Food becoming more calorific but less nutritious due to rising carbon dioxide

"The results, she said, were a shock: although crop yields increase, they become less nutrient-dense. While zinc levels in particular drop, lead levels increase. Seeing how dramatic some of the nutritional changes were, and how this differed across plants, was a big surprise, she told the Guardian. We aren't seeing a simple dilution effect but rather a complete shift in the composition of our foods This also raises the question of whether we should adjust our diets in some way, or how we grow or produce our food."

"While scientists have been looking at the effects of more CO2 in the atmosphere on plants for a decade, their work has been difficult to compare. The new research established a baseline measurement derived from the observation that the gas appears to have a linear effect on growth, meaning that if the CO2 level doubles, so does the effect on nutrients. This made it possible to compare almost 60,000 measurements across 32 nutrients and 43 crops, including rice, potatoes, tomatoes and wheat."

"Although there was a lot of data from previous studies, there were few answers, said Ter Haar. These studies used paired experiments, where plants were grown under identical conditions except for one thing: the CO2 level. This gives insight into possible changes, but the sample sizes were usually too small to draw conclusions from. Comparing these individual studies with each other was difficult because, as we know, the baseline of CO2 is continuously increasing in our atmosphere, meaning that the baseline in these experiments is also increasing."

More atmospheric carbon dioxide increases crop yields while making food more calorific, less nutrient-dense and potentially more toxic. Zinc concentrations fall in many crops while lead concentrations rise, indicating a shift in food composition rather than a simple dilution. The CO2 effect on plant growth appears approximately linear, allowing a 350 ppm baseline to be used for comparisons. Almost 60,000 measurements across 32 nutrients and 43 crops, including rice, potatoes, tomatoes and wheat, reveal varied nutritional changes across species. Paired experiments often had small samples and shifting baselines as atmospheric CO2 rises, prompting questions about dietary adjustments and agricultural practices.

Read at www.theguardian.com