Forests cover one-quarter of the world’s land mass and hold as much carbon as the atmosphere, making them the most important ecosystem for the global carbon cycle. Deforestation is the single largest component of emissions from land-use change; and avoiding deforestation, reforestation and forest management hold the bulk of global mitigation potential. Forests have been a focus of climate policy for decades, and the state of science, economics and policy is fairly advanced.
The Paris Climate Agreement stated that countries should protect and enhance forests in order to maintain and create carbon ‘sinks’. To this end, the researchers located the greatest additional emissions reduction potential in reforestation, through tree-planting and natural regeneration in formerly forested lands with less than 25% tree cover, while avoiding areas cleared for crop production. This approach can deliver 3 gigatonnes of cost-effective carbon emissions reduction by 2030, equivalent to taking 642 million gasoline-burning cars off the road, 5% more than through avoided forest conversion. Both these pathways are complementary to the need to maintain the absorptive capacity of intact ecosystems, especially intact forests, which take up around a net amount of around 11 gigatonnes of CO2 per year at little incremental cost beyond protective measures.
Natural forest management meanwhile offers close to a gigatonne (882 million tonnes) a year in cost-effective emissions reductions, equivalent to taking 189 million cars off the road, through the wider deployment of sustainable forestry practices such as reduced-impact logging (RIL), liana cutting and extending harvest cycles, and without reducing wood production.