The beginning of this fall’s football season coincides with an ominous report published on July 25 in the Journal of the American Medical Association.


Dr. Ann McKee, a neuropathologist at Boston University School of Medicine, studied the brains of 111 deceased National Football League players and found that a staggering 110 of them were afflicted with chronic traumatic encephalopathy (CTE), a condition associated with repeated blows to the head.


McKee acknowledges that these dramatic results are skewed by selection bias; the brains were largely donated by the families of NFL players who already exhibited signs of CTE, including depression, memory loss and addiction.


Nevertheless, as the New York Times report on the study notes, even if the 1200 other NFL players who died during the course of the study had been CTE-free — which is unlikely — the 9 percent rate of CTE for NFL players would be far higher than for the general population.


Dr. McKee concludes: “It is no longer debatable whether or not there is a problem in football — there is a problem.”


Still, this report is less new information than confirmation of something that we already know but prefer to ignore.


In fact, our denial of football’s concussion issue rivals our denial of climate change. Two days after the report came out, Rush Limbaugh, a persistent climate-change denier, was contending that concerns over concussions were merely part of the left’s scheme to increase its power by making everyone into a victim.


For its part, the NFL is playing a loose, prevent-style defense. In a statement to Sports Illustrated, it expressed appreciation to Dr. McKee and her colleagues for supporting “the ongoing quest for a better understanding of CTE.” The NFL promises to work with “a wide range of experts to improve the health of current and former NFL athletes.”


But in the tradition of climate-change denial, the NFL notes that “there are still many unanswered questions relating to the cause, incidence and prevalence of long-term effects of head trauma.”


Frankly, the NFL doesn’t seem worried. Football is a spectacular, exciting game and our devotion to the NFL’s $10-billion-per-year product likely makes it an institution that’s too big to fail.


In light of the near-certain confirmation that their way of making a living will damage the quality and length of their lives, some players are philosophical or fatalistic.


As Brandon Brooks, a right guard for the Philadelphia Eagles, told NJ.com’s Matt Lombardo: “As grim as it is to say, I’ve played long enough that either it’s going to happen, or it’s not. I’m not going to change my career-path. I’m playing the game I love.”


A few have retired early because of concussion concerns, but the NFL is unlikely to suffer from a lack of players. Many players don’t see other options. They are unlikely to find anywhere else the status and financial rewards that they find in the NFL, whatever the physical and mental cost.


Furthermore, the NFL resides securely at the end of a high-attrition supply chain of players that begins in youth football and culminates, many hard blows to the head later, with the rewards of the professional level.


In many respects, the NFL is the driving engine of the supply chain of players. As one enormous, powerful and sweet-natured offensive tackle, a freshman in my writing class decades ago at the University of Texas at Austin, told me: “Every guy out there on the practice field thinks he gonna make it in the NFL someday.”


But, of course, they don’t. Vanishingly few footballers ever reach the pros, and the path is strewn with considerable carnage. Credible evidence indicates that CTE begins at least as early as high school. McKee’s study included the brains of 53 college players; 48 showed CTE.


Here’s the undeniable fact: football is just too hard on the brain.


Individuals can do little to slow down the undeniable progress of climate change; individual parents, however, can refuse to allow their sons to play football.


But they have to be quick: it’s nearly autumn, and the brain damage has begun.


John M. Crisp, an op-ed columnist for Tribune News Service, teaches in the English Department at Del Mar College in Corpus Christi, Texas. Readers may send him email at jcrisp@delmar.edu.