Global mitigation potential of carbon stored in harvested wood products

Abstract

Carbon stored in harvested wood products (HWPs) can affect national greenhouse gas (GHG) inventories, in which the production and end use of HWPs play a key role. The Intergovernmental Panel on Climate Change (IPCC) provides guidance on HWP carbon accounting, which is sensitive to future developments of socioeconomic factors including population, income, and trade. We estimated the carbon stored within HWPs from 1961 to 2065 for 180 countries following IPCC carbon-accounting guidelines, consistent with Food and Agriculture Organization of the United Nations (FAOSTAT) historical data and plausible futures outlined by the shared socioeconomic pathways. We found that the global HWP pool was a net annual sink of 335 Mt of CO₂ equivalent (CO₂e)⋅y^-1 in 2015, offsetting substantial amounts of industrial processes within some countries, and as much as 441 Mt of CO₂e⋅y^-1 by 2030 under certain socioeconomic developments. Furthermore, there is a considerable sequestration gap (71 Mt of CO₂e⋅y^-1 of unaccounted carbon storage in 2015 and 120 Mt of CO₂e⋅y^-1 by 2065) under current IPCC Good Practice Guidance, as traded feedstock is ineligible for national GHG inventories. However, even under favorable socioeconomic conditions, and when accounting for the sequestration gap, carbon stored annually in HWPs is <1% of global emissions. Furthermore, economic shocks can turn the HWP pool into a carbon source either long-term-e.g., the collapse of the USSR-or short-term-e.g., the US economic recession of 2008/09. In conclusion, carbon stored within end-use HWPs varies widely across countries and depends on evolving market forces.

Keywords: carbon sequestration; climate change; forest sector; harvested wood products; shared socioeconomic pathways.

Fig. 1.

Projected global HWP market and carbon-pool data for 1961–2015 from FAOSTAT, projections for 2016–2065 from the GFPM for SSP1–5. (A–C) Global production of feedstock (A) and end-product groupings (B) drive the total level of carbon stored within HWPs and the net annual carbon flux (year-to-year change) in the HWP pool (C). (D and E) Current IPCC accounting methods ignore carbon stored in products manufactured from foreign feedstock, with D displaying the proportion of unaccounted feedstock, leading to an amount of unaccounted removals each year (E). (F) Consequently, a gap exists between the actual global carbon cycle of HWPs and those inventoried under IPCC 2013 Good Practice Guidance. Global estimates are based on disaggregated country and commodity information.

Fig. 2.

Spatial patterns in socioeconomic and carbon-pool information for 2015 and projections for 2065. Left shows income per capita, first for 2015 measured in GDP/capita purchasing power parity US$2005 dollars, and then in annual average growth rate from 2015 to 2065 for SSP2, SSP3, and SSP5. Center depicts the relative magnitude of the carbon pool in each country in terms of tCO₂ per capita in 2015 and in 2065 for SSP2, SSP3, and SSP5. Right depicts the annual carbon flux in each country in 2015 and in 2065 for SSP2, SSP3, and SSP5.

Fig. 3.

Spatial patterns in degree with which the domestic HWP pool could offset select IPCC emissions sectors. Calculated as the ratio in the annual carbon flux in the HWP pool to the reported United Nations Framework Convention on Climate Change. GHG data for a given sector. 2015 data were used for all Annex I countries. For non-Annex I countries, the most recent available year’s GHG emissions data were used and matched to the annual carbon flux in the HWP pool in that same year. See SI Appendix, Table S15 for specific data and years used. Excl., excluding.

Fig. 4.

The effects of economic shocks on the HWP carbon flux in the United States (A), Russia (B), and China (C): For 1961–2015 from FAOSTAT; projections for 2016–2065 from the GFPM for SSP1–5. The development of socioeconomic factors helps determine production levels whereby carbon is added to the HWP pools when new products are produced. Net release of emissions occurs when current production is unable to offset carbon release from previously consumed products as they decay.