Scientists have discovered that thawing permafrost may trigger a natural geological process capable of removing significant amounts of carbon dioxide from the atmosphere, partially counteracting greenhouse gas emissions released from melting frozen soils.
The findings published in the journal Nature challenge the widely held view that thawing permafrost acts solely as a source of climate warming emissions. Researchers from Umea University in Sweden and East China Normal University in China found that as frozen ground thaws, it can accelerate rock weathering a natural process that absorbs atmospheric carbon dioxide.
Permafrost which stores vast quantities of ancient organic matter, is thawing rapidly due to rising global temperatures. When frozen soils melt, microbes decompose long preserved organic carbon and release greenhouse gases such as carbon dioxide and methane. This process has long been considered a major climate concern.
However, the new study highlights an overlooked mechanism occurring simultaneously. As permafrost degrades, previously buried minerals become exposed and water comes into greater contact with rock surfaces. These interactions enhance chemical weathering, a geological process that consumes carbon dioxide and converts it into dissolved inorganic carbon.
To investigate the phenomenon researchers examined 50 rivers across the Qinghai Tibet Plateau, the world’s largest high-altitude frozen region outside the polar areas. They analyzed river carbon dioxide emissions, dissolved carbon concentrations isotopic tracers and geochemical data to better understand how thawing landscapes influence carbon cycling.
The results revealed that increased rock weathering significantly reduced the amount of carbon dioxide released from rivers. On average, weathering offset about 35 percent of river carbon dioxide emissions across the study area.
In some regions where permafrost had become fragmented or patchy, the carbon absorbed through weathering exceeded the amount of carbon dioxide emitted by rivers. Researchers found that areas with discontinuous permafrost experienced the strongest carbon uptake, while regions with continuous permafrost showed more modest effects.
Lead researcher Liwei Zhang said the team observed a clear pattern: river carbon dioxide emissions declined while carbon uptake through rock weathering increased as permafrost cover decreased. In several river catchments, weathering driven carbon removal was large enough to completely offset river emissions.
The findings suggest that biological and geological processes are closely linked in thawing landscapes. While microbes release greenhouse gases from ancient organic matter, geological reactions occurring in exposed rocks can remove carbon dioxide from the atmosphere at the same time.
Researchers caution that rock weathering should not be viewed as a simple solution to climate change. The carbon cycle in thawing permafrost regions remains highly complex, and some weathering reactions can also release carbon dioxide depending on the types of minerals involved.
Nevertheless, the study highlights an important natural process that is often overlooked in climate models. The scientists argue that future climate assessments should account for both biological carbon emissions and geological carbon sinks to provide a more complete picture of how thawing permafrost will influence global warming.
According to the researchers understanding the balance between carbon released from ancient frozen soils and carbon consumed through rock weathering will be essential for predicting the long-term climate impacts of permafrost degradation in a warming world.