1. General Model Information

Name: Graz / Oak Ridge Carbon Accounting Model

Acronym: GORCAM

Main medium: terrestrial
Main subject: biogeochemistry, forestry
Organization level: ecosphere
Type of model: not specified
Main application: research
Keywords: carbon cycle, global change, land management, carbon sequestration,bioenergy, wood products, energy substitution, materials substitution,forestry


and authors: B. Schlamadinger and L. CanellaJOANNEUM RESEARCH
Institute of Energy Research
Elisabethstrasse 11a
A-8010 Graz
AUSTRIA Tel: +43 316 876 340Fax: +43 316 876 320Email: bernhard.schlamadinger@joanneum.ac.atG. Marland
Oak Ridge National Laboratory
Environmental Sciences Division
Oak Ridge, TN 37831-6335
USATel: +1 423 241 4850Fax: +1 423 574 2232Email: gum@ornl.gov



Land management and biomass utilization strategies offer opportunities to mitigate the increase of the CO2 concentration in the earth's atmosphere. For example, land can be used to sequester carbon (afforestation, forest protection), to produce bioenergy as a substitute for fossil fuels, or to produce other renewable raw materials like timber.

GORCAM is a spreadsheet model that has been developed to calculate the net fluxes of carbon to and from the atmosphere associated with such strategies.

The model considers

Input parameters of the model describe the management regime (harvest cycle, growth rate etc.), the land use before the project, and the way in which the biomass is used for carbon mitigation. The model output is presented in diagrams with cumulative carbon sequestration over time.

Abstract author: B. Schlamadinger, G. Marland, and L. Canella

II. Technical Information

II.1 Executables:

Operating System(s):

II.2 Source-code:

Programming Language(s): spreadsheat (Microsoft Excel)

II.3 Manuals:

II.4 Data:

Currently about 200 input parameters.

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References

papers by Gregg Marland and Bernhard Schlamadinger
Fax: +1/423/574 2232, e-mail: gum@ornl.gov, uvu@ornl.gov
All papers except 1., 9., 12., 15., 21. and 22. were prepared using GORCAM (Graz / Oak Ridge Carbon Accounting Model, http://www.joanneum.ac.at/GORCAM.htm). The most complete description of GORCAM, with parameter listings and equations, can be found in paper 13.
  1. Marland, G., and S. Marland, 1992, Should We Store Carbon in Trees?,
    Water, Air, and Soil Pollution 64: 181-195.

    Raises the question whether there is greater carbon benefit when carbon is stored in trees or when trees are harvested to produce biomass fuels. The most effective strategy depends on the initial status of the land, the productivity that can be expected, the efficiency with which forest harvest is used, and the time perspective of the analysis.

  2. Marland, G. and B. Schlamadinger, 1995, Biomass Fuels and Forest-Management Strategies: How Do We Calculate the Greenhouse-Gas Emissions Benefits?
    Energy 20: 1131-1140.

    Discusses some basic ideas for carbon accounting and notes that it is important to consider the full affected system. Production of by-products and the foregone opportunity to use finite land resources in other ways should be considered.

  3. Schlamadinger, B. and G. Marland, 1996, Carbon Implications of Forest Management Strategies, pp. 217-232
    in M.J. Apps and D.T. Price (eds.), Forest Ecosystems, Forest Management and the Global Carbon Cycle, Proceedings of a NATO Advanced Research Workshop, NATO ASI Series I, Volume 40, Springer-Verlag, Berlin.

    Develops several scenarios to illustrate that forest managment can affect the net flux of carbon to the atmosphere by sequestering carbon in living and dead biomass, by sequestering carbon in long-lived wood products, by direct displacement of fossil fuels, and by indirect displacement of fossil fuels when wood products are less energy intensive than are the products they replace.

  4. Schlamadinger, B., and G. Marland, 1996, The Role of Forest and Bioenergy Strategies in the Global Carbon Cycle,
    Biomass and Bioenergy 10: 275-300.

    A longer version of the preceding paper provides a more complete description of the model GORCAM (Graz/Oak Ridge Carbon Accounting Model) and detailed discussion of the basic parameters and parameter values used in this and other GORCAM modeling papers. Carbon balances are described both at the stand level and for a normal forest.

  5. Schlamadinger, B. and G. Marland, 1996, Full Fuel-Cycle Carbon Balances of Bioenergy and Forestry Options,
    Energy Conservation and Management 37:813-818.

    A sensitivity analysis on some of the principal parameters in GORCAM reveals the importance of high yields and high efficiency in product use for yielding large benefits in carbon mitigation.

  6. Marland, G., B. Schlamadinger, and L. Canella, 1997, Forest Management for Mitigation of CO2 Emissions: How Much Mitigation and Who Gets the Credits?
    Mitigation and Adaptation Strategies for Global Change 2: 303-318.

    Shows that whereas there may be significant net benefits to the global carbon budget when forest products are used for energy or other purposes, it may be difficult for the forest manager or forest products industry to claim credit for all of these benefits.

  7. Marland, G., B. Schlamadinger, and P. Leiby, 1997, Forest/Biomass Based Mitigation Strategies: Does the Timing of Carbon Reductions Matter?
    Critical Reviews in Environmental Science and Technology 27: 213-226.

    Many of the strategies proposed for using forest management to mitigate the increasing concentration of atmospheric CO2 are characterized by C emissions reductsions which are not uniform over time. This paper illustrates the effect of a “carbon discount rate” on the net present value of future carbon flows and addresses the question whether the timing of emission reductions matters.

  8. Marland, G., and B. Schlamadinger, 1997, Forests for Carbon Sequestration or Fossil Fuel Substitution? A Sensitivity Analysis,
    Biomass and Bioenergy 13: 389-397.

    see also
    Non-forest land can be afforested/reforested to sequester C, or for producing sustainable forest harvests to displace fossil fuels. This paper compares the net effect on C emissions to the atmosphere for the two approaches over a range of values of forest productivity and the efficiency of product use.

  9. Schlamadinger, B., M. Apps, F. Bohlin, L. Gustavson, G. Jungmeier, G. Marland, K. Pingoud, and I. Savolainen, 1997, Towards a Standard Methodology for Greenhouse Gas Balances of Bioenergy Systems in Comparison with Fossil Energy Systems,
    Biomass and Bioenergy 13: 359-375.

    Outlines a standard methodology for comparing the greenhouse gas balances of bioenergy systems with those of fossil energy systems. Emphasis is on careful definition of system boundaries. Includes recommendations on how bioenergy systems should be optimized from a greenhouse-gas emissions point of view.

  10. Schlamadinger, B., and G. Marland, 1998, Substitution of Wood from Plantation Forestry for Wood from Deforestation: Modeling the Effects on Carbon Storage, pp. 205-218
    in G. H. Kohlmaier, M. Weber, and R. A. Houghton (eds.), Carbon Mitigation Potentials of Forestry and Wood Industry, Springer Verlag, ISBN 3-540-63433-9.

    Discusses the carbon implications when plantation grown wood is used to displace wood from unsustainable harvest of mature forest. The results are compared with a basic scenario which assumes that biofuels and wood products from the plantation displace fossil fuels and alternate, more energy-intensive materials.

  11. Marland, G., B. Schlamadinger, and D. Feldman, 1998, Reforestation: What Happens When the JI Project Ends? pp. 239-244
    in P.W.F Riemer, A.Y. Smith and K.V. Thambimuthu (eds.), Greenhouse Gas Mitigation: Technologies for Activities Implemented Jointly, Pergamon/Elsevier , ISBN 0 08 0433 251.

    Discusses forestry project for carbon sequestration in the context of Joint Implementation. Host countries must assume responsibility for the stored carbon even after the project lifetime, because otherwise emission limits would be circumvented.

  12. Winjum, J.K., Brown, S., and B. Schlamadinger, 1998, Forest Harvests and Wood Products: Sources and Sinks of Atmospheric Carbon Dioxide,
    Forest Science 44: 272-284.

  13. Schlamadinger, B., L. Canella, G. Marland, J. Spitzer, 1998, Bioenergy Strategies and the Global Carbon Cycle,
    Sciences Geologiques 50, 1-4, p. x-y, in press.

    Gives a detailed description of the GORCAM model, with all input and output parameters, and equations for carbon pools and fluxes.

  14. Schlamadinger, B., and G. Marland, 1998, Net Effect of Forest Harvest on CO2 Emissions to the Atmosphere: A Sensitivity Analysis on the Influence of Time,
    paper presented at the 5th International Carbon Dioxide Conference, Cairns, Australia, 8-12 Sept., 1997, Tellus B (in press).

    This paper asks how long it takes for the net C sequestered to return to its initial balance when standing forest is harvested for products and replanted. Sensitivity analyses show the impact on this break-even time of varying
    • the rates of regrowth,
    • efficiency of product use for fossil fuel substitution, and
    • the amount of carbon stored on the site initially.
    The discounting of future carbon flows is discussed.

  15. Schlamadinger, B., and G. Marland, 1998, Some Technical Issues Regarding Land-use Change and Forestry in the Kyoto Protocol,
    in Proceedings of the IEA Bioenergy Task 25 Workshop “Effects of the Kyoto Protocol on Forestry and Bioenergy Projects for Mitigation of Net Carbon Emissions”, Rotorua/NZ, 13 March 1998 (http://www.joanneum.ac.at/IEA-Bioenergy-TaskXV), Environmental Science and Policy 1: x-y (in press).

    Describes the implications of the Kyoto Protocol for land-use change and forestry and addresses some of the technical issues that merit further consideration before the treaty comes into force.

  16. Marland, G., and B. Schlamadinger, 1998, Does the Kyoto Protocol Make a Difference for the Optimal Forest-based C Mitigation Strategy? Some Results from GORCAM,
    in Proceedings of the IEA Bioenergy Task 25 Workshop “Effects of the Kyoto Protocol on Forestry and Bioenergy Projects for Mitigation of Net Carbon Emissions”, Rotorua/NZ, 13 March 1998 (http://www.joanneum.ac.at/IEA-Bioenergy-TaskXV), submitted for publication.

    An adapted version of the model GORCAM has been used to asess eligible carbon credits under the Kyoto regime and to illustrate how the optimal forest-based strategy for carbon mitigation might change under the provisions of the Kyoto Protocol.

  17. Marland, G., and B. Schlamadinger, 1995, CO2 Emissions Coefficients for Biofuels Systems: Process and Site-Specific Details Can Make a Difference,
    paper presented at an Advisory Group Meeting organized by the International Atomic Energy Agency, Vienna, Austria, Sept. 26-28, 1995, IAEA Working Materials Document 623-II-AG-832.3.

  18. Cushman, J., G. Marland, and B. Schlamadinger, 1995, Biomass Fuels, Energy, Carbon, and Global Climate Change,
    Oak Ridge National Laboratory Review, v. 28, nos. 2/3, p/ 14-21, Oak Ridge National Laboratory, Oak Ridge, TN, USA. Reprinted in Biologue. v. 13, no. 4 p. 33-37, 1995.

  19. Marland, G., and B. Schlamadinger, 1996, Greenhouse Gas Balances of Biomass Energy Systems, in Comparison of Energy Sources in Terms of Their Full-Energy-Chain Emission Factors of Greenhouse Gases:
    Proceedings of an IAEA Advisory Group Meeting/Workshop, 4-7 Oct., 1994, Beijing, China, IAEA-TECDOC-892, International Atomic Energy Agency, Vienna, Austria.

  20. Marland, G., and B. Schlamadinger, 1996, Evaluating the Effect of Deforestation on the Net Flux of CO2 to the Atmosphere, pp. 136-140
    in Proceedings of the Fourth Japan-U.S. Workshop on Global Change: Land Use/Cover Change and Global Environmental Conservation, February 27-29, 1996, Tsukuba, Japan; Science and Technology Agency, Chiyoda-ku, Japan.
  21. Apps, M, T. Karajalainen, G. Marland, and B. Schlamadinger, 1997, Accounting Considerations: CO2 Emissions from Forests, Forest Products, and Land-Use Change: A Statement from Edmonton, 6 pp., unpublished manuscript see also.
  22. Schlamadinger, B., and G. Marland, 1997, A Proposal for Inclusion of Land-Use Change and Forestry in a Protocol to be Adopted in Kyoto, unpublished manuscript,
    available from: uvu@ornl.gov or gum@ornl.gov.

V. Further information in the World-Wide-Web

The home page of themodel GORCAM (JOANNEUM RESEARCH - Institute of Energy Research).

VI. Additional remarks

The model allows sensitivity analyses (with 1 or 2 independent inputparameters).

The model in its current version can be used to calculate carbon balancesof even-aged forest stands as well as for normal forests (plantations).An extension to be able to model age-class dynamics, based on the Lesliematrix approach, is under way.

The model will be improved to become more use-friendly and is plannedto be made available through the Carbon Dioxide Information Analysis Center(CDIAC) at Oak Ridge National Laboratory (ORNL) in 1999 (http://cdiac.ESD.ORNL.GOV/cdiac).

Last review of this document by: B.Schlamadinger and M. Sonntag:April, 16th 1997
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:44 CEST 2002

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