1. Comments on HWP estimation methods
Ken Skog
Kim Pingoud

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

3. 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

4. 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

5. 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

6. Variables needed to estimate for any approach

7. Harvested Wood Products: Stocks and flowsB D C EC EB ED Ex I

8. 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