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Increasing CO2 threatens human nutrition (From the Annals of Hype)

Disaster Disaster! Driving a car in 2014 could one day cause 2 billion people to suffer from zinc and iron deficiencies leaving them anaemic and prone to infection, and causing a loss of 63 million life-years annually. This is brought to you from the  Annals of Hyped-Science (formerly known as Nature). A sad day indeed.

It’s true that carbon dioxide is plant fertilizer and increases plant yields, so future crops, grown in a CO2 rich world, may not have exactly the same nutrient profile. Presumably future plants will have slightly more useless starchy carbohydrate. It is a kind of dilution effect at work, where plants keep absorbing the same amount of minerals, but spread them out among more carbohydrate.

Before we hit the panic button, lets look the numbers. The new Myers et al study[1] reports that zinc and iron content of rice may fall by, wait for it, five percent. In wheat the iron content could fall by as much as 10%. But no one who has a choice, eats grains like rice or wheat for their iron and zinc content, since both these are poor sources of both. We’re talking about low grade bulk filler food.

Assuming the reduction in nutrients is real (and it might not be — see Craig Idso’s links below) to overcome this “threat” some people are wondering if we could compensate with mineral fertilizer or genetic engineering. But we don’t need to — we just eat slightly less bulk filler and slightly more food with a higher nutrient profile. In the case of rice and wheat, this means swapping a fraction of these grains for almost any edible plant or animal. Actually, it’s hard to think of ingredients with a lower nutrient profile than rice, except for pure white sugar and beach sand. Indeed, nearly anything will do: go right ahead and swap some rice for bacteria, algae or fungus.

According to the USDA nutrient profiles Gelatinous White Rice, Cooked (doesn’t that sound delicious) has all of 0.14mg of iron per 100 grams and 0.41mg of zinc. Chick peas on the other hand have 2.89mg  of iron per 100g  and 1.53mg  of zinc. So chickpeas have 20 times the iron content, and 3.7 times the zinc content. In other words, to solve a shortage of a 10% reduction in iron and zinc in rice, the average person eating 100g of rice would need to eat an extra 2.6 grams of chickpeas (or is that chickpea, singular?). As a bonus they would be getting five times more iron than what they are missing out on in the rice.

Wheat is richer than rice, and contains significant protein for people without access to meat.  But a mere 5- 10% deficiency is still easily solveable with a shift in dietry composition. Indeed, even if all food types became slightly diluted (like if poorer grain-feed leads to poorer beef steak) the principle still works.

For sure, the poorest of the poor find even small changes difficult — but that’s exactly why we need to help them develop and raise their standards of living. Making energy expensive will kill far more people in the third world. For those who face famine and starvation, the increased crop yields of extra CO2 surely are a net benefit.  Being low in iron is bad, but being dead is worse, right?

For the 2 billion people who allegedly depend on rice for their daily iron and zinc the real problem is that they need better quality food in 2014, not a panic attack over a hypothetical 5% nutrient reduction by 2050.

How about we stop funding scaremonger-science and start something productive instead, say, with something as simple as applications of the right Mycorrhiza — which symbiotically help plant roots extract minerals, as well as improving yields and shortening time to fruit by as much as 40%.

Craig Idso has already assembled many studies on plant yield and nutrition — with mixed results, and some which showed increases in nutrients when CO2 was enriched.

This is such a blatant scare story.

Background information on Peak Food Production

Another article related to peak grain production is  “Plants suck half the CO2 out of the air around them before lunchtime each day”.

[Science Daily]


[1^] Samuel S. Myers, Antonella Zanobetti, Itai Kloog, Peter Huybers, Andrew D. B. Leakey, Arnold J. Bloom, Eli Carlisle, Lee H. Dietterich, Glenn Fitzgerald, Toshihiro Hasegawa, N. Michele Holbrook, Randall L. Nelson, Michael J. Ottman, Victor Raboy, Hidemitsu Sakai, Karla A. Sartor, Joel Schwartz, Saman Seneweera, Michael Tausz, Yasuhiro Usui. Increasing CO2 threatens human nutrition. Nature, 2014; DOI: 10.1038/nature13179

see also

Loladze, I. 2002. Rising atmospheric CO2 and human nutrition: toward globally imbalanced plant stoichiometry? Trends in Ecology and Evolution 17: 457-461.

Duval, B.D., Blankinship, J.C., Dijkstra, P. and Hungate, B.A. 2012. CO2 effects on plant nutrient concentration depend on plant functional group and available nitrogen: a meta-analysis. Plant Ecology 213: 505-521.

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