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Methods

Policy Questions

Methods

Our global public interface focuses on inter-model differences regarding emissions projections.

We carry out projections across numerous Integrated Assessment Models with a specific focus on policy representation and harmonisation methods.

We used four different scenarios for representing policies: Two scenarios for up to 2030, corresponding to Current Policies and Nationally Determined Contributions, and two different ways of extrapolating after 2030 accordingly (to represent possible interpretations of continued ambition). NDC scenarios were modelled on top of Current Policies. The first post-2030 extension method takes the equivalent carbon price in 2030, increasing it with GDP per capita; the second method takes the rate of emissions intensity reductions implied between 2020 and 2030 and applies it after 2030.

Harmonisation Methods: Harmonisation efforts have been undertaken as a novelty in multi model comparison bearing in mind differences across model features and heterogeneity. Expert users of models within the PR modelling consortium have conducted a coordinated effort on whether variables have been fully, partially or not harmonized and/or checked for consistency across models.

The models that have been used for the global interface are the following global models:

Model World regions
FortyTwo(42) 50
E3ME 61
GCAM 32
Gemini-E3 11
ICES 45
MUSE 28
TIAM 15

Policy Questions