In 2015, for the first time in more than three decades, traffic-related deaths increased. Thanks in part to a few high-profile accidents involving the app Snapchat, transportation experts placed the blame on cell phone use. But there is little empirical evidence to suggest that cell phone ownership or use increased between 2014 and 2015. So what's behind the spike? A new paper identifies an alternative culprit: climate change.
Using Census, traffic, and weather data from the 100 most populous counties in the United States, the new study, published today in the journal Injury Prevention, found that, for each degree increase in temperature, drivers were on the road for an average of an extra 60 miles a year. Between 2014 and 2015, the average annual temperature increased by 1.5 degrees Fahrenheit, meaning that, collectively, drivers in urban areas drove an extra 13.6 billion miles.
It's not just drivers who are at risk: Pedestrians and bikers, who are both likely to be outside more in warmer weather, accounted for 22 percent of the increase in road deaths in 2015.
Of course, correlation does not equal causation, but more miles logged means more opportunities for accidents. And the study does raise the possibility of a troubling feedback loop: If people drive more as the temperature rises, their cars spew out more carbon dioxide, which in turn contributes to global warming.