Reforestation Boosts Biodiversity Where Other Carbon Capture Methods Fall Short, Study Finds

As CO2 emissions continue to rise year after year, capturing and storing carbon is essential to keeping global warming below 1.5°C. However, not all carbon capture methods are created equal, with some perhaps doing more harm than good for biodiversity.

A new study published Thursday which modeled three prominent land-based carbon capture and storage (CCS) strategies found that reforestation is the only option that, along with effectively sequestering carbon, actively boosts biodiversity rather than potentially harms it.

The three CCS strategies analyzed were reforestation, the practice of restoring native trees on previously deforested or damaged land to sequester carbon; afforestation, adding trees where there were previously none; and bioenergy cropping, raising fast-growing crops — which sequester carbon as they grow — to burn for energy while collecting any emissions released in the process.

“Of the strategies we modeled… we found that all three strategies have the potential to benefit biodiversity by helping to mitigate climate change,” Jeffrey Smith, lead author and researcher at Princeton University told EcoWatch on a video call.  

However, he added, “In the case of afforestation and bioenergy cropping, we found that even if we account for the benefits they provide to biodiversity by helping to mitigate climate change, that wasn’t enough to outweigh the harms that they caused biodiversity by driving the loss of habitat.”

Bioenergy cropping requires razing land for crop growth which destroys part of an ecosystem. And it’s the transformation from natural ecosystems to agricultural plots that’s been the single largest driving factor of biodiversity worldwide, he said.

For afforestation, which may be feasible in savannahs, for example, Smith says that artificially placing trees could hinder the ecosystem by interfering with certain interactions, like those between shrub and herbivore species and frequent fires that burn across the landscape in an open ecosystem. “If you convert one of these savannahs to, say, a forest, you’re actually taking away habitat from lions and ostriches and things like that,” Smith said.

On the other hand, the authors found that reforestation provided a win-win by both capturing carbon and restoring vital parts of ecosystems that many species rely on.

The researchers, using data from the Global Biodiversity Information Facility and International Union for Conservation of Nature (IUCN), created statistical computer models tracking the species distribution and habitat affinities of more than 14,000 vertebrate species across different parts of the globe across potential climate conditions.

They then paired that model with data from the Intergovernmental Panel on Climate Change (IPCC) and the Coupled Model Intercomparison Project, an enormous collaborative global project that models Earth’s climate conditions, for the research.

“To me, it seems like a fairly intensive amount of computational and data power that goes into this,” Smith said. “And so for example, the model takes a day to run, but it runs on one hundred computers simultaneously.”

“Addressing climate change is going to have to start with large-scale transformations to the energy production system. There’s sort of no way around that, and no way are these land-based mitigation strategies going to fix climate change. It’s going to require us to reduce our reliance on fossil fuels, increase energy efficiency, and fundamentally transition the energy system,” he added. “That said, the thing that’s interesting about these strategies is they actually allow us to sort of reverse past emissions.”

However, we may not have the luxury of always choosing climate mitigation practices that maximize biodiversity. “People are dying from climate change because of flooding in Pakistan and all of these different places around the world, and so there might be reasonable expectations that maybe we should be addressing climate change more aggressively, even if that is not the optimal thing to do from a biodiversity perspective,” Smith said.

An earlier study published in the journal Nature Climate Change from September 2024 found that an enormous investment in CCS is required to meet the Paris Agreement’s goal of keeping global warming under 2°C, and that even with such an investment, meeting the 1.5°C goal is unlikely. 

Smith said he and his colleagues hope to continue this research, citing questions on how different taxonomic groups might respond to different scenarios and “expanding out to other potentially significant ways humans might change the landscape to address climate change… We didn’t model wind and solar panels, but those are two things that we’re going to have to use to help address climate change, and they’re likely going to affect biodiversity in a fairly meaningful way,” he added.