Global warming may have 'devastating' effects on rice, study says

Friday, 25 May, 2018

Rise in Carbon dioxide level declines quality of important food crop, according to the new findings.

Rice is one of the world's most important cereal crops and the primary food source for more than two billion people worldwide.

As carbon dioxide rises due to the burning of fossil fuels, rice will lose some of its protein and vitamin content, putting millions of people at risk of malnutrition, scientists warned on Wednesday.

Rep. Lamar Smith, a Texas Republican who leads the House Science, Space and Technology Committee, argued that more carbon dioxide will tends to increased plant growth, spurring "a greater volume of food production and better quality food". However the new research discredits those claims. "But how plants respond to that sudden increase in food will impact human health as well, from nutritional deficits, to ethno-pharmacology, to seasonal pollen allergies-in ways that we don't yet understand", said study co-author Lewis Ziska, research plant physiologist for the Adaptive Cropping Systems Lab of the United States Department of Agriculture's Agricultural Research Service. "On the other side of that coin is the quality of that seed also being diminished in response to CO2".

Because of this, Ebi and Ziska said, rice could in fact already be losing some of its nutritional content under current atmospheric carbon dioxide concentrations - but the research has not been done at this point to confirm that. The research also confirmed previously discovered declines in protein, iron and zinc.

Average Vitamin B1 levels decreased by 17.1 percent; average Vitamin B2 by 16.6 percent; average Vitamin B5 by 12.7 percent; and average Vitamin B9 by 30.3 percent, according to the study. All of the rice varieties saw dramatic declines in vitamins B1, B2, B5 and B9, though they contained higher levels of vitamin E.

The reasons for the changes have to do with how higher Carbon dioxide affects the plant's structure and growth, increasing carbohydrate content and reducing protein and minerals, said the study. The concentration of carbon dioxide the plants were exposed to was monitored at the centre of each ring, and the rice produced by each crop was collected and analysed. Currently, atmospheric carbon dioxide concentrations hover around 410 ppm-but at the rate they're currently rising, they could reach the high levels used in the study by the end of the century, if action isn't taken to curb them. The scientists have found that human-caused greenhouse gas emissions in the atmosphere will make rice less nutritious.

Some varieties of rice may not experience as severe of a nutrient loss as carbon dioxide levels go up. However, it turns out too much of it can really be damaging.

In previous studies, Myers and his colleagues have used models to simulate the diets of people around the world, the nutrients they receive from those foods and the declines in nutritiousness if Carbon dioxide levels rise.

Among the countries expected to be worst hit by a lower nutritional content of rice would be Bangladesh and Madagascar.

Still, "what the nature of that impact is in terms of nutritional effects and health effects" remains to be seen, Ziska noted.

Nine of the world's ten most rice-subordinate nations are in Asia.

"Trying to understand those complexities and trying to understand those interactions is one of the things we think is very important", he said.

Reprinted from Climatewire with permission from E&E News.