Substitution Estimates for Wood Products in the United States, 1990 to 2020

Abstract

Abstract Forest carbon stock changes are routinely reported at the national level. Such accounting usually includes carbon sequestered by live trees and stored in living and dead trees, litter, and soil. The carbon stored in harvested wood products (HWPs), while in use and after disposal, may also be reported. However, wood products may provide a further indirect carbon benefit by providing an alternative to materials that require relatively large inputs of fossil-derived carbon. This “substitution impact” of HWPs is not explicitly considered in national reporting for forest carbon accounts because it is not directly comparable with absolute emissions and removals. However, the substitution impact is avoided fossil emissions, which do affect the net climate impact of wood use. Here, we estimate the total substitution impact for wood products harvested recently from forests in the United States. The total substitution impact is based on reported volumes of national wood production and the substitution factors for individual products. The substitution factors are obtained from comparative life-cycle assessments of specific wood products and their nonwood alternatives. The total substitution impact for wood products in the United States in 2020 was 188 TgCO2 equivalents. Calculation of substitution factors is challenged by assumptions about the use of wood products and their alternatives and by limited availability of current and specific life-cycle assessment data; however, our findings indicate that the substitution impact of forest products are a relatively important component of the carbon benefits of wood-based products.