Baseball players, coaches, and spectators have watched for years as the number of home run (when the batter hits the ball far enough to cover all the bases and complete a run) in major competitions are on the rise. In recent Major League seasons, the number of home run it has grown drastically, which has led to a debate among sports analysts throwing up different suspicions that explain the phenomenon: from changes in the construction of the fields to changes in the ball or the performance of the players.
However, several scientific studies suggest another, more surprising reason: rising temperatures due to climate change.
The study. Research from Darthmoud University published in the Bulletin of the American Meteorological Society set out to test all of these assumptions. To do this, they analyzed data from more than 100,000 official competition games and more than 200,000 batted balls, as well as observing game-day temperatures.
As? They used data from high-speed cameras that ballparks have had since 2015, which provide information like the launch angle and launch speed of each hit. That means they were able to compare a ball coming off a bat with the same angle and velocity on a warm day and on a cold day.
Hitting hot vs hitting cold. According to the laws of physics, warm air is less dense than cold air. As the air gets hotter and the molecules move faster, the air expands, leaving more space between the molecules. Thus, a batted ball should be thrown farther on a warmer day than on a colder day due to less air resistance.
Some scientists like Alan Nathan have been determined to demonstrate the connection between climate change and the home run, that the balls go further at higher temperatures, but no official research had ever been done on this. Until now.
The results. Thanks to the experiment in Darthmoud, they concluded that a game on a day that is 10ºC warmer than average has almost 20% more home run. In fact, they found that more than 500 home run since 2010 could be directly related to the reduction in air density driven by human-caused global warming.
The authors also determined that a 1°C rise in maximum temperature on the day a baseball game is played (in an uncovered stadium) increases the amount of home run 1.96%. In games played in the early afternoon, even more: 2.4%. Therefore, each degree caused by climate change is associated with about 95 home run more per baseball season. Which indicates that it will cause 192 home run more per year until 2050 and another 467 by 2100.
Because? As Jana Houser, an associate professor of meteorology at The Ohio State University, explains in this Bloomberg article, the relationship between heat, lower air density, and the path of a baseball is clear: “The hotter temperatures warmer are associated with lower density air. As such, a flying object will encounter less molecular resistance in the air as a result of having to move through fewer air molecules. This would imply that for an equal amount of force applied to the ball , it will go further in warmer air temperatures than in colder temperatures.”
Solutions. Although there are still other factors that also explain the more or less home run in baseball, such as the architecture of the ball, the doping between athletes, the change of training or the differences in elevation between the stadiums, the temperature represents a drastic change.
To avoid this, some experts have suggested that match times be modified so that they are played at night (like most football matches in Europe), or that domes be built over the stadiums. In Denver, where the air is less dense due to its higher elevation, the Rockies team began storing game balls in a humidification system in 2002 to make them “softer.”
Image: daiji umemoto (Unsplash)
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