In a study published in the journal Environmental Science and Technology, researchers from Florida State University report that, in two major Arctic rivers, 40 years of climate change seem to have fortified a natural process that consumes and stores atmospheric carbon dioxide.

The process of interest to researchers was the production of riverine alkalinity, or the ability of river water to resist changes that would make it more acidic. Alkalinity is produced when carbon dioxide dissolved in rainwater weathers rock surfaces. As the rocks are weathered, the carbon atom contained in carbon dioxide is transformed from a gas in the atmosphere into a salt that can be geologically stored for millennia.

The production of alkalinity constitutes a carbon dioxide “sink,” a system that works in opposition to natural and anthropogenic carbon dioxide emission. The researchers set out to determine how changing human activity and the dramatic shifts in Arctic climate might be affecting alkalinity production in two of the region’s largest rivers, the Ob’ and the Yenisei.