Higher Carbon Dioxide Levels Lead to More Calorific but Less Nutritious Food, Study Finds
A meta-analysis led by Leiden University has developed a baseline-adjusted method to compare 60,000 measurements of nutrient content across 32 nutrients and 43 crops to assess the effects of rising atmospheric carbon dioxide (CO2) on food. The study, published in Global Change Biology, found that higher CO2 increases crop yields and calorific content but reduces nutrient density, indicating a shift in food composition rather than a simple dilution effect.
The researchers analyzed data from a variety of crops including rice, potatoes, tomatoes, and wheat grown in different contexts. They identified significant nutrient changes, including declines in zinc and increases in lead in some crops. On average, nutrient levels are expected to decline by about 3.2% when CO2 concentrations rise from 350 parts per million (ppm) to 550 ppm, a level anticipated around the year 2065.
Protein, zinc, and iron showed marked decreases in essential staples such as rice and wheat, with zinc in chickpeas potentially falling by up to 37.5%. The current atmospheric CO2 level of approximately 425.2 ppm is already associated with reduced plant nutrition, raising concerns about the health consequences of "hidden hunger."
To enable cross-study comparisons, the team used a linear model relating CO2 levels to nutrient response, comparing present-day levels to future scenarios. Experts received the study positively, emphasizing its importance for understanding food security. Courtney Leisner highlighted its critical role, while Jan Verhagen noted that factors such as fertilizer use also influence crop nutrition, calling for more experiments to guide breeding and agricultural practices.
