Is a Spike in Major League Baseball Home Runs Linked to Climate Change?

By Rob Dillard - Last Updated: April 7, 2023

Baseball has been through the dead-ball era, the live-ball era, and the steroid era, but a new study indicates Major League Baseball may be on the cusp of a “climate-ball” era where higher temperatures result in more long balls. The study was conducted by Dartmouth College and reported in Bulletin of the American Meteorological Society.

In this study, researchers assessed more than 100,000 major league games and 220,000 individual hits in an effort to link the number of home runs with the occurrence of unseasonably warm temperatures. Subsequently, they estimated the extent to which the reduced air density caused by higher temperatures contributed to home runs on a given day compared to other games.

“We asked whether there are more home runs on unseasonably warm days than on unseasonably cold days during the course of a season,” said senior author Justin Mankin, an assistant professor of geography via a press release. “We’re able to compare those days with the implicit assumption that the other factors affecting batter performance don’t vary day to day or are affected if a day is unseasonably warm or cold.”

The study found that only 1% of recent home runs can be correlated to climate change, but they noted that rising temperatures could account for 10% or more of home runs by 2100 if greenhouse gas emissions and climate change persist.

“A key question for the organization at large is what’s an acceptable level of heat exposure for everybody and what’s the acceptable cost for maximizing home runs,” Mankin said. “Home runs are one pathway by which temperature is affecting game play, but there are other pathways that are more concerning because they have human risk attached to them.” He added that: “Major League Baseball is a multibillion-dollar industry that is very data-rich, and that privilege allowed us to identify the effect of climate. This critical cultural touchstone for what it means to be American also happens to have a very salient relationship with physics in that temperature actually affects game play.”



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