More CO is now coming from African forests2 than they record. Scientists describe in a new study published in the leading scientific journal Naturehow from 2010 to 2017 the role of forests on the African continent in CO2storage and emissions changed radically. “Our findings underline the urgent need to implement policies to halt global deforestation,” write the seventeen scientists who participated in the study.
The study shows that “the three most important rainforest areas on Earth – the South American Amazon, Southeast Asia and Africa – are no longer allies in the fight against climate change, but part of the problem,” writes the British newspaper The Guardian.
Trees absorb CO2 from the air and store its carbon in their biomass (wood, leaves, roots). For example, forests have traditionally functioned as important carbon stores. But when trees emit more carbon than they absorb, this increases the concentration of CO2 in the atmosphere, causing the Earth to warm faster. The fact that forests emit more than they absorb is mainly the result of deforestation.
‘Moist deciduous forests’
For their conclusions, the researchers used satellite maps of above-ground biomass, which were validated with measurements in the field. Biomass increased between 2007 and 2010, but decreased in the following years. On average, African forests lost about 106 billion kilos of biomass per year in the seven years the researchers looked at. Biomass on the savannah did increase, probably due to shrub growth, but not enough to compensate. According to the researchers, this is the first time that above-ground biomass has been assessed across the entire continent and over several years.
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According to the scientists, the shift is mainly due to deforestation in so-called moist deciduous forests, mainly in countries such as Congo. That country contains the most above-ground biomass in all of Africa. It was already stated earlier known that never before had so much area been deforested in Congo as last year, with 590,000 hectares lost. This deforestation is caused by people, for example through logging and mining, and by natural disturbances, such as changing weather conditions. Although changes in the weather can also be caused by humans.
Delicate balance
These are significant new insights, says Gert-Jan Nabuurs, professor of European forests and IPCC lead author. “We know very little about the African forests, so whatever you can scrape together is very important.” For this reason, according to Nabuurs, caution is required when interpreting this research. In Europe, the forest is measured at around 400,000 points, but such measuring points hardly exist in African forests, says Nabuurs.
“Large assumptions are based on few measuring points here, while… ground based data are important to validate satellite data and for insight into the enormous area where there was no deforestation – and therefore CO2 records. Because these are missing, insight into African forests remains uncertain.” The researchers state that the actual effects are probably even greater than they have shown.
According to Nabuurs, it is normal that measurements from the period 2010 to 2017 are only now appearing in a study. “It takes a long time to take measurements on the ground at all, and before they are processed it can take six or seven years. On top of that, there are sometimes unsafe working conditions in African countries.”
What this research shows in any case, says Nabuurs, is that the balance between absorption and loss of CO2 is sensitive even to small changes. “These results show how quickly that balance is changing.”
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