Farmer's Weekly (South Africa)
Africa goes from net carbon sink to source
New research shows Africa’s impact on greenhouse gases and the need to focus on climate-smart agriculture, writes Jyothi Laldas.
New research by a team at the University of the Witwatersrand (Wits) shows that, in only nine years, Africa has gone from being a net carbon sink to being a net carbon source.
Researchers from the Future Ecosystems for Africa programme, based at Wits, found that between 2010 and 2019, the continent has made the transition.
It is estimated that Africa is a source of 4,5 petagrams, or 4,5 billion tons, of carbon dioxide equivalents per year.
According to Prof Sally Archibald, principal investigator at the Future Ecosystems for Africa Programme, and professor at the Wits School of Animal, Plant and Environmental Sciences, until now, Africa has been producing about 4% of the anthropogenic greenhouse gases (GHG) that lead to climate change globally. The continent has also been offering climate services to the globe, largely through the intact ecosystems in the tropics that have been sequestering more GHGs than were released through anthropogenic activities.
“While it still serves this purpose, in the last decade the rate at which carbon is being released from the continent increased. In terms of global numbers this means Africa still hovers around 4% of fossil fuel emissions, but actually emits nearly 40% of the global emissions from land use, and is now, for the first time, contributing 3% to 5% of the growing amount of GHGs in the atmosphere.”
She said with the population of Africa currently at about 1,4 billion people and set to exceed two billion by 2040, the trend is likely to continue.
According to Dr Yolandi Ernst, researcher at the Wits Global Change Institute and lead author of the study, key factors in the rise of GHGs include fossil fuel burning, methane emissions from livestock, and soil carbon losses and nitrous oxide emissions as land is converted for agricultural use.
“While natural ecosystems continue to act as carbon sinks across the region and are taking up about 30% of what is being emitted to the atmosphere through human activities, greater swaths of land than ever before are being used for agriculture and livestock numbers are increasing, with the net result being that these changes in land use have affected Africa’s role in the global carbon cycle.”
To make their estimates, Ernst and the team followed the budget assessment protocol laid out by the Regional Carbon Cycle Assessment and Processes. They took a comprehensive look at all major potential carbon sources, including human sources such as agriculture and fossil fuel emissions, and natural sources such as termites and wildfires.
They also considered natural sinks such as the grasslands, savannas and forests that still cover much of the continent.
Overall, they estimated that Africa was a source of 4,5 billion tons of carbon dioxide equivalents per year, with land use emissions still being higher than fossil fuel emissions.
“Both are growing rapidly. In the last year, the total anthropogenic emissions (emissions resulting from human activity), including trade, livestock and fuel burning, were estimated at 1,2 petagrams of carbon per year. Moderate climate conditions and high productivity of the tropical forests helped natural ecosystems to take up about 0,6 petagrams of carbon per year, leaving approximately 0,6 petagrams of carbon as the net flux, released into the atmosphere,” Ernst said.
She explained that the information from this research on Africa’s carbon budget was key to identifying which aspects of the GHG cycle were most important to be managed in the quest to achieve net zero, and possibly restore the continent’s role as a carbon sink.
“Investing in carbon-neutral energy sources could reduce about 30% of Africa’s anthropogenic emissions, but novel ways to manage landscapes for livelihoods and carbon storage would be needed to slow the emissions from agriculture and land use,” said Ernst.
“As demand for food production increases, we need a focus on climate-smart agricultural practices on the continent, as well as a focus on investments that address socio-economic challenges in naturepreserving ways across Africa.”
Archibald added that protecting, managing and restoring the landscapes that are helping to take up the excess CO2 was an important part of the solution, but there were challenges with making carbon storage the main goal of conservation, and it could cause conflict with biodiversity and water provision.
“The Future Ecosystems for Africa Programme is working with scientists, policymakers and carbon projects across the continent to try to navigate this and identify opportunities to store carbon in natural ecosystems that do not damage the ecology,” said Archibald.