Carbon sequestration via wood harvest and storage: An assessment of its harvest potential

Abstract

A carbon sequestration strategy has recently been proposed in which a forest is actively managed, and a fraction of the wood is selectively harvested and stored to prevent decomposition. The forest serves as a ‘carbon scrubber’ or ‘carbon remover’ that provides continuous sequestration (negative emissions). Earlier estimates of the theoretical potential of wood harvest and storage (WHS) based on coarse wood production rates were 10 ± 5 GtC y−1. Starting from this physical limit, here we apply a number of practical constraints: (1) land not available due to agriculture; (2) forest set aside as protected areas, assuming 50 % in the tropics and 20 % in temperate and boreal forests; (3) forests difficult to access due to steep terrain; (4) wood use for other purposes such as timber and paper. This ‘top-down’ approach yields a WHS potential 2.8 GtC y−1. Alternatively, a ‘bottom-up’ approach, assuming more efficient wood use without increasing harvest, finds 0.1–0.5 GtC y−1 available for carbon sequestration. We suggest a range of 1–3 GtC y−1 carbon sequestration potential if major effort is made to expand managed forests and/or to increase harvest intensity. The implementation of such a scheme at our estimated lower value of 1 GtC y−1 would imply a doubling of the current world wood harvest rate. This can be achieved by harvesting wood at a moderate harvesting intensity of 1.2 tC ha−1 y−1, over a forest area of 8 Mkm2 (800 Mha). To achieve the higher value of 3 GtC y−1, forests need to be managed this way on half of the world’s forested land, or on a smaller area but with higher harvest intensity. We recommend WHS be considered part of the portfolio of climate mitigation and adaptation options that needs further research.