Why planting trees in the Arctic is not a good climate solution

Tree planting has often been seen as an affordable, effective way to combat global warming due to trees’ ability to capture large amounts of carbon from the atmosphere.

Yet, a new study warns that large-scale tree planting at high latitudes may actually worsen global warming rather than mitigate it. 

As climate change enables the planting of trees further north, initiatives to establish forests in Arctic regions have gained support.

But according to a team of international scientists, led by assistant professor Jeppe Kristensen from Aarhus University, this approach could have unintended climate consequences in sensitive northern ecosystems.

Carbon storage in Arctic soils

The Arctic and sub-Arctic regions are unique in their ecological characteristics, and Kristensen emphasizes that these areas are unsuited to afforestation as a climate mitigation strategy. 

“Soils in the Arctic store more carbon than all vegetation on Earth,” said Kristensen. “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.” 

Natural disturbances are intensifying 

Regions around the North Pole, including parts of North America, Asia, and Scandinavia, are already prone to natural disturbances, such as wildfires and droughts, which can kill vegetation. Climate change has only intensified these threats. 

Kristensen warns that northern forests are at particular risk: “This is a risky place to be a tree, particularly as part of a homogeneous plantation that is more vulnerable to such disturbances.” 

If these trees burn, the stored carbon is likely to be released into the atmosphere within decades, reversing any intended climate benefits.

Balancing solar reflection and carbon storage

While carbon storage is a common focus in climate solutions, the researchers argue that at high latitudes, managing solar reflection (albedo) is even more crucial. 

“Climate change results from the balance between solar energy entering the atmosphere and how much leaves again,” Kristensen said. 

The albedo effect is essential in polar and subpolar regions because light-colored snow and ice naturally reflect solar energy. Dark tree canopies, however, absorb it, converting sunlight into heat, which impacts the energy balance more than carbon storage.

A holistic approach to climate solutions

Rather than solely emphasizing carbon storage, the study calls for a more comprehensive understanding of ecosystem dynamics. 

“A holistic approach is imperative if we’re going to make a difference in the real world,” said co-author Marc Macias-Fauria, a researcher at the University of Cambridge’s Scott Polar Research Institute. 

Macias-Fauria adds that while tree planting may be valuable for timber production or self-sufficiency, it should not be marketed as a climate mitigation strategy without accounting for its environmental impact.

“Forestry in the far North should be viewed like any other production system and compensate for its negative impact on climate and biodiversity,” he said. “By selling northern afforestation as a climate solution, we’re only fooling ourselves.”

Sustainable populations of large herbivores

If tree planting is not ideal for high latitudes like the Arctic, what nature-based strategies could help mitigate climate change in these areas?

The researchers suggest an alternative: supporting sustainable populations of large herbivores, like caribou, which could offer a more viable climate solution. 

“There is ample evidence that large herbivores affect plant communities and snow conditions in ways that result in net cooling,” Macias-Fauria said. 

Large herbivores keep tundra landscapes open and prevent excess snow buildup, which insulates the soil and accelerates permafrost thaw. 

Their activity, including winter grazing, helps lower soil temperatures and preserve the permafrost layer, which plays a crucial role in regulating global temperatures.

Prioritizing biodiversity and local communities

Finally, the study underscores the importance of considering biodiversity and the needs of local communities when developing climate solutions. 

Large herbivores not only aid in reducing climate-driven biodiversity loss in Arctic ecosystems but are also a key food source for Indigenous and local communities. 

“Biodiversity and local communities are not an added benefit to nature-based solutions: they are fundamental,” said Macias-Fauria, emphasizing that these efforts must be community-led, particularly by those directly affected by climate change.

In sum, while tree planting remains valuable in many contexts, implementing it in Arctic and sub-Arctic regions could inadvertently increase warming. 

Instead, focusing on nature-based solutions that respect and work with local ecosystems and communities offers a more balanced and effective path to mitigating climate impacts.

The study is published in the journal Nature Geoscience.

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