LEEDS, UK, January 17, 2017 (ENS) – An extensive peatland in the Congo Basin has been mapped for the first time, showing it to be the largest such tropical peatland in the world, covering an area larger than England.
The new study found that the Cuvette Centrale peatlands in the swamps of the central Congo Basin, unknown just five years ago, cover 145,500 square kilometers (56,178 square miles). The peat locks in 30 billion tonnes of carbon, making the region one of the most carbon-rich ecosystems on Earth.
Peat is an organic wetland soil made from partly decomposed plant debris, found most commonly in cool environments.
Peatlands cover three to five percent of the Earth’s surface but store over 30 percent of all soil carbon.
Healthy peatlands act as carbon sinks, removing the greenhouse gas carbon dioxide (CO2) from the atmosphere through plant growth.
Not just important for carbon storage, the Congo Basin swamps also are refuges for endangered species, including lowland gorillas and forest elephants.
Co-leaders of the study, Professor Simon Lewis and Dr. Greta Dargie from University of Leeds’ School of Geography, first discovered the peatlands during fieldwork in the Congo Basin in 2012. Dr. Dargie is also with the University College London.
“We have found 30 billion tonnes of carbon that nobody knew existed,” said Professor Lewis. “The peat covers only four percent of the whole Congo Basin, but stores the same amount of carbon below ground as that stored above ground in the trees covering the other 96 percent.”
“Our new peatland map is the first step in understanding this vast ecosystem,” he said. “These swamp forests have been wrongly classified in all previous maps.”
Lewis said, “Our research shows that the peat in the central Congo Basin covers a colossal amount of land. It is 16 times larger than the previous estimate and is the single largest peatland complex found anywhere in the tropics.”
“These peatlands hold nearly 30 percent of the world’s tropical peatland carbon, that’s about 20 years of the fossil fuel emissions of the United States of America,” he said.
“The sheer expanse of these peatlands makes central Africa home to the world’s most extensive peatland complex,” Dr. Dargie said. “It is astonishing that in 2016 discoveries like this can still be made.”
The UK-Congolese research team spent three years exploring remote tropical swamp forests to find samples of peat for laboratory analysis.
Their research paper, “Age, extent, and carbon storage of the central Congo Basin peatland complex,” was published in the January 11 issue of the journal “Nature.”
Their study combined peat analysis with satellite data to estimate that the Congo Basin peatlands store the equivalent of three years of the world’s total fossil fuel emissions.
Dr. Dargie said, “Our 2012 discovery of the Congo Basin peat gave us just enough insight to refine our searches. In 2014, when we found the deepest peat deposits in the most remote areas of swamp we realized the importance of the Cuvette Centrale peatlands.”
The Cuvette Centrale wetlands occupy about 10 percent of the Congo Basin. About 40 percent of all the Cuvette Centrale wetlands has peat underneath.
Study co-author Dr. Ifo Suspense, from the Université Marien Ngouabi in the Republic of Congo’s capital Brazzaville, said, “The discovery of the Cuvette Centrale peatlands could have a large impact on the climate and conservation policies of the Congo. The maintenance and protection of this peatland complex, alongside protecting our forests, could be central Africa’s great contribution to the global climate change problem.”
The peat may be vulnerable to the effects of climate change in two ways, if rising temperatures increase evaporation, or if average rainfall is reduced, to a level when the peat begins to dry out. At this point the peat would begin to release its carbon dioxide into the atmosphere.
Year-round waterlogging is needed for peat to form in the tropics. If peatlands dry out, either through changes in land use such as drainage for agriculture or reduced rainfall, further decomposition resumes, releasing carbon dioxide into the atmosphere.
Professor Lewis said, “Peatlands are only a resource in the fight against climate change when left intact, and so maintaining large stores of carbon in undisturbed peatlands should be a priority. Our new results show that carbon has been building up in the Congo Basin’s peat for nearly 11,000 years.”
“If the Congo Basin peatland complex was to be destroyed, this would release billions of tonnes of carbon dioxide into our atmosphere,” Lewis warned.
The study details the researchers’ use of core samples to confirm the presence of peat soil and determine its depth. The average depth was 2.4 meters but at its deepest, it reached 5.9 meters – roughly the height of a two-story building.
The study used field measurements that confirmed the presence of peat, and the vegetation that overlies it, to determine that only two specific forest types have peat underneath – a year-round waterlogged swamp of hardwood trees and a year-round waterlogged swamp dominated by one species of palm.
The researchers then used data from U.S. and Japanese satellites to map the two specific peat swamp forest types across the whole region to determine the boundaries of the Congo Basin peatlands. Combining this area with peat depth and peat carbon content from the laboratory analyses allowed the total carbon stocks to be calculated.
The study places the Democratic Republic of Congo and the Republic of Congo as the second and third most important countries in the world for tropical peat carbon stocks.
In first place is Indonesia, as it contains tropical peatlands across the islands of Borneo, Sumatra and New Guinea. In the past few decades, these Asian islands have suffered damage or loss to about 94,000 square kilometers of peatland that have been burned by forest fires or drained for agricultural use.
Forest fires on peatlands are particularly worrying, says the UN’s environment agency. The 2015 forest fires in Indonesia, set for slash-and-burn agriculture, are estimated to have generated more CO2 on some days than average daily emissions for the whole of the United States.
Due to their remote location, the peatlands in the Congo Basin are relatively undisturbed. But they could face threats from drainage for agricultural plantations, particularly for palm oil, as is happening in Indonesia.
As the Congolese peatlands are so newly discovered, they do not feature in conservation plans to ensure they remain undisturbed.
“It is of the utmost importance that governments, conservation and scientific communities work with the people of the Cuvette Centrale to improve local livelihoods without compromising the integrity of this globally significant region of Earth,” said Dr. Suspense.
“I hope our work encourages much more investment in this neglected region to better understand the role of peatlands within the global carbon cycle and the climate system,” Lewis said.
Dr. Emma Stokes, director of the Central Africa Program of the nonprofit New York-based Wildlife Conservation Society, said, “This research highlights the immense significance of these swamp forests for the stability of our climate. However, these forests, in the geographical heart of Africa, are also a vital refuge for many thousands of great apes, elephants and other large forest mammals that are threatened by developments in the surrounding landscape.”
The RoC government is considering the expansion of Lac Tele Community Reserve, which could safeguard from future disturbance an additional 50,000 square kilometers of swamp forest, much of it overlying peat.
Dr. Dargie said, “With so many of the world’s tropical peatlands under threat from land development and the need to reduce carbon emissions to zero over the coming decades, it is essential that the Congo Basin peatlands remain intact.”
The UN Environment Programme, now called UN Environment, is responding to peatland destruction through the newly-formed Global Peatlands Initiative, or GPI.
The Initiative aims to provide an updated overall assessment of the status of peatlands and their importance for the achievement of the Paris Agreement on climate change.
It will mobilize countries and partners, including the private sector, to respond to the urgent need to improve awareness of the value of peatlands and the threats they face.
The Initiative will work in three pilot countries – Indonesia, Peru and the Republic of Congo -to build the knowledge base and develop options for sustainable peatland management.
UNEP peat expert Jaime Webbe said, “A lot of people are working on peat in their own way, but we want to bring together partners in the GPI so that they can agree on the very best ways to maximize peat’s contribution to implementing the 2015 Paris Agreement on climate change.”
Active partners in GPI include the European Space Agency, GRID-Arendal, Wetlands International, the Food and Agriculture Organization of the UN, the UNEP-World Conservation Monitoring Centre, the World Resources Institute, and the governments of the three pilot countries.