The transport sector is now the second largest emitter of greenhouse gases after the energy sector. However, unlike energy, transport emissions continue to grow at a high rate. By 2050, transport could become the world’s largest emitter of greenhouse gases on a global scale. In the face of such a challenge, how do authorities intend to ensure the long-term sustainability of transport systems? What measures do they propose? Are these enough? How can we do more? To answer these questions, the Forum launched an unprecedented research project that mobilized seven researchers over four years and across fourteen countries around the world.