Ecological carbon sequestration via wood harvest and storage: Practical constraints and real-world possibilities

Abstract:

A carbon sequestration strategy was recently proposed in which a forest is sustainably managed, and a fraction of the wood is selectively harvested and stored to prevent decomposition under anaerobic, dry or cold conditions. Because a large flux of CO2 is constantly assimilated into the world’s forests via photosynthesis, partially cutting off its return pathway to the atmosphere forms an effective carbon sink. The live trees serve as a ‘carbon scrubber’ or ‘carbon remover’ that provides continuous sequestration. The stored wood is a semi-permanent carbon sink, but also serves as a ‘biomass/bioenergy reserve’ that could be utilized in the future if deemed more beneficial, for instance, by contributing to supply infrastructure for biomass power generation.

Based on global forest coarse wood production rate, land availability, conservation, other wood use, and other practical constraints, we estimate a carbon sequestration potential for wood harvest and storage (WHS) 1-3 GtC y^-1. 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 modest 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. However, any successful implementation strategy will need to balance the needs of the local community and environment. It nonethelss provides a novel new addition to a portfolio of existing forest management strategies. We propose ‘carbon sequestration and biomass farms’ with mixed land use for carbon, energy, agriculture, as well as conservation, provided that governance issues are properly dealt with. In another example, the forests damaged by insects, fire, storms such as in the America West could be thinned to reduce fire danger and harvested for carbon sequestration.

Based on forestry data, We estimate a cost of $10-50/tCO2 for harvest and storage around the landing site. The technique is low tech, distributed, easy to monitor and verify. We compare the potential and cost of WHS with a number of other carbon sequestration methods, and recommend research into WHS as a 'down-to-earth' strategy for climate mitigation.