In the Saturday broadcast of the Milwaukee Brewers and St. Louis Cardinals, analyst Tim McCarver said, “It has not been proven, but I think ultimately it will be proven that the air is thinner now, there have been climactic changes over the last 50 years in the world, and I think that’s one of the reasons balls are carrying much better now than I remember.”
Jason Samenow of the Washington Post came to McCarver’s defense with this graph, which shows a general upward trend in temperature and home runs.
The graph I’ve displayed at the top of this post shows home run rates (number of home runs per team per game) have closely tracked the long-term changes in global temperature. They went up until the 1950s , leveled off through the 70s, and then ramped back up before showing a pause over the last decade or so. There are minor differences with the temperature curve but the similarities are eerie . . . To be sure, the changes in homerun numbers over time are complex . . . But it would be naive to discount weather from playing any role.
His argument is flawed for numerous reasons.
First, correlation does not equal causation. I could graph home runs per team per game alongside the amount of tobacco chewed by baseball players. Neither graph proves anything. Moreover, the correlation is not even that strong. There’s a huge discrepancy between home runs and temperatures in the 1950s and 1960s. Not very “eerie,” after all.
Second, before Babe Ruth, no home runs hitters compared to today’s hitters. John “Home Run” Baker led the American League in home runs four straight seasons, from 1911 to 1914. The most home runs he ever hit in a season was 12 in 1913. Babe Ruth’s 1920 season, in which he swatted 54 home runs, revolutionized baseball. Any comparison between home runs and temperature should not account for pre-1920 seasons. No serious fan would claim that the lack of home runs before then was caused by global temperatures. The increase in home runs from 1920 to 1940 can probably be explained by the spread of Babe Ruth’s techniques. Take away 1880 to 1920 and much of the upward trend is basically gone. Start the graph in 1940, and the trend is even less noticeable.
Third, there has been a steady decline in the amount of home runs in the past few seasons. Obviously, stricter testing for steroids has had a large part of that. The graph shows that the amount of home runs per team per game has decreased to levels that are comparable to the late 1950s and early 1960s–a period that is often considered a Golden Age for baseball. If there were a direct correlation between global warming and home runs (and global warming were worsening), then we should expect to see more home runs. The exact opposite is happening, though.
And finally, my biggest complaint: Can’t we just enjoy a baseball game without being lectured?