New study assesses freshwater methane on a global scale
FRISCO — After recalculating Earth’s greenhouse gas budget, Princeton scientists say that methane emissions will start increasing at a faster pace than carbon dioxide, primarily due to the release of methane from microscopic freshwater organisms.
Methane is about 30 times more effective than CO2 at trapping the sun’s heat, and for every degree of warming, methane emissions will increase several times over, according to the research published in Nature.
In freshwater systems, methane is produced as microorganisms digest organic matter. The complexities of the methanogenesis process has muddled climate projections, but the new study is an ambitious effort to clarify the equation.
The findings suggest that methane emissions from freshwater systems will likely rise with the global temperature, said co-author Cristian Gudasz, a visiting postdoctoral research associate in Princeton’s Department of Ecology and Evolutionary Biology. But to not know the extent of methane contribution from such a widely dispersed ecosystem that includes lakes, swamps, marshes and rice paddies leaves a glaring hole in climate projections.
“The freshwater systems we talk about in our paper are an important component to the climate system,” Gudasz said. “There is more and more evidence that they have a contribution to the methane emissions. Methane produced from natural or manmade freshwater systems will increase with temperature.”
After analyzing more than 1,600 measurements of temperature and methane emissions from freshwater ecosystems around the world, the researchers found that methane generation very much thrives on high temperatures. Methane emissions at 0 degrees Celsius would rise 57 times higher when the temperature reached 30 degrees Celsius, the researchers report.
“We all want to make predictions about greenhouse gas emissions and their impact on global warming,” Gudasz said. “Looking across these scales and constraining them as we have in this paper will allow us to make better predictions.”