Nutritional sack of rice

Study claims climate change is having a ‘devastating’ effect on nourishment of rice

Rice – the staple food for billions – will become less nutritious as carbon dioxide (CO2) levels increase, a new study suggests.

Through cultivating the grain in the high CO2 environments projected for the second half of the century, researchers found a drop in essential nutrients such as protein, zinc, iron, and various B vitamins.

A finding that could have “devastating effects” on health, particularly in Southeast Asia where roughly 600 million people rely on rice for at least 50 per cent of their daily calories and protein requirements. “Rice is not just a major source of calories, but also proteins and vitamins for many people in developing countries and for poorer communities within developed countries,” said study co-author Kazuhiko Kobayashi of the University of Tokyo.

Nutritional deficiencies, the researchers note, “can directly (cognitive development, metabolism, and immune system) and indirectly (obesity, type 2 diabetes mellitus) affect human health on a panoptic scale.”

The researchers chose to examine the effect of heightened CO2 levels on rice because more than two billion people depend on it as a primary food, with 90 per cent of the world’s rice eaten in Asia. “Anything that impacts rice in terms of its nutritional quality is going to have an impact,” Lewis H. Ziska, study co-author, told The Guardian.

Researchers used an “open-field method” in paddy fields in China and Japan to analyze the impact of climate change on 18 different varieties of rice. Regardless of rice paddy location, all crops grown in higher CO2 environments were less nutritious: “containing about 10 per cent less protein, 8 per cent less iron and 5 per cent less zinc than rice grown under current levels of carbon dioxide,” The Guardian reports. All varieties also showed a drop in vitamins B1, B2, B5 and B9, and contained more vitamin E than the rice of today. Previous studies have linked soaring levels of CO2 to reduced protein and increased carbohydrates in barley, potatoes, rice and wheat – something “math biologist” Irakli Loladze dubbed the “junk-food effect.”

“We still don’t understand why some plant genotypes show a bigger response to higher levels of carbon dioxide,” Andrew Leakey, crop biologist, told The New York Times. “That’s important if we want to move from understanding the problem to solving it.”