Even if all direct human management of global forests ended immediately, their carbon sequestration potential would not be enough to curb ongoing climate change, according to a new study. The findings suggest that the planet’s current forests have only limited remaining carbon storage potential – even under the most unlikely of scenarios – to substantially mitigate atmospheric carbon dioxide (CO2) without major reductions in emissions. By capturing and storing carbon in biomass and soil organic matter, forests are integral to the global carbon cycle. As a result, the planet’s forests are often considered a central component in climate change policymaking, and many climate mitigation plans rely on forest-based carbon storage strategies to complement hard reductions in anthropogenic carbon emissions to achieve carbon neutrality. Despite this, the total amount of carbon that could realistically be stored in global forests remains poorly understood, nor has it been fully considered in climate mitigation strategies and policies. To address this, Caspar Roebroek and colleagues investigated the natural limits to additional carbon accumulation in the biomass of existing forests in the hypothetical absence of all direct human forest management activities, including wood harvesting, planting, and fire suppression, for example. Combining global maps of forest biomass in natural and managed forests with a novel machine learning, Roebroek et al. discovered that, under current climatic conditions and atmospheric CO2 concentrations, and the removal of all human forest management activities, existing global forests could increase their aboveground biomass by an additional ~44.1 petagrams of carbon. According to the authors, this represents an increase of roughly 15% more carbon than is currently stored in global forests, which would only offset about 4 years of worth of anthropogenic CO2 under current emission rates.
Releasing global forests from human management: How much more carbon could be stored?
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