Counting the cost of ozone pollution on crops

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Source: European Commission, Environment DG

A recent study has calculated crop losses as a result of surface ozone pollution. The study suggests that future earnings will be significantly reduced by ozone damage to crops, especially for some developing and agriculture-dependent countries. Surface ozone is an air pollutant that forms as a result of chemical reactions between other pollutants, particularly emissions from motor vehicles and industry. The study predicts the impact of ozone pollution on crops for the year 2030, and compares the results to estimates of losses in crop yields at the start of the millennium. This allowed the researchers to investigate how yields could be affected over the 30 year period. A global air quality model was used to calculate exposure to ozone for four crops grown across the world - wheat, rice, maize and soybeans. The predicted impact of air quality legislation on global surface ozone pollution was also included in the model. The study was conducted under the EU-funded ACCENT and EUCAARI projects1,2.

Ozone pollution caused significant damage to crops in the year 2000 and greater reductions in yields are predicted for 2030 for some regions of the world. In 2000, the global economic value of crop losses through surface ozone was estimated to be between US $14 and $26 billion, with 40 per cent of this cost occurring in China and India. Estimated losses for specific regions were:

European (defined as EU25) - $0.9 to $1.1 billion
North America - $1.8 to $4 billion
India - $2.8 to $6.1 billion
China - $3 to $5.5 billion

In comparison, climate change is estimated to cause global crop losses totaling approximately just US $5 billion per year.

The results show the impact of ozone on different crops by region. Soybeans and wheat are especially sensitive already showing reductions in yield of a fifth to a quarter. For example, the greatest losses for wheat were in India and China, with India losing up to 28 per cent and China up to 19 per cent of crop yields. Europe suffered the greatest relative yield loss (RYL) for soybeans (20 to 27 per cent), followed by China at 11 to 21 per cent. Maize, across all four regions, was the least affected crop with RYLs between 2 to 7 per cent.

The study predicts that by 2030, global wheat yields will be reduced by a further 2 to 6 per cent on top of 2000 levels in most regions, assuming current emissions control legislation is implemented. The study suggests that current legislation3 will reduce ground ozone levels for most developed countries and China, and consequently lessen the impact on crop losses. However, in other parts of Asia and in Africa current legislation is inadequate and countries in these regions are projected to suffer more severe reductions in crop yields, which could significantly damage GDP growth rates. For example, the Indian subcontinent is projected to still be strongly affected by ozone pollution, with Pakistan particularly severely affected. The study suggests that Pakistan could face a further RYL of 26 per cent for wheat and 28 per cent for soybean, compared with 2000 levels. Countries in the Central and East Mediterranean area are likely to show the greatest improvement in relative yield losses, particularly Turkey and Italy, and these countries could see improvements in crop yields.

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