More Carbon Dioxide, Fewer Crop Nutrients

Plants grown in higher concentrations of CO2 have greater yields, but lower amounts of essential nutrients.

By | May 8, 2014

WIKIMEDIA, DAVID MANNIAUXField tests of crops grown in different carbon dioxide conditions reveal new untoward consequences of global warming. Elevated levels of carbon dioxide (CO2) produced crops with greater yields, but fewer essential nutrients, including zinc, iron, and in some cases, protein, according to a study published this week (May 7) in Nature.

Lead author, Samuel Myers, a researcher in Harvard University’s department of environmental health, told Voice of America: “What our study is showing is that, unequivocally, as CO2 concentrations rise up to levels that we expect to see in the next 40 years, there are very significant reductions in nutrients that are really important for public health.”

Myers and his team grew soybeans, maize, wheat, and rice in both current CO2 conditions of close to 400 parts per million (ppm) and at levels predicted for 2050—around 550 ppm. The sites were in Japan, Australia, and the U.S. “It does depend on environment, rainfall, temperature, et cetera, but here at Horsham, [Victoria, Australia], we’re seeing, on average, an increase of about 20 [percent] to 25 percent increase in yield, but you also get then this 5 [percent] to 10 percent decrease in protein and zinc and iron concentrations,” coauthor Glenn Fitzgerald of the State of Victoria Department of Environment and Primary Industries told the ABC in Australia.

The big concern is that reductions in zinc, iron, or protein in crops could exacerbate global malnourishment. Hannah Stoddart, Oxfam’s head of policy for food and climate, told The Guardian that “with 25 million more children under five at risk of malnutrition by 2050 because of climate change, action to cut emissions and support communities to adapt is crucial.”

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Avatar of: T S Raman

T S Raman

Posts: 51

May 8, 2014

Maize, rice and wheat are cereal crops that form the staple food for most of the world's population. The only factor that matters in their cultivation is YIELD; even protein content is not of primary concern — particularly because there are other available dietary sources of protein including the legumes. The protein content of soybean and the nutritive quality of the protein are high enough for us to ignore small putative decreases in quantity. It is to be noted also that soybean is not consumed as such, but, unlike most cereal grains, it requires extensive processing before it becomes fit for consumption because of the anti-nutritive factors present in it.

Avatar of: Paul Stein

Paul Stein

Posts: 237

May 9, 2014

While the recent experiments with 550 ppm are predictive, I'm just wondering if the diminution in the observed content of protein in corn over the decades has been due to the prior rise in carbon dioxide.

Avatar of: arbor123


Posts: 1

May 9, 2014

Can someone explain why the 1970s prediction that due to the increase in atmospheric carbon dioxide  there will be such a dramatic rise in the oceans by the turn of the century that many coastal cities will be under water did not occur. At this time we have difficulty acurately predicting the weather a week in advance yet we again can acurately predict the atmospheric carbon dioxide concentration fifty years from now.

Avatar of: Chrisgan


Posts: 1

May 9, 2014

As usual when it comes to climate change, the wrong questions are asked and  good news is presented in such a way as to appear as bad news.


The true finding of the report is that not only yield has increased but so has total nutrition. If yield is up 25% and concentration is only down 5% then when we actually have an increase in total food and nutrition.


Secondly the wrong question was asked. What is important to know is not the yield of current variants under conditions of higher CO2, but what yields and what concentration of nutrients are possible with variants bred to take advantage of higher concentration of CO2. It seems more than plausible that very significant gains are possible.

Avatar of: fromSam


Posts: 1

May 9, 2014

Its really an important contribution in the field of photosynthesis, could be prospective, although nature is very complex, understanding itself is very big challenging, as i feel ecolological balance for fovourable situation matters for healthy growth, but in adverse situations, due to lack of favourable factors, adaptation occor towards near to or complete to healthy growth, it may further cause memory most of organisms for both plants & animals.

Avatar of: Maya An

Maya An

Posts: 1

May 10, 2014

Harvard arrogance. They just confirmed the 2002 study:

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