Climate Change Could Be Contributing to Male Infertility, Scientists Warn

There's evidence that heat has always been bad for sperm, and data indicates it could get much worse.

Climate change is not just inconveniencing polar bears and coastal communities — it may soon begin impacting male fertility, too. “The existing science shows that extreme heat leads to fewer conceptions,” Alan Barreca an environmental economist from UCLA told Fatherly. The exact reason why there’s fewer conceptions is not totally clear.”

Although anecdotal evidence (and some unpublished researchsuggests that people have higher sex drives in the summer, more babies are conceived in September. Heat exposure has been linked with poor sperm quality, and scientists suspect that men are simply more fertile in the winter. In a recent study, published in the journal Demography, Barreca and his team analyzed birth records in the U.S. from 1931 to 2010 along with weather data. They found that days with a mean temperature above 80 degrees Fahrenheit saw the steepest declines in birth rates 8 to 10 months later. Climate change could give many Americans more of those sweltering days. “Today, there’s about 30 days where the maximum temperature is above 90 degrees for the average person in the U.S. By the end of the century, climatologists are predicting that there will be 90 such days,” Barreca explains.

With fertility rates already declining, and Americans starting families later in life, another hit to fertility is the last thing aspiring parents need. “We can speculate that climate change will harm sperm production. It’s speculative, but it’s certainly possible that the climate change that’s occurred over the past 30 years has lead to more fertility problems,” Barreca says.

“The climate’s effect is likely to be only a small part of the story for why male fertility has declined in recent years. “