Crops in crisis: Climate change threatens nutritional value of plants, researchers warn amid COP27

07 Nov 2022 --- Published during the build up to COP27 – the United Nations conference on climate change currently taking place in Sharm el Sheikh, Egypt – a new study in Trends in Plant Science has warned about the dangers of increasing levels of atmospheric carbon dioxide (CO2) on the nutritional value of crops.

The researchers argue that the CO2 increase creates difficulties for plants to obtain the necessary minerals to grow nutritious food, especially two primary nutrients essential for human health.

“The first nutrient is proteins built from nitrogen. This is a big issue in developing nations because many diets are poor in proteins. Plants grown at elevated CO2 can have 20 to 30% less protein,” flags Alain Gojon, lead author of the study and research director of France’s National Research Institute for Agriculture, Food and the Environment.

“The second one is iron. Iron deficiency already affects an estimated two billion people worldwide. It is crucial to understand why growing plants at elevated CO2 has such a negative effect on the protein content of most staple crops and the future of food.”

“Leaders and decision makers must come together at COP27 to put health at the heart of the negotiations,” adds Dr. Tedros Adhanom Ghebreyesus, director general at the World Health Organization (WHO).

The root of the problem
Plants use photosynthesis to incorporate CO2 into sugars, which becomes the plant’s energy source. However, photosynthesis lacks the essential minerals that plants need to grow, the researchers point out.

Instead, most plants pick up minerals such as nitrogen, phosphorus and iron from the soil through their root system. Nitrogen is especially important as it acts as a key building block for amino acids used to create protein.

Photosynthesis lacks the essential minerals that plants need to grow, the researchers flag.“There are many reports in the literature showing that the CO2 levels expected at the end of the twenty-first century will lead to a lower concentration of nitrogen in most plants, mainly affecting the protein content in plant products,” says Gojon.

A lowered mineral status in plants may create a negative feedback loop beyond global food systems that mitigates climate change, driven by the increased CO2 levels. The scientists stress that further research is needed to determine to what extent CO2 emissions must be reduced.

“The terrestrial carbon sink associated with enhanced photosynthesis may be limited if most of the vegetation is deficient in nitrogen and other minerals, which may prevent any additional increase of CO2 capture from the atmosphere,” says Gojon.

A fragile system
The WHO stresses that human health is dependent on the ecosystem, which is under serious threat from agriculture, deforestation, changes in land use and rapid urban development.

“What is clear is that the nutrient composition of the main crops used worldwide, such as rice and wheat, is negatively impacted by the elevation of CO2. This will have a strong impact on food quality and global food security,” says Antoine Martin, corresponding author and researcher of the French National Centre for Scientific Research.

“We would like to understand the mechanisms responsible for the negative effects of elevated CO2 on the mineral composition of plants. For example, we are currently exploring the natural genetic variation behind these negative effects that could be used afterward to improve crops’ nutritional value under future CO2 atmosphere,” says Martin.

Transition in focus at COP27
The WHO warns that 90% of the world’s population breathes polluted air that exceeds the recommended quality limit. This threat to human health “must be at the center of negotiations” at COP27, it stresses.The WHO stresses that climate change is already affecting people’s health and will continue to accelerate unless urgent action is taken.

“Our focus will be placing the health threat from the climate crisis and the huge health gains from stronger climate action at the center of discussions. Climate change is already affecting people’s health and will continue to accelerate unless urgent action is taken,” the WHO elaborates.

“Climate change is making millions of people sick or more vulnerable to disease all over the world, and the increasing destructiveness of extreme weather events disproportionately affects poor and marginalized communities,” Ghebreyesus underscores.

The WHO also again stresses the impact extreme weather has on human health, such as droughts and flooding, as it drives food insecurity and inaccessibility to nutritious foods.

The green transformation of agri-food systems has been “at the heart of COP27 agenda,” FoodIngredientsFirst reports. Setting transition targets for more sustainable food systems is widely recognized as vital to overcoming the climate crisis.

By Beatrice Wihlander