Could Climate Change Mean Less Sex and Fewer Babies?

Even if it does, perhaps that’s not a bad thing

heatwave couple
It's getting too hot in here Jim Craigmyle/CORBIS

The changing climate has infiltrated every aspect of society, from natural disasters to struggling animal species, but is it sneeking into our bedrooms? Warmer temperatures could mean less sex and—at the risk of stating the obvious—fewer babies, Eric Roston reports for Bloomberg Business.

A team of three economists poured over 80 years of U.S. fertility data and concluded that sweltering days, when temperatures climb above 80 degrees Fahrenheit, are followed by fewer births 8 to 10 months later. To put it delicately, these heatwaves coincided with "not tonight, honey."

Before people start panicking, there are some important facts to consider. The drop in birth rates is a very slight, only 0.4 percent or 1,165 fewer babies delivered, Roston reports. A rebound in the months following that dip (relief from the heatwave, perhaps?) makes up about a third of that drop. 

"That means the effect of hot days on the birth rate in 2015 is probably only about 0.13 percent—the researchers would probably find a bigger effect each time a new season of a popular show is released on Netflix," writes Eric Holthaus for Slate.

Also, cause and effect are notoriously hard to prove, and this connection definitely isn't strong enough to say that the hot weather provokes not-so-hot moods in the bedroom. The paper itself also hasn’t yet been reviewed by outside experts, like most scientific reports are.

But this study isn't the first to record seasonal effects on birth rates. In the northern hemisphere, the most babies are born in August and September thanks to the onset of cold weather and holidays about one gestation period earlier. That effect tracks with latitude, although social factors may play a role as well.

Even so, the connection is more complicated than that. The economists only examined the effect of unusually hot days on fertility rates. That explains why in places where warm or even hot weather normally prevails, the newly found pattern doesn’t necessarily hold. U.S. birth rates are highest in Texas and Alaska, the hottest and coldest states, Holthaus points out.

Why are the economists concerned about a potential drop in birth rates? After all, overpopulation is a problem that helped get humans into this climate change mess. Jessica Irvine at The Sydney Morning Herald explains that governments are always worried about declining population. "[G]overnments will need taxpayers to foot the bill of climate change," she writes.

Unless a stronger effect is discovered, governments need not worry much, at least about climate change’s effects on sex. There are many more pressing effects of rising temperatures.

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