The study, which was co-authored by researchers from Colorado State University, examined the Southern Alps in New Zealand, Central Mountain Range in Taiwan, and eastern Tibetan Plateau in China.
These diverse mountain ranges tower in different climates and across various rates of erosion weathering, when rock is exposed to wind and water. The researchers found that many mountains exist on a spectrum of removing or releasing carbon, said Jeremy Rugenstein, an assistant professor of geosciences at Colorado State who co-authored the study.
“Sometimes they’re a CO2 sink – that is, they’re actually removing CO2 from the atmosphere,” Rugenstein said. “But in many cases, they’re also a CO2 source – that is, the minerals that are weathering are actually producing CO2 that enters the atmosphere.”
Rugenstein said they identified a tipping point at which they switch roles. An erosion rate of roughly 0.1 millimeters per year – what he called “a moderate rate” – turns mountains into carbon sinks. That’s because minerals that remove carbon are exposed long enough for the necessary chemical reactions to unfold.
At high erosion rates, mountains become carbon producers. The minerals capable of removing carbon are rapidly worn away, leaving behind minerals that release carbon into the atmosphere.
Low erosion rates do not impact the climate, the study found, because the minerals needed to remove carbon have been depleted.
Researchers from Ludwig Maximilian University of Munich and the German Research Centre for Geosciences participated in the study, which examined metasedimentary mountains made of compressed marine sediments uplifted by tectonic activity.
Rugenstein said they next plan to analyze ranges made of granite, such as the Sierra Nevada and Rocky Mountains.
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
