Are atmospheric CO2 levels negatively impacting the nutritional values of the crops we produce?
Growers have always prided themselves on providing the nutrient-rich grains, fruits and vegetables required to feed a growing global population. At the same time, responsible parents have insisted their children eat naturally grown food to get the minerals, vitamins and proteins the body needs for healthy growth and development.
A new field of research is shedding light on a concerning, yet little known phenomenon that has been identified in recent years. It is a story that has been documented in a thought-provoking article by Helena Bottemiller Evich, which was recently published in The Agenda. While we do not necessarily endorse its findings, it does raise some interesting questions.
There has been a great deal of sound agricultural research that has confirmed that farm-grown foods are getting less nutritious – with a significant decline in key vitamins, minerals and proteins between the 1950s and present day. A landmark study in 2004 confirmed such a decline in protein, calcium, iron and vitamin C in broccoli, tomatoes and wheat.
The causes were often attributed to the industry’s focus on higher-yielding crops versus high-nutrient crops. Yet scientists are now correlating this to a somewhat surprising source: rapidly rising CO2 levels in the atmosphere.
Prior to the Industrial Revolution, there were 280 parts per million of CO2 in the earth’s atmosphere. By 2017 that number had climbed past 400 ppm.
From an agronomic perspective, it seems counterintuitive.
After all, plants rely on CO2 like we rely on oxygen. It is essential to photosynthesis and other plant functions. So, it would stand to reason that increased CO2 levels should aid plant growth, right?
As the article explains, researchers have found that higher atmospheric CO2 “revs up” photosynthesis. It increases the plant’s ability to transform sunlight to food. The accelerated growth causes the plants to produce more sugars – leading them to create more carbohydrates (such as glucose). This comes at the expense of other vital nutrients found in grains, fruits and vegetables, including protein, calcium, potassium, zinc and iron. The author of the article likens it to “junk food”.
To what degree are nutrient levels changing in plants?
The author cites data collected over three decades, from 15,000 plant samples representing 130 varieties. Over this short time, the overall concentration of calcium, magnesium, potassium, zinc and iron had dropped by an average of 8 percent.
Another study published earlier this summer estimates 150 million people could face protein deficiency, while lower levels of zinc (essential for maternal and infant health) could put 130 million people at risk. A further 1 billion mothers and 354 million children could face serious challenges associated with lower natural sources of dietary iron.
While these issues are of biggest concerns in third world countries, it has been pointed out that the increased levels of sugars in plants could be contributing to the already epidemic levels of obesity and cardiovascular disease in developed nations.
For growers, the findings do give pause for thought.
Smart agronomic and environmental practices are allowing us to reduce CO2 by using less fuel and through smart fertilizer practices. But it is a big picture issue that goes beyond farming.
As agricultural research continues to expand in this area, it will be interesting to see what solutions are put forward in an effort to help us produce the most nutritious crops possible, and better manage the challenges around CO2.