How Global Warming Leaches Nutrients Out of Food

One of the few supposedly silver linings to be found in the dark cloud of global warming is its effect on agriculture (at least in some regions). As optimists and the who-cares crowd like to note, in the hotter world we're making, some areas might actually increase their production of food crops. According to a raft of recent studies, though, even that pale ray of hope is false light. They've found that increased levels of atmospheric carbon dioxide (the main greenhouse gas) have an unfortunate effect on the nutritional value of plants. There's not going to any reason to celebrate greater quantities of food crops when the quality of food is declining.

In a paper out this week in the journal eLife, the mathematical biologist Irakli Loladze has analyzed data from thousands of experiments on 130 species of food plants performed in "free-air CO2 enrichment experiments," looking for effects on quantities of 27 chemical elements. (He used elements because plant metabolism is so complex that looking for the effects of carbon dioxide on complex molecules has produced only conflicting results.) People don't need large quantities manganese or potassium they get from plants, but they do need some. And for billions of people, plants are their only source.  Loladze's analysis found that increased carbon dioxide reduces mineral content.

Moreover, the CO2 also spurs increases in starches and sugars in the same plants. In other words, with increases in atmospheric carbon dioxide, the valuable nutrients in these food crops are scarcer, and carbohydrates are more abundant—in effect, the nutrients are "diluted." With higher CO2 levels, plant's store of digestible sugars and starches rises between 10 and 45 percent, Loladze notes, quoting previous studies. Loladze believes it reasonable that there is an inverse relationship between the amount of carbohydrates in a food plant and the amount of proteins it offers. As the latter increase in familiar foods, the former decrease.

It's important to note that Loladze found the effect only for plants that use the less complex and effective c3 process of taking up carbon from the atmosphere. Some important food crops, like maize (what we Americans call corn), get their carbon by a different metabolic process (c4), and for those crops (which generally evolved to thrive in tougher conditions than their c3 counterparts), Loladze found no nutritional effect. Which sounds kind of like good news. Except that he thinks one reason for the difference is simply lack of data on the c4 plants. Also to be filed under "not so good": the c3 group includes crops that sustain many millions of people, including rice, wheat and potatoes. (Also quinoa, if you're following that trend.)

Now, a number of people have proposed a link between global heating and the global spread of obesity, through the effects of climate change on people's psychology. (Here, for example, Tom Laskawy explains how climate-induced food insecurity could lead people to eat more obesity-promoting foods.) But Loladze suggests there may be a direct physiological connection between the two crises: By raising the atmosphere's level of carbon dioxide, we may be ensuring that our staple foods become more "obesogenic." "What are health consequences," he writes, "of diluting every 100g […] of raw plant products with a spoonful of starch-and-sugar mixture? What are the consequences if the dilution is not sporadic but lifelong for every plant eater?"

There are competing theories about why carbon affects the nutrient value in plants. In this paper, published last month in Nature Climate Change, Arnold J. Bloom and his colleagues say they have found evidence for one: Carbon interferes with plants' conversion of soil nitrogen into the molecules that we eat food to obtain. The proof, they write, is in data from wheat plants grown in the 1990s in air with different concentrations of carbon dioxide. The higher levels of CO2 correlated with lower levels of nitrogen uptake.

As reported here, Bloom believes the overall amount of protein people get from their food plants will drop some 3 percent if climate change proceeds on its current track. That won't be because crops dramatically fail (that's a separate threat). It will be a more insidious change in the foods we trust.

An easy no-rocking-the-boat way to compensate for such a decline would be to simply dump more nitrogen on the plants in the form of fertilizer. Unfortunately, our fertilizing methods are so inefficient that today worldwide out of 200 million metric tons of fertilizer used in agriculture, only 60 million stays put and fertilizes crops. The rest is carried off in rain, streams and rivers, where some contaminates ground water, and the rest flows into the sea. There, all the excess nitrogen feeds colossal population booms of algae. Such a boom scarfs up all the available oxygen around it, driving away fish and other life. Result: Vast dead zones along coasts where people once fished. So that food solution would worsen another food problem. Climate change really has no silver linings.

UPDATE 5/8/14: Since I wrote this post, the journal Nature's latest issue came out with another report of nutrient loss in food due to global warming. Samuel S. Myers and his co-authors report that c3 grains and legumes, when grown with the concentrations of CO2 expected for 2050, have lower amounts of zinc and iron. Those are both essential nutrients, which 2 billion people already fail to get enough of in 2014. Moreover, Myers et al. found that c3 grains also had lower concentrations of protein when they grew with more carbon dioxide in the air. They recommend that plant breeders start developing strains of crops that resist this carbon effect.

Myers, S., Zanobetti, A., Kloog, I., Huybers, P., Leakey, A., Bloom, A., Carlisle, E., Dietterich, L., Fitzgerald, G., Hasegawa, T., Holbrook, N., Nelson, R., Ottman, M., Raboy, V., Sakai, H., Sartor, K., Schwartz, J., Seneweera, S., Tausz, M., & Usui, Y. (2014). Increasing CO2 threatens human nutrition Nature DOI: 10.1038/nature13179

J. Bloom, A., Burger, M., A. Kimball, B., & J. Pinter, Jr, P. (2014). Nitrate assimilation is inhibited by elevated CO2 in field-grown wheat Nature Climate Change DOI: 10.1038/nclimate2183

Follow me on Twitter: @davidberreby


America’s education system is centuries old. Can we build something better?

The Lumina Foundation lays out steps for increasing access to quality post-secondary education credentials.

Sponsored by Lumina Foundation
  • America's post-high school education landscape was not created with the modern student in mind. Today, clear and flexible pathways are necessary to help individuals access education that can help them lead a better life.
  • Elizabeth Garlow explains the Lumina Foundation's strategy to create a post-secondary education system that works for all students. This includes credential recognition, affordability, a more competency-based system, and quality assurance.
  • Systemic historic factors have contributed to inequality in the education system. Lumina aims to close those gaps in educational attainment.
  • In 2019, Lumina Foundation and Big Think teamed up to create the Lumina Prize, a search to find the most innovative and scalable ideas in post-secondary education. You can see the winners of the Lumina Prize here – congratulations to PeerForward and Greater Commons!

First solar roadway in France turned out to be a 'total disaster'

French newspapers report that the trial hasn't lived up to expectations.

Image source: Charly Triballeau / AFP / Getty Images
Technology & Innovation
  • The French government initially invested in a rural solar roadway in 2016.
  • French newspapers report that the trial hasn't lived up to expectations.
  • Solar panel "paved" roadways are proving to be inefficient and too expensive.
Keep reading Show less

What was it like to live in a Japanese concentration camp?

During World War II, the U.S. incarcerated over 100,000 Japanese Americans in concentration camps throughout the West.

Universal History Archive/Universal Images Group via Getty Images
Politics & Current Affairs
  • Now that the issue of concentration camps in the U.S. has once again reared its head, it can be beneficial to recall the last time such camps were employed in the U.S.
  • After Pearl Harbor, the U.S. incarcerated over 100,000 Japanese Americans in camps, ostensibly for national security purposes.
  • In truth, the incarceration was primarily motivated by racism. What was life like in the U.S.'s concentration camps?

On February 19, 1942, President Roosevelt issued Executive Order 9066, which authorized and directed military commanders "to prescribe military areas … from which any or all persons may be excluded, and with respect to which, the right of any person to enter, remain in, or leave shall be subject to whatever restrictions the Secretary of War or the appropriate Military Commander may impose in his discretion." Under the authority of this executive order, roughly 112,000 men, women, and children of Japanese descent — nearly two-thirds of which were American citizens — were detained in concentration camps.

How did the camps get their start?

With the benefit of a nearly 80-year perspective, it's clear that the internment of Japanese Americans was racially motivated. In response to Japan's growing military power in the buildup to World War II, President Roosevelt commissioned two reports to determine whether it would be necessary to intern Japanese Americans should conflict break out between Japan and the U.S. Neither's conclusions supported the plan, with one even going so far as to "certify a remarkable, even extraordinary degree of loyalty among this generally suspect ethnic group." But of course, the Pearl Harbor attacks proved to be far more persuasive than these reports.

Pearl Harbor turned simmering resentment against the Japanese to a full boil, putting pressure on the Roosevelt administration to intern Japanese Americans. Lieutenant General John DeWitt, who would become the administrator of the internment program, testified to Congress

"I don't want any of them here. They are a dangerous element. There is no way to determine their loyalty... It makes no difference whether he is an American citizen, he is still a Japanese. American citizenship does not necessarily determine loyalty... But we must worry about the Japanese all the time until he is wiped off the map."

DeWitt's position was backed up by a number of pre-existing anti-immigrant groups based out of the West Coast, such as the Joint Immigration Committee and the Native Sons and Daughters of the Golden West. For many, the war simply served as an excuse to get rid of Japanese Americans. In an interview with the Saturday Evening Post, Austin Anson, the managing secretary of the Salinas Vegetable Grower-Shipper Administration, said:

"We're charged with wanting to get rid of the Japs for selfish reasons. We do. It's a question of whether the White man lives on the Pacific Coast or the brown men. ... If all the Japs were removed tomorrow, we'd never miss them in two weeks because the White farmers can take over and produce everything the Jap grows. And we do not want them back when the war ends, either."

Ironically for Anson, the mass deportation of Japanese Americans under Executive Order 9066 meant there was a significant shortage of agricultural labor. Many Caucasians left to fight the war, so the U.S. signed an agreement with Mexico to permit the immigration of several million Mexicans agricultural workers under the so-called bracero program.

Life in the camps

Japanese American concentration camp

Hulton Archive/Getty Images

Circa 1943: Aerial view of a Japanese American relocation center in Amache, Colorado, during World War II. Each family was provided with a space 20 by 25 ft. The barracks were set in blocks and each block was provided with a community bath house and mess hall.

For the most part, Japanese Americans remained stoic in the face of their incarceration. The phrase shikata ga nai was frequently invoked — the phrase roughly translates to "it cannot be helped," which, for many, represents the perceived attitude of the Japanese people to withstand suffering that's out of their control.

Initially, most Japanese Americans were sent to temporary assembly centers, typically located at fairgrounds or racetracks. These were hastily constructed barracks, where prisoners were often packed into tight quarters and made to use toilets that were little more than pits in the ground. From here, they were relocated to more permanent camps — replete with barbed wire and armed guards — in remote, isolated places across the seven states of California, Arizona, Colorado, Wyoming, Idaho, Utah, and Arkansas.

Many of these camps, also known as War Relocation Centers, were little better than the temporary assembly centers. One report described the buildings as "tar paper-covered barracks of simple frame construction without plumbing or cooking facilities of any kind." Again, overcrowding was common.

As a result, disease became a major concern, including dysentery, malaria, and tuberculosis. This was problematic due to the chronic shortage of medical professionals and supplies, an issue that was not helped by the War Relocation Authority's decision to cap Japanese American medical professional's pay at $20 a month (about $315 in 2019 dollars), while Caucasian workers had no such restriction. As a comparison, Caucasian nurses earned $150 ($2,361) a month in one camp.

The U.S. government also administered loyalty questionnaires to incarcerated Japanese Americans with the ultimate goal of seeing whether they could be used as soldiers and to segregate "loyal" citizens from "disloyal" ones. The questionnaires often asked whether they would be willing to join the military and if they would completely renounce their loyalty to Japan. Due to fears of being drafted, general confusion, and justified anger at the U.S. government, thousands of Japanese Americans "failed" the loyalty questionnaire and were sent to the concentration camp at Tule Lake. When Roosevelt later signed a bill that would permit Japanese Americans to renounce their citizenship, 98 percent of the 5,589 who did were located at Tule Lake. Some apologists cite this an example of genuine disloyalty towards the U.S., but this argument clearly ignores the gross violation of Japanese Americans' rights. Later, it became clear that many of these renunciations had been made under duress, and nearly all of those who had renounced their citizenship sought to gain it back.

Since many children lived in the camps, they came equipped with schools. Of course, these schools weren't ideal — student-teacher ratios reached as high as 48:1, and supplies were limited. The irony of learning about American history and ideals was not lost on the students, one of whom wrote in an essay --

"They, the first generation [of Japanese immigrants], without the least knowledge of the English language nor the new surroundings, came to this land with the American pioneering spirit of resettling. ...Though undergoing many hardships, they did reach their goal only to be resettled by the order of evacuation under the emergency for our protection and public security."

Potentially the best part of life in the camps — and the best way for determined prisoners to demonstrate their fundamental American-ness — was playing baseball. One camp even featured nearly 100 baseball teams. Former prisoner Herb Kurima recalled the importance of baseball in their lives in an interview with Christian Science Monitor. "I wanted our fathers, who worked so hard, to have a chance to see a ball game," he said. "Over half the camp used to come out to watch. It was the only enjoyment in the camps."

The aftermath

When the camps finally closed in 1945, the lives of the incarcerated Japanese Americans had been totally upended. Some were repatriated to Japan, while others settled in whichever part of the country they had been arbitrarily placed in. Those who wished to return to the West Coast were given $25 and a train ticket, but few had anything to return to. Many had sold their property to predatory buyers prior to being incarcerated, while theft had wiped out whatever else they had left behind. Many, many years later, the 1988 Civil Liberties Act mandated that each surviving victim be paid $20,000, though that seems like a small fine to pay for irrevocably changing the courses of more than 100,000 lives.