Carbon estimation in harvested wood products using a country-specific method: Portugal as a case study

This study aims to contribute to the ongoing international debate on the choice of approaches and methods to be used for estimating the amount of carbon that has accumulated in harvested wood products (HWP), within the context of national greenhouse gas emission inventories. A method for estimating carbon accumulation in HWP was developed and applied to three accounting approaches currently under discussion, namely: the stock-change approach, the production approach and the atmospheric-flow approach. This method is consistent with tier 3 methods suggested by the Intergovernmental Panel on Climate Change.An estimation of the carbon accumulation in HWP in Portugal for the period 1990–2000 varied between 112 and 1016 Gg C year−1. The atmospheric-flow approach provided the most favourable results for the whole period, largely because Portugal acted as a net exporter of carbon. The production approach ranked second, because the HWP exported were mainly produced from domestically grown wood. The uncertainty level of the estimates was in general lower than the uncertainty level expected when using a method based on generic default data. In conclusion, a simple method such as the one developed in this study may be used to estimate carbon accumulation in HWP with acceptable uncertainty levels, provided that country-specific data are available.