This report analyses global transition pathways to a low Greenhouse Gas (GHG) emissions economy The main scenarios presented have been designed to be compatible with the 2°C and 1.5°C temperature targets put forward in the UNFCCC Paris Agreement, in order to minimise irreversible climate damages. Reaching these targets requires action from all world countries and in all economic sectors. Global net GHG emissions would have to drop to zero by around 2080 to limit temperature increase to 2°C above pre-industrial levels (by around 2065 for the 1.5°C limit). The analysis shows that this ambitious low-carbon transition can be achieved with robust economic growth, implying small mitigation costs. Results furthermore highlight that the combination of climate and air policies can contribute to improving air quality across the globe, thus enabling progress on the UN Sustainable Development Goals for climate action, clean energy and good health. Key uncertainties in future pathways related to the availability of future technological options have been assessed for Carbon Capture and Sequestration (CCS) and bioenergy. If CCS technologies would not develop, a 2°C pathway would have a similar mitigation trajectory in the first half of the century as a 1.5°C scenario with CCS.