The peatland module calculates GHG emissions from degrading/drained peatlands.
| Description | Unit | A | B | |
|---|---|---|---|---|
| pcm_land (j, land) |
Land area in previous time step | \(10^6 ha\) | x | |
| pm_climate_class (j, clcl) |
Koeppen-Geiger climate classification on the simulation cluster level | \(1\) | x | |
| pm_interest (t_all, i) |
Interest rate in each region and timestep | \(\%/yr\) | x | |
| vm_land (j, land) |
Land area of the different land types | \(10^6 ha\) | x |
| Description | Unit | |
|---|---|---|
| vm_peatland_cost (j) |
One-time and recurring cost of managed peatland | \(10^6 USD_{05MER}/yr\) |
| vm_peatland_emis (j) |
GHG emissions from managed peatland | \(t CO2eq/year\) |
In this realization GHG emissions from degrading peatlands are assumed zero.
Limitations GHG emissions from degrading peatlands are assumed zero
In this realization GHG emissions from degrading/drained peatlands are calculated based on GHG emission factors from the “2013 Supplement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories: Wetlands”. Also rewetting of drained peatlands as mitigation option is available.
\[\begin{multline*} \sum_{from58,to58} v58\_lu\_transitions(j2,from58,to58) = p58\_peatland\_area(j2) \end{multline*}\]
\[\begin{multline*} \sum_{from58} v58\_lu\_transitions(j2,from58,to58) = v58\_peatland\_man(j2,"degrad","crop")\$sameas(to58,"degrad\_crop") + v58\_peatland\_man(j2,"degrad","past")\$sameas(to58,"degrad\_past") + v58\_peatland\_man(j2,"degrad","forestry")\$sameas(to58,"degrad\_forestry") + v58\_peatland\_man(j2,"unused","crop")\$sameas(to58,"unused\_crop") + v58\_peatland\_man(j2,"unused","past")\$sameas(to58,"unused\_past") + v58\_peatland\_man(j2,"unused","forestry")\$sameas(to58,"unused\_forestry") + v58\_peatland\_man(j2,"rewet","crop")\$sameas(to58,"rewet\_crop") + v58\_peatland\_man(j2,"rewet","past")\$sameas(to58,"rewet\_past") + v58\_peatland\_man(j2,"rewet","forestry")\$sameas(to58,"rewet\_forestry") + v58\_peatland\_intact(j2)\$sameas(to58,"intact") \end{multline*}\]
\[\begin{multline*} \sum_{to58} v58\_lu\_transitions(j2,from58,to58) = pc58\_peatland\_man(j2,"degrad","crop")\$sameas(from58,"degrad\_crop") + pc58\_peatland\_man(j2,"degrad","past")\$sameas(from58,"degrad\_past") + pc58\_peatland\_man(j2,"degrad","forestry")\$sameas(from58,"degrad\_forestry") + pc58\_peatland\_man(j2,"unused","crop")\$sameas(from58,"unused\_crop") + pc58\_peatland\_man(j2,"unused","past")\$sameas(from58,"unused\_past") + pc58\_peatland\_man(j2,"unused","forestry")\$sameas(from58,"unused\_forestry") + pc58\_peatland\_man(j2,"rewet","crop")\$sameas(from58,"rewet\_crop") + pc58\_peatland\_man(j2,"rewet","past")\$sameas(from58,"rewet\_past") + pc58\_peatland\_man(j2,"rewet","forestry")\$sameas(from58,"rewet\_forestry") + pc58\_peatland\_intact(j2)\$sameas(from58,"intact") \end{multline*}\]
The following two equations calculate land expansion and land contraction based on the above land transition matrix.
\[\begin{multline*} v58\_expansion(j2,to58) = \sum_{from58\$\left(not sameas(from58,to58)\right)}\left( v58\_lu\_transitions(j2,from58,to58)\right) \end{multline*}\]
\[\begin{multline*} v58\_reduction(j2,from58) = \sum_{to58\$\left(not sameas(from58,to58)\right)}\left( v58\_lu\_transitions(j2,from58,to58)\right) \end{multline*}\]
Future peatland degradation (v58_peatland_man) depends on changes of managed land, scaled with the ratio of total peatland area and total land area (p58_scaling_factor). By multiplying changes in managed land with this scaling factor we implicitly assume that intact peatlands are distributed equally within a grid cell. The following example illustrates the mechanism used for projecting peatland dynamics: In a given grid cell, the total land area is 50 Mha and the total peatland area is 10 Mha. Therefore, the scaling factor is 0.2 (10 Mha divided by 50 Mha). If cropland expands by 5 Mha, 1 Mha of intact peatland is converted to degraded peatland (5 Mha0.2). If the total cell would become cropland, degraded peatland would equal to the total peatland area (50 Mha 0.2 = 10 Mha).
\[\begin{multline*} v58\_peatland\_man(j2,"degrad",land58) = pc58\_peatland\_man(j2,"degrad",land58) + \left(\left(vm\_land(j2,land58)-pcm\_land(j2,land58)\right) \cdot p58\_scaling\_factor(j2)\right)\$\left(\sum_{ct} m\_year(ct)>2015\right) \end{multline*}\]
Either conversion of intact to degraded peatland OR conversion of degraded to rewetted peatland. This constraint avoid the conversion of intact peatland into rewetted peatland.
\[\begin{multline*} \sum_{stat\_degrad58} v58\_lu\_transitions(j2,"intact",stat\_degrad58) \cdot \sum_{stat\_degrad58,stat\_rewet58} v58\_lu\_transitions(j2,stat\_degrad58,stat\_rewet58) = 0 \end{multline*}\]
\[\begin{multline*} vm\_peatland\_cost(j2) = v58\_peatland\_cost\_annuity(j2) + \sum_{land58}\left( v58\_peatland\_man(j2,"rewet",land58) \cdot s58\_rewet\_cost\_recur\right) \end{multline*}\]
\[\begin{multline*} v58\_peatland\_cost\_annuity(j2) = \sum_{from58,stat\_rewet58}\left( v58\_lu\_transitions(j2,from58,stat\_rewet58) \cdot s58\_rewet\_cost\_onetime\right) \cdot \sum_{cell(i2,j2),ct}\left(\frac{pm\_interest(ct,i2)}{\left(1+pm\_interest(ct,i2)\right)}\right) \end{multline*}\]
\[\begin{multline*} v58\_peatland\_emis(j2,emis58) = \sum_{man58,land58,clcl58}\left( v58\_peatland\_man(j2,man58,land58) \cdot p58\_mapping\_cell\_climate(j2,clcl58) \cdot p58\_ipcc\_wetland\_ef(clcl58,land58,emis58,man58)\right) \end{multline*}\]
\[\begin{multline*} vm\_peatland\_emis(j2) = \sum_{emis58} v58\_peatland\_emis(j2,emis58) \end{multline*}\]
Initialization of peatland First, all degraded peatland is assigned to cropland. However, if the degraded peatland is larger than the actual cropland multiplied by a scaling factor (see below), degraded peatland used as cropland is reduced accordingly. In each cell, we scale the actual cropland with the ratio of total peatland area and total land area (factor between 0 and 1) because we use this scaling factor for modeling future peatland dynamics based on agricultural land use (see equations). Accounting for this scaling factor in the initial distribution of degraded peatland to cropland makes sure that a full reduction of cropland would also reduce degraded peatland used as cropland to zero in a given cell, which is of particular importance for the peatland restoration scenarios. After this first step, the remaining degraded peatland (if any exists) is assigned to pasture with the same rules, i.e. assignment to pasture is constrained by the scaled actual pasture area. In a third step, all remaining degraded peatland is assigned to forestry with these rules. Finally, any remaining degraded peatland in a cell after these 3 steps is added to the degraded peatland category with equal distribution among cropland, pasture and forestry (land-use categories are important for the application of the wetland GHG emission factors). In total, we therefore have 3 peatland categories: intact, degraded and unused. And for degraded and unused we know the current/previous land use: cropland, pasture and forestry.
Limitations Organic carbon stocks in peatlands are not accounted for.
| Description | Unit | A | B | |
|---|---|---|---|---|
| f58_ipcc_wetland_ef (clcl58, land58, emis58, ef58) |
Wetland GWP100 emission factors | \(t CO2eq/ha\) | x | |
| f58_peatland_degrad (j) |
Degrading peatland area | \(10^6 ha\) | x | |
| f58_peatland_intact (j) |
Intact peatland area | \(10^6 ha\) | x | |
| p58_intact_ratio (t, j) |
Ratio of intact and total peatland | \(1\) | x | |
| p58_ipcc_wetland_ef (clcl58, land58, emis58, man58) |
Wetland GWP100 emission factors | \(t CO2eq/ha\) | x | |
| p58_land_area (j) |
Total land area | \(10^6 ha\) | x | |
| p58_mapping_cell_climate (j, clcl58) |
Mapping between cells and climate regions | \(binary\) | x | |
| p58_peatland_area (j) |
Total peatland area | \(10^6 ha\) | x | |
| p58_peatland_degrad_unused (j) |
Intermediate calculation in peatland initialization | \(10^6 ha\) | x | |
| p58_peatland_degrad_unused_weight (j, land58) |
Weight for intermediate calculation in peatland initialization | \(1\) | x | |
| p58_peatland_degrad_used (j) |
Intermediate calculation in peatland initialization | \(10^6 ha\) | x | |
| p58_scaling_factor (j) |
Scaling factor for managed peatland | \(1\) | x | |
| pc58_man_land (j) |
Total managed land | \(10^6 ha\) | x | |
| pc58_man_land_shr (j, land58) |
Share of total managed land | \(1\) | x | |
| pc58_peatland_intact (j) |
Intact peatland | \(10^6 ha\) | x | |
| pc58_peatland_man (j, man58, land58) |
Managed peatland | \(10^6 ha\) | x | |
| q58_expansion (j, to58) |
Peatland expansion | \(10^6 ha\) | x | |
| q58_peatland_cost (j) |
One-time and recurring cost of managed peatland | \(10^6 USD_{05MER}/yr\) | x | |
| q58_peatland_cost_annuity (j) |
Annuity costs of managed peatland expansion in the current timestep | \(10^6 USD_{05MER}/yr\) | x | |
| q58_peatland_degrad (j, land58) |
Degraded peatland area constraint | \(10^6 ha\) | x | |
| q58_peatland_emis (j) |
GHG emissions from managed peatland | \(t CO2eq/year\) | x | |
| q58_peatland_emis_detail (j, emis58) |
Detailed GHG emissions from managed peatland | \(t CO2eq/year\) | x | |
| q58_peatland_intact (j) |
Intact to degrad peatland constraint | \(10^6 ha\) | x | |
| q58_reduction (j, from58) |
Peatland reduction | \(10^6 ha\) | x | |
| q58_transition_from (j, from58) |
Peatland transitions from | \(10^6 ha\) | x | |
| q58_transition_matrix (j) |
Peatland transitions | \(10^6 ha\) | x | |
| q58_transition_to (j, to58) |
Peatland transitions to | \(10^6 ha\) | x | |
| s58_rewet_cost_onetime | One-time costs for peatland rewetting | \(USD_{05MER}/ha\) | x | |
| s58_rewet_cost_recur | Recurring costs for peatland rewetting | \(USD_{05MER}/ha\) | x | |
| s58_rewetting_switch | Peatland rewetting on (Inf) or off | \(0\) | x | |
| v58_expansion (j, stat58) |
Peatland expansion | \(10^6 ha\) | x | |
| v58_lu_transitions (j, from58, to58) |
Peatland transitions | \(10^6 ha\) | x | |
| v58_peatland_cost_annuity (j) |
Annuity costs of managed peatland expansion in the current timestep | \(10^6 USD_{05MER}/yr\) | x | |
| v58_peatland_emis (j, emis58) |
Detailed GHG emissions from managed peatland | \(t CO2eq/year\) | x | |
| v58_peatland_intact (j) |
Intact peatland | \(10^6 ha\) | x | |
| v58_peatland_man (j, man58, land58) |
Managed peatland | \(10^6 ha\) | x | |
| v58_reduction (j, stat58) |
Peatland reduction | \(10^6 ha\) | x |
| description | |
|---|---|
| cell(i, j) | number of LPJ cells per region i |
| clcl | climate classification types |
| clcl_mapping(clcl, clcl58) | Mapping between detailed and simple climate classes |
| clcl58 | simple climate classes |
| ct(t) | Current time period |
| ef58(man58) | Peatland ef categories |
| emis58 | Wetland emission types |
| i | all economic regions |
| i2(i) | World regions (dynamic set) |
| j | number of LPJ cells |
| j2(j) | Spatial Clusters (dynamic set) |
| land | Land pools |
| land58(land) | Managed land types |
| man58 | Peatland status managed |
| stat_degrad58(stat58) | Peatland status degrad |
| stat_man58(stat58) | Peatland status managed land |
| stat_rewet58(stat58) | Peatland status rewet |
| stat58 | Peatland status |
| t_all(t_ext) | 5-year time periods |
| t(t_all) | Simulated time periods |
| type | GAMS variable attribute used for the output |
Florian Humpenöder
10_land, 11_costs, 12_interest_rate, 45_climate, 56_ghg_policy