A planet with two billion cars Michael Gross  Current Biology  Volume 26, Issue 8, Pages R307-R310 (April 2016) DOI: 10.1016/j.cub.2016.04.019 Copyright © 2016 Terms and Conditions

Road block: Economists predict that there will be two billion motor vehicles on the roads by 2030, as private vehicle ownership spreads to the developing world. The image shows an urban motorway in Beijing, China. (Photo: Bev Sykes.) Current Biology 2016 26, R307-R310DOI: (10.1016/j.cub.2016.04.019) Copyright © 2016 Terms and Conditions

Blurred vision: Air pollution due to road traffic is on the rise again, due to the rapid spread of car use in developing countries, and to the switch to diesel engines in Europe. The picture shows smog over Shanghai, China. (Photo: Seader/Wikimedia Commons.) Current Biology 2016 26, R307-R310DOI: (10.1016/j.cub.2016.04.019) Copyright © 2016 Terms and Conditions

Naked truth: Few politicians take a stand against the epidemic spread of vehicle traffic. The annual World Naked Bike Ride held in many cities in the US and UK (shown here: Bristol 2015), as well as in several other countries around the world (http://wiki.worldnakedbikeride.org/) is possibly the most vocal criticism of car culture today. (Photo: Michael Gross.) Current Biology 2016 26, R307-R310DOI: (10.1016/j.cub.2016.04.019) Copyright © 2016 Terms and Conditions

Cut through: Roads built in wilderness areas not only fragment habitat and endanger the viability of larger species, they also act as nuclei for further deforestation and habitat degradation. (Photo: http://travel.mongabay.com/). Current Biology 2016 26, R307-R310DOI: (10.1016/j.cub.2016.04.019) Copyright © 2016 Terms and Conditions