Climate change has been blamed for many things over the years. Never, until now, has anyone thought it was possible to see it as a kind of contraceptive.
Hot weather leads to diminished “coital frequency," according to a new working paper put out by the National Bureau of Economic Research.
Three economists studied 80 years of US fertility and temperature data and found that when it’s hotter than 80 degrees F, a large decline in births follows within 10 months. Would-be parents tend not to make up for lost time in subsequent, cooler months.
An extra "hot day" (the economists use quotation marks with the phrase) leads to a 0.4 percent drop in birth rates nine months later, or fewer 1,165 deliveries across the U.S. There's a rebound in subsequent months that makes up just 32 percent of the gap.
The researchers, who hail from Tulane, the University of California at Santa Barbara, and the University of Central Florida, believe that their findings give policymakers three major things to think about.
1. Birth rates do not bounce back completely after heat waves.
That's a problem. As summers heat up, developed countries may see already-low birth rates sink even lower. Sinking birth rates can play havoc with an economy.
China's leaders recently acknowledged that fact by ditching the longtime one-child policy and doubling the number of children couples are allowed to have.
A sub-replacement U.S. birthrate means fewer workers to pay Social Security benefits for their retired parents, among other consequences.
2. More autumn conceptions means more more deliveries in summer.
Infants experience a higher rate of poor health in cooler months.
"Though the reasons for worse health in the summer are not well-established," the authors write. One possibility may be "third-trimester exposure to high temperatures."3. Air conditioning might prove to be a aphrodisiac.
Control over the climate at home might make a difference. The researchers suggest that the rise of A/C may have helped offset some of the heat-related fertility losses in the U.S. since the 1970s.
The paper's title is about as lascivious as the National Bureau of Economic Research gets: "Maybe Next Month? Temperature Shocks, Climate Change, and Dynamic Adjustments in Birth Rates."
The researchers assume that climate change will proceed according to the most severe scenarios, with no substantial efforts to reduce emissions.
The scenario they use projects that from 2070 to 2099, the U.S. may have 64 more days above 80F than the baseline period, 1990 to 2002, which has 31. Their result? The U.S. may see a 2.6 percent decline in its birth rate, or 107,000 fewer deliveries a year.
Just when you thought climate change policy couldn't get any less sexy.
