Surge in Global Methane Emissions Traced Back to East African Wetland

Satellite view of the Sudd wetland in South Sudan.

Satellite view of the Sudd wetland in South Sudan. COPERNICUS DATA 2019/ESA/SENTINEL-2

Scientists believe they have found one of the key drivers behind a spike in global methane emissions in recent years. Satellite data captured a large influx of water entering the Sudd wetland in South Sudan, fueling plant growth and soil microbial activity and producing extra methane, BBC News reported.

Researchers estimate that wetlands in Africa’s tropics could account for up to a third of the spike in global methane emissions between 2010 and 2016, with most of this coming from the Sudd. The South Sudanese wetland is one of the largest freshwater ecosystems in the world, covering an estimated 22,000 square miles.

Satellite images “show the Sudd wetlands expanded in size, and you can even see it in aerial imagery - they became greener,” Paul Palmer, an atmospheric scientist at the University of Edinburgh who co-authored the research, told BBC News. “There’s not much ground-monitoring in this region that can prove or disprove our results, but the data we have fits together beautifully.” The scientists published their findings this week in the journal Atmospheric Chemistry and Physics.

The surge of water entering the Sudd wetlands is likely the result of dam releases upstream on the Nile River and its tributaries, they said.

“The levels of the East African lakes, which feed down the Nile to the Sudd, increased considerably over the period we were studying,” said Mark Lunt, a geoscientist at the University of Edinburgh who led the research. “It coincided with the increase in methane that we saw, and would imply that we were getting this increased flow down the river into the wetlands.”

Scientists have long debated the cause of the recent increase in methane emissions, which first spiked in 2007 and again in 2014. Some have attributed it to agriculture and the expansion of the natural gas industry. Recently, more attention has been given to the role of trees, especially in tropical wetlands, as a major source of methane.