A counterfactual emissions scenarios database for end-to-end climate impact attribution

Establishing causation from conduct to environmental harm is crucial for successful climate litigation. End-to-end attribution of climate impacts to a certain entity’s greenhouse gas emissions can serve this purpose and requires counterfactual emissions scenarios appropriate to the respective attribution question. 

We here present a comprehensive database of historical counterfactual emissions scenarios and showcase global mean temperature (GMT) change trajectories attributable to large emitters based on a selection of these scenarios using the simple climate model (SCM) MAGICC. Counterfactual design covers systematic choices of (i) the accounting basis, (ii) the starting years from which the scenarios deviate from historical emissions, and (iii) the evaluation time frame for various types of emitters (countries, country groups, carbon majors, income groups, sectors).

The database provides complete global emissions scenarios following the OpenSCM standard for use with SCMs. It will be available as a public repository, allowing for users to generate additional counterfactual emissions scenarios of their own design, laying the groundwork for the attribution of GMT changes using SCMs, and of regional impacts using regional climate emulators. This will enable the accessible and systematic exploration of end-to-end attribution at scale, helping to inform discussions of accountability and to facilitate counterfactual climate impact assessments on-demand for a wide range of combinations of different emitters.