A hotter world could wind up being a less populated one, according to a new study linking climate change to birthrates.

Research produced for the National Bureau of Economic Research says this century is likely to experience more days of 80°F or higher than the 20th century, and that the increase won’t bode well for “coital frequency.”

Experts at Tulane University in New Orleans, the University of Central Florida and UC Santa Barbara concluded global warming will result in the U.S. having 64 more days above 80°F between 2070 and 2099 than during the period from 1990 to 2002, which had 31.

That’s not good news for human reproduction because they found birthrates were 0.7% lower nine months after a hot day than following cooler ones.

“Extreme heat leads to a sizeable fall in births,” the researchers said. “Temperature extremes could affect coital frequency. It could affect hormone levels and sex drives. Alternatively, high temperatures may adversely affect reproductive health or semen quality on the male side, or ovulation on the female side.”

A lower birthrate could play havoc with the U.S. retirement system. Fewer births will result in fewer people paying into Social Security for the benefit of older Americans.

The effects are already being noticed in other countries. China, which for years had a one-child policy has responded to the slowing birthrate by allowing couples to have two children.

-Noel Brinkerhoff

To Learn More:

Global Warming Could Harm Birth Rates as Hot Temperatures ‘Make People Less Likely to have Sex’ (by Tom Bawden, The Independent)

Is Global Warming Cooling YOUR Sex Life? Rising Temperatures Linked to Drop in Birth Rates (by Amanda Williams, Daily Mail)

Climate Change Kills the Mood: Economists Warn of Less Sex on a Warmer Planet (by Eric Roston, Bloomberg)

Maybe Next Month? Temperature Shocks, Climate Change, and Dynamic Adjustments in Birth Rates (by Alan Barreca, Olivier Deschenes, Melanie Guldi, National Bureau of Economic Research)