The Effect of Land and Bioenergy Policy on the Path to Achieving Climate Targets: Supporting

The effect of land and bioenergy policy on the path to achieving climate targets: Supporting Online Material

Katherine Calvin, Marshall Wise, Page Kyle, Pralit Patel, Leon Clarke, Jae Edmonds

Joint Global Change Research Institute, College Park, MD 20740 USA

Phone: +1 301 314 6744

Fax: +1 301 314 6719

E-mail:

Implementation of the Scenarios

This article explores the implications of several different types of land policy scenarios. In this section, we discuss the implementation of each of these scenarios in the Global Change Assessment Model (GCAM), offering additional information on how land cover decisions are made in the model in the process.

1. Fossil Fuel and Industrial Carbon Tax Scenario (FFICT)

The FFICT scenario includes a price on emissions in the energy system, but has no policy, price, control, or otherwise, applied to the terrestrial system. In this case, decisions made about land cover assume that farmers maximize profit. For agricultural land and commercial forests, the profit of each land type depends on the price of the product sold, the cost of production, and the yield of the land, where yields differ by region and land type. For natural ecosystems, the profit of the land is derived as part of the calibration routine. This profit represents the intrinsic value of the land and is computed as the “profit” required for that land type to receive the allocation observed in the base year. In the FFICT scenario, all arable land is technically available for food, fiber, bioenergy, and forestry production. That is, desert, urban lands, and tundra are the only lands that are inaccessible, leaving 108 million km2 or 85% of total land available for use. However, food demand in GCAM has a very low price elasticity, which prevents large changes in its production (either increases or decreases). This prevents significant expansion of croplands and also prevents some land from use for bioenergy production.

2. Universal Carbon Tax Scenario (UCT)

The UCT scenario includes a price on emissions in the energy system, AND an equivalent price on emissions in the terrestrial system. Like in the FFICT, decisions made about land cover in the UCT assume that farmers maximize profit. However, profit in the UCT is adjusted to include a subsidy based on the carbon content of the land. This subsidy is applied to all land types, including natural systems, and is based on both vegetation and soil carbon. It can be shown that applying a subsidy to carbon stocks is equivalent to taxing carbon emissions under certain conditions, conditions that hold in GCAM. The imposition of this subsidy incentivizes the expansion of carbon-rich ecosystems, like forests. However, it is important to note that the carbon density and forest potential in GCAM vary by region. Some regions in GCAM, particularly arid regions, never expand their forest cover regardless of the carbon price applied (See Figure S2 and S3).

3. Protected Land Scenarios (99% Land, 99% Forest, 50% Forest)

The protected land scenarios remove some land from economic competition. By doing so, we prevent expansion into this land by any activity, including crop production, timber production, and grazing. We examine three levels of protection. The first protects 99% of natural ecosystems, including grassland, shrub land, and non-commercial forest. We limit our protection to 99% to allow some expansion of commercial forest, the demand for which increases with population. The second case protects 99% of non-commercial forest, leaving grassland and shrub land unprotected. The third case protects 50% of non-commercial forest, leaving grassland, shrub land, and 50% of non-commercial forest unprotected. In each case, we protect the same fraction of land in all regions in the model. For example, in the 50% Forest scenario, 50% of forest in each of the 151 land regions is protected. Unprotected land is allocated in the same manner as in the FFICT case.

4. Bioenergy Constraint Scenario (Bio 100)

The bioenergy constraint scenario limits the amount of global bioenergy consumption to 100 EJ per year. The constraint is applied in every year, but is only binding in the second half of the century. 1st and 2nd generation bioenergy, residue bioenergy, and municipal solid waste all count toward this constraint, but traditional bioenergy is not included. Land allocation decisions are made in the same manner as in the FFICT scenario.

5. LUC Proxy Scenario (Bio LUC Proxy)

The LUC proxy scenario imposes a penalty on bioenergy at its point of consumption. The penalty is intended to reflect the potential consequences of bioenergy production on LUC emissions on the cost of bioenergy. Thus, the penalty is essentially a tax applied to bioenergy, where the value of the tax is linked to the carbon price in the energy system. The penalty is applied in every year. The costs of 2nd generation bioenergy, residue bioenergy, and municipal solid waste all rise because of this penalty. Land allocation decisions are made in the same manner as in the FFICT scenario.

Additional Figures

Panel A: Global GDP and Population
/ Panel B: Global Primary Energy

Panel C: Global Land Cover
/ Panel D: Global CO2 Emissions

Figure 1: Reference Scenario Results

Figure 2: Forest Cover in 2005 and 2095 by GCAM Region in Bioenergy and Land Policy Scenarios

Figure 3: Fraction of Region Covered by Forest in 2095 in the UCT Scenario

Figure 4: Price of Bioenergy across Land Policy Scenarios. Note that the prices in this figure are producer prices and exclude any taxes.

Figure 5: Bioenergy Consumption across Scenarios

Figure 6: Beef Consumption across Scenarios

Figure 7: Refined Liquids Production in 2050

Figure 8: Cumulative GHG Emissions across Land Policy Scenarios