When Vietnam commits to restoring 14.6 million hectares of natural forest, it’s not just a climate pledge—it’s a lifeline for the planet. Yet across the tropics, from Brazil to Nigeria, international forest restoration plans are veering off course, according to groundbreaking research from UCL and the University of Edinburgh. Nearly half of the 292 million hectares pledged by 43 countries—part of a global push to restore an area larger than India by 2030—is set to become commercial tree plantations, not natural forests. And that distinction, scientists warn, could make or break humanity’s shot at limiting global warming to 1.5°C.
Natural forests aren’t just trees; they’re carbon vaults. The study, published in Nature, reveals that land restored to natural forest stores 40 times more carbon than plantations and six times more than agroforestry systems. Using current pledges—which allocate 45% of land to plantations, 34% to natural forests, and 21% to agroforestry—the world would capture just 16 billion tonnes of carbon by 2100. But if all 350 million hectares were allowed to become natural forests, that number soars to 42 billion tonnes. The difference is staggering: a shortfall of 26 billion tonnes, equivalent to more than two years of global fossil fuel emissions.
The reason? Plantations are harvested every decade, releasing stored carbon back into the atmosphere as wood products decay. “To most people forest restoration means bringing back natural forests, but policy makers are calling vast monocultures ‘forest restoration’,” says lead author Professor Simon Lewis of UCL Geography. “And worse, the advertised climate benefits are absent.” Brazil, for instance, has pledged 19 million hectares to plantations—carbon-poor landscapes dominated by fast-growing eucalyptus or acacia—while Nigeria is banking on 15.7 million hectares of agroforestry, which, while beneficial for livelihoods, captures far less carbon.
The science is clear: if we want forests to help stabilize the climate, they must be allowed to grow wild. Natural regeneration in high-biomass regions like Amazonia, Borneo, and the Congo Basin offers the greatest carbon returns. The researchers also stress the importance of protecting existing degraded forests, where natural recovery can build on residual carbon stocks. Once restored, these forests must be safeguarded—permanently.
“Restoring all 350 million hectares back to natural forests can meet the role forests need to play” in keeping warming below 1.5°C, says co-author Dr. Charlotte Wheeler of the University of Edinburgh. But she’s quick to add: forests alone aren’t a silver bullet. Fossil fuel emissions must end, and deforestation must stop. Still, no credible climate pathway exists without large-scale natural forest restoration. The path forward isn’t about planting trees—it’s about letting forests return.