Heterogeneous impacts of fire-sourced ozone (O₃) pollution on global crop yields in the future climate scenarios

Abstract. Wildfire smoke often aggravates the ozone (O₃) pollution and negatively affect crop yields. To date, the global impact of fire-sourced O₃ exposure on crop yields still remained unknown. To address this issue, a multi-stage model was developed to quantify the global wildfire-induced ambient O₃ concentrations in the future scenarios. The results suggested that the relationship between observed K⁺ level and simulated fire-sourced maximum daily MDA 8-hour average (MDA8) O₃ concentration reached 0.67, indicating the robustness of fire-sourced O₃ estimate. In both of historical and future scenarios, Sub-Sahara Africa (SS: 14.9 ± 8.4 (historical) and 18.3 ± 9.6 (mean of the future scenarios) μg/m³) and South America (SA: 4.0 ± 2.5 and 4.7 ± 3.2 μg/m³) showed the highest fire-sourced MDA8 O₃ concentrations among all of the regions. However, the crop production losses (CPL) caused by O₃ exposure reached the highest values in China due to very high total crop yields and relatively high wildfire-induced MDA8 O₃ levels. Moreover, CPL in China was sensitive to emission scenario, indicating the effective emission control could largely decrease fire-sourced O₃ damage to crop. In contrast, both of SS and SA even showed the higher CPL in low-carbon scenario (SSP1-2.6), suggesting more stringent control measures are required to offset the wildfire contribution. Our findings call for attention on the threat to future global food security from the absence of pollution mitigation and the persistence of global warming.