Based upon the lessons from the current initiatives under the climate regime as well as relevant literature, this paper discuss specific steps and time frames that aim to add ex-ante clarity to nationally determined contributions to climate change mitigation and enhance their levels of ambition. The process proposed has three distinctive features: 1) A consortium of research institutes is established with a view to providing benchmarks to which Parties can refer to when proposing their initial contributions, and against which each Party’s relative contribution to the 2°C target is assessed; 2) To enhance ex-ante clarity and comparability of Parties’ contributions, the consortium also provides a common and clear template for information on mitigation contributions that Parties will complete ex-ante; 3) A limited number of Parties—for example, the G20 member countries—are requested to complete the common template and go through an international consultation process with a view to amending contributions to meet the required aggregate contribution for the 2°C goal.