COVID-19 Disruption Demonstrates Win-Win Climate Solutions for Major League Sports.

Unlike other greenhouse gas sources associated with professional sports, team air travel is highly visible, under direct league control, and extremely difficult to decarbonize with technological advancement alone. In an analysis of air travel emissions from the four largest North American sports leagues, I estimate that teams traveled a combined 7.5 million kilometers in 2018, generating nearly 122 000 tonnes of carbon dioxide emissions. But the 2020 season saw major declines in travel as teams and leagues adjusted for the pandemic. Scheduling changes with cobenefits for player health and performance were central to this strategy including increased sorting of schedules by region and more consecutive repeated games ("baseball-style" series). If the scheduling changes implemented in 2020 were maintained in future years, air travel emissions reductions of 22% each year could be expected. Additional reductions in air travel emissions could also be achieved by using more fuel-efficient aircraft and shortened regular seasons.