Higher CO2 levels may lead to decreased nutrients in rice

  • Higher CO2 levels may lead to decreased nutrients in rice

Higher CO2 levels may lead to decreased nutrients in rice

An worldwide research team led by the University of Tokyo has found that rising levels of carbon dioxide (CO2) will lower the nutritional value of rice. Its stores of protein, iron, zinc and some important B vitamins all decline.

The findings suggested that such a nutritional loss would have serious consequences on the poorest citizens of some of the least-developed countries, who heavily depend on rice as a staple in their diets.

We fill our planet's atmosphere with carbon dioxide, impacting the whole globe.

The findings challenge a common argument floated among doubters of accepted climate science-that rising Carbon dioxide concentrations are a net positive for global vegetation, including crops.

Rep. Lamar Smith, a Texas Republican who leads the House Science, Space and Technology Committee, is one outspoken proponent of the idea. However the new research discredits those claims. "On the other side of that coin is the quality of that seed also being diminished in response to CO2". It reinforces the inference of the earlier studies that the expected rise in the carbon dioxide level by 2100 has shown a considerable decrease in the amount of zinc, protein and the iron contents of the rice grains.

The findings were based on field studies in Japan and China, simulating the amount of Carbon dioxide expected in the atmosphere by the second half of this century - 568 to 590 parts per million. Currently, levels of Carbon dioxide in the atmosphere average about 410 parts per million, up from 350 parts per million in the 1980s, largely from the burning of fossil fuels.

In addition to changes in vitamins, they reported an average 10.3 percent reduction in protein, 8 percent reduction in iron and 5.1 percent reduction in zinc, when compared with rice grown under current Carbon dioxide concentrations, researchers say. Both proteins and iron decreased by 10 percent, while zinc levels decreased by 5 percent.

Higher CO2 means less exposure to nitrogen, which also may affect vitamin content, researchers said.

People in countries with the highest rice consumption and the lowest gross domestic product could face increasing rates of malnutrition as the nutritional value of rice and other low-cost foods decline.

The research "corroborates previous work that we've done, showing that elevated Carbon dioxide alters the protein, iron and zinc content of rice-and, in the case of our work, in other staple food crops, as well", said Samuel Myers, a Harvard University expert on climate change and human health. The study infers that the higher carbon dioxide level reduced the amount of the vitamins such as the B1, B2, B5, and B9. "So the experiment sees what happens to the same rice under different carbon dioxide concentrations". Bigger crops aren't necessarily useful to human societies if they're less nutritious.

In plants like rice and wheat that undergo what is known as C3 photosynthesis, higher levels of carbon dioxide may spur plants to produce more carbohydrates, which dilute some of the more nutritious components. Experts interested in the effects of human-caused changes on agriculture crops like rice have typically focused their studies on effects on agricultural production. Scientists are still evaluating exactly how much of a problem these nutrient declines might turn out to be.

Researchers are warning the nutritional changes could have significant health implications - especially in poorer countries. Some populations could experience nutrient deficiencies in the future, some studies found.

Hence, an additional 150 million people globally may be at risk of protein deficiency by 2050.