Climate change and crops: How heat stress and CO2 threaten the nutritional value of leafy greens

Hotter temperatures and increased carbon dioxide (CO2) reduce the vitamins, minerals, and overall nutritional quality and content of leafy vegetables, according to new research. The researchers warn that these climate-induced changes may accelerate obesity, type 2 diabetes, and vitamin deficiency rates, impacting the health and well-being of humans and animals.

Until now, most research on the impact of climate change on food production has focused on crop yield. “Our work looks beyond quantity to the quality of what we eat,” says Jiata Ugwah Ekele, a Ph.D. student at Liverpool John Moores University, UK, and presenter at the recent Society for Experimental Biology Annual Conference in Antwerp, Belgium.

“It’s crucial to understand these impacts because we are what we eat, and plants form the foundation of our food network as the primary producers of the ecosystem. By studying these interactions, we can better predict how climate change will shape the nutritional landscape of our food and work toward mitigating those effects.”

Irreversible damage to plants 

Ekele’s research focuses on leafy vegetables like kale, rocket, and spinach. Although higher atmospheric CO2 levels were found to help crops grow faster and bigger, she underlines that nutritional quality is not improved.

“This altered balance could contribute to diets that are higher in calories but poorer in nutritional value,” says Ekele. “Increased sugar content in crops, especially fruits and vegetables, could lead to greater risks of obesity and type 2 diabetes, particularly in populations already struggling with non-communicable diseases.”

“It’s not just about how much food we grow, but also what’s inside that food and how it supports long-term human well-being.”

Ekele states food is more than calories; it’s vital for human development and climate adaptation (Image credit: Ekele).The research warns that climate change is set to have “devastating and irreversible” damage to plants. “These environmental changes can affect everything from photosynthesis and growth rates to the synthesis and storage of nutrients in crops,” says Ekele.

Future climate scenarios duplicated in lab 

Ekele grew crops in environment-controlled growth chambers at Liverpool John Moores University, in which she altered the CO2 and temperature levels based on the UK’s predicted future climate scenarios.

“Photosynthetic markers such as chlorophyll fluorescence and quantum yield are assessed as the crops grow, while yield and biomass are recorded at harvest,” she adds. 

High-performance liquid chromatography and X-ray fluorescence profiling were used to check the plant’s concentrations of sugar, protein, phenolics, flavonoids, vitamins, and antioxidants. “After some time, the crops showed a reduction in key minerals like calcium and certain antioxidant compounds,” Ekele emphasizes.

“The interaction between CO2 and heat stress has complex effects — the crops do not grow as big or fast, and the decline in nutritional quality intensifies.”

She adds that a preliminary finding is that various crops respond according to different intensities to climate stressors.

Climate change is set to have “devastating and irreversible” damage to plants (Image credit: Ekele).“This diversity in response highlights that we can’t generalize across crops. This complexity has been both fascinating and challenging and reminds us why it’s important to study multiple stressors together,” says Ekele.

Global issue

Ekele’s research focuses on the UK’s climate challenges; however, she warns of similar effects taking place globally. “Food systems in the Global North are already being challenged by shifting weather patterns, unpredictable growing seasons, and more frequent heat waves.” 

“In tropical and subtropical regions, these areas also contend with overlapping stressors such as drought, pests, and soil degradation, and are home to millions who depend directly on agriculture for food and income.”

Ekele and her team are also looking to partner with more researchers in agriculture, nutrition, and climate policy.

“It’s important to connect plant science with broader issues of human well-being. As the climate continues to change, we must think holistically about the kind of food system we’re building — one that not only produces enough food but also promotes health, equity, and resilience,” she says. 

“Food is more than just calories; it’s a foundation for human development and climate adaptation.”

Ekele presented her research at the Society for Experimental Biology Annual Conference on July 8. She will update Nutrition Insight as her research continues to unfold to the next stage.