Analyse de la tendance des émissions anthropiques de méthane (CH4) en Afrique de l’Ouest entre 1970 et 2023 : une approche par cluster
Abstract
Trend analysis of anthropogenic methane (CH₄) emissions in West Africa from 1970 to 2023: A Cluster-Based Approach
Temporal trends in anthropogenic CH4 emissions over West Africa derived from EDGAR data for the period 1970–2023 were analyzed using a clustering technique. The Liebmann method and Hubert segmentation were employed to characterize the time series within each cluster and to identify breakpoints as well as modes of variability in anthropogenic emissions. This approach made it possible to distinguish three clusters, described as follows: Cluster 1 (Benin, Cape Verde, The Gambia, Guinea-Bissau, Liberia, Mauritania, Senegal, Sierra Leone, and Togo), characterized by low emissions; Cluster 2 (Côte d’Ivoire, Ghana, Guinea, Burkina Faso, and Mali), exhibiting intermediate emission levels; and Cluster 3 (Nigeria), characterized by high emissions. The mean emission growth rates were estimated at 19.27 ± 5.78 Gg yr-1, 64.18 ± 19.25 Gg yr-1, and 43.49 ± 13.04 Gg yr-1 for Clusters 1, 2, and 3, respectively. The results indicate that the number of breakpoints ranges from one to three, with different durations and intensities. Cluster 3 exhibits the smallest number of breakpoints (one), whereas Cluster 2 shows the largest (three). Furthermore, a trend analysis based on least-squares linear regression reveals the existence of two modes of variability: a low-frequency variability (time windows > 35 years), characterized exclusively by a gradual increase in emissions; and a high-frequency variability (time windows ≤ 20 years), associated with alternating positive and negative phases, reflecting significant short-term fluctuations.
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