While tree planting is a popular and effective way to mitigate climate change, it’s not always effective. A group of scientists at the University of Cambridge has agreed that planting trees at higher latitudes will worsen global warming.
Owing to the plant’s ability to accumulate anthropogenic carbon dioxide from the atmosphere, governments are incorporating large-scale tree-planting projects. However, several pieces of evidence suggest that tree planting in higher latitudes is counterproductive to climate change mitigation.
The lead author Jeppe Kristensen from Aarhus University in Denmark has marked the Arctic and sub-Arctic ecosystems unsuitable for tree plantation. The soil in the Arctic is very vulnerable to any disturbances and stores more carbon dioxide than all vegetation on Earth.
The disturbances are not limited to the cultivation of forests, but also the penetration of tree roots. Also, the white snow reflects most of the sunlight without absorbing it. Tree plantations in northern boreal or arctic regions will decrease albedo, resulting in net warming.
Furthermore, the study published in Nature Geoscience states a negative impact on native Arctic biota and livelihoods. Therefore, tree planting in areas of limited biomass and low resilience will counteract potential mitigation effects.
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“This is a risky place to be a tree, particularly as part of a homogeneous plantation that is more vulnerable to such disturbances. The carbon stored in these trees risks fuelling disturbances and getting released back to the atmosphere within a few decades,” said Kristensen.
The lead author of the study argues that the climate debate is very carbon-focused. It’s not just about emitting greenhouse gases, but also about solar energy entering the atmosphere and leaving (energy balance).
“Despite the immediate economic prospects that northern tree planting may represent, this approach does not constitute a valid climate-warming-mitigation strategy in either the Arctic or most of the boreal forest region,” says the study.
“This has been known for decades, but as policies that incentivize tree planting are increasingly adopted across the high-latitude region, we warn against a narrow focus on biomass carbon storage“
Researchers suggest that supporting local communities to populate caribou could be a more viable nature-based solution. Caribou is a species of deer, native to the Arctic and sub-Arctic.
These herbivore species devour plant communities and keep the Tundra landscape open, which directly results in net cooling. Additionally, the herbivore winter forage reduces soil temperatures and permafrost thaw.
“Large herbivores can reduce climate-driven biodiversity loss in Arctic ecosystems and remain a fundamental food resource for local communities,” said Macias-Fauria.
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Journal Reference
- Kristensen, J. Å., Barrio, I. C., Jacobsen, I. B., Kerby, J. T., Malhi, Y., Le Moullec, M., Mueller, C. W., Post, E., & Raundrup, K. (2024). Tree planting is no climate solution at northern high latitudes. Nature Geoscience, 17(11), 1087-1092. DOI: 10.1038/s41561-024-01573-4