Rightsizing Reforestation: New Maps Show We Can’t Put Trees Everywhere
Latest science gives unprecedented clarity on where best to restore forest cover for climate—yielding 71-92% less area than previously estimated
Media Contacts
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Tom Jennings
Email: tom.jennings@tnc.org -
Ann Kaiser
Email: ann.kaiser@tnc.org -
From vast tracts of wilderness to city streets and our own backyards, restoring trees has long been recognised as a powerful option for limiting the impacts of global warming. Reforestation can absorb and store atmospheric carbon, while also supporting nature’s recovery.
Given the accelerating pace of the climate crisis, however—alongside growing competition with other forms of land-use like agriculture, energy production and infrastructure—experts have debated past studies and critiqued previous estimates about the climate power of reforestation as overly optimistic.
Published today in the journal Nature Communications, a new study led by scientists from The Nature Conservancy (TNC) and other leading institutions brings fresh perspective to this conversation by mapping with unprecedented clarity where reforestation can help fight climate change.
Collating insights from 89 previous studies, these new maps show areas least likely to involve trade-offs between reforestation and other urgent priorities like wildlife habitat, food production, and freshwater availability. By combining the latest science with a conservative approach, researchers identified a total available land area of 195 million hectares (Mha) globally, or about half the size of the United States.
Quote: Kurt Fesenmyer
Our goal for this study was to right-size the estimate of how much reforestation can contribute to climate change by mapping where trees can actually be planted or regrown with minimum trade-offs and maximum benefits for people and nature.
The drop from previous estimates—about 71-92% less—is due to layers that previous maps haven’t been able to incorporate because the research was still nascent at the time. It accounts for albedo, for example—how restoring tree cover can, in some locations, actively heat the Earth rather than cool it by affecting how much sunlight is absorbed or reflected. It also excludes native grasslands and other ecosystems where carpeting the land with trees would harm biodiversity and exacerbate fire regimes.
“Our goal for this study was to right-size the estimate of how much reforestation can contribute to climate change by mapping where trees can actually be planted or regrown with minimum trade-offs and maximum benefits for people and nature,” explains lead author Kurt Fesenmyer, Forest Spatial Data Scientist for TNC’s global NCS team.
“We need to ensure the finite funding and policy momentum for reforestation are focused on the locations of greatest opportunity. By adopting a conservative stance that is realistic about the other escalating demands on land-use—as well as what recent science tells us about trade-offs—we hope these maps will bring previous, rather broad-brush estimates of reforestation’s full climate potential into sharper focus for decision-makers. This is something our collaborative Naturebase platform is also helping to achieve,” he adds.
Quote: Dr. Susan Cook-Patton
As the number of climate-fuelled disasters stack up worldwide, it’s increasingly obvious that we can’t waste time on well-meaning but hazily-understood interventions. Make no mistake: Reforestation remains one of the most cost-effective CO2 removal solutions we know of.
The study also provides estimates of the impact of policies and land rights on the availability of land for reforestation. "Previous studies often failed to address how reforestation could have negative effects on human well-being, especially for poor people living in the remote rural areas often targeted for reforestation. These negative effects are more likely when people lack secure land rights, are highly dependent on natural resources for food and/or fuel and live in countries where political rights are not respected," says Forrest Fleischman, Associate Professor at the University of Minnesota and a co-author of the study.
"Our study points to places where reforestation is most likely to produce win-win outcomes for people and nature, as well as where extra care will need to be taken to ensure that reforestation incorporates local concerns in light of limited land rights, political freedoms, and economic opportunities."
Expanding on the paper’s implications, senior co-author Susan Cook-Patton, Lead Reforestation Scientist at TNC, says: “As the number of climate-fuelled disasters stack up worldwide, it’s increasingly obvious that we can’t waste time on well-meaning but hazily-understood interventions. Make no mistake: Reforestation remains one of the most cost-effective CO2 removal solutions we know of. But we can’t do it everywhere. While there are certainly opportunities to plant and regrow trees beyond what we’ve mapped here, we must fast-track our focus toward the places with greatest benefits and the fewest downsides. This study will help leaders and investors do just that.”
As policymakers plan for UN Climate COP30, hosted in the most iconic forest on Earth, this study provides a timely reminder that tree-planting is not a sole solution. Only by restoring—and protecting—forests in lockstep with industrial decarbonisation can it make a meaningful difference to bending the curve on climate change back toward safe limits.
TNC will be advocating for a swifter transition to renewable energy sources, greater use of natural climate solutions, and more investment from both the public and private sectors, especially to help those countries that have been most affected by the impacts of climate change.
Naturebase
The potential of reforestation to help tackle climate change—including the findings of this latest study—can be explored alongside other natural climate solutions (NCS) that protect, restore, and improve the management of carbon-critical forest, wetlands, grasslands and agricultural lands, via naturebase.
The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world’s toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at an unprecedented scale, providing food and water sustainably and helping make cities more resilient. The Nature Conservancy is working to make a lasting difference around the world in 81 countries and territories (40 by direct conservation impact and 41 through partners) through a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit nature.org or follow @nature_press on X.