Rising ozone pollution as a threat to wheat yield in India: insights from a concentration-based approach

Rising levels of surface ozone (O₃) in the arable ecosystem have emerged as a serious threat to food security by reducing the yield of major food grains, yet long-term, stage-specific assessments of O₃ exposure and yield loss for wheat crop in India remain limited. Here, we present a comprehensive analysis of potential ozone-induced losses in yield and production of wheat across India for the past two decades (2005-2021) using a high-resolution surface O₃ data and the concentration-based accumulated ozone above a threshold of 40 (AOT40) method. Our analysis reveals a substantial increase in relative yield loss (RYL) of wheat from 2005 to 2021 (25.2-35.3%), resulting in an annual wheat production loss (WPL) of 21 ± 11.48 million tonnes (Mt) in 2005, rising to 48.6 ± 11.48 Mt by 2020. Critical reproductive stages of wheat, such as anthesis and grain filling, consistently experience AOT40 exposures exceeding the safe limit of 3000 parts per billion hour (ppb h) for crops, particularly across the Indo-Gangetic Plain (IGP). Prolonged and intense O₃ exposure during these sensitive phenological stages exacerbates yield loss and underscores the vulnerability of wheat in India relative to other major wheat producing regions. To safeguard national food security amid climate change, rising air pollution and growing population, future efforts must prioritise long-term air quality and crop monitoring, crop-specific ozone tolerance studies and integrated mitigation strategies linking agriculture and air quality policies.