Global Warming: the surprising effects on male fertility

Whatever one’s opinion on the realities and consequences of climate change, one fact remains certain: Since most all of the effects of global warming are viewed as occurring over a long arc – with substantive changes likely to be noticed only after decades, or even centuries – the time for taking proactive steps ought to be now, not further down the road, when efforts might amount to a case of too little, too late.

This is especially true for couples trying to conceive. According to a new study led by UCLA environmental economist Alan Barreca, hot weather puts a damper on one’s chances of getting pregnant. And the effects of global climate change aren’t helping to improve the odds.

Think Barreca is overstating the case? Take a. loser look at his findings.

The study, published in the August 2018 of the journal Demography, minces no words: “We find that days with a mean temperature above 80°F cause a large decline in birth rates 8 to 10 months later.”

And Barreca’s research team isn’t talking merely about recent higher temperatures since talk of climate change entered the common lexicon. On the contrary, they estimated the effects on birth rates in the U.S. by examining statistics from 1931 through 2010, or 80 years’ worth in all.

In what he says is a marked departure from prior studies on the subject, Barreca’s team showed that the start of the birth-rate decline is followed by a fractional surge in births over a period of following months, which suggests that populations help to reduce some of the damage by changing the month in which conception occurs.

In a UCLA press release, Barreca said, “If you look nine months after a heat wave in August, the following May you see significantly fewer births.”

The drop in births isn’t due to people having less sex when the temperature rises, Barreca added. The opposite, in fact, proves true. Citing studies that show sperm production decreases in hot weather, he argued that the pattern is probably attributable to heat’s effect on male fertility.

But what about elevated birth rates in countries such as India, where temperatures run toward the high end of the thermometer?

Turns out that temperature is just one factor influencing birth rates; Barreca notes that regions with higher poverty rates -- not to mention a dearth of equal rights for women – usually have higher birth rates.

It also turns out that even India has experienced problems with higher temperatures affecting fertility – problems that appear to match Barreca’s.

Medical experts in Mumbai were recently quoted in The Asian Age as saying that rising temperatures in that city will have negative effects on male fertility. Over the last 20 years, doctors there have noticed a 20 to 25 percent decrease in sperm counts.

“If there is a long span of days when the temperature is above 27 degrees Celsius [80.6 degrees Fahrenheit], then it affects the fertility in men as the sperm count drops,” said Dr. Suchitra Pandit, gynecologist and obstetrician, Kokilaben Dhirubhai Ambani Hospital.

Dr. Hetal Parekh, consultant fertility physician from Hiranandani Hospital, added that in winter months, men display increased fertility than in summer months. Which means that if winters continue to become warmer, as The Indian Express reports has been the trend recently, men will experience lower fertility, resulting in an accompanying lowered reproduction rate.

Another aspect of the effects of climate change that stands to impact reproduction rates involves the male-female ratio.

A 2014 study published in the journal Fertility and Sterility examined the effects of higher temperatures on fetuses and newborn infants in Japan.

Researchers looked at possible links between temperatures recorded between 1968 and 2012, and sex ratios of births and fetal deaths. Their conclusion: “The recent temperature fluctuations in Japan seem to be linked to a lower male:female sex ratio of newborn infants, partly via increased male fetal deaths.”

This finding further suggests that, with fewer males as compared to the number of females, birth rates will continue to remain lower and perhaps reduce even more as the effects of global warming continue to manifest. And Japan already is experiencing its lowest birth rate in half a century.

As with all things climate change, skeptics doubt the certitude of the study findings in Japan, noting that prior research indicates that male embryos can experience negative effects from toxic agents and, of all things, earthquakes.

Given the most recent research, however, coupled with the long-accepted view that any marked increase in scrotal temperature has negative consequences for sperm production and survival, it seems better to err on the side of caution when it comes to climate change.

Indeed, as the UCLA study declares, “Historical evidence suggests that air conditioning could be used to substantially offset the fertility costs of high temperatures.”

All the more reason to take a safer leap further and cryogenically preserve your assets today.