CCt, RCP, carbonrental = Pct, RCP[sum over i of HC it+(SOLC it+1- SOLC it)]+; Rct, RCP sum over i of TFCP it
(12)
2018), p. 133.
The first part of Eq. 11 is the carbon transferred to long-lived wood products (HCti) from each forest i valued at the carbon price Pt,RCPc. The change in soil carbon (SOLCti) when land switches between forests and agriculture is also valued at the carbon price (13, 15). The second term is the annual rent, Rt,RCPc, whereby the total carbon stocks in forests TFCPti are rented during the time period that the carbon is stored following Sohngen and Mendelsohn (4). The rental value for carbon is
Rct, RCP = Pct, RCP-Pct+1, RCP/(1+r)t
(13)
S. Kobayashi, E. Kriegler, L. Mundaca, R. Séférian, M. V. Vilariño, Chapter 2: Mitigation
where r is the interest rate. This equation accounts for potential price increases in carbon that occur as carbon accumulates in the atmosphere.
Last, in the carbon penalty scenario, forest owners pay a penalty for the carbon released when timber is harvested to supply bioenergy demand.
CCt,RCP,penalty = -Pct,RCP sum over i of BIOCit
(14)
527–528 (2009).
Table S1 provides the list of parameter values used to parameterize equations for the simulations presented in this study. More details on the version of GTM used in this analysis are available in (18) and (22).
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/
content/full/6/13/eaay6792/DC1
Supplementary Materials and Methods
Model estimates
Fig. S1. GTM—Regional Aggregation.
Fig. S2. Global assumptions for alternative RCP scenarios.
Fig. S3. Yield for representative species in the GTM.
Fig. S4. Estimated changes in global forest carbon stock pools in GtCO2 relative to the baseline scenario under each RCP.
Fig. S5. Changes in global forest area by major ecosystem versus woody biomass supply under the bioenergy demand scenario relative to the baseline scenario.
Fig. S6. IAMs' estimates of forest areas and crop areas (2010–2100) under the RCP 1.9 and RCP 2.6 from the IIASA SSP database.
Fig. S7. Estimated changes in global forest carbon stock pools in GtCO2 relative to the baseline scenario under each RCP and the two policy approaches.
Fig. S8. Key parameter sensitivity impacts relative to 2010 for RCP 2.6 Forest Carbon Rental scenario.
Table S1. GTM parameter values.
Table S2. Baseline key GTM estimates, 2010–2100.
Table S3. Baseline global forest area (Mha) by major ecosystem, 2010–2100.
Table S4. Baseline global total forest carbon stocks by major ecosystem, 2010–2100.
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world in which the carbon price and/or subsidy is implemented simultaneously everywhere, and there are no trade barriers or other limitations in the use of woody biomass for energy or governance issues. This is an ideal framework: Carbon obviously has not been traded globally, and there are widespread reservations about trading it in the atmosphere as well as in forests. There are measurement, monitoring, and verification problems, as well as concerns about leakage and permanence.
Starting with the scenarios simulated in Favero et al. (22), this study explores four possible policy scenarios:
Reference scenario: No bioenergy demand and carbon price are implemented;
Bioenergy scenario: Exogenous bioenergy demands from SSP2 across RCPs Qt, RCPwbio are included;
Forest carbon rental scenario: Exogenous bioenergy demands from SSP2 across RCPs are included, and forest owners are compensated by annual rent for providing annual carbon sequestration according to the carbon prices from the IIASA SSP database;
Carbon penalty scenario: Bioenergy demands from SSP2 across RCPs are included, and carbon emissions upon harvests for energy are taxed.
The policy scenarios are described in Eq. 1 with the term CCt,RCP,policy. Moreover, in the reference and bioenergy scenarios, the term CCt,RCP,policy is assumed to be equal to zero since no policy efforts are implemented to value or penalize bioenergy demand.
On the other hand, in the forest carbon rental scenario, forest owners receive carbon payments for the carbon permanently stored in wood products and are compensated by annual rent for providing annual carbon sequestration according to the carbon prices Pt, RCPc from the IIASA SSP database (fig. S2C) as follows