Methane emissions from rice cultivation in West Africa and compensation options from nature reserve forests

Abstract Methane (CH 4 ) is a major and potent greenhouse gas (GHG), and its emissions from agricultural activities, particularly rice cultivation, are a significant concern for climate change. Due to the high demand for food security, driven by rapid population growth and national initiatives to reduce dependency on rice imports, rice cultivation is intensified in West Africa. However, its contribution to atmospheric CH 4 remains largely unknown. Here, for the first time, cutting-edge eddy covariance tower measurements were conducted parallelly in a rice field (Janga) and a reserve forest (Mole National Park), both located in the Guinea savanna region of West Africa. Using CH 4 measurement data from June to October 2023 (rice cultivation period), the dynamic interplay between methane emissions from rice cultivation and its potential mitigation through forest methane uptake was assessed. Our results show that the rice field acted as a net source of CH 4 at a rate of 2037 mgCH 4 m −2 , whereas the most intense flooded period (August) accounted for 70% of the total emissions. On the other hand, the forest reserve acted as a sink, with a net uptake of −560 mgCH 4 m −2 , and the highest uptake observed in October. Accounting for the global warming potential (GWP) of CH 4 over a 20 year period, the forest had a wet season negative GWP of −47.04 gCO 2 eq, while the rice field emitted CH 4 of 171.36 gCO 2 eq. This implies that under similar conditions during the measurement campaigns, the forest per square area needs approximately a factor of ∼4 to balance the positive radiative effect per square area of rice cultivated. This work emphasizes the need to integrate forests to compensate for methane released by rice cultivation in the semi-arid West African savannah region.