Carbon dioxide fertilization offsets negative impacts of climate change on Arabica coffee yield in Brazil

Arabica coffee production provides a livelihood to millions of people worldwide. Climate change impact studies consistently project a drastic decrease of Arabica yields in current production regions by 2050. However, none of these studies incorporated the beneficial effects that elevated CO2 concentrations are found to have on Arabica coffee yields, the so-called CO2 fertilization effect. To assess the impacts of climate change and elevated CO2 concentrations on the cultivation of Arabica coffee in Brazil, a coffee yield simulation model was extended with a CO2 fertilization and irrigation factor. The model was calibrated and validated with yield data from 1989 to 2013 of 42 municipalities in Brazil and found to perform satisfactorily in both the calibration (R 2 = 0.91, d = 0.96, mean absolute percentage error (MAPE) = 8.58%) and validation phases (R 2 = 0.96, d = 0.95, MAPE = 11.16%). The model was run for the 42 municipalities from 1980 to 2010 with interpolated climate data and from 2040 to 2070 with climate data projected by five global circulation models according to the Representative Concentration Pathway 4.5 scenario. The model projects that yield losses due to high air temperatures and water deficit will increase, while losses due to frost will decrease. Nevertheless, extra losses are offset by the CO2 fertilization effect, resulting in a small net increase of the average Brazilian Arabica coffee yield of 0.8% to 1.48 t ha−1 in 2040–2070, assuming growing locations and irrigation remain unchanged. Simulations further indicate that future yields can reach up to 1.81 t ha−1 provided that irrigation use is expanded.