The large-scale loss of stored carbon – which on an annual basis is almost four times the CO2 emissions of Nigeria – was driven by a series of severe droughts across the continent, as well as deforestation, the research suggests.
The results were gathered using a novel satellite technique, which allowed researchers to measure “deeper below the vegetation canopy” than ever before, the lead author tells Carbon Brief.
Blank canvas
The world’s trees, plants and shrubs are capable of storing large amounts of carbon. This is because they absorb carbon from the atmosphere during photosynthesis and then use it to grow new leaves, shoots and roots.
However, vegetation can also release large amounts of carbon into the atmosphere. This can be caused by deforestation as well as climate-related factors, such as drought and wildfires.
Africa holds one third of the world’s tropical rainforests. On top of this, 50% of the continent’s surface is covered by savannah – grasslands with sparsely distributed trees – and woodlands, forested areas that fall outside of humid zones. Despite this, data on the total amount of carbon held by African vegetation is scant.
The new study, published in Nature Ecology and Evolution, aims to provide an overview of how sub-Saharan Africa’s vegetation carbon stocks changed between 2010 and 2016.
It finds that Africa’s green regions experienced an overall loss of 2.6bn tonnes of CO2 in the past seven years, with yearly losses averaging at 367m tonnes of CO2.
Carbon losses occurred across a range of ecosystems, including rainforests, savannahs, and woodlands, explains lead author Dr Martin Brandt from the University of Copenhagen. He tells Carbon Brief:
We find that severe droughts have caused huge carbon losses which are not restricted to rainforests but also happened in savannahs. Over the full period, losses in savannahs and woodlands were almost as high as in rainforests.
Read more at Africa’s Vegetation Has Lost 2.6bn Tonnes of CO2 in Just Seven Years
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