Climate change could hinder the ability of trees to store carbon, despite warmer summers encouraging faster growth. That is according to a new study, published in the Proceedings of the National Academy of Sciences this week, which examined six plots of forest located in the Hubbard Brook Experimental Forest in New Hampshire to investigate the effects of changing soil temperatures and reduced snowpack over a 10-year period.
“Our findings advance our understanding of forest ecosystem carbon cycle response to climate change by showing that not incorporating the effects of a shrinking winter snowpack into Earth system models likely leads to overestimation of carbon sequestration of northern temperate forests in response to climate change by at least 50%,” according to the study led by Emerson Conrad-Rooney from Boston University, who is now pushing for more research to understand the impact of warmer climates and increased freeze and thaw cycles in temperate forests.
By measuring tree growth, snow levels, and soil temperatures across plots, and comparing two untouched plots against two warmed by 5 degrees, and two others that were warmed and had snow remove, the researchers assessed the impact of the changing climate on red maple trees: “All plots that experienced warmer soil during the growing season showed more tree growth than those without the warming cables,” they said. “However, the uptake of carbon by trees with reduced snowpack in the winter and those that were only warmed in the growing season showed a marked difference in their carbon sequestering abilities.”
And when evaluating the tree stem biomass carbon—a measure of how much carbon the tree has taken from the surrounding environment—they found that the trees with heated soil during the growing season increased carbon uptake by 63% compared to the reference plots. Meanwhile, the trees with reduced snowpack in the winter only stored 31% more carbon than the reference plots. “This indicates that the reduced snowpack—and thus, increased freeze/thaw cycles—in the winter impaired the carbon sequestering abilities of the trees by a significant amount. The plots that maintained a more consistent snowpack experienced a protective effect, while the increased freeze/thaw cycles appear to have caused enough damage to tree roots in the other plots to impair their carbon uptake.”
- For more information: Emerson Conrad-Rooney et al, Declining winter snowpack offsets carbon storage enhancement from growing season warming in northern temperate forest ecosystems, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2412873122.
