Pollution from North America ‘destroying wheat’

The research, led by Leeds University and co-authored by York University, shows the extent of northern hemisphere crop losses caused by ozone – a chemical partly produced by fossil fuels.

The study suggests that increasing levels of air pollution from one continent may partly offset efforts to cut carbon emissions in another and says these findings have important implications for international strategies on food, climate and human health.

In a paper published in Biogeosciences, the researchers look at how ozone generated in the industrialised regions of Europe, North America and South East Asia, damages six important agricultural crops (wheat, maize, soybean, cotton, potato and rice) not only locally but also by travelling many thousands of kilometres downwind.

Of the yield losses to Europe caused by ozone, pollution originating from North America is responsible for a 1.2 million tonne annual loss of wheat. This is the biggest intercontinental ozone-related impact on any food crop.

Worldwide, the biggest impacts on both wheat and rice are from Asian pollution. But North America contributes most to worldwide losses of maize and soybean. The impact of Europe’s pollution on other continents is minor due to air flow patterns.

Michael Hollaway, a PhD student at Leeds, used a computer model to predict reductions in global surface ozone if man-made emissions of nitrogen oxide from the three continents were shut off. Using crop location and yield calculations, he and his team were able to predict impacts on staple food crops, each with their own unique sensitivity to ozone pollution.

Steve Arnold, the Leeds lecturer who oversaw the study, summed up: “The negative impacts of air pollution may have to be addressed at an international level rather than through local air quality policies alone.”