Researchers now believe that they can justify a part of the recently increased levels in methane (CH4) in the atmosphere. A team of scientists says that their studies indicate a massive spike in methane emissions coming from the swamps of South Sudan.
Man-Made and Natural Emissions are the Culprit
The scientists, led from Edinburgh University, say that satellite data suggest the area received a massive surge of water from East African lakes, including Victoria. This would have increased CH4 from the wetlands, justifying a significant part of the boost in global methane.
Probably up to a third of the boost was registered between 2010 and 2016, when reviewed 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 added.
Methane is an active greenhouse gas and is growing its concentration in the atmosphere, similar to carbon dioxide. It has not been a persistent increase, but CH4 is now growing incredibly rapid and currently stands at over 1,860 parts per billion by volume.
There is, at the moment, a dispute over the likely causes, with emissions from government activities certainly being a massive part. However, there is a large natural factor as well, and some current studies are focused on contributions from the tropics.
The Edinburgh researchers have been utilizing the Japanese GOSAT probe to observe the CH4 activity over peatlands and wetlands in Africa and discovered massive increases in the greenhouse gas emissions above South Sudan between 2011 and 2014.
Considering the region known as the Sudd as the cause, as soil microbes in wetlands and known to create a lot of methane, scientists started analyzing other satellite datasets to make the connection.
Methane Emissions Are Still Elevated
Observations regarding land surface temperature backed up the idea that soils in the area had become wetter as gravity measurements all over East Africa also identified a rise in the weight of water located in the ground. Satellite altimeters had also registered changes in the height of lakes and rivers in the southern region.
“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,” Dr. Mark Lunt said.
A lot of the additional water probably resulted in an effect of blocked releases upstream. The team of researchers published the paper in the journal Atmospheric Chemistry and Physics.
Dr. Lunt has been analyzing the methane datasets collected by the EU’s Sentinel-5P satellite, as its Tropomi instrument captures CH4 at a more detailed resolution than GOSAT. Judging from the images, it is obvious methane emissions are still high over South Sudan.
The level of activity is unprecedented from the early 2010s, but the Sudd wetlands are still a primary source of the increase.
“It’s a huge area, so it’s not surprising that it’s pumping out a lot of methane. To give context – the Sudd is 40,000 sq km: two times the size of Wales. And being that big, we expect to see the emissions from space,” Dr. Lunt explained.