Climate change could trigger toxic corn: what can be done?

Climate change and extreme weather events stress crops out – enough to make them toxic for human and animal consumption. But scientists see challenge as opportunity to find more efficient ways to grow food.

Mike Hutchings/Reuters
A Malawian trader counts money as he sells maize near the capital Lilongwe, Malawi, in February.

Crops respond to the stress of warming temperatures in much the same way that humans respond to traffic or job interviews, according to a new United Nations Environment Program report.

The UNEP report states that food crops respond to climate stress by producing chemical compounds to protect themselves from extreme weather. The only problem is the heightened presence of the chemicals could prove toxic to humans and animals.

"We are just beginning to recognize the magnitude of toxin-related issues confronting farmers in developing countries of the tropics and sub-tropics," write the report's authors.

Scientists say that at normal temperatures, under normal growing conditions, plants are able to convert nitrate into amino acids and proteins. Extreme weather events, however, can cause the accumulation of a compound called hydrogen cyanide as well as a type of fungus called mycotoxins.

Accumulations of nitrate, hydrogen cyanide, and mycotoxins can have injurious effects on human health, and have prompted researchers to examine both the origin and possible solutions to the problem.

Studying crops under the stress of extreme weather is a first lesson in understanding the long-ranging and sometimes unexpected effects of climate change, scientists say.

"These kinds of health effects are an important dimension of climate change," Chris Field, the founding director of the Carnegie Institution's Department of Global Ecology, told The Christian Science Monitor by phone. "The things that often get us about climate change are the surprises."

There have been a number of studies on how different plants react to extreme climate events and climate change in terms of their physical growing season, Dr. Field told the Monitor. For instance, recent studies have shown the effect of rising carbon dioxide levels in the atmosphere on corn growth. Yet, Field says, few studies have examined if there are complications associated with eating these plants.

Stress reactions to climate change and extreme weather events found in plants are nothing new, however. In some cultures, farmers have traditional ways of mitigating the effects of the chemical compounds that these plants generate. Modern science, too, can help solve the burgeoning problem.

"Research centers with the Consultative Group on International Agricultural Research are developing seeds that are suitable in various regions that have been hit by climate change," Jacqueline McGlade, chief scientist and director of the Division of Early Warning and Assessment at UNEP, told Reuters.

According to Marilyn Warburton, a scientist with the US Department of Agriculture's Agricultural Research Service, there are several techniques that can be used singly or in concert to combat plant toxicity in warmer climates.

Dr. Warburton tells the Monitor that scientists are currently working on breeding mycotoxin-resistant maize hybrids, with one variety currently being tested in Africa. Scientists also have a way to "vaccinate" plants against one potent mycotoxin producing fungus, Aspergillus flavus, with a nontoxic form of the fungus.

Farmers can also treat corn seeds that carry the toxin with clay compounds or lime, a technique already in use in Mexico that has prevented toxic crops from being more of an issue there.

Scientists say that despite the apparently bleak outlook for global crops, there is a silver lining to this cloud. There is a great overlap between strategies that can protect the world's food supply, they say, and strategies that create a more ethical, more robust global community.

"One of the great opportunity areas offered by this problem is ... [providing] access to the knowledge and technologies that allow people to grow food as efficiently and safely as possible," says Field.

Katharine Mach, a senior research associate at Carnegie Science, told the Monitor that research on protecting crops from climate change is just in its early stages.

Dr. Mach echoed Field's worlds, saying, "Climate change can be the way to build a better world."

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