Famines, sea level rise, extreme weather, more pandemics—by this point, you’ve probably heard about the most disturbing consequences of climate change. What you might not have heard is that it could also hurt Major League Baseball. That’s right, America’s favorite pastime is imperiled by its other favorite hobby: burning fossil fuels.
Thanks, in part, to warming air temperatures, home runs in the MLB are becoming a more frequent occurrence. And the impact of global warming on dinger rate is set to become more pronounced in the future, according to a study published Friday in the Bulletin of the American Meteorological Society.
Between 2010 and 2019, climate change led to an additional 577 home runs in Major League games than there would’ve been otherwise, according to the researchers’ calculations. That’s 58 additional homers per season, on average.
The statistical analysis further suggests that, for every 1 degree Celsius (1.8 degrees Fahrenheit) temperature increase, the number of home runs in a given game goes up by nearly 2%. As climate change progresses, the researchers expect this effect to scale linearly—pushing homer count higher and higher—unless adjustments are made. Old school lovers of the sport aren’t psyched about it.
Why does temperature matter in baseball?
First, a little physics lesson. As air gets hotter, it becomes less dense. Temperature is really, on a molecular level, about how much energy particles have—how much they vibrate and bounce around. As air molecules get hotter and more energetic, they move around more, collide and repel more, spreading each other thinner and thinner.
When a baseball is slicing through the air, what it’s really doing is pushing particles of gas out of the way. In turn, these particles push back, creating the opposing force of drag that, coupled with gravity, will eventually culminate in a baseball (or any thrown object not in a vacuum) ending its forward trajectory and falling to the ground.
Day-to-day variations in temperature are huge in determining the course of a baseball game. This has been known for a long time, explained University of Illinois baseball physicist Alan Nathan in a phone call with Earther. Nathan was not involved in the new research but has studied temperature and home run rate before.
In a brief, not-peer-reviewed 2017 analysis, Nathan’s own models produced a thermal degree/home run rate relationship very similar to the one identified by the new research, but using different methods. He found that a 1 degree Fahrenheit change leads to about a 1% boost in home run number—converted to Celsius, it’s basically a dead-on match.
“The fact that we agree, given the very different ways we were approaching it, should make all of us feel good about [the work],” he said. The new study is the most in-depth analysis of baseball home runs and temperature to date, Nathan added—let alone the role of climate change. “It’s very comprehensive.”
But still, though temperature matters a lot in baseball, the changes in temperature wrought by climate change matter less. Right now, at current warming levels, global warming’s overall impact on MLB play is tiny, compared with other factors like day-to-day variation in weather, the baseball itself, and player behavior.
The new research notes that climate change-related homers accounted for only about 1% of the season total in 2019. Nonetheless, the influence of climate change on the sport is a significant, detectable signal that has far-reaching implications for how our fossil fuel reliance could impact a dear tradition, said Nathanial Dominy, an anthropologist at Dartmouth College and one of the authors of the new study, in a phone call with Earther.
This is a story about baseball. But it’s also a story about the future of human culture under climate change.
Are there too many home runs in baseball?
Home run rates in the major leagues fluctuate. Generally, they’ve increased since the 1980s. In more recent years, the number of home runs in the Major League has exploded (and then contracted slightly). There are probably multiple reasons why, and only a tiny fraction of that overall phenomenon is attributable to climate change.
The MLB has been studying the home run increase for a few years now. The league even assembled a whole committee dedicated to deciphering the issue (Nathan, the physicist, is on that committee.) The most significant factor those scientists and data experts have zeroed in on is the ball itself.
Something about baseballs has changed such that they experience less drag than they did in decades past. Though what, exactly, that determining alteration is remains up for debate. It could be the height of the stitching or something else about the ball’s surface or size. Then, there’s the issue of batter behavior and pitcher strategy.
But, even controlling for these factors, temperature remains important. Amid all the noise, Dominy’s data-focused team was able to isolate climate change’s effects.
To come to their conclusions, the scientists looked at the extensive recent Statcast data on baseballs thrown and hit at MLB games. They also considered historical U.S. baseball records going back as far as 1962 and, of course, temperature and weather data for each game as well as climate change trends. They accounted for precipitation, humidity, wind speed, home and visiting team scenarios, and more. The ~2% home run increase per degree Celsius remained.
Who cares about baseball when the world’s on fire?
It’s a small but still meaningful shift for a sport that epitomizes American culture, Dominy said.
“I’m a lifelong baseball fan. But I’m also a researcher who studies cultural institutions,” he said. The way he sees it, baseball is more than a sport; it’s a “metaphor for the American experience.” Through the opposing concepts of team/individual, losing/wining, tradition/change, youth/experience, work/recreation, and logic/luck, he views the baseball field as a place where the quintessential tensions of the United States play out every spring and summer. Climate change, he adds, seems to be going much the same way. And here, with the analysis that Dominy helped put together, the two intersect.
In the anthropologist’s assessment, climate change is shifting the very essence of one of our society’s traditions. And not for the better. “It makes me a little sad,” Dominy said. “Home runs are an exciting play, but I would say a triple is even more exciting,” he explained. All in all, increasing home runs will “make baseball worse because it’ll make an exciting play a little bit mundane, and it will make triples extremely rare.”
He’s not alone in this view. For the uninitiated: Though home runs are a well-known, often thrilling in-game feature of baseball, many old-school, diehard fans and analysts of the sport agree there can be too much of a good thing. As home runs rise, baseball’s complexity and other allures decline, according to Dominy, Nathan, and Christopher Callahan, a PhD candidate studying climate change’s economic impacts at Dartmouth who led the new research.
Plus, though the air density changes brought on by global warming might have a relatively teeny impact on the events of a game, hotter temperatures are likely changing baseball in other ways, Callahan noted. Heat stress for players and ballpark fans, for instance, is something he’d like to examine in the future.
But baseball isn’t all that’s at play here for Callahan. “Major League Baseball is an incredibly well studied phenomenon,” he explained. “It’s one of the most well-documented activities in the history of humankind.”
“We can say things about how climate change affects baseball because we have that data. But there are so many situations where we don’t have that data,” Callahan said. In a sense, Major League Baseball here is a proxy for all of the cultural touchstones and human behaviors that are being subtly (or not-so subtly) shifted through global warming. Some of these changes have been previously described, like the climate-driven disappearance of Indigenous practices, knowledge, and archaeological sites in the Arctic. But so many yet remain invisible to science.
Compared with the grand threat of climate change, baseball alone doesn’t really matter, admits Alan, a diehard fan who retired from a career in nuclear physics to commit to full-time study of the sport. “If there were a larger increase in global temperatures, baseball would be the least of our worries,” he said. And, if the MLB decided to account for climate change, it could easily adjust circumstances, stadiums, or even ball design to minimize temperature’s impact on the game, every source I spoke to noted.
But climate change matters, and the study demonstrates that its tendrils are worming their way into just about everything.
While working on the study, Callahan, Dominy, and their other Dartmouth-based co-authors took a “research trip” to Fenway Park to watch a game together. It was May 5, 2022. The Red Sox were up against the Angels. Shohei Ohtani owned the day (for those who care). It was a warm spring afternoon, with a high around 70 degrees, 7 degrees F higher than the historical normal, according to NOAA data. There were two home runs, per ESPN’s recap. Dominy enjoyed the spectacle, of course. But as he sat in the nosebleed section with his fellow academics, it was probably hard for him not to wonder if—on a healthier planet—those homers could’ve been triples.