Scientists analyse effects of global warming, atmospheric ozone on crops

July 28, 2014

A research team from the and  of the  and the  of the  has analysed effects of  and  over 2000–2050 on the worldwide production of, ,  and. The study was published in journal  yesterday.

The scientists found reduction of crop yields by 2050 exceeded 10% of 2000 levels, substantially decreasing, in all cases examined. Several scenarios were considered because of uncertainty of future levels of ozone pollution. They estimated by 2050, increasing and changing  would increase world food needs by 50 percent. As coauthor Colette Heald told, "The climate projections are quite consistent [...] the future of ozone pollution is very different [...] leading to either offsetting or reinforcing effects [of climate change] on crops". By 2050, would increase by either 49 percent or by 27 percent, depending on the scenario.

The study focuses on ozone–temperature : increases with temperatures. Heald said although temperature and ozone are separately known to impact crop yields, "nobody has looked at these together". Depending on region and crops, the yields may be primarily sensitive to ozone &mdash;in the case of wheat&mdash; or heat &mdash;in the case of maize&mdash; alone, providing a local estimation of relative benefits of versus.

The notes, "Ground-level ozone causes more damage to plants than all other air pollutants combined", highlighting the importance of air quality for agriculture. Results of studies, published in a paper by AS Heagle in 1989, show  species, such as soybean,, and , lose more yield from ozone than do  species such as , , and. The researchers found that ozone pollution caused 46 percent of previously heat-attributed damage to soybean crops.

The model does not include the effect of rising, which has complex and potentially offsetting impacts on global food supply. The says some crops may have higher yields with increased levels of. However, global warming also increases probability of extreme crops-damaging weather events such as, , and extreme temperatures. affects distribution of weeds, pests, and. Heald noted the findings show reduction is also important. "An air-quality cleanup would improve crop yields [...] Ozone is something that we understand the causes of, and the steps that need to be taken to improve air quality."

As Heald told, US surface ozone has dropped partly due to the. "Despite an increase in vehicle miles driven and consumption, surface ozone has declined by 25 percent on average across the U.S. from 1980 to 2012 [...] However, the future of ozone  in the U.S. and around the world will depend on local emissions, the use of pollution control technology, regulations, and air quality policy."

The study was supported by the, , and.