Modeling current and projected carbon storage in wood and paper Ken Skog USDA Forest Products Lab Madison, WI

Modeling current and projected carbon storage in wood and paper Model Framework Accounting for Imports and Exports Data needs/ uncertainty Results

Cycling of Carbon Through Wood and Paper Products Atmosphere Burned Decayed Forests Harvest Products Recycling Wood-in- use Methane and CO2 Landfills

The System Framework – Harvested wood carbon Stock change and Atmospheric Flow approaches Emissions Imports Products in use Products in landfills Harvest Points If you focus on measuring flows and emissions you can still get estimates of change in stocks. If you focus on measuring change in Stocks you can still get estimates of emissions. Darkar report suggested incorrectly that you could not get an estimate of stock change if you only have emissions data. Exports ΔProduct stocks = Harvest + Imports – Exports – Emissions Net Flow to system = Harvest - Emissions Net Flow to system = - ΔProduct stocks - Net Imports

ΔProduct stocks = Harvest – Emissions The System Framework – Harvest wood carbon stocks and flows for Production approach Emissions Products in use Products in landfills Harvest Exports Points The production approach focuses on estimating change in domestic product stocks and export product stocks The production approach has a “production emissions” counterpart which would focus on emissions of a countries wood harvest. Production approach would require estimates of how a countries exported products decay in countries where they are shipped. ΔProduct stocks = Harvest – Emissions Flow to system = Harvest - Emissions

Data needs Low uncertainty (±10%) Wood and paper product production Product exports Product imports Product use by end use (e.g. construction) Medium / High uncertainty (±20%+) Waste when using products and disposition of waste Years products are in use Disposition of products after use – burn, decay, landfill Rate of decay in landfills Maximum decay in landfills (% ever emitted) Data on wood and paper products production, and trade and end uses is fairly accurate for the U.S. and is available for all countries from FAO. FAO fuelwood data is less accurate than indurtrial product data Data is less accurate on lifetimes of wood in use, disposition after use, landfill decay rates and limits

Decay of wood and paper in landfills Material type in landfill Maximum released Sold wood (lignin attached) 3% Newsprint 18% Coated paper 20% Boxboard 35% Office paper 43% One key factor that limits U.S. decay in our calculations is the estimate that decay of wood and paper in landfills if limited. While oxygen is available white-rot fungus can decay lignin. After Oxygen is depleted, lignin is not decayed by anaerobic bacteria and any cellulose incased in lignin is not decayed. Exposed cellulose will be decayed by anaerobic bacteria.

Disposition of 1990 harvested wood used for paper through 2050 (Tg) 1990 harvested wood that goes into paper and paperboard (or imports) goes through it’s life cycle shifting from product in use to emissions and to landfills. Paper goes out of use quickly but is retained in landfills – after 50 year 24% is still retained in landfills. 24% in stocks in 2050 In use In landfills

54% in stocks in 2050 In landfills In use Disposition of 1990 harvested wood used for fuel and solid wood products in the U.S. through 2050 (Tg) 54% in stocks in 2050 After 50 years 54% of harvest used for fuel and solid wood products is estimateed to still be in use or landfills due to long used life and limited decay in landfills. In landfills In use

41% in stocks in 2050 In landfills In use Disposition of 1990 wood harvest used for fuel and all products in the U.S. through 2050 (Tg) 41% in stocks in 2050 For 1990 U.S. harvest used in U.S. products 41% is estimated to still be in stocks in 60 years later. In landfills In use

Sensitivity to use life and decay rates -- Year 2000 Harvested wood carbon in 2050 58% 76% Emitted The persistence of carbon is stocks is particularly sensitive to estimates of use life and limits of decay in landfills. But even if we cut use life estimates in half, assume all paper and half of wood in landfills decays 20% of harvested wood carbon is still in stocks after 60 years.

U.S. Net Annual Changes to Stocks, and Emissions from Harvested Wood* Emitted Energy We have estimated flows of harvested carbon since 1910 with projections to 2050. Landfill accumulation is estimated to have increased in recent years. Since the 1980s wood and paper goes to landfills rather than dumps where much was burned and decay was greater. Landfill Products *Includes net imports. SOURCE: Skog and Nicholson, 2000

Managed forest lands, US, 2008-2012 Avg. annual C stock change C taken up by trees in managed forests 381.9 C released by harvesting trees -276.0 Net C taken up in Soil 52.4 Net C taken up in Floor 12.8 Net C taken up in Understory 0.7 Net C accrued in live biomass & soil 171.8 C increase in logging residue 26.1 C in products in use 39.1 C in products in landfills 51.3 C stored in products & landfills 90.4 Net C removals related to managed forests 288 +/- 15% MMT/yr NOTE: the model is currently being updated, and we expect these estimates to change. However, all indications are that the trends and relative size of the estimate will be similar. The update is expected to be completed by spring of 2001. (Most of the work is writing manuscripts about the model for peer-review.) This table shows the carbon flux estimate by component for the first commitment period. Positive values indicate carbon is being removed from the atmosphere and stored in the forest or transferred into another forest-related pool; a negative value indicates a release of carbon to the atmosphere or a transfer to another forest-related pool. The modeling system produces carbon stock projections for the years 2005, 2010, 2015, etc. Carbon stock change is calculated as the difference between inventories. Estimates for the period 2008-2012 are weighted averages of the periods (1 January) 2005-2009 (end of December), and 2010-2014. The amount of net carbon accrued in live biomass & soil is the subtotal of the first five rows. Of the C released by harvesting trees (-276 Million Metric Tons/yr), 26.1 MMT/yr is transferred to logging residue, and 90 MMT/yr is transferred into products in use or landfills. The sum of the subtotals indicates 288 MMT per year is sequestered in the forest sector during 2008-2012. The uncertainty is estimated at plus/minus 15% at the 80% confidence interval.

Modeling current and projected carbon storage in wood and paper Current studies Develop generic national method using FAO product statistics Assess effects of uncertainty on U.S. estimates Project carbon storage associated with 2000 RPA Timber Assessment projections