Climate policy needs to aim at ambitious long-term climate stabilization. This will require managing the transition from carbon intensive to low carbon economies within this century. For the transition to be sustainable, it must not impede economic development and avoid environmental side effects. Research on mitigation pathways to a low carbon society and the associated mitigation costs is indispensable for informing policy makers. The project AMPERE will assess the multitude of mitigation pathways in a multi-model intercomparison exercise, their sensitivity to key socioeconomic and climate factors, and the robustness of mitigation costs. It will focus on three central areas: (i) The role of climate feedbacks and land use constraints on the remaining carbon budget for supplying societies around the globe with energy, (ii) the role of path dependency and innovation in the energy sector, (iii) the role of real world policy imperfections like market barriers and limited participation in climate policy regimes, and (iv) the implications for decarbonisation pathways for Europe.