For decades, we have relied on a basic assumption in our climate models: large forest ecosystems, like those in Africa, are our faithful allies. They act as gigantic natural sponges that tirelessly absorb carbon dioxide from the atmosphere, helping to mitigate the impacts of climate change. This certainty was one of the pillars of our hope that nature would help us repair the damage we have done.

New breakthrough study, based on analysis of high-resolution satellite data, has shaken this fundamental certainty to its foundations. It has revealed a dramatic and deeply disturbing reversal that took place between 2010 and 2017. Africa’s forests, our key ally, have undergone a shocking transformation. From a carbon sink, they have become a net source of carbon – now releasing more into the atmosphere than they are removing.

Let's take a look at three of the most surprising findings from this research that are changing our view of the role of African ecosystems in the global climate equation.

1. The Big Turnaround: From Carbon Sponge to Emission Source

The story the numbers tell is stark and uncompromising. Africa’s forests and woodlands have undergone a complete reversal in their carbon balance. The scale of this change is staggering. In just a few years, the continent has gone from a powerful climate ally, gaining a net 439 million tonnes of biomass annually, to an active contributor to the problem, losing up to 132 million tonnes annually.

The data clearly illustrates this change: while between 2007 and 2010 the continent was gaining a net 439 Tg (teragrams, where one teragram is equal to one million metric tons) of biomass per year, between 2010 and 2015 it was already losing biomass at a rate of -132 Tg per year. This negative trend continued between 2015 and 2017, with a loss of -41 Tg per year. This reversal is shocking because it undermines one of the pillars of our planet’s natural defenses against climate change and reveals that one of our most important natural shields is failing.

The evidence we present here suggests that African forests and woodlands have changed from a net carbon sink to a net carbon source due to increased biomass losses caused by human activities and natural disturbances.

2. A Tale of Two Ecosystems: Not All Greenery is the Same

But this dramatic shift is not happening evenly across the continent. The study reveals a fascinating and disturbing story of two distinct ecosystems that respond in opposite ways to environmental pressures.

The main driver of carbon loss is deforestation in tropical moist deciduous forests, such as those in the Congo Basin. These dense forests have undergone a catastrophic transformation: from a net gain of +192 Tg of biomass per year (in the period 2007–2010) to a massive loss of -154 Tg per year (in the period 2015–2017). On the other hand, savannah These losses are partially compensated for by an increase in biomass. The reason is full of bitter irony – scientists believe that this growth is due to the so-called „shrub expansion“, which is probably supported by the effect of „carbon fertilization“. In other words, the increased concentration of CO2 in the atmosphere, which is causing the climate crisis, helps trees in the savannas to grow at the expense of grasses.

This is not just an academic distinction; it is a key blueprint for conservation. It tells us that a one-size-fits-all approach to protecting Africa's ecosystems is doomed to fail, and that our efforts must be highly targeted.

3. A sobering reality check: A global problem that's probably getting worse

When one of the world's largest carbon sinks fails, the consequences are global. This regional reversal makes it harder to meet goals of the Paris Agreement and is widening the „global greenhouse gas emissions gap“ – the gap between what we have promised to do and what is actually needed to avert climate catastrophe.

But the study also brings another, more chilling piece of news. The authors believe that the situation is likely even worse, as their results suggest. The research revealed that the greatest carbon losses are occurring in dense tropical forests. The authors then make a second, even more troubling finding: these are precisely the areas where current satellite technologies have the most difficulty accurately estimating biomass and tend to underestimate it. This means that the catastrophic losses we measured are most likely just a conservative estimate.

The implications of this shift are profound. Africa’s forests and woodlands, historically serving as carbon sinks, are now contributing to the global greenhouse gas emissions gap that needs to be filled to meet the goals of the Paris Agreement.

What next?

New high-resolution data has uncompromisingly revealed a deeply worrying reversal in Africa’s carbon cycle, driven largely by deforestation of its tropical forests. This is not just an „African problem“ – it is a global threat that directly impacts our shared climate goals.

The implications of this finding for global climate policy are clear: when one of nature's key carbon sinks is shut down, the rest of the world must do even more to make up for the loss. The findings highlight the urgent need to implement policies to halt deforestation, as called for by the Glasgow Leaders' Declaration, and to support the restoration of these vital ecosystems.

As one of the planet's key natural defenses against climate change fails, what bold political, economic and social steps are needed to reverse this trend before it's too late? JRi