climate-footprint

Method Description

Our climate footprints change over time, as yields vary from year to year, and as science progresses with more exact measurements or better understanding of the underlying chemistry and biology becoming available. Our automation of the climate calculations allows us to update all our footprints whenever we get better data, which is a unique feature of the CarbonCloud modeling approach.

The CarbonCloud agricultural computer model is based on the best currently available descriptions of the processes generating the greenhouse gas emissions in the agricultural sector. Our primary source of information is the IPCC standards (1).

Each calculation requires over 45 pieces of input data, a number we expect to grow as we take more things into account. This means that we are continuously importing data from high quality sources. Some of the parameters are available on crop and country level, such as yields from FAOSTAT, but other parameters are only available at a lower resolution. The fact that not all parameters are available for every crop/country combination means that some form of extrapolation or approximation is necessary. We use a consistent extrapolation method to substitute any missing piece of data with closely related data.

Missing data is a problem that must be dealt with in all climate calculations. By automating this process we can make sure that all of our footprints are of consistent quality and comparable to each other. This is something which is impossible to achieve using stand-alone assessments performed in different projects by different experts.

Functional unit

The functional unit of the data is one kg of producas is at the farm gate. Some products are typically dried at the farm, in these cases we use dry weight for the functional unit. For products not typically dried at the farm, we use fresh weight.

Weighting of gases

The footprints include emissions of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). These are aggregated into a single number expressed as kilograms of carbon dioxide equivalents (kg CO2e). The non-CO2 gases are converted using global warming potentials (GWP) which includes climate-carbon feedbacks, over a 100-year time frame, as per IPCC 5th assessment report from 2013 (2).

System boundaries

The footprints include the relevant emissions up until the farm gate. This means that these footprints do not include things like transport, packaging, or other processing.

The mechanisms currently included in our footprint calculations

All mechanisms are not applicable for all crops or countries.

  • CO2 emissions from organic soils
  • N2O emissions from organic soils
  • CO2 emissions from the production of fertilizers
  • N2O emissions from the production of fertilizers
  • N2O emissions from soil organic processes. Specifically, directN2O emissions, indirectN2O emissions from volatilization of N and from leeching and runoff of N. These are caused by the application of both synthetic and organic fertilizers, and from nitrogen in crop residues left in the fields
  • CO2 emissions from application of lime
  • CO2 emissions from the application of urea
  • CO2 emissions from pesticide production
  • CO2 emissions from the use of farm equipment
  • CO2 emissions from the drying of cereals, pulses and other crops typically dried at the farm
  • CH4 emissions from rice cultivation

Soon to be included in the assessment

  • CO2 from energy use associated with irrigation
  • Greenhouse production
  • Land-use change emissions
  • Soil carbon changes in mineral soils
  • Emissions from burning of crop residues

Excluded from the assessment

  • The production of capital goods
  • Maintenance of farm equipment
  • Commute of personnel to and from the farms
  • Housing of personnel working at the farms
  • Indirect land-use change, or any other market-based mechanisms
  • Albedo changes due to the production of the crops

Sources

  1. IPCC 2006 Guidelines IPCC 2006, 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Prepared by the National Greenhouse Gas Inventories Programme, Eggleston H.S., Buendia L., Miwa K., Ngara T. and Tanabe K. (eds). Published: IGES, Japan.

    2013 Wetlands supplement IPCC 2014, 2013 Supplement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories: Wetlands, Hiraishi, T., Krug, T., Tanabe, K., Srivastava, N., Baasansuren, J., Fukuda, M. and Troxler, T.G. (eds). Published: IPCC, Switzerland.

    2019 Refinement IPCC 2019, 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Calvo Buendia, E., Tanabe, K., Kranjc, A., Baasansuren, J., Fukuda, M., Ngarize, S., Osako, A., Pyrozhenko, Y., Shermanau, P. and Federici, S. (eds). Published: IPCC, Switzerland.

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  2. IPCC 5th assessment report (Chapter 8, page 714, table 8.7) Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA

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