Reassessing Global Afforestation and Reforestation Potentials under Climate Change Scenarios

Afforestation and reforestation (A&R) are central components of current climate mitigation strategies and hold substantial potential for supplying biomass. However, large uncertainties remain regarding their actual mitigation potential, with considerable variation across global estimates, partly due to methodological differences. This study refines existing estimates of A&R potential by integrating temporal dynamics, climate change impacts, and land-use competition within a deliberately conservative framework.

We combine climate-sensitive forest biome projections with current land-use cover data to assess global A&R potentials under three representative concentration pathways (RCP 2.6, 4.5, and 8.5) up to 2080 at a spatial resolution of 1 × 1 km. To account for land-use competition, A&R is restricted to non-managed pastureland. Potential biomass production and associated carbon sequestration are estimated using region-specific growth data in accordance with IPCC guidelines.

Across all RCPs, we identify 731 million hectares globally as suitable for A&R through 2080. Relative to the historical baseline, climate change scenarios lead to a a net reduction of up to 24 million hectares of potential A&R area. While global potentials decline, regional patterns diverge markedly: boreal regions experience an increase in suitable area (+34 million hectares), whereas tropical and temperate regions exhibit substantial reductions (–33 and -18 million hectares, respectively). The A&R potentials presented here are intentionally conservative with respect to climate uncertainty, land-use competition, and long-term viability. Integrating these estimates with complementary scientific assessments is essential to underpin the feasibility of current climate policy targets and to support robust projections of biomass availability for scaling up the bioeconomy.

If implemented in accordance with local ecological conditions, the identified A&R potentials can inform policy responses to climate-related risks and may contribute to climate mitigation while supporting a biomass supply as a substitute for fossil-based products. However, successful implementation requires careful consideration of resource constraints (e.g., water availability) and future abiotic and biotic risks.