Climate change is creating toxic crops and poisoning some of world’s poorest people, scientists warn

Popular food crops including maize and beans respond to extreme conditions by releasing dangerous chemicals

Josh Gabbatiss
Science Correspondent
Saturday 16 March 2019 15:33
Sir David Attenborough at the United Nations Climate Change Conference in Katowice: Climate change 'our greatest threat'

Climate change threatens to poison the food supply of some of the world’s poorest people as crops respond to rising temperatures by pumping out dangerous chemicals.

Experts are already concerned about the devastating impact extreme weather can inflict on vital crops, but these conditions also pose subtler hazards.

When drought strikes, plants like maize, beans and cassava response by flooding themselves with nitrates and hydrogen cyanide – substances that can be fatal to livestock and humans alike.

Further problems arise from the spread of toxin-producing fungal infections under warmer conditions, which are already responsible for thousands of liver cancer cases in Africa every year.

While these issues are a particular concern in developing nations with hotter climates, if temperatures rise as scientists predict, they will probably begin to take their toll further north as well.

The alarm was raised by Professor Jacqueline McGlade, a former chief scientist at the United Nations Environment Programme, at a Gresham College lecture in London.

Her interest in the problem was first roused when reports emerged from Ethiopia of impoverished farmers and their animals dying in mysterious circumstances.

The country was in the grip of a drought, but this did not explain the neurological problems that were afflicting these people, including blindness, difficult movements and ultimately death.

Researchers working in the area realised the drought had damaged the farmers’ crops, forcing people to consume wild plants they found by the roadside.

Unfortunately, the stress of drought had also triggered a defence mechanism inside these plants, flooding them with hydrogen cyanide.

Professor McGlade collected all the available information on this topic into a report for the UN back in 2016, in which she and a team of scientists attempted to identify emerging environmental problems.

“What I was trying to do was raise issues long before they become embedded as problems – raising the red flag,” she said.

“Fast-forward to today and we are talking about climate change – here is something that is really going to challenge food safety, because the very plants we are relying on are themselves adapting to climate change.

Support free-thinking journalism and attend Independent events

“One of the ways they adapt is dangerous to livestock and humans – clearly we need to pay attention.”

Since her report, the most recent findings from the UN’s Intergovernmental Panel on Climate Change have laid out the impact of global warming on extreme weather and food systems worldwide.

Scientists think these effects are already being felt, with the extreme heatwaves and droughts that struck last year from California to Sweden bringing an associated panic about crops. In the UK, farmers said some vegetable yields had been cut by as much as half.

These problems could be exacerbated as aflatoxin, a substance produced by fungi growing on maize and other crops during drought conditions, spreads beyond its normal range.

The European Food Standards Agency has warned the toxin, which is linked to cancer, immune problems and stunted foetal growth, is likely to become a food safety concern in Europe even if the global temperature rise is limited to 2C.

Though the outcomes look bleak, Professor McGlade said hope for the future could come from locally grown and wild crop species that have higher tolerance for heat and disease.

Dr Carlo Fadda, a researcher at Bioversity International, said he had been working on varieties of barley and durum wheat that has been cultivated in Ethiopia for 4,000 years.

“These varieties are much more tolerant to drought conditions, they maintain relatively good productivity even in bad years and are rarely susceptible to diseases,” he said.

By combining these resilient strains with surveillance systems for drought and disease, Professor McGlade said she hoped the worst impact of these toxic crops could be avoided.

Register for free to continue reading

Registration is a free and easy way to support our truly independent journalism

By registering, you will also enjoy limited access to Premium articles, exclusive newsletters, commenting, and virtual events with our leading journalists

Please enter a valid email
Please enter a valid email
Must be at least 6 characters, include an upper and lower case character and a number
Must be at least 6 characters, include an upper and lower case character and a number
Must be at least 6 characters, include an upper and lower case character and a number
Please enter your first name
Special characters aren’t allowed
Please enter a name between 1 and 40 characters
Please enter your last name
Special characters aren’t allowed
Please enter a name between 1 and 40 characters
You must be over 18 years old to register
You must be over 18 years old to register
You can opt-out at any time by signing in to your account to manage your preferences. Each email has a link to unsubscribe.

Already have an account? sign in

By clicking ‘Register’ you confirm that your data has been entered correctly and you have read and agree to our Terms of use, Cookie policy and Privacy notice.

This site is protected by reCAPTCHA and the Google Privacy policy and Terms of service apply.

Join our new commenting forum

Join thought-provoking conversations, follow other Independent readers and see their replies


Thank you for registering

Please refresh the page or navigate to another page on the site to be automatically logged in