The great nutrient collapse
http://www.politico.com/agenda/story/2017/09/13/food-nutrients-carbon-dioxide-000511
tldr: cim vyssi koncentrace co2 (brzy dvojnasobna oproti dobe pred prumyslovou revoluci), tim rychlejsi fotosyntetizace, ale zaroven tim nizsi obsah mineralu v rostlinach - problem pro vetsinu lidstva, ktere se stravuje dominantne roslinne, zaroven i u nas musime postupne upgradovat predstavu o tom, co je tzv. vyzivne.
“Every leaf and every grass blade on earth makes more and more sugars as CO2 levels keep rising ,” Loladze said. “ We are witnessing the greatest injection of carbohydrates into the biosphere in human history―[an] injection that dilutes other nutrients in our food supply.”
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Measurements of fruits and vegetables show that their minerals, vitamin and protein content has measurably dropped over the past 50 to 70 years. Researchers have generally assumed the reason is fairly straightforward: We’ve been breeding and choosing crops for higher yields, rather than nutrition, and higher-yielding crops—whether broccoli, tomatoes, or wheat—tend to be less nutrient-packed.
[T]he atmosphere itself may be changing the food we eat. Plants need carbon dioxide to live like humans need oxygen. And in the increasingly polarized debate about climate science, one thing that isn’t up for debate is that the level of CO2 in the atmosphere is rising. Before the industrial revolution, the earth’s atmosphere had about 280 parts per million of carbon dioxide. Last year, the planet crossed over the 400 parts per million threshold; scientists predict we will likely reach 550 parts per million within the next half-century—essentially twice the amount that was in the air when Americans started farming with tractors.
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To say that it’s little known that key crops are getting less nutritious due to rising CO2 is an understatement. It is simply not discussed in the agriculture, public health or nutrition communities. At all.
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Within the category of plants known as “C3”―which includes approximately 95 percent of plant species on earth, including ones we eat like wheat, rice, barley and potatoes―elevated CO2 has been shown to drive down important minerals like calcium, potassium, zinc and iron. The data we have, which look at how plants would respond to the kind of CO2 concentrations we may see in our lifetimes, show these important minerals drop by 8 percent, on average. The same conditions have been shown to drive down the protein content of C3 crops, in some cases significantly, with wheat and rice dropping 6 percent and 8 percent, respectively.
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Goldenrod, a wildflower many consider a weed, is extremely important to bees. It flowers late in the season, and its pollen provides an important source of protein for bees as they head into the harshness of winter. Since goldenrod is wild and humans haven’t bred it into new strains, it hasn’t changed over time as much as, say, corn or wheat. And the Smithsonian Institution also happens to have hundreds of samples of goldenrod, dating back to 1842, in its massive historical archive—which gave Ziska and his colleagues a chance to figure out how one plant has changed over time.
They found that the protein content of goldenrod pollen has declined by a third since the industrial revolution—and the change closely tracks with the rise in CO2. Scientists have been trying to figure out why bee populations around the world have been in decline, which threatens many crops that rely on bees for pollination. Ziska’s paper suggested that a decline in protein prior to winter could be an additional factor making it hard for bees to survive other stressors.
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[In 2014] Loladze, then teaching math at the The Catholic University of Daegu in South Korea, published his own paper, the result of more than 15 years of gathering data on the same subject. It was the largest study in the world on rising CO2 and its impact on plant nutrients. ... Across nearly 130 varieties of plants and more than 15,000 samples collected from experiments over the past three decades, the overall concentration of minerals like calcium, magnesium, potassium, zinc and iron had dropped by 8 percent on average. The ratio of carbohydrates to minerals was going up.
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What that means for humans―whose main food intake is plants―is only just starting to be investigated. Researchers who dive into it will have to surmount obstacles like its low profile and slow pace, and a political environment where the word “climate” is enough to derail a funding conversation. It will also require entirely new bridges to be built in the world of science―a problem that Loladze himself wryly acknowledges in his own research. When his paper was finally published in 2014, Loladze listed his grant rejections in the acknowledgements.