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doi:10.1038/nindia.2014.148 Published online 31 October 2014

Ozone killing enough crops to feed millions of poor

Subhra Priyadarshini

Ozone pollution is destroying 12% of India’s annual cereal production – enough to feed 94 million people below the poverty line through the year. This startling estimate has been revealed in the first ever calculation of ozone pollution in the country1.

A study by the Indian Institute of Tropical Meteorology (IITM), Pune points a finger at the absence of air quality standards to protect agriculture from ground-level ozone pollution, primarily from vehicles and cooking stoves.

Ground level ozone is the main component of smog and is formed when polluting vehicles, industries or burning matter emit nitrogen oxides, carbon monoxide and volatile organic compounds. These pollutants react with sunlight to form ground level ozone, which is killer for vegetations.

Sachin Ghude

IITM scientist Sachin Ghude and Veerabhadran Ramanathan, a professor of climate and atmospheric sciences at Scripps Institution of Oceanography, at the University of California San Diego carried out the modeling study, supported by emission inventories and crop production data. They quantified the impact of ozone on the yields of cotton, soybeans, rice and wheat crops in India for the year 2005, an year they used as representative of the first decade of the 21st century.

Through the simulation studies, the scientists estimated that wheat was the most impacted crop – every year the country was losing around 3.5 metric tonnes – followed by rice at around 2.1 metric tonnes, mostly in central and north India.

On national scale, this loss is about 12% of the cereals required every year (61.2 Mt) under the provision of recently implemented National Food Security Bill (September-2013) by Government of India, the duo report.

“This study, since it was led by Indian government institutions, should have a major impact on the country’s approach to air pollution mitigation. It should speed up India’s attempts to drastically cut pollution,” Ramanathan told Nature India. High surface ozone concentration over major agriculture regions in India, particularly the Indo-Gangetic Plains, one of the world’s most important fertile agricultural lands is a threat to the country’s food security, the scientists say. They estimate that ozone concentrations will only increase further in the future.

Veerabhadran Ramanathan

The greatest losses of rice and wheat crops were reported from Maharashtra, Madhya Pradesh, Gujarat, West Bengal and Uttaranchal states.

“The possible ways to minimize these losses is to reduce anthropogenic emissions especially from vehicular and Industrial source and cooking stoves,” Ghude points out. He says another alternative could be to breed ozone-tolerant crops.

Ramanathan says some off-the-shelf technologies could be put to use immediately to cut the most damaging pollution – the emission of nitrous oxides from the transportation sector. “This contributes to more than half of the nitrous oxides produced and controlling it would have a major impact in reducing ozone. In so doing, we will also reduce the global warming effect of ozone,” he says.

The study puts India’s economic losses from ozone-induced crop damage at $1.29 billion in 2005, mostly stemming from losses in rice and wheat crops.


References

1. Ghude, S. D. et al. Reductions in India's crop yield due to ozone. Geophys. Res. Lett. (2014) doi: 10.1002/2014GL060930