Right dab in the middle of the Congo basin is a low lying swamp called the Cuvette Centrale depession. It is the earth’s second largest tropical wetland, after the Panatanal in Brazil. The Congo basin is covered by tropical rainforests and swamps. Together these ecosystems make up the bulk of Central Africa's rainforest. Tropical wetlands are able to absorb and store about 80 percent more carbon than can wetlands in the world’s temperate zones.
Peatlands are rich in carbon. They cover just three per cent of Earth’s land surface, but store one-third of soil carbon, according to a study published in the journal Nature. The Congo has the largest tropical peatland on earth.
Thought to be the largest tropical peatland area on Earth, it contains three years’ worth of global fossil fuel emissions, and scientists are now worried that development in the region could release the gas.
A joint UK and Congolese team has been exploring the area for several years now, and using a combination of fieldwork and satellite imagery, they've produced the first extensive map of the newly identified peatland.
They say that the fact that it’s so rugged, swampy, and remote has kept it - and its massive carbon store - safe from developers until now, but that might not always be the case.
And if its water-logged soil begins to dry out due to land clearing and cultivation, that’s when carbon dioxide will start leaking out into the atmosphere.
"It's very remote, but what we've seen in south-east Asia is that these once-remote areas have been dried out and converted to oil palm plantations and rice plantations and other forms of industrial agriculture, causing a huge release of carbon dioxide into the atmosphere," Simon Lewis from the University of Leeds in the UK told Reuters.
Peat soils are susceptible to climatic changes if they cause the peat to dry out, which starts the decomposition process again, releasing the stored carbon back into the atmosphere. Protecting peat soils – along with other ecosystems that store carbon – is an important part of the global effort to cut carbon emissions. And the first step in peatland protection is knowing where they are.In a guest post for Climate Brief, Prof Simon Lewis, professor of global change science at the University College London and the University of Leeds writes on the massive peat-land discovery and it’s implications for climate change.
He notes that while peat covers only “4% of the whole Congo Basin, it stores below ground roughly the same amount of carbon stored above ground by the trees that cover the other 96%”.
But is this carbon vulnerable? Fortunately, the area is not currently threatened with drainage for industrial agriculture – the fate of many peatlands in southeast Asia. But oil companies are focusing in on the last remaining areas of Earth to explore for fossil fuels.
In terms of climate change, the peatlands are rainfed, so reductions in rainfall or an increase in evaporation from higher temperatures could reduce waterlogging. This could then allow the peat to decompose and release its carbon.
Predicting whether the 30bn tonnes of carbon in the central Congo peatlands will remain out of the atmosphere due to climate impacts is difficult. Few weather stations exist in the region, the central Congo area has been neglected by modellers, and climate projections for rainfall are not consistent.
But our new discovery will hopefully lead to significant scientific investments in the region. This will allow us to make better estimates of the carbon stocks, understand how vulnerable the peatland is to rainfall any future reduction in rainfall, and what those rainfall patterns are likely to be in a warmer world this century.
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