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MLB players are hitting more home runs. Researchers say it's linked to climate change

A photo of a red sox player swinging a bat with people in the stands blurred in the background
Michael Dwyer
Associated Press
Boston Red Sox's Justin Turner plays against the Los Angeles Angels during the eighth inning on Monday, April 17, 2023, in Boston. New research from Dartmouth shows how warmer temperatures caused by climate change are contributing to more home runs in Major League Baseball.

As a fan of the Boston Red Sox already grousing about the team’s early play, I’ve discovered a scapegoat for the barrage of home runs the team has yielded in the first weeks of the new season.

No, it’s not lousy starting pitching that’s the culprit… it’s climate change. At least in part.

Research out of Dartmouth College has revealed a link between climate change and an increase in Major League Baseball home runs.

Vermont Public’s Mitch Wertlieb spoke with climate scientist Chris Callahan, a PhD student in Dartmouth College's geography department. Their conversation below has been condensed and edited for clarity.

Mitch Wertlieb: So this report, this is kind of fascinating, especially for baseball fans, but also for anybody who's concerned about climate change. In the Bulletin of the American Meteorological Society, with research from Dartmouth, the study findings are that more than 500 home runs since 2010 can be attributed to higher temperatures due to climate change. How in the world did you conduct the research to find out those numbers?

Chris Callahan: Well, we know the basic physical process here is that when the air is warmer, it's less dense, which means there's less air resistance for a ball to fly through. And so we know that balls hit in warmer air will carry farther. So that basic physical relationship was understood.

What we did was take data on over 100,000 baseball games, over 200,000 individual batted balls, and correlate increases in temperature with increases in home runs, during games, controlling for the other factors that might affect home runs and temperature, like the dimensions and the climate of the ballpark, trends in things like PED use or changes in the construction of the ball. And we were able to show that abnormally warm temperatures due to climate change have already driven an increase in home runs.

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It's that last thing that you said, Chris, abnormal temperatures due to climate change, and I know that there are going to be people who are going to be skeptical. How do you know that this research shows that those warmer temperatures are in fact, due to climate change?

It's a good question. We use something that we call climate models, which are computer simulations of the climate, which allow us to distinguish human-caused climate change from natural variations in temperature and the climate. And so we were able to use those climate model experiments to show what the world would have looked like had temperatures not risen. And we can show that there would have been about 500 fewer home runs over the last 10 years, if we had not had human-caused climate change.

I do want to emphasize that that's only about 1% of all home runs in Major League Baseball. And so climate change is certainly not the only factor affecting home runs. But it certainly is one factor.

What prompted you to do this research in the first place? Because I understand that as a baseball fan yourself, you had some impetus watching baseball games to say, "Hey, I want to take a look into this."

Yeah, you know, I think about baseball a lot as a baseball fan as a Cubs fan. I also think about climate change for my day job. And so eventually those two things were going to collide. And I had known about this sort of basic physical mechanism where people were expecting more home runs with higher temperatures, but it had not really been formally tested. And so I decided, we can use the methodologies and the tools that we normally use for climate science research and apply them to this really interesting and fun problem.

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And didn't the late Tim McCarver, the great All Star catcher, mention some of this when he was broadcasting games, saying that the air being thinner may be causing these balls to fly farther out of the park?

Absolutely. Tim McCarver on a TV broadcast in 2012 brought up this idea. And he was roundly mocked for it, actually, but I think we've vindicated him.

You know, you mentioned that you're a Cubs fan. And it occurs to me that one of the great things about the Cubs, one of the oldest teams in the league, like the Red Sox, is that they play a lot of day games at Wrigley Field. But also this research is showing that most of this increase in home runs, perhaps due to climate change — that 1% you're talking about —occurs more often during day games, is that right?

Absolutely. Day games are played during the hottest part of the day in the early afternoon. And so they are experiencing these high temperatures the most. Whereas night games in the early evening are much milder. Wrigley Field plays most of its games in the day. And so it is going to see a much stronger increase in home runs due to climate change than many other parks.

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I mean, I'm only being again, you know, slightly facetious here, but as a Cubs fan, isn't it more likely that the Cubs need to have better pitchers on their team given that they're playing more day games, and if their pitching isn't as good, they're going to be more susceptible to giving up home runs?

I would hope that the effect would go both ways. I would hope that the Cubs would also hit more home runs but I can never trust them. They failed me too many times.

Don't forget 2016 — you've got your back pocket always.

You know, obviously climate change is a really serious thing and we're talking about baseball in relation to it. Obviously not the biggest concern for the planet. But I'm wondering what kind of reaction has come about from this study since it's been published? What are you hearing from people, from peers, and just from regular folks who take a look at this? What's their reaction to it?

I think folks have realized something that we wanted to highlight going into doing this study, which is just that this is a illustration of the ways that climate change has perniciously altered many of the aspects of our lives in really subtle ways, and really drives home the influence of climate change for people and brings it to something that they really care about.

And so while it's not the most catastrophic or important impact, it is one that people can feel when they're thinking about baseball in their day to day lives. And so it really highlights the reality of climate change for people.

Have questions, comments or tips?Send us a message.

A graduate of NYU with a Master's Degree in journalism, Mitch has more than 20 years experience in radio news. He got his start as news director at NYU's college station, and moved on to a news director (and part-time DJ position) for commercial radio station WMVY on Martha's Vineyard. But public radio was where Mitch wanted to be and he eventually moved on to Boston where he worked for six years in a number of different capacities at member station a Senior Producer, Editor, and fill-in co-host of the nationally distributed Here and Now. Mitch has been a guest host of the national NPR sports program "Only A Game". He's also worked as an editor and producer for international news coverage with Monitor Radio in Boston.
Karen is Vermont Public's Director of Radio Programming, serving Vermonters by overseeing the sound of Vermont Public's radio broadcast service. Karen has a long history with public radio, beginning in the early 2000's with the launch of the weekly classical music program, Sunday Bach. Karen's undergraduate degree is in Broadcast Journalism, and she has worked for public radio in Vermont and St. Louis, MO, in areas of production, programming, traffic, operations and news. She has produced many projects for broadcast over the years, including the Vermont Public Choral Hour, with host Linda Radtke, and interviews with local newsmakers with Morning Edition host Mitch Wertlieb. In 2021 Karen worked with co-producer Betty Smith on a national collaboration with StoryCorps One Small Step, connecting Vermonters one conversation at a time.
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