Breaking new ground: First AquaCrop calibration and climate change impact assessment on Arabica coffee

Climate change threatens global coffee yield stability, especially in Brazil, the largest Arabica exporter. Yield modeling is key to climate-resilient strategies and effective planning. To this end, the AquaCrop model was parameterized, calibrated, and validated for Arabica coffee in Brazil and subsequently applied to project yield under future climate scenarios. These processes were carried out across 58 municipalities in Brazil's two largest coffee-growing regions, covering the growing years from 2014 to 2019. AquaCrop accurately simulated Arabica coffee yield during calibration and validation processes, with root mean square error values of ∼0.15 t ha^-1, mean bias error of ∼0.007 t ha^-1, and d-index of ∼0.76. To project yield, AquaCrop used as input daily near-surface air temperature (minimum and maximum), precipitation, and reference evapotranspiration data from 9 General Circulation Models (GCMs) from the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP), which are derived from the Coupled Model Intercomparison Project Phase 6 (CMIP6), under three Shared Socioeconomic Pathways scenarios (SSP2-4.5, SSP3-7.0 and SSP5-8.5). Under future climate conditions, reductions in the coffee growing cycle duration and heterogeneous yield changes are projected, with increases (between 0.25 and 0.55 t ha^-1) along a belt extending from southeastern São Paulo to southern Minas Gerais, and decreases (between -0.05 and -0.15 t ha^-1) in northeastern Minas Gerais. Even though yield increases are projected for much of the study region, adopting effective adaptive measures will be essential to address climate change threats.