Climate change will impact whether babies are born male or female

There is a growing collection of studies which demonstrate the shocking impacts that climate change will have on our planet. According to a new study from Japan, global warming may even affect the proportion of babies who are born male or female.

Researchers have determined that more boys will be born in places where temperatures rise, while fewer boys will be born among other environmental changes, such as extreme weather events.

Study lead author Dr. Misao Fukuda, who is the founder of the M&K Health Institute in Hyogo, explained to CNN that conceptions of boys are particularly vulnerable to external stress factors.

Last year, the team published a separate study that was focused on births in regions where extreme weather events had caused major stress, including the Hyogo Prefecture after the Kobe earthquake of 1995, Tohoku after the Great East Japan Earthquake and Fukushima disaster of 2011, and the Kumamoto Prefecture after the 2016 earthquakes.

Looking into births nine months after the disasters, the experts found that the proportion of male babies born in these prefectures declined by up to 14 percent compared to the previous year.

Fukuda told CNN in an email that pressure stemming directly from weather events associated with global warming may also affect the sex ratio. While the underlying cause is unclear, Fukuda theorized that changes in sex ratios are due to the sensitivity of male-bearing sperm cells, male embryos, or male fetuses to stress.

A separate study from the University of Turku in Finland found that “warmer temperatures bring sons.” The investigation, which was focused on the Sami people of Northern Finland, revealed that there was a 0.06 percent increase in the ratio of newborn boys compared with girls for every degree Celsius of temperature rise.

“Not a dramatic influence at first sight but it should be remembered that in large populations such effect size might mean thousands of ‘extra’ boys annually,” study author Samuli Helle said in an email.

Ray Catalano is a professor in the School of Public Health at the University of California, Berkeley. He explained to CNN that the impacts of global warming will also drive the process of natural selection in utero.

“For every society, for every year, the human being most likely to die (prematurely) is male infants. And that’s true for every society that we have data for,” Professor Catalano told CNN.

“If you start to change the environment relatively quickly – within 100, 150 years; in evolutionary time, that’s a blink of the eye – what that means is that you’re going to change the environment in which human gestations occur.”
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By Chrissy Sexton, Earth.com Staff Writer

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