The success of international commitments to stop tropical deforestation by 2030, made by the Glasgow Leaders' Declaration on Forests and Land Use, depends on suitable information on where, when and why forests are changing. A new study, led by Wageningen University & Research, provides a continentally comprehensive dataset on carbon losses in Africa's rainforest at a higher speed and in much more spatial detail than ever before. For the first time, hotspots of forest carbon loss – an indicator of deforestation – can be tracked monthly.
Forest carbon monitoring efforts have evolved in the past few years, which can help analyse where forest areas are being disturbed. However, limited details about location and time hinder their usefulness for tracking collective progress towards forest-specific climate mitigation goals. This particularly is an issue for Africa's humid forest changes that remain poorly understood and quantified.
Near-real-time carbon loss monitoring
In the new study published in Nature Communications recently, researchers have used near-real-time forest disturbance alerts based on all-weather satellite radar data (for which cloud coverage is no obstacle). The research team combined this information with a new and spatially detailed global map of the distribution of forest biomass. Dr Johannes Reiche, Associate Professor of Wageningen University & Research: "With this method, we have identified hotspots of when and where carbon loss occurs throughout the year. We analysed this in 23 countries during 2019 and 2020. For example, we found that 75% of the total annual carbon loss in the Central African Republic happened within the first three months of 2020, while Madagascar lost 89% of the carbon within the last five months of the same year."
Figure 1: Local carbon losses in Republic of Congo: Gold mining (west part) and logging road expansion and selective logging (east part)
Seasonal variability
Temporal variability in local carbon loss is caused by different drivers of forest disturbance. The researchers found that countries like Cameroon, Liberia, Nigeria, the Central African Republic and Madagascar showed a clear dry-wet seasonal variation in carbon loss per year. On the other hand, due to their latitudinal extent, the Republic of the Congo and the Democratic Republic of the Congo exhibited two dry-wet season variations per year with varying intensities. Reiche: "This seasonal variation can be explained by higher accessibility to forests during the dry months. Activities related to smallholder agriculture and logging are then more feasible than in the wet season when many roads become inaccessible."
Figure 2: Local carbon loss in the Central African Republic: Selective logging activities (west part) active throughout the entire year, and smallholder agriculture (east part) primarily active during dry season in December-Feb)
Enhancing countries' capacities to track progress
Detailed spatiotemporal mapping of carbon loss creates opportunities for a much more transparent, timely, and efficient assessment of forest carbon changes. For example, at the level of specific activities affecting forests, such as tracking or prioritising interventions on the ground. But also for more rapid greenhouse gas emission estimation, or large-area comparative analysis, the new approach can help to increase the frequency and awareness of forest carbon information. It can be easily adapted to add new datasets, and also be expanded globally. Reiche: "In that way, it can provide a benchmarking approach that will enhance countries' capacities to track their progress towards the goals of the Glasgow Declaration, as well as the Paris Agreement."
