By now, it’s fairly well-established that climate change is going to be a major challenge for food production.
Rising temperatures are set to severely damage crop yields, lessen the nutritional value of important crops, and make large portions of the planet inhospitable to crop production. And some studies argue that it won’t be easy to innovate our way out of these problems, with data suggesting that developed countries have a more difficult time maintaining yields during droughts and heat waves — two things set to increase with climate change — than developing countries.
Now, we can add one more terrible thing to that growing list: climate change could actually make important crops toxic to animals and humans.
That’s the conclusion of a new report released this week by the United Nations Environmental Program (UNEP), which warns that warming temperatures could cause crops to accumulate mycotoxins — poisons produced by fungi that can lead to cancer and death — at higher rates.
Mycotoxins are already found in crops like wheat, maize, and barley — a 1998 estimate suggested that mycotoxins exist in at least 25 percent of cereal grains worldwide. They’re the toxins that come from mold, and a big reason why we avoid food that’s gone bad. Mycotoxins mainly occur in tropical areas, where warm temperatures encourage fungal growth. According to the UNEP, however, rising temperatures coupled with unpredictable precipitation — downpours and droughts — could help mycotoxins thrive in more temperate areas, like Europe.
One particularly dangerous mycotoxin is aflatoxin, which is produced by a species of Aspergillus fungi; long periods of exposure can lead to cancer, while acute exposure can cause death. If aflatoxin-contaminated crops are fed to livestock, it can severely hinder their productivity, and the toxin can persist in livestock-sourced products, like dairy. According to a study of Serbian maize, particularly warm weather and a prolonged drought in 2012 led to a greater occurrence of aflatoxin in the maize crop, even though Serbia’s climate typically does not encourage the growth of aflatoxins. If the climate warms by 2 degrees Celsius, the UNEP warns that aflatoxins could become a major food safety issue for Europe.
But it’s not just the fungi-based mycotoxins that could threaten public health — common chemicals like nitrate could also become toxic in crops thanks to climate change. The report warns that prolonged drought conditions can slow or prevent crops from converting nitrates into amino acids and proteins. In those cases, crops accumulate nitrate at high levels, which, when eaten by humans or animals, can lead to serious health issues. For humans, nitrate poisoning can cause miscarriage, respiratory problems, and death. For livestock, nitrate poisoning can also cause death, which could threaten livestock farmers that depend on their herds for subsistence.
And if a crop is faced with too much rain, after a prolonged drought, that could also be bad news. Studies suggest that when water-stressed plants experience a sudden precipitation event, they could take up too much of a toxic compound known as hydrogen cyanide.
To combat these issues in the meantime, the report suggests that breeding programs need to focus on creating drought-tolerant or disease-resistant crops that could fight off mycotoxins and other toxic chemicals. In areas where mycotoxins are already a public health issue, the report notes that a robust set of crop monitoring programs could help identify contaminated crops before they are consumed by animals and humans.