Parametric regional GHG cap (AR6 GWP) + trade self-sufficiency floor (+ NZB grid)

config/default.cfg

@@ -707,6 +707,29 @@ cfg$gms$s21_trade_tariff_targetyear <- 2050
 # * (inflated from default originally in USD05 using USD05 --> USD17 inflation rate:1.23)
 cfg$gms$s21_min_trade_margin_forestry <- 62   # def = 50 * 1.23
 
+# * ISO codes of the region(s) subject to the self-sufficiency floor below (e.g. "BRA");
+# * default = all countries. Works exactly like policy_countries56: a region is included
+# * only if all of its countries are listed, because the trade balance (like the cap) is a
+# * hard region-level constraint and can't apply to only part of a region.
+cfg$gms$policy_countries21 <- all_iso_countries   # def = all_iso_countries
+
+# * Minimum self-sufficiency floor: require production >= s21_forcesuff_value *
+# * f21_self_suff * demand for the commodities in forcesuff21, in the regions selected
+# * via policy_countries21, from sm_fix_SSP2 onwards. One-sided floor (binds only from
+# * below). This subsumes the former wood-only switch: to force wood/woodfuel
+# * self-sufficiency, include them in forcesuff21. 1 = on, 0 = unchanged develop behaviour.
+cfg$gms$s21_force_selfsuff <- 0   # def = 0
+# * Commodities subject to the floor (subset of k_trade). Empty by default (no-op);
+# * populate to protect exports, e.g. for BRA net exporters:
+# * "wood, woodfuel, soybean, oilcakes, oils, maiz, sugar, livst_rum, livst_chick".
+cfg$gms$forcesuff21 <- ""   # def = empty (no commodities)
+# * Retention fraction of the 2025 baseline self-sufficiency (production / demand),
+# * held as a floor for every future timestep when s21_force_selfsuff = 1. The floor
+# * tracks f21_self_suff (constant over time), so it holds each commodity's 2025
+# * export/import intensity. No baseline run needed.
+# * 1 = freeze exactly at 2025; 0.9 = allow at most ~10% erosion below 2025.
+cfg$gms$s21_forcesuff_value <- 1   # def = 1
+
 
 # ***---------------------    22_land_conservation    --------------------------------------
 # * (area_based_apr22):    Area-based conservation (baseline and future)
@@ -1616,6 +1639,14 @@ cfg$gms$s56_emis_cap_start    <- 2025
 cfg$gms$s56_emis_cap_penalty  <- 1e5
 cfg$gms$c56_cap_policy        <- "reddnatveg_nosoil"
 cfg$gms$s56_source_bounds_on  <- 0
+# continuous parametric regional cap (overrides the cs3 path when =1; applied to
+# the regions selected via policy_countries56). Free before start_year, linear
+# ramp start_value -> target by target_year, held at target afterwards.
+cfg$gms$s56_emis_cap_parametric  <- 0      # def = 0 (cs3 path used)
+cfg$gms$s56_emis_cap_start_year  <- 2035   # def = 2035
+cfg$gms$s56_emis_cap_start_value <- 600    # def = 600
+cfg$gms$s56_emis_cap_target_year <- 2050   # def = 2050
+cfg$gms$s56_emis_cap_target      <- 0      # def = 0
 
 # * Switch for scaling GHG price with development state (1=on 0=off)
 cfg$gms$s56_ghgprice_devstate_scaling <- 0    # def = 0
@@ -1847,6 +1878,11 @@ cfg$gms$s57_maxmac_n_awms  <- -1   # def = -1
 cfg$gms$s57_maxmac_ch4_rice   <- -1   # def = -1
 cfg$gms$s57_maxmac_ch4_entferm <- -1   # def = -1
 cfg$gms$s57_maxmac_ch4_awms  <- -1   # def = -1
+# optional linear fade-in of the prescribed s57_maxmac steps over time
+# (fadein=0 reproduces the flat baseline; only relevant when s57_maxmac_* >= 0)
+cfg$gms$s57_maxmac_fadein       <- 0      # def = 0
+cfg$gms$s57_maxmac_fadein_start <- 2025   # def = 2025
+cfg$gms$s57_maxmac_fadein_end   <- 2050   # def = 2050
 
 # ***---------------------    58_peatland   ------------------------------------
 # * (off):  Peatland area and associated GHG emissions are assumed zero

modules/14_yields/managementcalib_aug19/declarations.gms

@@ -15,6 +15,7 @@ parameters
  i14_lambda_yields(t,i,kcr)                              Scaling factor for non-linear management calibration (1)
  i14_managementcalib(t,j,kcr,w)                          Regional management calibration factor accounting for FAO yield levels (1)
  im_growing_stock(t,j,ac,land_timber)                    Harvestable stem biomass per ha by age class (tDM per ha)
+ im_growing_stock_ysf(t,j,ac)                            Harvestable stem biomass per ha by age class for young secondary forest on other land (tDM per ha)
  pm_yields_semi_calib(j,kve,w)                           Potential yields calibrated to FAO regional levels (tDM per ha per yr)
  i14_calib_yields_hist(i,w)                              Calibrated yields average over region and crop type at the historical reference year (tDM per ha per yr)
  i14_calib_yields_ratio(i)                               Irrigated to rainfed yield ratio for calibrated yields (1)

modules/14_yields/managementcalib_aug19/presolve.gms

@@ -57,9 +57,29 @@ im_growing_stock(t,j,ac,"other") =
     )
     ;
 
+*' Young secondary forest on other land (`youngsecdf` in [35_natveg]) is forest
+*' regrowth from natural succession. Its carbon stock follows the uncalibrated
+*' natveg curve `pm_carbon_density_secdforest_ac_uncalib` (set in [52_carbon]),
+*' NOT the FRA-calibrated secondary-forest curve. The harvestable growing stock
+*' must be derived from the SAME (uncalibrated) curve so that wood yield and
+*' carbon stock are consistent; using the calibrated `secdforest` growing stock
+*' would decouple high wood yield from low booked carbon. The aboveground
+*' fraction is that of secondary forest, because youngsecdf is forest biomass.
+
+im_growing_stock_ysf(t,j,ac) =
+    (
+     pm_carbon_density_secdforest_ac_uncalib(t,j,ac,"vegc")
+     / sm_carbon_fraction
+     * fm_aboveground_fraction("secdforest")
+     / sum(clcl, pm_climate_class(j,clcl) * fm_ipcc_bef(clcl))
+    )
+    ;
+
 *' @stop
 
 ** Hard constraint to always have a positive number in im_growing_stock
 im_growing_stock(t,j,ac,land_timber) = im_growing_stock(t,j,ac,land_timber)$(im_growing_stock(t,j,ac,land_timber) > 0) + 0.0001$(im_growing_stock(t,j,ac,land_timber) = 0);
+im_growing_stock_ysf(t,j,ac) = im_growing_stock_ysf(t,j,ac)$(im_growing_stock_ysf(t,j,ac) > 0) + 0.0001$(im_growing_stock_ysf(t,j,ac) = 0);
 ** Set growing stock to 0 where it does not exceed a minimum for harvest
 im_growing_stock(t,j,ac,land_natveg)$(im_growing_stock(t,j,ac,land_natveg) < s14_minimum_growing_stock) = 0;
+im_growing_stock_ysf(t,j,ac)$(im_growing_stock_ysf(t,j,ac) < s14_minimum_growing_stock) = 0;

modules/21_trade/selfsuff_reduced/declarations.gms

@@ -6,7 +6,10 @@
 *** |  Contact: magpie@pik-potsdam.de
 
 parameters
- i21_trade_bal_reduction(t_all,k_trade)         Trade balance reduction (1)
+ p21_country_switch(iso)                        Switch: country selected for the forced self-sufficiency floor (1)
+ p21_selfsuff_region(h)                         Superregions eligible for the self-sufficiency floor (1=fully selected via policy_countries21) (1)
+ i21_min_selfsuff(t_all,h,k_trade)              Minimum self-sufficiency ratio floor applied to forcesuff21 commodities (1)
+ i21_trade_bal_reduction(t_all,h,k_trade)       Trade balance reduction (1)
  i21_exp_shr(t_all,h,k_trade)                   Trade export shr (1)
  i21_trade_margin(h,k_trade)                    Trade margins (USD17MER per tDM)
  i21_trade_tariff(h,k_trade)                    Trade tariffs (USD17MER per tDM)
@@ -28,6 +31,7 @@ equations
  q21_notrade(h,k_notrade)                Superregional production constraint of non-tradable commodities (mio. tDM per yr)
  q21_trade_reg(h,k_trade)                Superregional trade balances i.e. minimum self-sufficiency ratio (1)
  q21_trade_reg_up(h,k_trade)             Superregional trade balances i.e. maximum self-sufficiency ratio (1)
+ q21_min_selfsuff(h,k_trade)             Superregional minimum self-sufficiency floor (mio. tDM per yr)
  q21_excess_dem(k_trade)                 Global excess demand (mio. tDM per yr)
  q21_excess_supply(h,k_trade)            Superregional excess production (mio. tDM per yr)
  q21_cost_trade_tariff(h)                Superregional tariff costs (mio. USD17MER per yr)
@@ -47,6 +51,7 @@ parameters
  oq21_notrade(t,h,k_notrade,type)              Superregional production constraint of non-tradable commodities (mio. tDM per yr)
  oq21_trade_reg(t,h,k_trade,type)              Superregional trade balances i.e. minimum self-sufficiency ratio (1)
  oq21_trade_reg_up(t,h,k_trade,type)           Superregional trade balances i.e. maximum self-sufficiency ratio (1)
+ oq21_min_selfsuff(t,h,k_trade,type)           Superregional minimum self-sufficiency floor (mio. tDM per yr)
  oq21_excess_dem(t,k_trade,type)               Global excess demand (mio. tDM per yr)
  oq21_excess_supply(t,h,k_trade,type)          Superregional excess production (mio. tDM per yr)
  oq21_cost_trade_tariff(t,h,type)              Superregional tariff costs (mio. USD17MER per yr)

modules/21_trade/selfsuff_reduced/equations.gms

@@ -31,15 +31,26 @@
  q21_trade_reg(h2,k_trade)..
  sum(supreg(h2,i2),vm_prod_reg(i2,k_trade)) =g=
   m21_baseline_production(vm_supply, v21_excess_prod, f21_self_suff)
-  * sum(ct,i21_trade_bal_reduction(ct,k_trade))
+  * sum(ct,i21_trade_bal_reduction(ct,h2,k_trade))
   - v21_import_for_feasibility(h2,k_trade);
 
 *' Upper bound for production.
 
  q21_trade_reg_up(h2,k_trade) ..
  sum(supreg(h2,i2),vm_prod_reg(i2,k_trade)) =l=
   m21_baseline_production(vm_supply, v21_excess_prod, f21_self_suff)
-  / sum(ct,i21_trade_bal_reduction(ct,k_trade));
+  / sum(ct,i21_trade_bal_reduction(ct,h2,k_trade));
+
+*' Optional minimum self-sufficiency floor: for the commodities in `forcesuff21` and
+*' the regions selected via `policy_countries21`, superregional production must cover
+*' at least `i21_min_selfsuff` (= `s21_forcesuff_value` x the 2025 baseline
+*' self-sufficiency) times superregional demand -- a one-sided lower bound holding each
+*' commodity's 2025 trade intensity. Inactive (`i21_min_selfsuff` = 0) leaves develop
+*' behaviour unchanged.
+
+ q21_min_selfsuff(h2,k_trade)$(sum(ct,i21_min_selfsuff(ct,h2,k_trade)) > 0)..
+ sum(supreg(h2,i2),vm_prod_reg(i2,k_trade)) =g=
+  sum(ct,i21_min_selfsuff(ct,h2,k_trade)) * sum(supreg(h2,i2),vm_supply(i2,k_trade));
 
 *' The global excess demand of each tradable good `v21_excess_demad` equals to
 *' the sum over all the imports of importing superregions.

modules/21_trade/selfsuff_reduced/input.gms

@@ -11,12 +11,44 @@ $setglobal c21_trade_liberalization  l909090r808080
 sets
   k_import21(k_trade) Commodities that can have additional imports to maintain feasibility
                     / wood, woodfuel /
+
+  forcesuff21(k_trade) Commodities forced to a minimum self-sufficiency floor for the (fully selected) regions in policy_countries21 (empty by default)
+                    / /
+
+  policy_countries21(iso) ISO codes of the region(s) subject to the self-sufficiency floor (like policy_countries56)
+                    / ABW,AFG,AGO,AIA,ALA,ALB,AND,ARE,ARG,ARM,
+                      ASM,ATA,ATF,ATG,AUS,AUT,AZE,BDI,BEL,BEN,
+                      BES,BFA,BGD,BGR,BHR,BHS,BIH,BLM,BLR,BLZ,
+                      BMU,BOL,BRA,BRB,BRN,BTN,BVT,BWA,CAF,CAN,
+                      CCK,CHN,CHE,CHL,CIV,CMR,COD,COG,COK,COL,
+                      COM,CPV,CRI,CUB,CUW,CXR,CYM,CYP,CZE,DEU,
+                      DJI,DMA,DNK,DOM,DZA,ECU,EGY,ERI,ESH,ESP,
+                      EST,ETH,FIN,FJI,FLK,FRA,FRO,FSM,GAB,GBR,
+                      GEO,GGY,GHA,GIB,GIN,GLP,GMB,GNB,GNQ,GRC,
+                      GRD,GRL,GTM,GUF,GUM,GUY,HKG,HMD,HND,HRV,
+                      HTI,HUN,IDN,IMN,IND,IOT,IRL,IRN,IRQ,ISL,
+                      ISR,ITA,JAM,JEY,JOR,JPN,KAZ,KEN,KGZ,KHM,
+                      KIR,KNA,KOR,KWT,LAO,LBN,LBR,LBY,LCA,LIE,
+                      LKA,LSO,LTU,LUX,LVA,MAC,MAF,MAR,MCO,MDA,
+                      MDG,MDV,MEX,MHL,MKD,MLI,MLT,MMR,MNE,MNG,
+                      MNP,MOZ,MRT,MSR,MTQ,MUS,MWI,MYS,MYT,NAM,
+                      NCL,NER,NFK,NGA,NIC,NIU,NLD,NOR,NPL,NRU,
+                      NZL,OMN,PAK,PAN,PCN,PER,PHL,PLW,PNG,POL,
+                      PRI,PRK,PRT,PRY,PSE,PYF,QAT,REU,ROU,RUS,
+                      RWA,SAU,SDN,SEN,SGP,SGS,SHN,SJM,SLB,SLE,
+                      SLV,SMR,SOM,SPM,SRB,SSD,STP,SUR,SVK,SVN,
+                      SWE,SWZ,SXM,SYC,SYR,TCA,TCD,TGO,THA,TJK,
+                      TKL,TKM,TLS,TON,TTO,TUN,TUR,TUV,TWN,TZA,
+                      UGA,UKR,UMI,URY,USA,UZB,VAT,VCT,VEN,VGB,
+                      VIR,VNM,VUT,WLF,WSM,YEM,ZAF,ZMB,ZWE /
 ;
 
 scalars
   s21_trade_tariff Trade tariff switch (1=on 0=off)  (1)                   / 1 /
   s21_cost_import Cost for additional imports to maintain feasibility (USD17MER per tDM) / 1500 /
   s21_min_trade_margin_forestry Minimum trade margin for forestry products (USD17MER per tDM) / 62 /
+  s21_force_selfsuff Force a minimum self-sufficiency floor (s21_forcesuff_value) on the forcesuff21 commodities for the regions selected via policy_countries21 (1=on 0=off) (1) / 0 /
+  s21_forcesuff_value Fraction of the 2025 baseline self-sufficiency (f21_self_suff) held as a floor when s21_force_selfsuff=1 (1=freeze exports and imports at their 2025 intensity) (1) / 1 /
 ;
 
 table f21_trade_bal_reduction(t_all,trade_groups21,trade_regime21) Share of inelastic trade pool (1)

modules/21_trade/selfsuff_reduced/postsolve.gms

@@ -16,6 +16,7 @@
  oq21_notrade(t,h,k_notrade,"marginal")              = q21_notrade.m(h,k_notrade);
  oq21_trade_reg(t,h,k_trade,"marginal")              = q21_trade_reg.m(h,k_trade);
  oq21_trade_reg_up(t,h,k_trade,"marginal")           = q21_trade_reg_up.m(h,k_trade);
+ oq21_min_selfsuff(t,h,k_trade,"marginal")           = q21_min_selfsuff.m(h,k_trade);
  oq21_excess_dem(t,k_trade,"marginal")               = q21_excess_dem.m(k_trade);
  oq21_excess_supply(t,h,k_trade,"marginal")          = q21_excess_supply.m(h,k_trade);
  oq21_cost_trade_tariff(t,h,"marginal")              = q21_cost_trade_tariff.m(h);
@@ -31,6 +32,7 @@
  oq21_notrade(t,h,k_notrade,"level")                 = q21_notrade.l(h,k_notrade);
  oq21_trade_reg(t,h,k_trade,"level")                 = q21_trade_reg.l(h,k_trade);
  oq21_trade_reg_up(t,h,k_trade,"level")              = q21_trade_reg_up.l(h,k_trade);
+ oq21_min_selfsuff(t,h,k_trade,"level")              = q21_min_selfsuff.l(h,k_trade);
  oq21_excess_dem(t,k_trade,"level")                  = q21_excess_dem.l(k_trade);
  oq21_excess_supply(t,h,k_trade,"level")             = q21_excess_supply.l(h,k_trade);
  oq21_cost_trade_tariff(t,h,"level")                 = q21_cost_trade_tariff.l(h);
@@ -46,6 +48,7 @@
  oq21_notrade(t,h,k_notrade,"upper")                 = q21_notrade.up(h,k_notrade);
  oq21_trade_reg(t,h,k_trade,"upper")                 = q21_trade_reg.up(h,k_trade);
  oq21_trade_reg_up(t,h,k_trade,"upper")              = q21_trade_reg_up.up(h,k_trade);
+ oq21_min_selfsuff(t,h,k_trade,"upper")              = q21_min_selfsuff.up(h,k_trade);
  oq21_excess_dem(t,k_trade,"upper")                  = q21_excess_dem.up(k_trade);
  oq21_excess_supply(t,h,k_trade,"upper")             = q21_excess_supply.up(h,k_trade);
  oq21_cost_trade_tariff(t,h,"upper")                 = q21_cost_trade_tariff.up(h);
@@ -61,6 +64,7 @@
  oq21_notrade(t,h,k_notrade,"lower")                 = q21_notrade.lo(h,k_notrade);
  oq21_trade_reg(t,h,k_trade,"lower")                 = q21_trade_reg.lo(h,k_trade);
  oq21_trade_reg_up(t,h,k_trade,"lower")              = q21_trade_reg_up.lo(h,k_trade);
+ oq21_min_selfsuff(t,h,k_trade,"lower")              = q21_min_selfsuff.lo(h,k_trade);
  oq21_excess_dem(t,k_trade,"lower")                  = q21_excess_dem.lo(k_trade);
  oq21_excess_supply(t,h,k_trade,"lower")             = q21_excess_supply.lo(h,k_trade);
  oq21_cost_trade_tariff(t,h,"lower")                 = q21_cost_trade_tariff.lo(h);

modules/21_trade/selfsuff_reduced/preloop.gms

@@ -10,14 +10,34 @@
 *' with sm_fix_SSP2 to keep values matching historical data until then.
 loop(t_all,
  if(m_year(t_all) <= sm_fix_SSP2,
- i21_trade_bal_reduction(t_all,k_trade)=f21_trade_bal_reduction(t_all,"easytrade","l909090r808080");
- i21_trade_bal_reduction(t_all,k_hardtrade21)=f21_trade_bal_reduction(t_all,"hardtrade","l909090r808080");
+ i21_trade_bal_reduction(t_all,h,k_trade)=f21_trade_bal_reduction(t_all,"easytrade","l909090r808080");
+ i21_trade_bal_reduction(t_all,h,k_hardtrade21)=f21_trade_bal_reduction(t_all,"hardtrade","l909090r808080");
  else
- i21_trade_bal_reduction(t_all,k_trade)=f21_trade_bal_reduction(t_all,"easytrade","%c21_trade_liberalization%");
-i21_trade_bal_reduction(t_all,k_hardtrade21)=f21_trade_bal_reduction(t_all,"hardtrade","%c21_trade_liberalization%");
+ i21_trade_bal_reduction(t_all,h,k_trade)=f21_trade_bal_reduction(t_all,"easytrade","%c21_trade_liberalization%");
+i21_trade_bal_reduction(t_all,h,k_hardtrade21)=f21_trade_bal_reduction(t_all,"hardtrade","%c21_trade_liberalization%");
  );
 );
 
+*' Region mask for the optional self-sufficiency floor (below): a superregion h is
+*' eligible only if ALL its countries are in policy_countries21 (forcing self-sufficiency
+*' on a partial superregion is not meaningful) -- i.e. every country in every region it
+*' contains (supreg(h,i), i_to_iso(i,iso)) is selected; an empty / partially-selected
+*' superregion makes it a no-op. Mirrors the region mask in module 56.
+p21_country_switch(iso) = 0;
+p21_country_switch(policy_countries21) = 1;
+p21_selfsuff_region(h) = 1$(sum((supreg(h,i), i_to_iso(i,iso)), 1 - p21_country_switch(iso)) = 0);
+
+*' Optional minimum self-sufficiency floor: for the commodities in forcesuff21 (empty by
+*' default) and the fully-selected regions in policy_countries21, hold self-sufficiency at
+*' (s21_forcesuff_value x) its 2025 baseline level from sm_fix_SSP2 onwards, enforced by
+*' q21_min_selfsuff. The floor tracks the input f21_self_suff (constant over time), so it
+*' holds each commodity's 2025 export/import intensity. This subsumes the former wood-only
+*' switch: to force wood/woodfuel self-sufficiency simply include them in forcesuff21.
+*' s21_forcesuff_value = 1 freezes exactly at 2025; < 1 allows some erosion. Empty
+*' forcesuff21 / s21_force_selfsuff = 0 keeps develop behaviour unchanged.
+i21_min_selfsuff(t_all,h,k_trade) = 0;
+i21_min_selfsuff(t_all,h,forcesuff21)$(s21_force_selfsuff = 1 AND p21_selfsuff_region(h) AND m_year(t_all) > sm_fix_SSP2) = s21_forcesuff_value * f21_self_suff(t_all,h,forcesuff21);
+
 i21_exports(t_all,h,k_trade) =  ((f21_self_suff(t_all,h,k_trade) * f21_dom_supply(t_all,h,k_trade)) - f21_dom_supply(t_all,h,k_trade))$(f21_self_suff(t_all,h,k_trade) > 1);
 i21_exp_glo(t_all,k_trade) = sum(h, i21_exports(t_all,h,k_trade));
 i21_exp_shr(t_all,h,k_trade) = i21_exports(t_all,h,k_trade) / (i21_exp_glo(t_all,k_trade) +  0.001$(i21_exp_glo(t_all,k_trade) = 0));

modules/35_natveg/pot_forest_may24/equations.gms

@@ -163,7 +163,7 @@ q35_prod_other(j2)..
               sum(kforestry, vm_prod_natveg(j2,"other",kforestry))
                =e=
                (sum(ac_sub, v35_hvarea_other(j2,"othernat",ac_sub) * sum(ct, im_growing_stock(ct,j2,ac_sub,"other")))
-              + sum(ac_sub, v35_hvarea_other(j2,"youngsecdf",ac_sub) * sum(ct, im_growing_stock(ct,j2,ac_sub,"secdforest"))))
+              + sum(ac_sub, v35_hvarea_other(j2,"youngsecdf",ac_sub) * sum(ct, im_growing_stock_ysf(ct,j2,ac_sub))))
               / m_timestep_length_forestry
                 ;
 

modules/56_ghg_policy/cap_apr26_reg/declarations.gms

@@ -24,6 +24,8 @@ parameters
  p56_gwp(pollutants)                   AR5 GWP factors for CO2eq conversion (Tg CO2eq per Tg native unit)
  p56_cap_mask(emis_source,pollutants)  Policy mask for cap scope: 1=included 0=excluded (1)
  p56_emis_cap(t_all,i)                 Active regional AFOLU cap per region (Tg CO2eq per yr)
+ p56_cap_region(i)                     Regions the parametric cap applies to (1=capped derived from policy_countries56) (1)
+ p56_emis_cap_param(t_all)             Parametric cap trajectory over time (Tg CO2eq per yr)
  p56_emis_cap_slack(t,i)              Regional slack level — platform infeasibility signal (Tg CO2eq per yr)
 * ov56_emis_co2eq declared here (not in R section) because it is computed manually
 * in postsolve rather than copied from a GAMS variable attribute (.l/.m/.up/.lo).