Global warming could harm birth rates as hot temperatures 'make people less likely to have sex'

New report reveals that the birth rate tails off significantly nine months after a particularly hot day

It is well documented that global warming poses one of the greatest threats to humanity due to rising sea levels, floods and droughts. Now a new problem can be added to the list – a collapsing birth rate.

Research suggests that, as temperatures increase, people may feel less inclined to have sex. Or, as the report from the National Bureau of Economic Research more delicately puts it, their “coital frequency” could diminish.

The research reveals that nine months after a particularly hot day the birth rate tails off significantly, coming in 0.7 per cent lower than it would following a cooler day. This indicates that rising temperatures either reduce fertility, decrease appetite for intercourse or, quite possibly, both.

“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.” 

Although the study relates to the US, the consequences are likely to be even more pronounced in the developing world – while the effect in the UK is likely to be similar to North America, report author Alan Barreca told The Independent.

“The decline in birth rates is a very serious issue for countries, like the United States and the UK, which have below-replacement birth rates,” said Mr Barreca, associate professor at Tulane University in New Orleans, who carried out the research with academics from the University of Central Florida and UC Santa Barbara. “This will put a lot of strain on social insurance programmes, like social security, because it will create large imbalances in the make-up of the population.”