Full-system Carbon Accounting

Many managed landscapes with trees, such as this rubber agroforest in North Sumatra, blend forest and agriculture, but may not fit existing forest definitions; Photo: Meine van Noordwijk

The current IPCC Good Practice Guidelines for National Greenhouse Gas Inventory provide a coherent framework for dealing with aboveground as well as belowground carbon impacts of Agriculture, Forestry and Other Land Use (AFOLU). The IPCC framework could become the primary framework for reporting and accountability in non-Annex I countries, aligned with the rules that currently apply to Annex-I countries.

According to expert opinion in the IPCC community that is responsible for the guidelines, however, the net emission estimates from land use and land cover change may carry an uncertainty margin of as much as 60%. On the positive side, the use of the IPCC guidelines over multiple measurement periods will lead to a reduction of the overall error, as annual updates correct for previous errors and address the permanence issue. On the negative side, the current uncertainty margin of 60% is unacceptably high. The opportunity to participate in a market for reduced AFOLU carbon emissions would generate clear incentives to improve the accuracy of the accounts.

Data and methods available in national and international research networks can be analyzed to improve the accuracy of estimates, derive better estimates of the uncertainty, and identify ways to reduce it. The two components of uncertainty are interlinked: error in classification of land cover and land cover change, and uncertainty in the mean carbon stocks per unit area in each land cover class. A binary classification (e.g. with forest and non-forest as classes) is insufficient. Analysis so far suggests that a classification that results in 5-10 land cover classes may lead to the lowest overall uncertainty. Further data compilation and analysis is needed and possible. This has already started. The IPCC support office (http://www.ipcc-nggip.iges.or.jp/tsu/tsustaff.htm) is providing support to full-system carbon accounting.

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