Fertility hit by climate change

Global warming isn't affecting only Mother Earth, it's affecting sperm, as well.

A report published Tuesday in Nature Communications is linking declining male fertility to soaring temperatures as research shows sperm production in hot climes declines significantly.

Using beetles as test subjects, the study showed “clear evidence” that stress from heat waves reduces “sperm number and viability” in the bugs.

In men, sperm production in the testicles must be cooler than the inner temperature, according to the University of Rochester Medical Center.

But scientists found “that heat wave conditions (9 to 13 degrees above the typical high temperature for five days) damaged male — but not female — reproduction,” the study revealed. “Heat waves reduce male fertility and sperm competitiveness, and successive heatwaves almost sterilize males.”

Further, the offspring of beetle fathers who had endured the intense heat lived shorter lives.

Heat waves are predicted to be much more frequent and extreme in the 21st century as human-caused climate change continues.

“Research has also shown that heat shock can damage male reproduction in warm-blooded animals, too, and past work has shown that this leads to infertility in mammals,” added researcher Kirs Sales. “Our research shows that heat waves halve male reproductive fitness, and it was surprising how consistent the effect was.”

A 2017 study noted that sperm counts in America, Australia and Europe had drastically plummeted by more than 50% over the past four decades, meaning men today are about half as potent as their grandfathers.

The report, co-authored by Mount Sinai Medical School and Hebrew University, alarmingly revealed that sperm counts declined from 99 million sperm per milliliter of semen in 1973 to only 47 million sperm in 2011.

Scientists have been warning for decades that males with lackluster semen quality are prone to suffer from cardiovascular disease, diabetes and cancer at higher rates than fertile men.