long-term planetary health alongside economic gains - balancing the sport and sustainability.