## 7.1 Greenhouse gas emissions

### 7.1.1 CO2 emissions

Total CO2 emissions are the sum of CO2 emissions from fossil-fuel combustion in the power sector, transportation, heavy industries, and from land-use change, summed with possible leakage from anthropogenic storage, minus emissions from avoided deforestation.

$Q_{CO2}(t,n) = Q_{CO2ind}(t,n) + Q_{CO2lu}(t,n) + Q_{CO2lk}(t,n) - Q_{redd}(t,n)$

Emissions from land-use change (and REDD) are provided by the land-use module.

CO2 emissions from fossil-fuel combustion in the power sector, for transportation, in heavy industries are computed given the fuel consumed in these sectors multiplied the stoichiometric coefficient emi_sf. Emissions deriving from fossil fuel extraction, $$EX_f$$ are also added and emissions stored underground, $$Q_{CCS}$$, (when the option is active) are subtracted. $Q_{CO2ind}(t,n) = \sum_f \left( emi_st(f)\times Q_f(t,n) \right) + \sum_f (t,n) - Q_{CCS}(t,n)$

### 7.1.2 Other greenhouse gas emissions

The other Kyoto greenhouse gases are CH4, N2O, short-lived and long-lived F-gases. The baseline emissions for these gasses are following the EPA projections. This baseline paths are corrected to account for endogenous and costly effort in abatement:

$Q_{oghg}(t,n) = emi\_baseline(oghg,t,n) \times (1 - ABAT(oghg,t,n) \times emi\_abat\_max(oghg,t,n))$

$$emi\_abat\_max$$ is the maximum possible abatement expressed as a share of baseline emissions ($$emi\_baseline$$).

### 7.1.3 Emission costs

Costs of emissions in case of a climate policy are given by the carbon tax or permit prices, see the section on Climate Policy.

The non-CO2 GHG emission costs are based on marginal abatement curves.

\begin{align*} C_{e}(n,t) =& ref_e(n,t) \times \overline{abat}_e(n,t) \times \left( a_e \times ABAT_e(n,t) + \frac{b_e}{c_e} \times \exp\left( c_e \times ABAT_e(n,t) - 1 \right) \right), \\& \forall e \in \{CH_4, N_2O, slf, llf\} \end{align*} where $$a_e$$, $$b_e$$ and $$c_e$$ are the coefficient of the marginal abatement curves.