Higher carbon dioxide level can affect crop yields. Some laboratory experiment suggests that elevated carbon dioxide level can increase plant growth. However, other factors such as changing temperature, ozone and water and nutrient constraints may counteract these potential increases in yield. Elevated carbon dioxide has been associated with reduced protein and nitrogen content in alfalfa and soybean plant, resulting in loss of quality. Many weeds, pests and fungi thrive under warmer temperatures, wetter climates and increased carbon dioxide levels. 

Though rising carbon dioxide can stimulate plant growth, it reduces the nutritional value of most food crops. It reduces the concentration of protein and essential minerals in most plant species, including wheat, soybean and rice, The direct effect of rising carbon dioxide on the nutritional value or crops represents a potential threat to human health.