From Source to Sink: Past Changes and Model Projections of Carbon Sequestration in the Global Forest Sector

An economic model of the global forest sector was used to estimate the carbon mitigating potential of the world’s forests to 2065 for 180 countries assuming future socioeconomic trends that do not change markedly from historical patterns, consistent with the IPCC-SSP2. Forest carbon pools were broken down into four categories; (i) above-ground and below-ground biomass, (ii) forest soil, (iii) dead wood and litter, and (iv) harvested wood products. Changes in forest carbon storage were driven by the dynamic relationship between endogenously determined timber harvest, wood product consumption, evolving forest biomass stock, forest area change and exogenous demographic and income changes. The results suggested that the forest sector was a net carbon source of approximately 3.6 GtCO₂e yr^-1 in 1992, decreasing to 2.4 GtCO₂e yr^-1 in 2014 (average rate: –0.05 GtCO₂e yr^-1), in general agreement with previous historical assessments. In the projections, the global forest sector achieved a net zero carbon balance by the year 2025, but with large variations by region and country. By 2030, the world’s forest sector became a net carbon sink of 1.5 GtCO₂e yr^-1, and eventually of 6.8 GtCO₂e yr^-1 by 2065. Uncertainties exist in projecting changes in forest area, including the influence of socioeconomic drivers and climate policy targets, as well as the interplay between forests and climate.