Food’s Defense on a Warming Planet

Just like people, plants react when they’re stressed. And according to a new report from the United Nations Environment Programme (UNEP), they’re doing just that.

plants in baked soilEveryday edible crops such as wheat and maize are stepping up the amount of toxins they generate to protect themselves from extreme weather patterns linked to climate change. Eaten over a period of time, those chemical compounds pose a distinct health risk to us.

Toxins? They’re heeeeeeere!

In a healthy growth cycle, plants absorb nitrates and turn them into nutrients, such as proteins and amino acids. In times of drought, which we in California are all too familiar with, the plant struggles to complete, or fails at, this transition. When this happens, an acute nitrate level can be stored in the plant and stay there, unconverted.

Those unconverted hamper red blood cells in their effort to oxygenate the body. This is the body’s reaction to the stress of these toxic crops, and it can contribute to a wide variety of health problems, including cancer and neurological diseases.

According to the UNEP report, crops most likely to be affected include

  • Wheat.
  • Maize.
  • Soybeans.
  • Barley.
  • Millet.
  • Sorghum.

But it’s not just drought that creates problems. Heavy rain can stress plants too. Compounding the problem, in many climates, rain and drought live in a symbiotic cycle with each other.

When crops are exposed to a large amount of rain suddenly, especially after a drought, they tend to grow rapidly. Sudden growth may trigger an accumulation of hydrogen cyanide or prussic acid. These compounds also hamper the body’s ability to oxygenate.

According to UNEP’s chief scientist and director of the Division of Early Warning and Assessment Jacqueline McGlade, even short-term exposure can be debilitating. Crops most likely harbor prussic acid include

  • Cassava – a/k/a tapioca, which Time named one of the 10 most dangerous foods. In root form, it contains traces of cyanide that must be carefully removed and may trigger a reaction for those with latex allergies.
  • Maize.
  • Flax.
  • Sorghum.

The report indicates that aflatoxins – a type of mycotoxin produced by certain strains of fungi – are also on the rise. Think black mold, and you’ll be close. Aflatoxins raise the risk of cancer, blindness, and liver damage and can stunt the growth of fetuses and infants.

How concerned should we be about all this? Well, let’s just put it this way: plenty.

Back in 2005, the impact of regional climate change on humans was said to claim 150,000 lives annually. There’s a growing body of evidence that suggests that number will only continue to increase.

Potentially vulnerable regions include the temperate latitudes, which are projected to warm disproportionately, the regions around the Pacific and Indian oceans that are currently subjected to large rainfall variability due to the El Niño/Southern Oscillation sub-Saharan Africa and sprawling cities where the urban heat island effect could intensify extreme climatic events.

Today, climate scientists believe that, globally, we’re likely to see an increase of more than 3 degrees Celsius. According to the UNEP report, if global temperature increases by just 2 degrees, Europe will be at risk of aflatoxins in local crops.

According to UNEP’s McGlade,

about 4.5 billion people in developing countries are exposed to aflatoxins each year, though the amounts are largely unmonitored, and the numbers are rising.

“We are just beginning to recognize the magnitude of toxin- related issues confronting farmers in developing countries of the tropics and sub-tropics,” the report noted.

“As warmer climate zones expand towards the poles, countries in more temperate regions are facing new threats,” it added.

Attempting to mitigate risk, the report also suggests solutions to these and related problems. Should we experience the full impact of climate change and its related increase in food crop toxins, it will further stress a global health system already struggling with food insecurity.

For more on the issue, check out this excellent podcast from DW. It’s take-home message? 70% of global agriculture will be affected by too much or too little rain. So much of what is forecasted is just a matter of temperature. And time.

Image by CAFNR