Mitigating climate change and ozone pollution will improve Chinese food security

Under climate warming, the trade-off between maintaining forest carbon sinks and meeting growing food demands presents a great challenge for land systems. Ground-level ozone, an oxidative air pollutant, exacerbates this issue by entering plant stomata and causing phytotoxic damage to crops. Previous studies have largely overlooked the physiological response of plant stomata (e.g., stomatal aperture) to meteorological factors such as temperatures and humidity, which determine the impact of ozone on plants and changes with climate change. Here, accounting for these effects, authors show that the ozone-induced crop losses in China are currently 39 Tg annually and project that, under low-emission scenarios, mitigating this damage would enable a net absorption of 22 million tons of CO₂ annually through reverting surplus cropland to natural ecosystems. These findings highlight the need for strict pollution controls to reduce land competition and mitigate climate change.
 

Highlights  

• Authors have quantified future ozone-induced crop losses due to stomatal ozone absorption
• Ozone-related crop losses in China amount to 39 Tg annually in the last decade  
• Achieving net-zero emissions could reduce crop losses, increasing food availability
• Reduced crop losses enable forest expansion, enhancing CO2 absorption by 22 Mt/year

Competition for land, partly driven by the trade-off between ensuring sufficient food production and expanding forest carbon sinks, intensifies the challenge of addressing climate change. This issue is further exacerbated by damage to plant stomata from ground-level ozone, reducing crop yields. Stomatal opening is regulated by meteorological processes that may change significantly under warming climate, but this effect has been largely overlooked in prior studies of crop ozone damage. Here, authors show historical crop losses across China are 39 Tg annually, valued at roughly $15 billion. In a scenario where carbon emissions reach net zero in 2060, projected crop production losses could decline most, enough to provide an additional 87,000 kcal per capita in China, or enabling a net absorption of 22 million tons of CO2 annually through reverting surplus cropland to natural ecosystems. These findings provide policy-relevant information to support continued efforts toward strict pollution control and climate mitigation.