The Impact of Increased CO₂ on Food Quality

A recent study has revealed that higher levels of carbon dioxide in the atmosphere are causing food to be more calorific yet less nutritious, and potentially more toxic.

Sterre ter Haar, a lecturer at Leiden University in the Netherlands, along with her research team, developed a method to evaluate various studies on how plants respond to rising CO₂ levels. The findings were startling: while crop yields may increase, the nutritional value diminishes. Notably, zinc levels are declining, while lead levels are on the rise.

Ter Haar expressed her surprise at the extent of these nutritional changes, which vary significantly across different plants. She highlighted that these shifts do not represent a mere dilution effect but indicate a fundamental change in food composition, raising concerns about necessary dietary adjustments or changes in food production methods.

For over a decade, scientists have been investigating the influence of increased atmospheric CO₂ on plants, but drawing clear comparisons has been challenging. This new research provided a baseline measurement that shows a linear relationship between CO₂ concentration and plant growth. By analyzing nearly 60,000 measurements across 32 nutrients and 43 crops, including rice and wheat, the study established clearer insights into these effects.

The researchers set their baseline at 350 parts per million of CO₂, deemed as the last “safe” level, and compared it to a projected 550 parts per million, expected to be reached by 2065. Most nutrients were found to decline by an average of 3.2% with the increase in CO₂ concentration, with zinc in chickpeas anticipated to decrease by up to 37.5%. This could lead to significant reductions in protein, zinc, and iron in vital crops such as rice and wheat, posing dire health risks associated with “hidden hunger.”

Currently, CO₂ levels are at 425.2 parts per million, already impacting plant nutrition adversely. The study highlights how climate change is not a distant issue but one that is already affecting what we eat.

Experts have praised this Dutch study as a strong foundation for further research. It sheds light on how environmental conditions influence crop nutritional quality, crucial for ensuring future food security. However, other factors like fertilizer application also play significant roles in crop nutrition, necessitating more experiments to understand the multifaceted nature of these changes.

Ter Haar remarked that the study raises important questions and emphasizes the need for more research on the interplay between climate change and nutrient content in crops. “Acknowledging the problem is the first step toward finding solutions,” she noted, reinforcing the study’s potential to contribute positively to the understanding of this pressing issue.

The full research is published in the journal Global Change Biology.