Detail on EMF 22 response surface boundaries
Introduction#When the CO2 levels fall below the lower boundary reported in by a model in its results for the EMF 22 international scnearios, that model's response surface is deemed unable to calculate mitigation costs for that proposal.
Rationale for this approach#In the case of aggressive climate policies, mitigation costs may rise rapidly for even modest incremental additional emission reductions.
Because of this, it could be highly misleading to extrapolate beyond the lower boundary of the EMF 22 data set.
As a result, a model's response surface does not report a mitigation cost value if a proposal's CO2 levels fall below that lower boundary.
Interpreting absence of mitigation cost value#The absence of a mitigation cost value can mean two possible things:
- Mitigation costs are greater than the values reported in the most aggressive scenario for which results were reported in the EMF 22 international scenarios (see the attachments to EMF 22 response surfaces to see which scenarios were reported for by each modeling team).
- The actions outlined by the proposal could be technically unfeasible, since it may not be possible to adopt decarbonization technologies rapidly enough to enable such aggressive emission reductions.
Technical unfeasibility is in a real possibility for proposals that incorporate very aggressive policy prescriptions (e.g. near complete decarbonization of the economy prior to 2050).
EMF 22 handling of aggressive emission scenarios#The review article for the internatinal scenarios described how the EMF 22 exercise handled aggressive emission reduction scenarios that could not be modeled.
"All modeling teams participating in the EMF 22 International Scenarios were required to attempt to produce scenarios for all ten climate-action cases. However, no team succeeded in producing scenarios for all ten. Modelers were instructed that they were not required to submit scenarios representing particular climate-action cases if at least one of the following conditions was met:
- Physical infeasibility: The climate-action case was physically infeasible according to the model because the radiative forcing target was exceeded prior to the initiation of mitigation in Group 2 (BRICs) and Group 3 (the Non-Annex 1 countries).
- Model solution: The model could not be solved for the particular climate-action case, which could be due to failures in the solution mechanism at higher CO2 prices, decline or expansion constraints that hold back the rate of change in key sectors such as energy, or CO2 price limits in model.
- High initial price:Modelers were requested not to produce scenarios if the initial carbon price in Group 1 exceeded $1000/tCO2 in 2012."
Leon Clark, Jae Edmonds, Volker Krey, Richard Richels, Steven Rose and Massimo Tavoni. International climate policy architectures: Overview of the EMF 22 International Scenarios. Energy Economics, 31, Supplement 2, (2009): S68.