Recent research has uncovered a surprising finding: tropical forests in West Africa are absorbing more CO₂ than the renowned Amazon rainforest. This revelation marks a pivotal shift, placing the spotlight firmly on the African continent in discussions surrounding the global carbon cycle. With extensive data collection and analysis, including a significant contribution from CMCC, this study underscores the critical role of African forests in the global discourse on climate change.

Tropical forests play a crucial role in absorbing carbon dioxide, acting as the planet’s lungs. While the significance of the Amazon rainforest in this regard is well-known, recent research has shifted focus to African forests. The paper “Contrasting carbon cycle along tropical forest aridity gradients in West Africa and Amazonia”, published in Nature Communications, marks the first time West African tropical forests, particularly those in Ghana, have been analyzed for their carbon absorption capacity.

The research, carried out by an international team of scientists, including CMCC’s Riccardo Valentini, revealed that these forests absorb more CO₂ than the Amazon rainforest. This finding is pivotal as it highlights the importance of African forests in the global carbon cycle.

The study suggests that the higher efficiency of African forests in capturing CO₂ may be due to aridity, which slows down the decomposition process of biomass, allowing more carbon to remain stored in the forest. Additionally, the semi-deciduous nature of these forests—trees that seasonally shed some, but not all, of their leaves, often found in transitional zones between savannah and tropical areas—enhances their carbon fixation capability. These factors together make African forests a more effective carbon sink compared to their Amazonian counterparts.

Historically, there has been a lack of biometric measurements to understand the carbon absorption capability of African forests. This research was facilitated by extensive data collection over several years from 14 forest areas along a gradient of African forests. The initiative was part of a project funded by an ERC Advanced Grant, coordinated by CMCC and led by Valentini, which included the construction of a measurement tower in the African tropical forest.

“CMCC played a pioneering role in this research, being one of the first to conduct such measurements in African tropical forests,” says Valentini. “This legacy of extensive data collection and analysis has now culminated in the publication of this significant paper, which places African forests at the center of the carbon cycle discussion.”

Deforestation is also a critical issue for African forests, similar to the challenges faced by the Amazon rainforest. Although the deforestation problem emerged earlier in the Amazon due to rapid economic growth and urbanization in Brazil, Africa is now experiencing high rates of deforestation. In Africa, deforestation is primarily driven by land grabbing linked to the need for agricultural land, exacerbated by demographic pressures and economic needs.

The issue of deforestation in Africa is becoming increasingly urgent, drawing global attention to the continent’s environmental and climate challenges. “This is framed in the context of the global discussion on climate change that sees Africa at the focal point of climate change research, impacts, and policy discussions,” says Valentini.

More information:

Zhang-Zheng, H., Adu-Bredu, S., Duah-Gyamfi, A. et al. Contrasting carbon cycle along tropical forest aridity gradients in West Africa and Amazonia. Nat Commun 15, 3158 (2024). https://doi.org/10.1038/s41467-024-47202-x