“The purpose of this second Hamburg Climate Futures Outlook is to systematically analyze and assess the plausibility of certain well-defined climate futures based on present knowledge of social drivers and physical processes. In particular, we assess the plausibility of those climate futures that are envisioned by the 2015 Paris Agreement, namely holding global warming to well below 2°C and, if possible, to 1.5°C, relative to pre-industrial levels (UNFCCC 2015, Article 2 paragraph 1a). The world will have to reach a state of deep decarbonization by 2050 to be compliant with the 1.5°C goal. We therefore work with a climate future scenario that combines emissions and temperature goals…”…In light of these findings, we conclude that reaching worldwide deep decarbonization by 2050 is currently not plausible, given the observable trajectories of social drivers. The select physical processes of public interest only moderately, if at all, inhibit the plausibility of attaining the Paris Agreement temperature goals, although they can substantially modify the physical boundary conditions for society. Meeting the 1.5°C Paris Agreement temperature goal is not plausible, but limiting the global temperature rise to well below 2°C can become plausible if ambition, implementation, and knowledge gaps are closed.”