Technical Specifications for the GHG Emissions Calculator

Transcription

1 Page1 The purpose of this document is to provide a transparent explanation for the process used to calculate greenhouse gas (GHG) emissions in the Carbon Benefits Project (CBP) Emissions Calculator, an internal component within the CBP Landscape Carbon MRV System. Accounting Principles The Emissions Calculator follows the guidelines on greenhouse gas accounting published by the Intergovernmental Panel on Climate Change (IPCC, 2003; IPCC, 2006a; IPCC, 2006b). The Emissions Calculator uses the stock-difference method of accounting to calculate the emissions and removals of carbon dioxide in agriculture, forestry and other land uses (AFOLU) by measuring the change between terrestrial carbon stocks at annual time periods. A reduction of terrestrial carbon stocks is a positive emission of greenhouse gases to the atmosphere while an increase in terrestrial carbon stocks is a negative emission or sequestration. The Emissions Calculator reports the annual stocks for six IPCC terrestrial carbon pools: above ground biomass, below ground biomass, dead wood, litter, soil organic carbon, and also harvested wood products. As these carbon pools change from year to year, CO 2 and non-co 2 greenhouse gasses are fluxed to and from the atmospheric pool. Default Values The Emissions Calculator computes carbon stocks by multiplying the land area of a parcel ( activity data ) by the carbon density of the land covers ( emission factors ) that describes that parcel. The land area (in units of hectares) of the parcel is always provided directly by the user. The carbon density attributes can be custom defined by the user based on inventory data of carbon stocks in the project area or they can be default values for global land covers that are provided by the Emissions Calculator. The pre-loaded default values made available to the user are taken from the various tables in the 2006 IPCC Guidelines for National Greenhouse Gas Inventories: Volume 4 Agriculture, Forestry and Other Land Use (IPCC, 2006b) as organized and implemented in the Ex-Ante Carbon Balance Tool (EX-ACT version 3.1.2) developed by the Food and Agriculture Organization of the United Nations (FAO, 2011). These tables provide a Tier 1 estimate of carbon stocks in multiple carbon pools and other emission factors according to climate and ecosystem throughout the world. Example tables adapted from the 2006 IPCC Guidelines include Table 4.7 Above-Ground Biomass in Forests, Table 4.8 Above-Ground Biomass in Plantations, Table 4.9 Above-Ground Biomass Growth in Natural Forests, and Table 4.10 Above-Ground Net Biomass Growth in Tropical and Sub-Tropical Forest Plantations (IPCC, 2006b). A complete listing of all of the default values for all of the parameters is available for download in an Excel spreadsheet hosted on the Landscape Carbon MRV System Help pages at Custom Measurements The Emissions Calculator provides flexibility and transparency by displaying and allowing modification of all data and parameters that define land covers. Users can modify an existing land cover by substituting new data for some or all parameters or they can create an entirely new land cover to describe their project area by entering data for all parameters required to define that land cover. These new data should be the results of field inventories that directly measure some or all of the five major carbon pools (above ground biomass, below ground biomass, litter, dead wood, soil organic matter) in the project area or these new data may be values from published literature from nearby projects or research studies. Users can also incorporate national forest inventory data if available for a Tier 2 estimate of GHG emissions.

2 Page2 Detailed Explanation of Calculations The calculations performed within the Emissions Calculator are a function of the inputs provided by the user in defining project location, project length, land covers, and two opposing scenarios. The location of the project influences the default land cover values that are matched to the regional ecosystem and climate. The length of the project determines how many years the calculator estimates carbon stocks and GHG emissions. The selection of default land covers or the creation of unique Tier 3 land covers defines the carbon densities for that parcel and the resulting emissions from land cover change. The user defines both a reference scenario and a project scenario that include several parameters that all influence the sequestration or emission of GHGs as a result of land cover change in a project. Project Description The user defines several parameters on the Project Description section that influence the calculation of GHG emissions (see Figure 1 below). The Duration of the project determines how many years the calculator computes carbon stocks and GHG emissions. The length of the project impacts net GHG emissions as a very long project may eventually sequester enough GHGs through forest re-growth to more than offset a large emission from deforestation in the first year of a project. The Emissions Calculator also uses twenty years as a transition point for reaching a new soil organic carbon stock equilibrium and also as the dividing point between young (fast) and old (slow) growth rates for forest biomass growth. Figure 1. Example of a Project description page in the Emissions Calculator. The Continent, Climate Zone, and Moisture Zone identified in the drop down menus will influence the selection of Tier 1 default land covers that are made available to the user to define the emission factors for the parcels and scenarios for the project.

3 Page3 The Soil Type selected in the drop down menu will influence values of the soil organic carbon (SOC) stocks in the Tier 1 default land covers made available to the user. HAC is high activity clay and LAC is low activity clay. The SOC stocks used in the Emissions Calculator are adapted from Table 2.3 in the 2006 IPCC Guidelines (IPCC, 2006b). The Carbon/Dry Matter ratio is set at the IPCC default value of 47% carbon in dry woody biomass. However, the user may revise this ratio by entering another value to define the carbon percentage of dry woody biomass. Altering the Carbon/Dry Matter ratio here will greatly influence the carbon stocks in live biomass for a land cover. Parcel Definition The user defines several parameters on the Parcel Description section that influence the calculation of GHG emissions. The Area of a parcel (in hectares) is the activity data used to calculate carbon stocks for that parcel by multiplying it times the carbon density (tc/ha) or emissions factor. The carbon density used in the preceding calculation is determined by the parameters in the Land Cover selected by the user whether those parameters are populated by Tier 1 default values or Tier 3 user-defined values from adding a new land cover populated with project measurement data (see Figure 2 below). Figure 2. Example of a Parcel definition page.

4 Page4 Reference Scenario and Project Scenario The user defines several parameters when describing the two scenarios that all influence the calculation of GHG emissions. The calculations are performed in the same manner for both a Reference Scenario and a Project Scenario. The Emissions Calculator also reports the difference between the Reference and Project Scenarios. Users may also add subsequent land cover changes within a single scenario to show multiple changes that occur later in the project time period on the same parcel of land. Figure 3. Example of a Reference Scenario definition page. Land Cover. The selection of the land cover determines the carbon stocks used in the emissions calculator as defined in the selected land cover (see Figure 4 below). All land covers, whether populated with Tier 1 default values, Tier 2 national data, or Tier 3 local measurement values, are defined by values that describe the five primary terrestrial carbon pools, the impacts of burning biomass, forest growth rates, and the ratio of above and below ground biomass. Young and old forest growth rates are defined as less than 20 years old and greater than 20 years old respectively. Forest biomass grows according to the defined growth rates but a maximum biomass is capped at the biomass levels used to define the land cover rather than allowing the forest to grow indefinitely in long project durations past a reasonable biomass level for that ecosystem.

5 Page5 Figure 4. Example of a Land Cover definition page. Start Year. The selection of the start year is only applicable for scenarios with multiple land cover changes within the time period of the project. Carbon stocks are emitted or sequestered in the year following the year identified in the start year for that land cover change. Degradation. Entering a value other than zero in the % Degradation reduces the carbon stocks in the following year by that percentage. Forest carbon stocks then begin to grow in the second year following degradation as the forest recovers from the disturbance. Forest growth is determined by the growth rates defined in the land cover. Unless the user adds local measurement data to define the young and old growth rates, the Tier 1 default growth rates are taken from Tables 4.9 and 4.10 in the 2006 IPCC Guidelines (IPCC, 2006b). For projects with very long durations, the forest is not allowed to grow past the maximum biomass stocks as defined in the land cover. Harvested Wood Products. When a forest is converted to non-forest or degraded to lower carbon stocks, users may set aside some of the forest biomass into long term storage in a harvested wood products (HWP) pool. Users define how many tonnes of dry matter are set aside. The entire HWP pool is set aside in the first year and remains stable (unchanged) throughout the duration of the project. Burned. If the user selects Burned, the Emissions Calculator estimates the amount of greenhouse gases emitted to the atmosphere from burning biomass following land cover change in year 1. Several parameters used to define a land cover (% dry matter released, CH4 released, and N2O released)

6 Page6 determine the amount of GHGs emitted to the atmosphere. The GHG calculations for burning are based on values taken from Tables 2.4, 2.5, and 2.6 in the 2006 IPCC Guidelines (IPCC, 2006b). Practice. The Practice describes the potential mitigation affects of implementing common agricultural practices on agricultural land cover. These values to describe the mitigation potential are in units of tco 2 e/ha/yr and range from 0.15 to Potential agricultural practices that have GHG mitigation potential include improved agronomic practices, nutrient management, tillage and residues management, water management, manure application, and agroforestry. The default practices perform GHG calculations, primarily on the soil organic carbon stocks, that are based on values adapted from Table 8.4 in the Fourth Assessment Report (IPCC, 2007). Users may choose the specific practices that occur in the project area or select Default where no practices are applied to the calculations. Figure 5. Example of a Practices definition page. Emissions Tables for Reference and Project Scenarios The Emissions Calculator reports GHG emissions for both the Reference Scenario and Project Scenarios in separate tables that show annual terrestrial carbon stocks and both CO 2 and non-co 2 fluxes to the atmospheric GHG pool (see Figure 6 below). This full reporting of annual stocks and GHG fluxes for both scenarios is intended to provide complete and transparent reporting of results. Users can verify and reproduce similar GHG emission estimates by replicating the calculations offline in a spreadsheet of their own design or by using the EX-ACT tool (FAO, 2011) using similar inputs.

7 Page7 Figure 6. Emissions Table for a Reference Scenario.

8 Page8 Database Tables within the Emissions Calculator The Emissions Calculator is written in Django and the front end html web pages are driven by multiple database tables. The overview of all tables within the Emissions Calculator is given below in Table 1. As stated previously, the tables within the Emissions Calculator are populated by values from the 2006 IPCC National Guidelines on Greenhouse Gas Inventories (IPCC, 2006b) as organized and implemented in the Ex-Ante Carbon Balance Tool (EX-ACT version 3.1.2) developed by the Food and Agriculture Organization of the United Nations (FAO, 2011). This document does not provide an exhaustive listing of the many hundreds of rows of data that define the multiple parameters but instead will show screenshots of the partial Django tables. A complete listing of all of the values for all of the parameters is available for download in an Excel spreadsheet hosted on the Landscape Carbon MRV System Help pages at Table 1. Emissions Calculator Database Tables

9 Page9 Table 2. AbovegroundBiomass Table 3. BelowgroundRatio

10 Page10 Table 4. BiomassLandUse Table 5. Carbonpools

11 Page11 Table 6. Combustion Factor Table 7. Combustionlanduse Table 8. Grasslandbiomass

12 Page12 Table 9. Grasslandsoil Table 10. Landcover

13 Page13 Table 11. Landuse Table 12. Necromass Table 13. Parcels

14 Page14 Table 14. Practices Table 15. Projects

15 Page15 Table 16. RiceEmission Table 17. RicePractice

16 Page16 Table 18. Scenarios Table 19. SoilCarbonFactor

17 Page17 Table 20. SoilCarbonRef

18 Page18 References FAO ExACT Version released March IPCC Good Practice Guidance for land Use, Land-Use Change and Forestry. Penman, J., Gytarsky, M., Hiraishi, T., Krug, T., Kruger, D., Pipatti, R., Buendia, L., Miwa, K., Ngara, T., Tanabe, K., and Wagner, F. IGES, Japan. IPCC. 2006a IPCC Guidelines for National Greenhouse Gas Inventories. Volume 1: General Guidance and Reporting. Prepared by the National Greenhouse Gas Inventories Programme, Eggleston H.S., Buendia L., Miwa K., Ngara T. and Tanabe K. (eds). IGES, Japan. IPCC. 2006b IPCC Guidelines for National Greenhouse Gas Inventories. Volume 4: Agriculture, Forestry and Other Land Use. Eggleston, H.S., Buendia, L., Ngara, T., and Tanabe, K. (eds). IGES, Japan. IPCC Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

19 Page19 For more information, contact: Mike Smalligan Patrick Paul Research Forester Research Programmer Michigan State University Michigan State University Global Observatory for Ecosystem Services Global Observatory for Ecosystem Services 1405 South Harrison, Suite South Harrison, Suite 101 East Lansing, Michigan USA East Lansing, Michigan USA Phone: (517) Phone: (517) Rob Braswell Matt Hanson Senior Research Scientist Imaging Scientist Applied GeoSolutions Inc. Applied GeoSolutions Inc. 87 Packers Falls Road 87 Packers Falls Road Durham, NH Durham, NH Phone: (603) Phone: (603)