A Method Countries Can Use to Estimate Changes in Carbon Stored in Harvested Wood Products and the Uncertainty of Such Estimates

A method is suggested for estimating additions to carbon stored in harvested wood products (HWP) and for evaluating uncertainty. The method uses data on HWP production and trade from several decades and tracks annual additions to pools of HWP in use, removals from use, additions to solid waste disposal sites (SWDS), and decay from SWDS. The method is consistent with IPCC guidance for estimating emissions from SWDS. Uncertainty is postulated in the form of probability density functions for 14 variables, using Monte Carlo simulation. Results for the United States suggest that uncertainty is most sensitive to uncertainty in production data for solidwood products, the factor used to convert products to carbon, and the proportion of solidwood and paper in SWDS. Uncertainty in the use (service) life of solidwood products has a limited effect because an error offsets changes in products in use and in SWDS. The method provides a starting point for meeting the aims of the IPCC Good Practice Guidance.