As climate change accelerates, the search for effective adaptation strategies has never been more urgent. One solution gaining traction is forest regeneration—a process heralded for its ability to absorb carbon dioxide and, potentially, regulate local climates. But forests are more than just carbon sinks. They play a complex, dual role in shaping local temperatures, sometimes cooling the air, other times contributing to warming. This duality presents a challenge for those looking to leverage forests as part of climate solutions. Yet, despite these uncertainties, governments, NGOs, and private organisations are championing forest regeneration projects on a global scale. So, how can we ensure these efforts are strategically implemented to truly enhance local climate resilience?

That’s exactly the question our latest study sought to answer. In “Natural Forest Regeneration is Projected to Reduce Local Temperatures,” we asked: can natural forest regeneration effectively lower local temperatures, and how do these cooling effects vary across different regions? Using cutting-edge machine learning and remote sensing, we set out to examine how naturally regenerating forests influence local climates by altering key factors such as albedo—the reflectivity of a forest’s surface—and evapotranspiration, the release of water from trees that cools the air. The findings? Forest regeneration can lower albedo, leading to local warming as more sunlight is absorbed. But it can also boost evapotranspiration, delivering a cooling effect. The trick is understanding which regions benefit most.

The results are both promising and complex. “In tropical, temperate, and Mediterranean regions, forest regeneration has the potential to significantly cool local climates—by as much as 2.03°C in some tropical areas. This is a crucial tool in the fight against rising temperatures.”, concludes the leading author Sara Alibakhshi rom the University of Helsinki. However, the picture changes in colder, snow-covered boreal regions, where forest regeneration can actually lead to local warming. The reason? Snow-covered open lands reflect more sunlight than forests, meaning a shift from snow to trees could cause the region to absorb more heat.

Global enthusiasm for forest regeneration often touts the potential to restore up to 1 billion hectares of land, but such sweeping plans face practical limitations. Competing land-use priorities, like agriculture and urban development, make large-scale restoration a challenge. That’s why we also considered a more realistic scenario—one where 148 million hectares are targeted for regeneration, factoring in both biodiversity and food security needs. Even in this scaled-down model, we found that 75% of this restorable land could experience cooler local temperatures, offering a strategic win in the face of climate change.

As heatwaves become more frequent and severe, knowing where forest regeneration is most likely to cool local climates is vital. Our research provides a crucial roadmap for policymakers, helping them prioritize areas where forest restoration will deliver the greatest local cooling benefits. This region-specific knowledge is key to developing targeted, effective strategies for reforestation that align with both carbon sequestration and climate adaptation goals.

The promise of natural forest regeneration is clear, but it’s not a one-size-fits-all solution. Careful, informed planning is essential to harnessing its full potential. Our study offers the insights needed to ensure that reforestation efforts benefit both people and the planet—helping us tackle climate change from the ground up.

Read paper here.

Read blog post here.