Africa's tropics account for a third of rise in methane emissions

Dec. 11 (UPI) — Methane emissions are on the rise, and new satellite data suggests Africa’s tropics are responsible for at least a third of the recent increase.

Methane concentrations in the atmosphere have risen steadily since 2007, according to several greenhouse gas monitoring efforts. Scientists have previously theorized that rising methane emissions in the tropics might explain the rise, but a lack of regional methane emissions data has made it difficult to pinpoint the source.

For the new study, published this week in the journal Atmospheric Chemistry and Physics, scientists used satellite measurements to track methane emissions in the tropics of Africa.

“There are very few studies that have focused in detail on Africa, primarily because there isn’t much atmospheric methane data from there,” Mark Lunt, lead study author and an atmospheric scientist at the University of Edinburgh in Scotland, said in a news release. “Using satellite data gives a unique perspective on the continent that wouldn’t otherwise be available.”

Most methane emission models rely on simulations run at relatively coarse resolutions, providing only continent-wide emissions totals. But instead of building a methane emissions model with a narrower geographic focus, honing in on sub-Saharan Africa, scientists designed a methane emissions model simulating all of Africa at much finer resolutions.

Data collected by GOSAT, the Japanese Greenhouse gases Observing Satellite, allowed the researchers to build a much more detailed methane emissions model.

The higher-resolution model allowed scientists to track country-by-country changes in methane emissions over the last decade. Simulations revealed rising methane emissions among the African tropics between 2010 and 2016 accounted for roughly a third of the increase in global methane emissions recorded during that time period.

East Africa was responsible for most of the increases in methane emissions, with the Sudd, South Sudan’s massive swamp, one of the largest wetlands in the world, responsible for an especially sizable uptick.

“Our research highlights the importance of Africa, and even individual wetlands, in terms of their contributions to the global methane budget,” said Lunt.

Because GOSAT only came online in 2010, scientists were able to document earlier sources of the methane emissions increase that began in 2007.

The model also wasn’t able to pinpoint specific methane sources in East Africa.

“Agriculture or other wetlands are likely suspects, but we need more evidence to prove this,” Lunt said.

Atmospheric methane concentrations are dwarfed by CO2 levels, but methane’s greenhouse gas effect is 28 times more potent than carbon dioxide, making it imperative that climate scientists identify methane emissions sources.

“In order to understand how methane might change in the future, it is essential that we can adequately explain changes in the present and recent past,” said Lunt. “Studies such as this can help narrow down the list of possible explanations, and hopefully improve our predictive capabilities for the future.”

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