Climate change linked to food safety, cost

plants more susceptible to disease; floods and heavy rains favor the growth of fungal pathogens on leaves, and many disease-causing organisms can spread in changing wind currents.

“Greenhouse gasses and atmospheric pollutants change plant structure and the ability of the plant to defend itself against pathogens,” he said.

Most scientists believe climate change is producing more severe storms and these apparently help spread diseases.

One classic example is Asian soybean rust, spores that cause gold speckles on the light green leaves and eventually kill the plant. The spores spread from Asia to Africa then to South American and finally the United States. The spread in the United States was unusually fast and wide. It turns out the spores were riding on the winds of hurricanes from the Gulf of Mexico, Knighton said.

That has huge implications for how food-borne diseases are monitored and the need for a sensitive network for tracking pathogens, he said.

Vibriosis, which comes from seafood, is known to increase with rises in the temperature and salinity of the oceans, said Hoffman. It peaks in the heat of summer. One species of the vibrio bacteria causes cholera. As temperatures rise, the implication is that the spread of vibriosis also will rise.

Increased water temperatures also can lead to increased mercury contamination of fish by 30-50 percent for every increase in degree Celsius, said Cristina Tirado of the University of California at Los Angeles. Desertification, another probable result of climate change, increases pesticide concentration in plants, she said. Flooding leads to soil contamination, and even biofuel production could be affected.

The danger of food poisoning could mean people change what they eat, Tirado added, avoiding foods grown where climate change has altered the path of germs and potentially increasing the price of food. One and a half billion people already pay 80 percent of their income for food and an increase in food prices would mean “more hunger and less money for health care and education.”

The scientists admitted a contradictory effect of climate change: the possibility that some areas, particularly in the north, not now able to grow extensive crops, will warm up and begin to grow more food. Additionally, the cause and effect between climate change and food security is not well-defined.

Part of the problem, Hoffman said, is that data on the incidence of food-borne disease is imprecise and hard to come by.

“There is significant uncertainty about all of this,” Hoffman admitted. “We don’t know what direction those cumulative effects will be.” That uncertainty, she said, will make difficult to design an effective adaptation policy.