New Study Redraws the Map on Global Reforestation Potential

By Muhammad OsamaReviewed by Laura ThomsonJun 24 2025

A recent study published in the journal Nature Communications presented a refined global assessment of reforestation potential by addressing the limitations of existing maps. Using high-resolution datasets, conservative ecological assumptions, and strict exclusion criteria, it provides more accurate estimates for reforestation as a climate change mitigation strategy through nature-based solutions.

The findings highlight the role of reforestation as a viable natural climate solution and the need for assessments that consider ecological and socio-economic factors, providing guidance for policymakers and stakeholders aiming to implement reforestation initiatives.

Reforestation as a Natural Climate Solution

Natural climate solutions (NCS) mitigate climate change by restoring natural and working lands. Reforestation is particularly promising due to its high carbon sequestration potential, as it restores tree cover in areas where forests once existed. However, uncertainties remain about the effectiveness of reforestation efforts, as existing maps have been criticized for inconsistent forest definitions and inadequate consideration of various factors. This study addresses these challenges by integrating high-quality data and improved methodologies.

Methodology for Assessing Global Reforestation Potential

Researchers reviewed 89 reforestation mapping studies published between 2011 and 2022 to assess their strengths and limitations, particularly in terms of forest definitions, data quality, and ecological safeguards. Based on this review, they developed new global reforestation maps using high-resolution datasets (10-30 meters) that address common critiques, particularly the overestimation of reforestation potential.

The study adopted a conservative forest definition, identifying areas capable of supporting at least 60% tree canopy cover, excluding open woodlands and savannas.

To map forest potential, the authors combined two independent global datasets, including the Bastin and Walker maps, and further refined the analysis by excluding areas with frequent wildfires.

Based on this approach, the preliminary global forest potential was estimated at 2,393 million hectares (Mha), with the final identified potential reduced to 2242 Mha. The study divided reforestation potential into two categories: the maximum reforestation potential, estimated at 305 Mha, and the more cautious constrained potential of 195 Mha, applying additional exclusions such as croplands, urban areas, and wetlands.

To further contextualize the feasibility of reforestation, the study incorporated additional data representing social and governance factors, including land tenure security and local livelihood dependence. This rigorous methodology enhances the reliability of global reforestation assessments and informs practical strategies for climate mitigation.

Key Outcomes from the Refined Mapping Approach

The refined forest potential map identified 2242 Mha globally as suitable for supporting dense forest cover, only 26-36% of the area shown in earlier global maps.

The maximum reforestation potential was estimated to be 305 Mha. When precautionary filters were applied, this value was reduced to 195 Mha of constrained reforestation potential, a 71-92% drop compared to previous estimates, which ranged between 678 and 2509 Mha.

Despite this reduction, the cautious estimate still provided significant climate benefits, with an annual net carbon removal of about 2,225 teragrams of carbon dioxide (CO₂) equivalent (TgCO₂e) over the first 30 years of forest regrowth, even after accounting for changes in surface reflectivity. When adjusted for natural forest regrowth, roughly 169 Mha of this land is expected to deliver actual new carbon removal, totaling around 2086 TgCO₂e per year.

The study also considered social factors, as approximately 98 million people live in areas with constrained reforestation opportunities. To reduce social conflicts and promote fairness, the authors created scenarios prioritizing regions with secure land ownership and low reliance on nature-based livelihoods. These scenarios limit reforestation to 116-158 Mha but still provide considerable climate benefits, estimated at 1428-1591 TgCO₂e annually.

Sensitivity analyses showed that results are most affected by how forest canopy cover is defined and which land tenure data are used. Loosening the forest definition or fire frequency limits would increase potential areas but could lead to ecological or social risks.

Applications for Nature-Based Climate Strategies

This refined mapping approach provides a more accurate and responsible estimate of global reforestation potential by correcting past overestimations and including safeguards to avoid ecological and social harm. The findings emphasize that although reforestation is a significant natural carbon removal option, it alone cannot meet the ambitious targets set by the International Panel on Climate Change (IPCC) or national pledges.

For professionals and policymakers, these updated maps serve as a valuable resource for directing reforestation efforts toward areas with the highest chances of long-term and sustainable success. By factoring in social elements like secure land rights and community involvement, the study supports climate solutions that are both effective and equitable.

Conclusion and Future Directions

This study advances reforestation mapping by refining global estimates using robust ecological, social, and data-driven criteria. It sets the foundation for more targeted and effective reforestation as a cleantech strategy for climate change mitigation.

Future work should focus on enhancing data on forest dynamics and local socio-economic conditions. Incorporating new datasets on agricultural productivity and food security will help balance climate goals with human well-being and biodiversity conservation. Overall, this research represents a key step toward scientifically credible and ecologically sound reforestation practices within the broader framework of natural climate solutions.

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