Comments on HWP estimation methods Ken Skog Kim Pingoud

Methods Topics Method types Applicability of methods to approaches Data needs and availability Components(variables) needed to estimate for any approach

Methods Types Flux data – Input from surveys Output: Use lifetimes to estimate outputs Use surveys to estimate outputs Stock data c) Estimate stock change between two inventories

Methods Applicability Stock Change Atmospheric Flow Production Flux using lifetimes Need domestic life times Need domestic lifetimes Need domestic and export lifetimes Flux using surveys of emissions Partial domestic coverage (not all emissions can be surveyed) (means to verify) Difficult need to separate domestic emissions survey into domestic and import wood sources Stock change Partial coverage (e.g. buildings in country) (means to verify need to separate inventory change into domestic and import wood sources Notes Potential incomplete coverage of secondary wood products Complete coverage for secondary products exports

Data Availability Data Sources Harvest, production, trade FAO, country data Conversion factors IPCC Forest GPG, country data Lifetime for products in use Limited – previous studies Need work validating against surveys of inventory Disposition after use Limited – need national estimates (possible aid from waste sector) SWDS decay limits / lifetimes IPCC Waste sector guidelines & GPG We need 8 types of annual data to make our estimates. For the production approach we assume data for items 4- 5 are the same for products uses in the U.S. and products we export to other countries

Variables needed to estimate for any approach

Harvested Wood Products: Stocks and flows B D C EC EB ED Ex I

Harvested Wood Products: Comparison of Approaches U.S. HWP Removals in 2002 = 59 Tg C Variables from U.S. HWP Estimation Methods Stock Change or Flow Variables Tg C A Domestic Product Stock Change (from domestic RW) 58 B Exported Product Stock Change (from domestic RW) 1 C Imported Product Stock Change 10 D Flow of imports 13 E Flow of exports 7 The U.S. reports wood product removals using the production approach, and includes information on imports and exports in its national inventory report. In making this calculation, the US estimates changes in carbon stocks in the domestic and exported products pools. The US also tracks information on the stocks of imported products and the flow of imports and exports. From these data, the U.S. could account for harvested wood products using any of the approaches. Because the U.S. is a net importer, if we were to use the Stock Change or Atmospheric flow approaches, our estimates for HWP would be higher. The U.S. uses the production approach because it is consistent with the IPCC default and it is simple to implement if you make assumptions about the exports product pool. An important thing to take from this table is that a core set of estimates can be reported and then combined under any of the approaches As a technical aside, these are stock change and flow variables, we’ve identified a minimum set of emissions variables that could also be used to make estimates for each approach. Approaches: Production (A+B) = 59 Stock Change (A+C) = 68 Atmospheric Flow (A + C – (D – E)) = 62