Functioning transportation systems are fundamental to modern, prosperous societies. They provide a means to get to work, connect us to friends and family, and catalyse economic activity. But transportation today comes with a cost. It produces approximately 18 per cent of human-related greenhouse gas (GHG) emissions and local air pollution that contributes to health problems for millions. Alliance issue: Climate philanthropy after Paris, June 2016, Volume 21 , Number 2.