Restored Wetlands in California May Be Source Of Greenhouse Gases

Tens of millions of dollars from California’s greenhouse gas reduction program are being used to restore wetlands. 

Scientists have long known that wetlands can store, or sequester, carbon dioxide. They can also be a source of methane, a more potent greenhouse gas. A study from the US Geological Survey finds that restored wetlands can release enough methane to reduce or negate the benefits of carbon sequestration. The study looked at restored wetlands in the Sacramento-San Joaquin Delta in 2010 and 2011.

“How that wetland was at that time was still a source of global warming potential, meaning methane was outweighing the productivity and it has that higher ability to trap heat for the earth,” says Frank Anderson, a USGS atmospheric scientist and the study's lead author.

Anderson says the study doesn’t mean all restored wetlands are greenhouse gas emission sources. The study was site-specific. He says wetlands should be continually monitored to understand their greenhouse gas reduction benefits.

He says wetlands still have numerous environmental benefits. They provide habitat and food sources for wildlife and can improve coastal protection in the face of sea level rise.