Harvested Wood Products in the U.S. National
Greenhouse Gas Inventory:
Methodology and Accounting
Harvested Wood Products: Topics
• Overview of U.S. Emissions and
Removals
• U.S. Estimation Method and Results for
Harvested Wood Products
• Accounting Approach
Overview of U.S. Greenhouse Gas Emissions, 2002
Emissions = 6,935 Tg CO2 eq.
Removals = 691 Tg CO2 eq.
Waste
3%
Industrial
processes
4%
Agriculture
7%
Solvents
<1%
Other
13%
Energy
85%
Landfilled
Wood
22%
Wood
Products
9%
HWP = 215 Tg CO2 eq.
Forest
56%
U.S. Estimation Method
Method details for the U.S.–
– Track Inputs to, and outputs from carbon pools
• Begin in 1910, track to current time
– Product carbon pools
• Products in use
• Products in dumps or solid waste disposal sites
– Use forest sector model framework – the
WOODCARB model
• to track all products from annual harvest
• to track imports/ exports
U.S. estimation example –
tracking carbon in single family houses
1900
1901
1902
x
x
2001
2002
Total
Change in
carbon
Remaining in use
Amount
Placed
in use 1900 1901 1902
2001
10.2
9.2 9.1 9.0 … 3.5
10.7
9.6 9.5 … 3.7
11.2
10.1 … 3.9
…
x
…
x
26.7
… 24.4
27.3
…
9.2 18.8 28.7 … 896.1
2002
3.4
3.6
3.8
x
x
24.2
24.7
913.4
17.3
Harvested Wood Products: Methodology
Disposition of Carbon in Harvested Wood - U.S. Average
100%
80%
Percent
60%
40%
20%
0%
0
10
20
30
40
45
Years since harvest
Removals
Products
Landfills
55
65
Emissions
Energy
Emissions
Source: Heath and others, 1996; Skog and Nicholson, 1998
75
U.S. data
Annual Data Requirements
1.
2.
3.
Harvest statistics
Product production
Product exports and imports
Coefficients
1.
2.
3.
4.
5.
6.
Factors to convert product units to carbon
Distribution of products to end uses
Use life of products in end uses
Portion of discarded wood to dumps vs SWDS vs burning
Portion of wood in permanent vs temporary storage in SWDS
Decay rates in dumps & SWDS
The U.S. assumes the coefficients are the same for products used
domestically and products exported
U.S. Product Lifetime
Half lives for end uses (years)
Wood and paper in SWDS
1 family homes (pre-1980)
80
1 family homes(post-1980)
100
Solidwood
3%
Multifamily homes
70
Newsprint
16%
Mobile homes
20
Coated paper
18%
Nonresidential construction
67
Boxboard
32%
Pallets
6
Office Paper
38%
Manufacturing
12
Furniture
30
Half life for portion that decays
Railroad ties
30
20 years
Paper (free sheet)
6
Paper (other)
1
Fraction that decays
Harvested Wood Products: Comparison of Approaches
U.S. HWP Removals in 2002 = 215 Tg CO2 eq.
Variables from U.S. HWP Estimation Methods
Tg CO2 eq.
Stock Change or Flow Variables
A
Domestic Product Stock Change (from domestic RW)
212
B
Exported Product Stock Change (from domestic RW)
3
C
Imported Product Stock Change
36
D
Flow of imports
47
E
Flow of exports
25
Approaches:
Production (A+B)
=
215
Stock Change (A+C)
=
248
Atmospheric Flow (A + C – (D – E))
=
227
Harvested Wood Products: Timeline
• September 2004, UNFCCC HWP workshop
• November 2004, IPCC Guidelines (GL)
revisions, HWP experts meeting
• **December 2004, SBSTA 21**
• March 2005, 1st review of IPCC GL revision
by experts
• September 2004, 2nd review of IPCC GL
revision by experts and governments
• May 2006, SBSTA 24, IPCC GL revision
presented to SBSTA
Conclusions
• HWP is an important sink in the U.S.
• Tracking HWP will highlight opportunities to better
manage HWP pools
• Transparency can be improved if countries report
stock changes associated with both imports and
exports regardless of approach
• Encourage transparent reporting now, such that any
approach can be applied in the future
• Accounting systems should be consistent with IPCC
default
• There is a narrow window of opportunity to provide
guidance to IPCC authors on HWP