Swiss researchers have shown that mountain streams emit far greater levels of CO2 than previously thought. The finding suggests that the impact of alpine waterways on the environment may have been previously underestimated.
Despite making up just 5% of the surface area of all rivers around the world, mountain streams are now estimated to account for 10% to 30% of CO2 emissions from fluvial networks.
The team from EPFL’s Stream Biofilm and Ecosystem Research Laboratory (SBERexternal link) measured gas exchanges in Swiss mountain streams. Using this data, they developed a model to estimate the natural CO2 emissions from more than 1.8 million mountain streams worldwide.
It is thought that mountain streams emit so much CO2 because they largely run over carbonate rock formed by the skeletons of marine microorganisms that lived millions of years ago when Earth was largely covered by oceans.
EPFL wants to follow up its initial research by pinpointing more accurately the source of CO2 escaping from mountain streams and finding out exactly how alpine waterways fit into the global carbon cycle.
“We have known for a number of years that freshwater ecosystems emit roughly the same amount of CO2 that oceans absorb,” stated Tom Battin, who heads SBER. “We are just starting to discover the role of mountain streams for the global carbon cycle.”