Monitoring Cocoa Health and Productivity Using Multispectral and Thermal Remote Sensing: A Thirty-Year Longitudinal Study in Sunyani West Municipality, Ghana

Abstract Cocoa (Theobroma cacao L.) production in Ghana faces mounting threats from climate variability, land-use change, and intensifying thermal stress. Yet spatially explicit, long-term assessments of cocoa health using remote sensing remain scarce for peri-urban districts of the Ghanaian cocoa belt. This study employs a 30-year longitudinal remote sensing analysis (1994–2024) over the Sunyani West Municipality, Bono Region, Ghana, integrating Landsat 5, 7, and 9 multispectral and thermal imagery to: (i) map cocoa-growing areas using Support Vector Machine (SVM) classification; (ii) assess temporal changes in cocoa vegetation health through the Normalized Difference Vegetation Index (NDVI); and (iii) quantify the relationship between land surface temperature (LST) variation and cocoa crop performance. Results reveal a significant spatial contraction of closed-forest cover from 26,937 ha (1994) to 9,046 ha (2024) alongside an 89% expansion of built-up and bareland areas, driven by rapid urbanization. Mean NDVI in cocoa zones declined progressively from 0.72 (1994) to 0.53 (2024), coinciding with a six-fold expansion of areas experiencing temperatures exceeding 37°C from 2.37% of the municipality in 1994 to 15.88% in 2024. Cocoa yields recorded minimum values of 0.55–0.60 tons ha⁻¹ in years of peak thermal anomaly. A significant inverse relationship between LST and NDVI was identified, indicating that landscape-scale thermal stress, amplified by deforestation and urban heat-island effects, is a principal driver of declining cocoa health. These findings underscore the urgent need for integrated land-use planning, agroforestry expansion, and spatially targeted extension services in cocoa-producing peri-urban districts of West Africa.