Brendan Koerner has an article Slate Magazine with the great title, Are the Yankees Bad for the Environment? The fun title is a bit spoiled by a distinctly mediocre economic analysis of the environmental impact of the "Big Four" professional sports. Basically, the article creates back-of-the-envelope calculations for the amount of energy used at a stadium or arena for a single game as well as the energy used in transportation to and from the stadium. NFL games, with the highest average single game attendances, create the biggest carbon footprint per game while MLB teams, with the largest annual attendances are deemed least environmentally friendly over the course of a season.
Of course, the biggest problem with the analysis is that the writer implicitly assumes that in the absence of sporting events, fans would simply have stayed at home with the AC and lights off dining on vegetables grown in the backyard and cooked in a solar oven. In other words, the article calculates gross environmental impact instead of net environmental impact just as economic impact studies published by proponents of publicly financed stadiums generally publish gross rather than net economic impact figures for frachises and stadiums. This error causes the author to almost laughably conclude that Arena football is the most environmentally friendly sport due to low attendances and small arenas.