Reconstitution des variations multidécennales et saisonnières de la mousson ouest-africaine au cours des deux derniers millénaires à partir de l’étude sclérochronologique des amas coquilliers fossiles dans le delta du Saloum, Sénégal.

A groundbreaking study reveals that the West African Monsoon (WAM) experienced significantly wetter conditions from 460 to 1090 A.D., with rainfall seasons lasting approximately five months—nearly double the current duration. This finding challenges modern climate perceptions and was uncovered through sclerochronological analysis of fossil shell mounds in the Saloum Delta, Senegal, a region highly sensitive to WAM variations. Researchers leveraged isotopic signatures (δ18O, δ13C) from the bivalve Anadara senilis to reconstruct hydrological changes with unprecedented precision, capturing seasonal shifts as small as 25 days. The study also indicates that winter and spring rains, rare today, were more frequent during this period, extending the monsoon season and increasing the precipitation-evaporation balance. This work highlights A. senilis as a high-resolution paleoclimatic archive, offering critical insights into past hydrological cycles in West Africa.

Azzoug, M. Reconstitution des variations multidécennales et saisonnières de la mousson ouest-africaine au cours des deux derniers millénaires à partir de l’étude sclérochronologique des amas coquilliers fossiles dans le delta du Saloum, Sénégal. https://doi.org/10.70675/868f2654z0aebz4fd3z96e9z617affde741f