global food supply
July 28, 2014

Researchers Explore Combined Impact Of Climate Change, Ozone Pollution On Crops

redOrbit Staff & Wire Reports - Your Universe Online

While previous research has investigated the potential impact that climate change and air pollution can have on crops individually, a new study suggests that the interaction between these two risk factors has been overlooked and could drastically increase the threat to the global food supply.

In research published in this week’s edition of the journal Nature Climate Change, MIT associate professor of civil and environmental engineering (CEE) Colette Heald and her colleagues explain that the interplay of increasing heat and ozone pollution levels are significant enough for policymakers to consider both phenomena when addressing food security issues.

Heald, along with former CEE postdoctoral researcher Amos Tai and Maria van Martin of Colorado State University, conducted a detailed analysis of four leading food crops: rice, wheat, corn and soy. Combined, those four crops account for over half of the calories consumed by humans worldwide, they reported.

The actual impact climate change and ozone pollution will have on these crops varies from region to region, and some types are harmed more by one than by the others. For example, wheat is more sensitive to air pollution and heat tends to have a more drastic effect on corn. While scientists know that both factors can damage plants and reduce crop yields, Heald said their combined impact has never really been analyzed.

“Nobody has looked at these together,” she explained in a statement Sunday. While stricter air quality standards in the US should cause ozone pollution levels to decrease sharply, mitigating its impact on crops, the impact in other parts of the world “will depend on domestic air-pollution policies. An air-quality cleanup would improve crop yields.”

With all other factors being equal, warming is expected to reduce global crop yields up to 10 percent by 2050, according to the new study. The impact of air pollution, however, is more difficult to pinpoint. It has a stronger impact on some crops than others, suggesting that pollution-control measures could drastically affect the outcomes.

The authors – whose research was supported by the National Science Foundation, the National Park Service, and the Croucher Foundation – also noted that ozone pollution can be somewhat difficult to identify, as the damage it causes is similar in nature to plant illnesses which produce flecks on leaves and cause discoloration. Regardless, Heald and her colleagues emphasize that the potential reduction in crop yields is cause for concern.

According to the authors, the world is expected to need about 50 percent more food by 2050 due to global population growth and changing dietary trends in the developing world. Potential reductions in food production due to climate change and pollution indicates the need to improve yields through improved crop selection and farming methods, as well as the allocation of additional farmland, they explained.

“While heat and ozone can each damage plants independently, the factors also interact,” said David L. Chandler of the MIT News Office. “For example, warmer temperatures significantly increase production of ozone from the reactions, in sunlight, of volatile organic compounds and nitrogen oxides. Because of these interactions, the team found that 46 percent of damage to soybean crops that had previously been attributed to heat is actually caused by increased ozone.”

In some scenarios, the study authors discovered that pollution-control measures could drastically reduce the anticipated crop reductions resulting from climate change. For instance, while one model projected a 15 percent decrease in global food production, an alternate scenario could cut that amount to just nine percent.

“Air pollution is even more decisive in shaping undernourishment in the developing world, the researchers found: Under the more pessimistic air-quality scenario, rates of malnourishment might increase from 18 to 27 percent by 2050 – about a 50 percent jump,” Chandler said. “Under the more optimistic scenario, the rate would still increase, but that increase would almost be cut in half, they found.” - Read eBooks using the FREE Kindle Reading App on Most Devices