Mato Grosso’s rainy season: past, present, and future trends justify immediate action

Abstract Mato Grosso (MT) state, the agricultural giant of Brazil, owes its success to the long rainy season that has allowed for the extensive adoption of double cropping, elevating the region to one of the world’s leading grain producers. However, recent studies warn of the adverse impacts of deforestation and climate variability, which are causing a decrease in rainfall and a delay in the rainy season onset. These changes pose significant threats to both ecosystems and intensive agriculture. To assess these threats, we compared past and present rainfall and rainy season duration in MT and conducted robust climate projections using climate simulations forced by realistic deforestation scenarios. Our analysis of observed rainfall data from the past four decades and Community Earth System Model simulations affirmed a worrying trend of decreasing rainfall volumes, delayed rainy season onset, and shorter rainy season length. Climate projections indicate that this pattern will intensify, with onsets expected in late October and rainy season durations shorter than 200 d by mid-century. These findings underscore the potential impact on MT’s double-cropping system, a cornerstone of the region’s agricultural success, and emphasize the urgent need for sustainable large-scale agricultural practices and strategic interventions by regional decision-makers to mitigate agricultural losses and ecosystem degradation.