Global Flux‐Based Assessment Reveals Declining Ozone Risk for Wheat in Future Climate Change Scenarios

Tropospheric ozone (O₃) is a widespread air pollutant that impairs crop physiology and threatens global food security. Most global-scale assessments have relied on exposure-based metrics, which overlook plant-environment interactions that control O₃ uptake. This study presents a global flux-based assessment of future O₃ risk for wheat (Triticum aestivum) using a dual-sink dry deposition model driven by Earth System Models from the Coupled Model Intercomparison Project 6 (CMIP6) under three Shared Socioeconomic Pathways (SSP1-2.6, SSP3-7.0, and SSP5-8.5). We quantify phytotoxic O₃ dose (POD₆) and production losses from 2000 to 2100, analyze regional trends, and perform multiple simulations to assess the influence of soil water availability and atmospheric CO₂ on O₃ risk. Finally, we explore the roles of radiative forcing (RF), emission policies on O₃ precursors (EP), and their interaction, in determining O₃ risk changes. We find a general decline in O₃ risk, although regional disparities remain. Under SSP1-2.6 (strong EP, low RF) POD₆ declines throughout the century, leading global mean production losses to decrease from 3.3% to 5.0% at the beginning of the century to less than 1.4% at its end. In contrast, SSP3-7.0 (weak EP, high RF) shows end-century losses between 1.3% and 4.9% and may exacerbate risks in several regions (South and East Asia, South America, Sub-Saharan Africa). SSP5-8.5 displays intermediate outcomes: O₃ risk increases until mid-century in many regions, and then declines by 2100 (0.5%-2.6%), due to delayed EP adoption. Increasing atmospheric CO₂ concentrations will likely hinder future O₃ risk due to reduced stomatal conductance, but some hotspots will persist near the Southern and Eastern edges of the Tibetan Plateau. These findings provide a basis for prioritizing region-specific mitigation strategies to reduce O₃ damage to wheat under future climate conditions.