Risk of a feedback loop between climatic warming and human mobility.

Human behaviours alter-and are altered by-climate. Might the impacts of warming on human behaviours amplify anthropogenic contributions to climate change? Here, we show that warmer temperatures substantially increase transportation use in the USA. To do so, we combine meteorological data with data on vehicle miles travelled (VMT) and public transit trips (PTT) between 2002 and 2018. Moving from freezing temperatures up to 30°C increases VMT by over 10% and amplifies use of public transit by nearly 15%. Temperatures beyond 30°C exert little influence on either outcome. We then examine climate model projections to highlight the possible transportation impacts of future climatic changes. We project that warming over the coming century may add over one trillion cumulative VMT and six billion PTT in the USA alone, presenting the risk of a novel feedback loop in the human-environmental system.