Jenna Ladd | February 23, 2017

A recent study shows that when freshwater ponds warm, they release more methane and are able to store less carbon dioxide.

Researchers at the University of Exeter and Queen Mary University of London warmed a collection of man-made ponds by four to five degrees Celsius over the course of seven years. The first of its kind, the study found that the amount of methane released by the ponds increased by double while the amount of carbon dioxide the ponds could store decreased by half.

Professor Gabriel Yvon-Durocher was the study’s lead investigator. He said, “Given the substantial contribution small ponds make to the emission of greenhouse gases, it is vital to understand how they might respond to global warming.”

While ponds and lakes only account for about 0.008 percent of the total volume of water on Earth, they are major contributors of carbon dioxide and methane. Greenhouse gases from freshwater sources are mostly the byproduct of organic matter breaking down in low-oxygen environments.

Yvon-Durocher continued, “Our findings show that warming can fundamentally alter the carbon balance of small ponds over a number of years, reducing their capacity to absorb carbon dioxide and increasing emissions of methane. This could ultimately accelerate climate change.”

The scientist noted that these findings are different than those normally observed on land, where the effect of rising temperatures lessen over time. In contrast, when ponds warm and release methane, a gas that is known to be 25 times more potent than carbon dioxide, they actually exacerbate warming.

Ponds of less than one meter, such as those used in the study, are responsible for the release of 40 percent of all inland methane emissions.

The professor noted, “This accelerating effect in ponds, which could have serious impacts on climate change, is not currently accounted for in Intergovernmental Panel on Climate Change models.”

The complete study can be found in the journal Nature Climate Change.