Shallow lakes in farming regions “will emit significantly greater amounts of methane, mostly in the form of bubbles” due to climate change, says a Aarhus University study in the journal Nature Climate Change. Methane is 25 times more potent than carbon dioxide as a greenhouse gas.
“Submerged plants are key predictors of methane ebullition,” says the Danish university, using the technical term for bubbles. “The combination of warming with the loss of plants appears to transform shallow lakes into methane bubbling machines.” The researchers say that shallow lakes are increasingly recognized as playing an important role in greenhouse gas cycling. “Methane is released from lakes in a number of ways, both by diffusion of dissolved gas and by bubbles released from the sediments, also called ebullition.”
According to the researchers, the combination of nutrient loading, from runoff, and a warming climate markedly increased methane emissions. “When nutrient levels were high, warming increased total methane emissions by at least six fold and in some cases 17 fold.” They concluded that careful management of agricultural landscapes and water entering the lakes could minimize the emissions of methane.