Future projections of global wood carbon flow and stock and climate change mitigation potential considering waste wood recycling

The climate change mitigation potential of carbon stocks and wood substitution for carbon-intensive material and energy has gained global attention. This study is the first to estimate global and country-specific wood carbon flow, stock, and associated carbon emission reduction potential under three socioeconomic development and policy implementation scenarios up to 2050, emphasizing global waste wood recycling. In Shared Socioeconomic Pathways 1 (SSP1) and 2 (SSP2) scenarios with recycling policies, global roundwood consumption by 2050 is projected at 5.3 and 4.9 billion m³/year, respectively, representing 1.3 and 1.2 times the 2018 levels, which are 20 % and 11 % lower, respectively, than in the cases without recycling, contributing to reduced forest harvesting. The carbon stocks of harvested wood products in 2050 are estimated at 13.6 GtC under SSP1 and 12.1 GtC under SSP2, equating to 1.8 and 1.6 times the 2018 levels. By country, the largest carbon stocks in 2050 under SSP1 are projected for China, the United States, Russia, India, and Germany. The total of increase in carbon stocks in harvested wood products and material/energy substitution, including waste wood used for material and energy, is expected to be approximately 0.4 GtC/year by 2050 relative to 2018 under SSP1. This corresponds to 4 % of current global carbon emissions from fossil fuel consumption and industrial processes. China, the United States, and India are anticipated to account for approximately 46 % of the global total. Implementing global waste wood recycling policies centered on these key countries can significantly contribute to climate change mitigation.