Satellite observations in South Sudan have shown recent growth in methane (CH4) levels in the area. The observations were made by scientists from the University of Edinburgh, using the Japanese GOSAT spacecraft to try to observe the greenhouse-gas behaviour over peatlands and wetlands in Africa.
According to the researchers, the increase in growth could be as a result of a surge of water from East African lakes, including Victoria, caused by water releases from dams, which would have heightened CH4 from the wetlands, accounting for a significant part of the rise in global methane, as indicated by satellite data.
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, one of the researchers.
Scientists have, therefore, established (from the satellite data available) the possibility that the Sudd region is a contributor to the increase in methane levels (as soil microbes in wetlands are known to produce a lot of methane) aside other debatable sources like emissions from human activities such as agriculture and the use of fossil fuels.
“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, member of the research group.
“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.
Methane is a greenhouse gas emitted by human activities such as leakage from natural gas systems and the raising of livestock, as well as by natural sources such as wetlands. It has a direct influence on climate, but also several indirect effects on human health, crop yields and the quality and productivity of vegetation through its role as a precursor to the formation of tropospheric ozone. While its lifetime in the atmosphere is much shorter than carbon dioxide (CO2), it is much more efficient at trapping radiation. Methane warms the planet 84 times as much as carbon dioxide over 20 years; over 100 years, it is 28 times greater.
According to satellite data available from 1980 to date, CH4 (methane) is now climbing rapidly and today stands at just over 1,860 parts per billion by volume, even after a period of stability experienced at the turn of the millennium.
Multiple studies have demonstrated that a selection of measures to cut methane emissions can reduce near-term warming of the climate, increase crop yields and prevent premature deaths.
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