Climate policy scenarios like the ‘450’ and the ‘550’ cases
simulate GHG emission prices to approximate a global CO2 eq.
emission profile of the climate target 450/550 ppmv in the
atmosphere. Here flexibility allows regional GHG emissions to
be endogenous. The ‘450’ and the ‘550’ climate policy cases
approximate the true 450/550 scenarios, because the climate
policy is implemented as a cumulative budget of global CO2
emissions for the period 2010–2050 (Kriegler et al., 2013). It
assumes a ‘consistent’ emission price for the other important
non-CO2 gases (CH4 and N2O). The time profile of the global
CO2 emissions – in the recursive dynamic framework used in
this paper – follows a linearly increasing percentage change
over time from the ‘RefPol’ scenario that matches the global
CO2 cumulative budget. The time profile for the global CO2
emissions is imposed as a constraint, and the model simulation
endogenously determines a uniform CO2 emission price for all
sectors and regions. This CO2 price is transformed to an
emission price of the non-CO2 gases using the Greenhouse
Warming Potential – GWP – of that particular GHG. Therefore
this price is labeled above as a ‘consistent’ emission price.
Although there is no constraint on total GHG emissions, the
non-CO2 gases are also subject to the same CO2 emission price,
so there are also non-CO2 emission reductions. Hence the CO2
budget simulates a restriction on energy markets comparable