Rainforests, long considered one of the planet’s strongest natural defences against climate change, are beginning to lose their ability to absorb carbon, according to a new scientific study. Research published in the journal *Nature* has found that parts of Africa’s forests, which once removed large amounts of carbon dioxide from the atmosphere, are now generating carbon as a result of increasing human activity.
The findings raise serious concerns for global climate goals, particularly as forests play a crucial role in limiting temperature rise under international agreements.
Africa’s forests shift from carbon sink to carbon source
The study reveals that Africa’s forests and woody savannas made a significant transition between 2010 and 2017, moving from acting as a carbon sink to becoming a net carbon source. Historically, these ecosystems absorbed atmospheric carbon and stored it in plant biomass and soil. Today, that balance is beginning to reverse.
Africa’s forests currently account for nearly one-fifth of global carbon removal, making the shift especially alarming. Researchers warn that this change is widening the gap between current greenhouse gas emissions and the reductions needed to meet the targets of the Paris Agreement.
Satellite data shows declining forest health
Using satellite observations, scientists from the National Centre for Earth Observation at the Universities of Leicester, Sheffield, and Edinburgh tracked changes in forest carbon absorption across the continent. Their analysis showed that between 2011 and 2017, Africa’s forests lost an average of 106 million tonnes of biomass each year.
This decline has sharply reduced the forests’ ability to remove carbon from the atmosphere. The most severely affected regions include tropical broadleaf forests in the Democratic Republic of the Congo, Madagascar, and parts of West Africa.
Human activity driving forest degradation
The primary driver behind this shift is human activity. Carbon emissions have risen dramatically since the industrial era, largely due to the burning of fossil fuels such as coal, oil, and gas. While forests were once able to absorb much of this excess carbon, deforestation and land-use change have weakened that capacity.
Large areas of forest have been cleared for agriculture, infrastructure development, timber extraction, and fuelwood. The study warns that population growth, rising export demand, and pressure on natural resources could further accelerate forest degradation if governance and sustainability measures are not strengthened.
A carbon sink is any natural system that absorbs more carbon dioxide than it releases. Forests act as carbon sinks through photosynthesis, storing carbon in trees, vegetation, and soil. When forests are cleared or degraded, this stored carbon is released back into the atmosphere, worsening climate change.
Oceans remain the world’s largest carbon sink, absorbing about one-quarter of global carbon emissions. However, scientists stress that land-based sinks such as forests are essential for maintaining climate stability.
Other global forests also under threat
Africa is not alone in facing this challenge. The Amazon rainforest has also shown signs of stress due to deforestation and land conversion for farming and livestock. While recent efforts by the Brazilian government to curb deforestation have slowed the damage, scientists caution that continued pressure could eventually weaken the Amazon’s role as a carbon sink.
Environmental organisations warn that the loss of major forest carbon sinks would have catastrophic consequences for ecosystems, economies, and human wellbeing worldwide.
Calls for stronger protection and reduced fossil fuel use
The study highlights initiatives such as Brazil’s Tropical Forest Forever Facility, which aims to raise 100 billion dollars to compensate countries for protecting their forests. So far, only a small fraction of that target has been achieved, underscoring the need for greater global commitment.
Researchers emphasise that protecting Africa’s forests is essential for meeting climate targets. They call for improved forest governance, sustainable land use, and investment in local capacity building. At the same time, experts stress that forest protection alone is not enough.
“If we are losing tropical forests as a tool for mitigating climate change, then we must reduce greenhouse gas emissions from fossil fuels even faster,” said Heiko Balzter, a professor of physical geography at the University of Leicester and one of the study’s authors.
Without rapid emissions cuts and stronger conservation efforts, scientists warn that the world risks losing one of its most powerful natural allies in the fight against climate change.