An international group of scientists has found that planting trees in the Arctic might worsen climate change, due to unique ecosystem characteristics and natural disturbances. The findings emphasize a need for holistic climate solutions tailored to specific regional conditions.
An international team of researchers, led by the University of Cambridge and the University of Århus, has issued a stark warning that planting trees in the Arctic could accelerate, rather than mitigate, global warming. The findings, published in Nature Geoscience, challenge the widespread belief that afforestation is universally beneficial for climate stabilization.
Despite being widely promoted as a method to sequester atmospheric carbon, tree planting at high latitudes might backfire. The unique ecosystems of these regions, paired with frequent natural disturbances, make the idea more problematic than previously thought.
“Soils in the Arctic store more carbon than all vegetation on Earth,” lead author Jeppe Kristensen, an assistant professor at Århus University, said in a news release. “These soils are vulnerable to disturbances, such as cultivation for forestry or agriculture, but also the penetration of tree roots. The semi-continuous daylight during the spring and early summer, when snow is still on the ground, also makes the energy balance in this region extremely sensitive to surface darkening, since green and brown trees will soak up more heat from the sun than white snow.”
The research team highlighted several adverse effects tree planting could have in Arctic regions, including increased soil decomposition, disrupted carbon storage and reduced surface albedo — the measure of how much sunlight is reflected back into space without being absorbed as heat.
Senior author Marc Macias-Fauria, a professor in the Scott Polar Research Institute at the University of Cambridge, emphasized the importance of a more nuanced approach.
“A holistic approach is not just a richer way of looking at the climate effects of nature-based solutions, but it’s imperative if we’re going to make a difference in the real world,” he said in the news release.
The darkening effect of tree canopies can lead to higher heat absorption, contrasting with the reflective properties of snow-covered landscapes.
Additionally, Kristensen pointed out that Arctic regions are uniquely susceptible to wildfires and droughts, which are becoming more frequent and severe with climate change. These disturbances could release stored carbon back into the atmosphere, undermining the initial intentions of afforestation projects.
“This is a risky place to be a tree, particularly as part of a homogeneous plantation that is more vulnerable to such disturbances,” Kristensen added. “The carbon stored in these trees risks fueling disturbances and getting released back to the atmosphere within a few decades.”
The research underscores the importance of considering the specific characteristics and vulnerabilities of different ecosystems when devising climate solutions. Efforts to mitigate climate change through afforestation need to take into account not only carbon storage but also the broader ecological impact.
Beyond questioning the climate benefits of planting trees in the Arctic, the researchers propose alternative approaches. One suggested solution involves collaborating with local communities to maintain sustainable populations of large herbivores, like caribou.
“There is ample evidence that large herbivores affect plant communities and snow conditions in ways that result in net cooling,” Macias-Fauria added.
These animals help keep the tundra landscape open and reduce soil temperatures by modifying the snow cover.
Ultimately, the researchers emphasize the need to integrate local biodiversity and community livelihoods into climate action strategies.
“Biodiversity and local communities are not an added benefit to nature-based solutions: they are fundamental,” added Macias-Fauria. “Any nature-based solutions must be led by the communities who live at the frontline of climate change.”