Vegetables could be in short supply by the middle of the century as a result of climate change, water shortage and loss of biodiversity, a study suggests.
Global average yields of vegetables and legumes such as soy beans and lentils are predicted to be reduced by 35% and 9% respectively.
There could be a knock-on effect on public health as key ingredients of a healthy diet become more scarce, scientists warn.
Previous research has indicated that raised levels of carbon dioxide greenhouse gas in the atmosphere might increase crop yields.
But the new study, based on a systematic review of evidence dating back to 1975, shows this benefit is likely to be cancelled out by other environmental effects.
Lead scientist Dr Pauline Scheelbeek, from the London School of Hygiene and Tropical Medicine, said: “Our study shows that environmental changes such as increased temperature and water scarcity may pose a real threat to global agricultural production, with likely further impacts on food security and population health.
“Vegetables and legumes are vital components of a healthy, balanced and sustainable diet and nutritional guidelines consistently advise people to incorporate more vegetables and legumes into their diet.
“Our new analysis suggests, however, that this advice conflicts with the potential impacts of environmental changes that will decrease the availability of these important crops unless action is taken.”
The researchers reviewed experimental work in 40 countries looking at the effects of altered environmental conditions on the yield and quality of vegetables.
They then estimated the future impact of key factors influencing crop production, including increased levels of greenhouse gases, reduced availability of water for irrigation, and rising temperatures.
New crop varieties and improvements in agriculture and mechanisation are urgently needed to protect vegetable supplies, said the team writing in the journal Proceedings of the National Academy of Sciences.
Co-author Professor Alan Dangour, also from LSHTM, said: “We have brought together all the available evidence on the impact of environmental change on yields and quality of vegetables and legumes for the first time.
“Our analysis suggests that if we take a ‘business as usual’ approach, environmental changes will substantially reduce the global availability of these important foods. Urgent action needs to be taken, including working to support the agriculture sector to increase its resilience to environmental changes and this must be a priority for governments across the world.”
The study was funded by the Wellcome Trust as part of its Our Planet, Our Health programme.
Dr Howie Frumkin, head of Our Planet, Our Health, said: “This research is a wake-up call, underlining the urgency of tackling climate change and of improving agricultural practices.”
