Photograph by David Evans, Nat Geo Image Collection
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Vendors like these at an indoor market in Sao Paolo, Brazil, may have fewer fruits and vegetables to sell.
Photograph by David Evans, Nat Geo Image Collection

In a Warmer World, There May Be Fewer Fruits and Vegetables

Concerns about climate change have caused researchers to warn that rising global temperatures will reduce crop yields and create food insecurity, the inability to get enough calories to survive. Now, scholars from the United Kingdom and the United States have revealed another possible result: an increase in deaths not just from hunger, but from chronic diseases that would be made worse as diets change.

Writing in the medical journal The Lancetthe medical journal The Lancet, the researchers from Oxford University and the International Food Policy Research Institute in Washington, D.C. predict that by 2050, more than a half-million people will die not just because not enough food will be available, but because the composition of their diets will change, losing nutrient-dense foods such as fruits and vegetables, and meats. But taking international action to reduce climate change, they say, could eliminate up to three-fourths of those deaths.

“The traditional interest in the interaction between climate change and agriculture has really been on calorie availability,” explains Marco Springmann, PhD, the paper’s first author, who is a research fellow at the Oxford Martin Programme on the Future of Food. “That is what most people understand when you say food security. But if you look at the health inpacts of food consumption, then you see that it is the composition of diets that leads to the most health impacts. Most deaths and also most disability-adjusted life years are already attributed to imbalanced diets; that is what kills people in most areas of the world. We wanted to shine a light on those implications.” (For more, see Why Micronutrient Deficiency Is a Macro-Problem.)

The researchers used a long-standing computer model of agricultural productivity, the International Model for Policy Analysis of Agricultural Commodities and Trade, along with other models that predict changes in temperature and precipitation for different climate-change scenarios, to estimate possible effects on the crops and foods that end up on our plates.

Without climate change, they say, existing trends would improve global food access and level out inequality: By 2050, people would have access to an average 289 more calories per day, and to an average 36 grams of fruits and vegetables and four grams more meat daily. But climate change would reverse that trend, taking away available food and especially nutritious food.

It’s possible, the authors acknowledge, that having less meat available might be a net positive, because meat-eating is associated with saturated fat consumption and with heart disease and cancers. But, globally, any lives saved in that scenario would be outweighed by lives lost because of fewer nutrients from vegetables and fruits, which improve health and reduce chronic disease. And in areas where food was already scarce, lives would be lost to insufficient food, as they are today, but in greater numbers.

Paul West, lead scientist of the Global Landscapes Initiative at the University of Minnesota’s Institute on the Environment, said the study highlights an issue that has been under-investigated because data is hard to obtain. “Most of the work done so far has focused on how the yields of staple grains will change in response to a change in climate,” he tells me. “A lot less is known about how a change in climate will affect our abilities to grow apples and oranges and peppers and lettuce. Those are a source of micronutrients, and  also, some research has shown that warming temperatures might change the nutrient makeup of crops as well.”

Much of the impact the U.S. and UK researchers identified is regional; the burden would fall hardest on the poorest societies, in Africa, Southeast Asia, and the western Pacific. In anticipation of such imbalances, West says it’s important for global authorities to think not just about improving how crops can withstand changes in rain and temperature as they grow, but also about moving them around once they are harvested. “Currently a third of all calories produced on crop lands are traded around the world,” he says. “So there is a system in place to meet countries’ needs for consumption. We could look at how to make the trade system more efficient, to use imports to offset crop losses around the globe.”