Over the past decade, baseball has experienced a surge as home runs have flown off the baseball diamond at record pace. In 2019, for example, pitchers gave up 1.4 home runs per nine innings, the highest home run rate for any reason on record and a 55.6 percent increase over the 2011 rate. first five days of this season, batters continued to hit home runs at a record pace.) game, robbing baseball of the “small ball” action (think single-base and stolen bases and big field plays) that made once the thrilling national pastime. A host of reasons have been advanced for this trend: snappier baseballs, improvements in player training, batters swinging bats at angles more likely to lift the ball out of the park.
And according to a new study published in the Bulletin of the American Meteorological Society, another factor is definitely at play: global warming.
An empirical analysis in the journal article, “Global warming, home runs and the future of America’s hobby,” found that after separating out factors such as baseball’s physical characteristics and advanced analysis of the data that indicate the pitching trends, a 1℃ increase in daily maximum temperature on the day of a game played in an outdoor stadium increases the number of home runs in that game by 1.95%. The study analyzed more than 100,000 games played between 1962 and 2019. A more granular analysis of recent data provided by Statcast, the system of high-speed cameras installed in MLB stadiums that tracks data on every fly ball, allowed seekers to effectively control for the skill of the hitter and hitter. Comparing balls leaving the bat at the same angle and speed on a hot day versus a cold day in outdoor baseball diamonds, Statcast analysis found that between 2015 and 2019, an increase of 1℃ temperature led to a 1.7% increase in home runs per game.
In total, the researchers conclude that global warming resulted in 58 additional home runs per year, and 577 home runs in all, between 2010 and 2019. That number represents 1.1 percent of all MLB home runs affected during that time. Although climate change played a relatively small role in the last decade’s wave of home runs, researchers predict that future warming will continue to give pitchers headaches. If greenhouse gas emissions and climate change continue unabated, modeling predicts warming could account for 10% or more of all affected home runs by 2100.
Fundamental physics explains this phenomenon. According to the ideal gas law, the density of air is inversely proportional to temperature. Hotter air is less dense, allowing a bullet to carry farther. “Just from the ballistics, we know there will be less resistance to baseball in hot weather,” says Justin Mankin, climatologist and professor of geography at Dartmouth, lead author of the study. “There is a very good physical relationship at work here.”
While this research may seem frivolous outside the cozy confines of baseball, for Mankin and his co-authors, it’s anything but. “The big thing that highlights is that data poverty is a huge problem,” Mankin says. “Major League Baseball is a privileged activity for which we have a wealth of data. High-speed cameras in every stadium, capturing the launch angle and launch speed of every ball hit, it’s nonsense. I’m concerned about the things we don’t have great metrics for.
For example, what is the impact of heat exposure on fans in baseball stadiums? Or on a larger scale, how does climate change influence public health in southern countries? “The human costs of climate change are far greater than changing the number of home runs in Major League Baseball,” Mankin says. “But we are able to design adaptation and response measures, such as building domes or switching to night games. We are able to attribute the effect of global warming to this in the first place because we have the data.
Sports stakeholders, however, are sure to gloss over these issues of global importance. Agents can be in contact with these researchers, asking for their help during arbitration hearings and free agent negotiations. Maybe it wasn’t their client’s crappy curveball that’s responsible for a bloated era.
It had to be global warming, right?
“It’s not something I thought about, but now it’s something I’m very concerned about, so thank you for that,” says study co-author Christopher Callahan, PhD candidate in geography at Dartmouth who designed the study. “We don’t identify the influence on an individual home run. We’re just saying that on average, over time, the probability of home runs will increase. It won’t stop people from calling me. But it’s worth saying. »
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