This study provides a conceptual framework for exploring the bargaining space within international climate negotiations based on important economic, political and environmental considerations. Based on it, we analyse combinations of the proposed emission reduction ranges for Annex I countries as a group (25–40% below 1990 levels) and non-Annex I as a group (15–30% below baseline) by 2020 to limit global warming to 2 °C. We use results of the FAIR model with costs estimates based on two energy system models. We conclude that the range of targets that comply with a set of criteria for economic, political and environmental considerations is smaller than that by environmental considerations alone. More specifically, we find that according to our criteria, a 30% Annex I reduction target below 1990 levels, combined with a 20% non-Annex I reduction target below baseline emission levels (i.e. 20 to 30% above 2005 levels), is the only combination of targets fulfilling all our criteria for both energy system models. Otherwise, reaching the 2 °C target becomes less likely, technically infeasible, or non-Annex I abatement costs are likely to exceed those of Annex I, a result, which we consider less plausible from a political viewpoint in our conceptual framework.