What's happening? Reforestation is an effective strategy to combat climate change and biodiversity loss when managed well. Recent studies suggest the mitigation “potential” of newly planted trees is up to 10bn mt (GtCO2) annually, greater than the US’ yearly emissions. A new paper published in Nature Communications aims to improve the accuracy of reforestation-potential estimates. The researchers incorporated multiple impacts of reforestation including the provision of ecosystem services and minimisation of social conflicts. Through modelling, they developed global maps at several scales of resolution. Their new net mitigation potential estimate for reforestation is 71% lower than previous estimates. They found 195 million ha are available, that would have the potential to capture 2,225 TgCO2e per year. (Carbon Brief)

Why does this matter? This study significantly refines our understanding of where and how reforestation can deliver the greatest climate and ecological benefit with the least social and environmental trade-offs. By reducing the estimated global reforestation potential by 71%, it brings much-needed realism to a highly politicised area of climate mitigation and offers more targeted guidance for governments, conservationists, and investors alike.

For policymakers, it provides clearer prioritisation: directing resources toward high-impact areas that also align with biodiversity, social, and land-use safeguards. For companies using tree-planting as part of climate or CSR commitments, it offers a more credible foundation to ensure initiatives are ecologically sound and socially responsible – not just symbolic gestures.

Crucially, the research supports a shift from quantity to quality: not all reforestation is equal, and not all land is suitable. This matters at a time when carbon offsetting and nature-based solutions are under increasing scrutiny.

To improve the accuracy of reforestation estimates, the study authors reviewed 89 existing maps and developed a new framework using conservative criteria. Forest potential was defined as land with at least 60% tree cover capacity, excluding savannas and frequently burned areas. The analysis utilised high-resolution land use data (10-30 m), adding safeguards such as excluding croplands, peatlands and areas with negative albedo effects – which if planted on would reduce the reflection capacity of the land surface and increasing solar heating.  

Eight scenarios were mapped to reflect different priorities, including biodiversity, social safeguards and policy alignment, providing decision-makers with more realistic, equitable and targeted reforestation opportunities. Of the 195 million ha identified as viable reforestation area, 83% of opportunities occur near to existing forests and 81% lie in places where there is low predicted conflict with rural livelihoods.  

An interactive tool linked to this paper is the Global Reforestation Hub from which users can explore an array of reforestation options for the identified areas. Countries within the tropical climate zone have many of the highest reforestation opportunities for climate mitigation such as Indonesia with up to 7.8 million ha, the Democratic Republic of the Congo with up to 5.1 million ha and Brazil with up to 32 million ha. Temperate countries, including France (3.3 million ha) and the US (19.8 million ha), could also make important climate mitigation contributions.

While not a silver bullet, tree planting remains one of the most cost-effective and scalable carbon removal strategies – particularly when guided by strong regulations and tailored to local ecological and social conditions. With the right regulatory safeguards in place, reforestation can deliver significant climate, biodiversity and community benefits. As COP30 approaches in Brazil, the world’s custodian for the Amazon rainforest, forest-based solutions are expected to be a major focus. The summit offers a crucial opportunity to scale up investment in sustainable land use and restoration efforts.