LAUSR

Carbon storage in forests is a cornerstone of policy-making to prevent global warming from exceeding 1.5°C. However, the global impact of management (for example, harvesting) on the carbon budget of forests remains poorly quantified. We integrated global maps of forest biomass and management with machine learning to show that by removing human intervention, under current climatic conditions and carbon dioxide (CO2) concentration, existing global forests could increase their aboveground biomass by up to 44.1 (error range: 21.0 to 63.0) petagrams of carbon. This is an increase of 15 to 16% over current levels, equating to about 4 years of current anthropogenic CO2 emissions. Therefore, without strong reductions in emissions, this strategy holds low mitigation potential, and the forest sink should be preserved to offset residual carbon emissions rather than to compensate for present emissions levels. Description Editor’s summary Harnessing the carbon-capturing potential of forests is a key component of plans to mitigate global climate change. Planting new forests is a common strategy, but this approach can have negative social and ecological impacts and substantial costs. Roebroek et al. instead investigated how ceasing management (e.g., wood harvesting or fire suppression) of forests would change their global carbon sequestration capacity. The authors assessed the differences between the biomass of similar forests with and without human activities and used machine learning to predict the additional biomass gain from removing human activities from global forests. Even if all management ceased (an extremely unlikely scenario), global forest carbon would only increase by about 15%. This work provides further evidence that changing forest management is not an alternative to cutting carbon emissions. —Bianca Lopez Even if all harvesting of forests ceased, their carbon sequestration potential would still not be enough to curb climate change.