Guest essay by Eric Worrall
Guardian author Nicola Davis is alarmed that adding CO2 to rice reduces the vitamins, minerals and protein – in some varieties of rice.
Climate change ‘will make rice less nutritious’
Thu 24 May 2018 04.00 AEST
When scientists exposed the crop to higher levels of carbon dioxide vitamin levels fell significantly
Rice will become less nutritious as carbon dioxide levels in the atmosphere rise, potentially jeopardising the health of the billions of people who rely on the crop as their main source of food, new research suggests.
Scientists have found that exposing rice to the levels of carbon dioxide that are expected in the atmosphere before the end of the century results in the grain containing lower levels of protein, iron and zinc, as well as reduced levels of a number of B vitamins.
“About two billion people rely on rice as a primary food source and among those that are the poorest, often the consumption of rice in terms of their daily calories is over 50%,” said Dr Lewis Ziska, a co-author of the research from the United States department of agriculture. “Anything that impacts rice in terms of its nutritional quality is going to have an impact.”
But with some of the varieties of rice apparently showing little change in levels of certain nutrients, the researchers say it might be possible to find or develop types of rice that will remain nutritious as the climate changes.
A drop in the nutritiousness of rice as a result of climate change could have profound health effects, particularly for those who rely most heavily on the crop, with the authors warning that it could affect early childhood development and worsen the impact of diseases including malaria.
The abstract of the study;
Carbon dioxide (CO2) levels this century will alter the protein, micronutrients, and vitamin content of rice grains with potential health consequences for the poorest rice-dependent countries
Chunwu Zhu, Kazuhiko Kobayashi, Irakli Loladze, Jianguo Zhu, Qian Jiang, Xi Xu, Gang Liu, Saman Seneweera, Kristie L. Ebi, Adam Drewnowski, Naomi K. Fukagawa and Lewis H. Ziska
Declines of protein and minerals essential for humans, including iron and zinc, have been reported for crops in response to rising atmospheric carbon dioxide concentration, [CO2]. For the current century, estimates of the potential human health impact of these declines range from 138 million to 1.4 billion, depending on the nutrient. However, changes in plant-based vitamin content in response to [CO2] have not been elucidated. Inclusion of vitamin information would substantially improve estimates of health risks. Among crop species, rice is the primary food source for more than 2 billion people. We used multiyear, multilocation in situ FACE (free-air CO2 enrichment) experiments for 18 genetically diverse rice lines, including Japonica, Indica, and hybrids currently grown throughout Asia. We report for the first time the integrated nutritional impact of those changes (protein, micronutrients, and vitamins) for the 10 countries that consume the most rice as part of their daily caloric supply. Whereas our results confirm the declines in protein, iron, and zinc, we also find consistent declines in vitamins B1, B2, B5, and B9 and, conversely, an increase in vitamin E. A strong correlation between the impacts of elevated [CO2] on vitamin content based on the molecular fraction of nitrogen within the vitamin was observed. Finally, potential health risks associated with anticipated CO2-induced deficits of protein, minerals, and vitamins in rice were correlated to the lowest overall gross domestic product per capita for the highest rice-consuming countries, suggesting potential consequences for a global population of approximately 600 million.
The “CO2 makes food less nutritious” narrative is my favourite climate absurdity.
To be fair to the researchers they appear to have conducted their research outdoors, keeping other factors as natural as possible.
But the fact some rice varieties don’t experience significantly reduced nutrient levels, even without selective breeding or genetic manipulation, completely undermines assertions that this issue presents any risk to human health. Delving into the research paper, some varieties even exhibited increased levels of key nutrients.
As the GM golden rice effort demonstrates, rice can and has been manipulated to enhance nutrient levels – in the case of golden rice, the rice was genetically modified to enhance vitamin beta-carotene / vitamin A levels. Shortage of vitamin A is a major cause of blindness in poor countries.
We have an entire century of genetic superscience to solve any issues with nutrient content. The creation of Golden Rice demonstrates we already have the technology to enhance individual nutrients. In 100 years we’ll probably have the technology to produce varieties of rice which sing sweet lullabies in the evening. Even if this slight reduction in nutrient content is an issue, it is an issue which will be well and truly solved long before it has any opportunity to cause harm to human health.