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Spike in Major League Baseball homeruns attributed to climate change

According to a recent study by Dartmouth College, baseball games may soon be affected by climate change. The researchers found that more than 500 home runs hit since 2010 can be attributed to higher-than-average temperatures resulting from climate change. The experts also predict that there will be several hundred more home runs per season as global warming continues.

While the study only attributes one percent of recent home runs to climate change, the researchers estimate that rising temperatures could account for 10 percent or more of home runs by 2100 if greenhouse gas emissions and climate change continue unabated.

“There’s a very clear physical mechanism at play in which warmer temperatures reduce the density of air. Baseball is a game of ballistics. A batted ball is going to fly farther on a warm day,” said study senior author Professor Justin Mankin.

How the study was done

The researchers analyzed more than 100,000 major league games and 220,000 individual hits. They used these numbers to correlate the number of home runs with the occurrence of unseasonably warm temperatures. They estimated the extent to which the reduced air density that results from higher temperatures was the driving force in the number of home runs on a given day compared to other games.

Study lead author Christopher Callahan, a doctoral candidate in Geography at Dartmouth, said that the researchers accounted for many factors. Some of those included the use of performance-enhancing drugs, the construction of bats and balls, and the adoption of cameras. Also factored in were launch analytics, and other technology intended to optimize a batter’s power and distance.

“We don’t think temperature is the dominant factor in the increase in home runs – batters are now primed to hit balls at optimal speeds and angles,” Callahan said. “That said, temperature matters and we’ve identified its effect. While climate change has been a minor influence so far, this influence will substantially increase by the end of the century if we continue to emit greenhouse gases and temperatures rise.”

Ballpark location also a factor

The research team also examined each major league ballpark in the United States. The goal was to gauge how the average number of home runs per year could rise with each one-degree Celsius increase in the global average temperature. They found that the Chicago Cubs’ open-air Wrigley Field would experience the largest spike with more than 15 home runs per season. The Tampa Bay Rays’ domed Tropicana Field would remain level at one home run or less no matter how hot it gets outside. The Boston Red Sox’s iconic Fenway Park and the home of their archrivals the New York Yankees fall in the middle and would experience nearly the same effect as temperatures rise.

Night games would lessen the influence that temperature and air density have on the distance a ball travels. Covered stadiums such as Tropicana Field would nearly eliminate it, the researchers report.

While this phenomenon might seem innocuous, there are additional factors to consider as global temperatures rise, particularly the exposure of players and fans to heat.

“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,” said Professor Mankin. “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.”

Wealth of MLB data available to researchers

Professor Mankin pointed out that the wealth of data available for major league baseball games. This provided a unique opportunity to identify the repercussions of climate change on a cultural institution. Climate scientists typically focus on the increased likelihood and severity of natural disasters such as hurricanes, floods, and heat waves because of the far-reaching devastation these events wreak — and because there are records to study them.

“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,” Mankin said.

“It is really difficult to document how climate change is affecting cultural institutions and forms of recreation generally. For most cultural institutions, we simply don’t have the data. In fact, we struggle to track climate impacts around the world because of data poverty. A project like this makes me worry that warming is affecting so many other things we just can’t document.”

The impact of climate change on cultural institutions

Study co-author Professor Jeremy DeSilva emphasized the importance of the study. Exploring the impact of climate change on cultural institutions can have a powerful impact on people’s daily lives. 

“Baseball is one of these ways that American society holds a mirror up to itself and global climate change is just another example – baseball is not immune to it,” DeSilva said. He also noted that baseball has been a catalyst for social change in the past. He referred to desegregation to growing corporatization and the outsized influence of money.

Study co-author Professor Nathaniel Dominy discussed how baseball reflects American cultural values that are often in opposition to each other.

“Think about the expression of American cultural values in baseball and how many of them exist in opposition to the other: winning and losing, tradition and change, teamwork and individualism, logic and luck,” he said. “These same tensions are frustrating our collective response to carbon emissions, so it is extremely fitting to explore the effects of climate change on baseball. It is a potent metaphor for the American experience.”


The experts analyzed data from the past century of baseball and found a correlation between rising temperatures and an increase in the number of home runs. As temperatures rise, baseballs become less dense, making them more bouncy and easier to hit farther. The study’s authors had a shocking prediction. The number of home runs hit each season could increase by up to 50 percent by the end of the century if current trends in global warming continue.

The researchers hope that this study can serve as an entry point to opening discussion. It can help people understand the impact of climate change on various aspects of their lives. This includes cultural institutions like baseball.

“Maybe people who otherwise wouldn’t have will think about, and have a bigger conversation about, the more impactful and dangerous aspects of climate change once they know how it’s affecting this quintessential game in the history of our country,” DeSilva said.

The research is published in the Bulletin of the American Meteorological Society.

History of homeruns in MLB

Throughout the history of Major League Baseball (MLB), fans have witnessed some incredible displays of power. Players are hitting balls out of the park at a record-breaking pace.

But what is the historical average of yearly home runs in MLB? Looking back over the past century, the answer is a little more complicated than you might think.

In the early years of baseball, home runs were a rarity. In fact, it wasn’t until Babe Ruth burst onto the scene in the 1920s that the home run began to take on its current importance. Ruth’s incredible power and penchant for hitting home runs revolutionized the game. In the decades that followed, other sluggers followed in his footsteps.

From the 1920s through the 1960s, home runs continued to rise in frequency. During this time period, the average number of home runs hit per season fluctuated quite a bit. In some years seeing more than 5,000 home runs hit across the league, while other years saw fewer than 3,000. However, by the end of the 1960s, it was clear that home runs had become a staple of the game.

Homerun totals began to surge

In the 1970s and 1980s, the average number of home runs per season continued to rise. The introduction of new stadiums and the use of lighter, more powerful bats helped contribute to this increase. By the mid-1990s, the average number of home runs hit per season had reached an all-time high. More than 5,500 homers were hit across the league in 1999.

However, this surge in home runs was not without controversy. Many suspected that players were using performance-enhancing drugs (PEDs) to boost their power and hit more home runs. In the years that followed, several high-profile players were caught using PEDs. The league cracked down on drug use with more frequent testing and harsher penalties.

As a result of these efforts, the average number of home runs hit per season has declined in recent years. In 2021, for example, there were just over 5,000 home runs hit across the league. This was down from the peak of nearly 6,000 in 2000.

In summary, the historical average of yearly home runs in MLB has fluctuated over the years. The frequency of home runs rising and falling depending on a variety of factors. However, despite these fluctuations, the home run remains one of the most exciting and memorable moments in baseball. Fans will undoubtedly continue to thrill at the sight of a ball soaring over the outfield wall.


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