The Arctic tundra’s response to warming may depend not only on the plants spreading across its surface, but also on what happens below ground. A review of Arctic carbon cycling argues that plant roots and the soil around them can influence whether tundra ecosystems store carbon or release it as greenhouse gases.

The stakes are large. Arctic permafrost contains an estimated 1,460 to 1,600 billion metric tons of organic carbon—roughly twice the amount currently in the atmosphere. As permafrost thaws, some of that carbon is released. Thaw is also allowing trees and shrubs to grow in places where they previously could not, changing the tundra landscape.

The review, published in Nature Reviews Earth & Environment, was led by Rebecca Hewitt of Amherst College and co-led by Gesche Blume-Werry of Umeå University and Thomas Parker of The James Hutton Institute. Researchers from eight other organizations also contributed. While the carbon effects of aboveground changes such as shrub growth and Arctic greening have drawn attention, the authors argue that roots and their surrounding soil may be just as important in determining the ecosystem’s climate effect.

Roots can help retain carbon in soil by supporting plant growth and adding organic matter. But they can also stimulate microbes that break down soil carbon, releasing greenhouse gases including carbon dioxide and methane. The two effects point in different directions: more plant growth does not, on its own, establish whether a tundra ecosystem will become a carbon sink or a carbon source.

The review reports evidence that rising temperatures and permafrost thaw can alter root productivity and depth, seasonal growth patterns, and interactions between plants and soil. Those changes could affect both sides of the carbon balance. The review’s central message is that understanding the Arctic’s contribution to future climate requires looking at roots, soil microbes and thawing permafrost together; the account does not identify one effect as dominant across the tundra.

Blume-Werry described the subject as understudied and said the authors hope their paper will inspire more research. That matters for climate predictions: if belowground processes can shift carbon storage and greenhouse-gas release, forecasts based mainly on visible vegetation changes may miss part of how thawing ecosystems affect the climate.

<a href="https://phys.org/news/2026-11-arctic-roots-play-key-role.html">Source: Phys.org report</a>