ncx-gitbot
commented
1 year ago NCX response: We appreciate the detailed comments raised about the absence of HWP accounting in the initial draft of our methodology. The carbon stored in trees is released into the atmosphere when a tree dies, some of it almost instantaneously and sometimes over years to decades. We believe it is important to account for all reasonable pools of emissions related to a harvest, and our revised methodology takes the storage of carbon in, and subsequent release of carbon from, harvest wood products into account.
Commenter Organization: NCASI
Commenter: Steve Prisley
2021 Deferred Harvest Methodology Section: 5 (Harvested wood products)
Comment: The methodology overstates carbon benefits of delayed harvest due to its omission of carbon stored in harvested wood products;:The NCX methodology does not include any accounting for carbon stored in harvested wood. The methodology states that carbon in wood products is not included because “harvest deferral leads only to a shift in the harvested wood products decay curve, whose impact differs depending on the number of years harvest is deferred during and after participation.” While this statement is true, the methodology ignores the fact that substantial portions of carbon in harvested wood remain stored for longer than 100 years (Hoover et al. 2014).
Computing harvest deferral credits based on what would have been harvested, rather than what would have been emitted, overstates the climate benefits obtained. For example, using US Forest Service factors for logging residues and decay of harvested wood products , if 100 tons of CO2e is removed from the live tree inventory in a pine stand in the US South, approximately 24 tons remains in the forest as logging residue where it will gradually decay, and approximately 30 tons is emitted from manufacturing residues within the first year after delivery to a mill. Some of the remaining carbon is emitted slowly over time, while up 30% remains in storage after 100 years. Even if we assume that all logging and manufacturing residues are emitted instantaneously, only about 54 tons of what is harvested is actually emitted the first year after harvest. Therefore, instead of the 100 ton-years credited under the harvest deferral scheme, the atmospheric benefit is only a deferral of 54 tons of CO2e.
The methodology proposed by NCX appears to be unique among similar Verified Carbon Standard methodologies in not recognizing the climate benefit of long-term storage of carbon in harvested wood. It does not seem that incorporating harvested wood in the NCX proposed methodology would add insurmountable complexity, given the high-level modeling that is required in other elements (computing the common practice baseline, leakage, etc.).
Proposed Change: Deduct carbon stored in harvested wood products after one year from the carbon in deferred harvest to accurately reflect that not all harvested carbon is emitted in the deferral period. Or, include ton-year accounting for the gradual release of CO2 from harvested carbon over a 100-year period using, for example data from Hoover et al. 2014 or Smith et al. 2006.
Hoover, C., R. Birdsey, B. Goines, P. Lahm, Y. Fan, D. Nowak, S. Prisley, E. Reinhardt, K. Skog, D. Skole, J. Smith, C. Trettin, and C. Woodall. 2014. Chapter 6: Quantifying greenhouse gas sources and sinks in managed forest systems. Quantifying Greenhouse Gas Fluxes in Agriculture and Forestry: Methods for Entity-Scale Inventory. Technical Bulletin. 1939., 6-1-6.114.
Smith, J.E., L.S. Heath, K.E. Skog, and R.A. Birdsey. 2006. Methods for calculating forest ecosystem and harvested carbon with standard estimates for forest types of the United States. General Technical Report NE-343. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station. 216 p.