The Dawn of Climate-Ball: Home Runs on the Rise

Global warming leads to higher temperatures, lowering air density and resulting in more home runs as found by a Dartmouth College study.

In the storied history of Major League Baseball, various eras have defined the game, from the low-scoring dead-ball era to the modern live-ball era, epitomized by legendary power hitters like Babe Ruth and Hank Aaron.

Sadly, the steroid era of the 1990s and early 2000s cast a shadow over the sport.

However, a new era could be dawning: the “climate-ball” era, where global warming’s rising temperatures may increasingly sway game outcomes, in part due to more home runs.

Climate Change’s Impact on Home Runs

A new study from Dartmouth College published in the Bulletin of the American Meteorological Society indicates this possibility.

The researchers found that over 500 home runs since 2010 can be linked to higher-than-average temperatures due to climate change, with hundreds more expected each season as warming continues.

While climate change accounts for only 1% of recent home runs, this figure could rise to 10% or more by 2100 if greenhouse gas emissions and climate change continue unchecked.

Warmer Temperatures Reduce the Density of the Air

The study’s co-author Justin Mankin, an assistant professor of geography, explained that “warmer temperatures reduce the density of air,” which in turn affects the ballistics of the game, causing batted balls to fly farther on warm days.

The study analyzed over 100,000 major league games and 220,000 individual hits to establish a correlation between home runs and unseasonably warm temperatures.

The team then estimated the impact of reduced air density resulting from higher temperatures on the number of home runs in a given day compared to other games.

The researchers considered various factors, including performance-enhancing drug use, bat and ball construction, and the implementation of technology designed to optimize batter power and distance.

Home Runs and Stadiums: How Temperature Affects the Great American Pastime

Co-author Christopher Callahan, a doctoral candidate in geography at Dartmouth, said that while temperature is not the dominant factor in the increase in home runs, “it matters, and we’ve identified its effect.”

If greenhouse gas emissions continue and temperatures rise, climate change will become a more significant influence on the game by the end of the century.

The researchers also evaluated how each major league ballpark in the US could see an increase in the average number of home runs per year with every 1-degree Celsius increase in global average temperature.

They discovered that open-air Wrigley Field, home of the Chicago Cubs, would experience the most significant spike, while the domed Tropicana Field of the Tampa Bay Rays would remain relatively unaffected.

Fenway Park and the New York Yankees’ stadium fall somewhere in between.

Night games and covered stadiums like Tropicana Field would mitigate temperature and air density effects on ball distance, the researchers noted.

As global temperatures rise, it is crucial to consider factors like heat exposure for players and fans.

Mankin emphasized the importance of determining an “acceptable level of heat exposure” and the trade-offs involved in maximizing home runs.

Baseball’s Unusual Wealth of Data Allows for Such Insights

The wealth of data available for major league baseball games allowed the researchers to examine climate change’s repercussions on a beloved cultural institution.

Mankin acknowledged the difficulty of documenting climate change’s effects on other cultural institutions and recreational activities due to data scarcity.

This study, initiated by baseball enthusiast Callahan, highlights the potentially pervasive ways climate change might subtly alter various aspects of our lives beyond heatwaves, megadroughts, or cataclysmic hurricanes.

Baseball as a Mirror: Climate Change and American Society

Co-author Jeremy DeSilva, professor and chair of anthropology at Dartmouth, emphasized the value of evaluating climate change’s impact on cultural institutions, as it can resonate more with people’s daily lives than large-scale disasters that seem random and uncontrollable.

Baseball has been a touchstone for social change in the past, from desegregation to growing corporatization and the outsized influence of money.

DeSilva believes that “baseball is one of these ways that American society holds a mirror up to itself,” and the sport is not immune to global climate change.

Studies like this can provide an entry point to understanding a phenomenon that affects the planet and every individual on it, potentially sparking broader conversations about climate change’s far-reaching consequences.

Nathaniel Dominy, the Charles Hansen Professor of Anthropology at Dartmouth and a co-author of the study, explained that cultural institutions, such as baseball, reflect societal values and encapsulate the American response to climate change.

He noted the tensions in baseball between winning and losing, tradition and change, teamwork and individualism, and logic and luck, which are also present in the collective response to carbon emissions.

As such, exploring climate change’s effects on baseball serves as a potent metaphor for the American experience.

The study, titled “Global warming, home runs, and the future of America’s pastime,” was published on April 7, 2023.

Funding came from a National Science Foundation Graduate Research Fellowship, the Neukom Institute for Computational Science, and the Nelson A. Rockefeller Center for Public Policy and the Social Sciences at Dartmouth College.


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