Climate change is turning major league sluggers into even hotter hitters, sending about 50 extra home runs a year over the fences, a new study has found.
Warmer, thinner air that allows balls to fly farther contributed somewhat to an increase in home runs since 2010, according to a statistical analysis by scientists at New Hampshire’s Dartmouth College released Friday. Bulletin of the American Meteorological Society. They analyzed 100,000 major league games and more than 200,000 balls put into play in recent years along with weather conditions, stadiums and other factors.
“Global warming is accelerating home runs in Major League Baseball,” said study co-author Justin Mankin, a Dartmouth climate scientist.
It’s basic physics.
less dense air
When air warms, the molecules move faster and away from each other, making the air less dense. Baseballs thrown from a bat travel farther through thinner air because there is less resistance to slow the ball down. Just a little more can mean the difference between a home run and a fly ball, said Alan Nathan, a physicist at the University of Illinois who was not part of the Dartmouth study.
Nathan, one of a group of scientists who consulted with Major League Baseball on the increase in home runs, made his own simple calculation, based solely on the known physics of ballistics and the density of air as it changes with temperature, and said which got the same result. like the Dartmouth researchers.
Both Nathan and the Dartmouth team found a 1.8 percent increase in the probability of home runs with each degree Celsius that the air warms. The total annual average number of home runs assisted by warm-ups is only one percent of all home runs, the Dartmouth researchers calculated.
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The number of home runs in the majors has increased in recent years, and not just because of improving skills and improving equipment. Christopher Callahan, a climate researcher at Dartmouth College in New Hampshire, found that about 500 more home runs have been hit since 2010 due to climate change. The physics are simple: warmer air is less dense, so the ball has an easier time hitting the park. His research was published in The Bulletin of the American Meteorological Society.
Non-climatic factors are further contributing to the spate of balls flying out of the park, scientists and baseball veterans said. The biggest things are the ball and the size of the points, Nathan said, and MLB made small adjustments to cushion the ball ahead of the 2021 season. Others include recent hitters’ attention to launch angle; stronger hitters; and faster pitches. The study began after the end of the infamous steroid era in baseball saw an increase in home runs.
Veteran baseball players and executives said the research fits with what they’ve seen on the field.
“We’ve always felt that way for years,” Phillies president of baseball operations Dave Dombrowski said. “When it’s hotter, the ball travels further and they have scientific evidence to back it up.”
Home runs have always varied by ballpark due to simple factors like dimensions that are friendlier to pitchers than hitters, or vice versa, as well as wind conditions.
The Dartmouth team also found that the effect of the climatic home run varied by field. Chicago’s Wrigley Field, which still hosts many day games, has the warmest home run friendly confines. Statistical analysis found no significant heat-assisted home runs at Tampa’s Tropicana Field, the only full-time domed ballpark in Major League Baseball.
“It’s interesting to think about,” said five-time All-Star pitcher David Cone, who once pitched a perfect game and is now a television baseball analyst. “I would probably look more at the composition of the baseball itself, the variations and the specifications. Of course, weather matters; I definitely wouldn’t scare it away.”
After a 1-0 victory Thursday at Coors Field in Denver, Colorado Rockies reliever Brent Suter said the study, which lists more than 500 home runs since 2010, rings a bell.
“Obviously, I’m not a fan in any way as a pitcher,” Suter said with a laugh. “500 seems like a lot, but I could believe it.”
Heat is also tough on players and fans, Suter said: “I remember throwing in a few games, I was like, ‘This doesn’t feel like normal heat. It’s crazy hot.’
Mankin called what is happening “a fingerprint of climate change on our recreation.”
Christopher Callahan, another climate researcher at Dartmouth, said what has been seen so far pales in comparison to projections of hundreds of more home runs in the future.
The number of extra home runs depends on how hot it is, which depends on the amount of greenhouse gases the world emits from burning coal, oil and gas. Callahan ran different carbon pollution scenarios through computer simulations.
In the worst-case warming trajectory, which some scientists say the world is no longer based on recent emissions, there would be about 192 hot home runs per year by the year 2050 and about 467 hot home runs for the year 2100. In more moderate carbon pollution scenarios, closer to where Earth is now tracking, there would be about 155 warming-assisted home runs a year by 2050 and about an additional 255 home runs by the end of the century, Callahan said.
Because baseball has so many statistics and analytics, such as the Statcast tracking system, trends can be seen more easily than other effects of climate change, Mankin said. Still, scientists can’t point to a single home run and say it’s a warm-up-assisted home run. It is a detail that can only be seen in the more than 63,000 home runs hit since 2010.