Large CO2 removal potential of woody debris preservation in managed forests

Abstract

Limiting climate warming to 1.5 °C requires reductions in greenhouse gas emissions and CO₂ removal. While various CO₂ removal strategies have been explored to achieve global net-zero greenhouse gas emissions and account for legacy emissions, additional exploration is warranted to examine more durable, scalable and sustainable approaches to achieve climate targets. Here we show that preserving woody debris in managed forests can remove gigatonnes of CO₂ from the atmosphere sustainably based on a carbon cycle analysis using three Earth system models. Woody debris is produced from logging, sawmill wastes and abandoned woody products, and can be preserved in deep soil to lengthen its residence time (a measure of durability) by thousands of years. Preserving annual woody debris production in managed forests has the capacity to remove 769–937 GtCO₂ from the atmosphere cumulatively (10.1–12.4 GtCO₂ yr⁻¹ on average) from 2025 to 2100, if its residence time is lengthened for 100–2,000 years and after 5% CO₂ removal is discounted to account for CO₂ emission due to machine operation for wood debris preservation. This translates to a reduction in global temperatures of 0.35–0.42 °C. Given the large potential, relatively low cost and long durability, future efforts should be focused on establishing large-scale demonstration projects for this technology in a variety of contexts, with rigorous monitoring of CO₂ removal, its co-benefits and side-effects.