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The Climate Policy Modelling Protocol

The Climate Policy Modelling Protocol is used to model the Current policies scenario. It includes climate and energy policies for major economies, and details the instruments, targets and sectors. Climate policy on the national level, is defined as the result of climate policy formulation and climate policy implementation that encompasses aspirational goals not secured by legislation, national targets that are secured by legislation, and policy instruments designed to implement these targets. Only implemented policies are included in this protocol, and are defined as policies adopted by the government through legislation or executive orders, and non-binding targets backed by effective policy instruments.


To create the Climate Policy Modelling Protocol, first a selection of climate policies with potentially high impact in terms of emission reductions is performed, by the policy teams of PBL and NewClimate, and translated into model input indicators.  With the help of national experts and consortium partners, an evaluation round of the selected policies is performed, before finalizing the complete policy list. Policy instruments are represented in the integrated assessment models as explicit as possible, but simplification is sometimes necessary, thereby considering replicating the impact on greenhouse gas emissions and energy as most important. In practice, policy instruments are implemented to achieve national, often aspirational goals (not secured by legislation or executive orders). These aspirational goals are documented in national policy documents (e.g., National Communication, strategy documents). In some cases, direct implementation policy instruments in IAMs is possible, such as carbon taxes or regulations (e.g., vehicle fuel-efficiency standards). In other cases, aspirational policy targets are assumed to represent currently implemented policies, but only if they are backed by effective policy instruments. This is for example the case with feed-in tariffs or renewable auctions. If the policy instrument would end before the policy target year, continuation of this instrument until the target year of the aspirational goal is assumed. In case a  major economy is part of a larger model region, the policy (indicator) is aggregated by assuming business-as-usual for those countries without policies, and implementation of the policy for countries with policies*. In some cases, models with less sector detail may use policy indicators (such as CO2 or final energy reduction) based on the impact of policies from more detailed models or on literature. It should be noted that the policy environment is constantly changing, thus policy changes with a possibly high impact may occur between protocol updates that are not included in certain versions.

*Roelfsema, M., van Soest, H.L., Harmsen, M. et al. Taking stock of national climate policies to evaluate implementation of the Paris Agreement. Nat Commun 11, 2096 (2020).

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