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Climate change: jump in Methane emissions coming from wetlands of South Sudan

Scientists think they can now explain at least part of the recent growth in methane (CH4) levels in the atmosphere.

Researchers, including NCEO’s Professor Paul Palmer from Edinburgh University, UK, say their studies point to a big jump in emissions coming from just the wetlands of South Sudan.

Satellite data indicates the region received a large surge of water from East African lakes, including Victoria.

This would have boosted CH4 from the wetlands, accounting for a significant part of the rise in global methane.

Perhaps even up to a third of the growth seen in the period 2010-2016, when considered with East Africa as a whole.

“There’s not much ground-monitoring in this region that can prove or disprove our results, but the data we have fits together beautifully,” said Prof Paul Palmer.

“We have independent lines of evidence to show the Sudd wetlands expanded in size, and you can even see it in aerial imagery – they became greener,” he told BBC News. Read the full BBC article by Jonathon Amos here

The Sudd Microbes in saturated soils will produce methane copyright-Copernicus/Data/2019/ESA/Sentinel-2
Tropomi detects a methane hotspot right over he Sudd (green square) Copyright Copernicus/Data/ESA/Tropomi

The Edinburgh group has been using the Japanese GOSAT spacecraft to try to observe the greenhouse-gas behaviour over peatlands and wetlands in Africa, and found significant rises in methane emissions above South Sudan centred on the years 2011-2014.

Believing the region called the Sudd could be the culprit (soil microbes in wetlands are known to produce a lot of methane), the team started looking through other satellite data-sets to make the link.

Land surface temperature observations supported the idea that soils in the region had become wetter; gravity measurements across East Africa also detected an increase in the weight of water held in the ground; and satellite altimeters had tracked changes in the height of lakes and rivers to the south.

“The levels of the East African lakes, which feed down the Nile to the Sudd, increased considerably over the period we were studying. 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,” explained Dr Mark Lunt.

Much of the extra water likely resulted as a consequence of dam releases upstream.

This work was published in the Atmospheric Chemistry and Physics journal of the EGU. Read the full journal article here