One third of the last global increase of methane comes from Africa

Laila Ali

A recent study published in the European Journal of Earth Sciences (EGU) "Atmosferic Chemistry and Physics", on December 11, 2019, indicates that about a third of the global increase of methane in the atmosphere observed between 2010 2016 has originated in the tropics of Africa.

Satellite data

The concentrations of methane, one of the greenhouse gases and 28 times stronger than carbon dioxide, have increased steadily in the Earth's atmosphere since 2007.

Although many possible explanations for the increase in methane emissions were that of the tropics, due to the lack of regional data, scientists have not been able to determine the source.

"One suggestion for methane to continue to rise in the atmosphere, based on ground data, was to increase the tropical sources," says Mark Lunt, the atmospheric scientist at the University of Edinburgh and lead author of the study.

To obtain the results of this study, Lunet and the co-authors used data retrieved from the Japanese satellite "Ghosat" to monitor greenhouse gases, to study the annual and seasonal trends in Africa between latitudes 26 degrees north and 26 degrees south.

"There are few studies that have focused in detail on Africa, mainly because there is not a lot of methane data in the atmosphere there ... and the use of satellite data gives a unique perspective to the African continent, which would not otherwise have been available," Lunt said.

Methane emissions measurement

Previous studies that looked at methane emissions estimates in Africa used global models, designed to measure emissions changes at continental scales.

As for Lunt and his colleagues, by focusing exclusively on sub-Saharan Africa, they managed to manage a regional model that was much more accurate than the global model. This difference allowed researchers to focus on the changes that take place in individual countries, providing a level of detail that could not have been achieved before.

The results indicate that about a third of the global increase of methane in the atmosphere observed between 2010-2016 originates in the tropical regions of Africa, and most of them came from East Africa, including a clear short-term increase in emissions from the dam's swamp. It is one of the largest wetlands in the world, located in southern Sudan.

The reason for calling it a dam is due to the huge natural barrier of plants and green spaces that make up the area. It covers an area of ​​approximately 30,000 square kilometers in dry seasons and reaches an area of ​​130,000 square kilometers in rainy seasons.

"Our research highlights the importance of Africa and wetlands, in terms of their contributions to increasing global methane," says Lunt. But, he says, it is also important to note that the study period only dates back to 2010, the year in which the Ghosat satellite became available.

"Based on this work, we cannot say anything about the start of an increase in methane in 2007, and the team also cannot determine the reason for the additional increase in methane emissions that they observed in East Africa, as agriculture or other wetlands are likely to be suspected," he added. In it, but we need more evidence to prove this. "

According to the research team leader, the results of the study can be used to improve wetland study models, and to determine where intensive field campaigns should be conducted to identify the root causes of tropical CH4 emissions, and ultimately help us understand the Earth's climate in the future.

"In order to understand how methane can change in the future, it is necessary that we are able to explain the changes adequately in the present and recent past, and such studies can help narrow down the list of possible interpretations, and we hope to improve our predictive capabilities for the future," Lunt said.