Global food security could be threatened by ozone pollution close to the Earth's surface, according to initial results of a study presented at the UK Royal Society on 26-27 April.
Previously, greenhouse studies suggested that higher concentrations of carbon dioxide from urban pollution might increase crop yields. But these studies ignored the role of ozone — increased by traffic fumes, for example — near the ground, despite the gas being known to interfere with plant growth.
Stephen Long of the University of Illinois at Urbana-Champaign, United States looked at what future pollution levels could mean for crop yields in open-air studies of 22 varieties of soya bean.
Ozone-damaged plant (left)
and normal plant
Photo: US EPA
The experiments mimicked carbon dioxide and ozone levels predicted for the year 2050. Preliminary results suggest that yields would fall by as much as 10 per cent.
John Porter, an ecologist at Denmark's Royal Veterinary and Agricultural University who attended the London meeting, agrees that ozone will be a threat to crops, particularly in rapidly industrialising countries such as China and India.
Ozone levels are predicted by the Intergovernmental Panel on Climate Change to rise most in the Middle East, in northern parts of South Asia and in China — one of the largest producers of soya beans.
By 2050, urban pollution is expected to increase ozone levels near the ground by at least 25 per cent in China.