The impact of climate change on nutritional deficiencies


The impact of climate change and global warming is well known: melting glaciers, more severe storms, increased droughts, and loss of species. However, the impacts of global warming on human health are only now beginning to be understood. Not only is climate change increasing the spread of infectious diseases, it is also affecting the food we eat. It is widely accepted that greenhouse gases warm the atmosphere and alter the water cycle, which has a direct effect on the growth of our crops. However, rising atmospheric concentrations of some greenhouse gases, specifically carbon dioxide, has also been proven to impair the nutritional value of many staple food crops.

Currently, humans obtain a majority of key nutrients from plants. Globally, 63% of dietary protein, 81% of iron, and 68% of zinc comes from plant sources1. These are essential nutrients for health: protein for repairing cells, iron for haemoglobin (the molecule that moves oxygen in our bloodstream) and zinc for a strong immune system. Deficiencies of these nutrients can cause an increased risk of various human diseases, ranging from blindness to abnormal brain development. Concerningly, recent studies have shown that rising levels of carbon dioxide could cause major staple crops, such as rice and wheat, to be less nutritious.

Studies have found that high atmospheric levels of carbon dioxide can result in less nutritious crop yields, with 3%-17% lower concentrations of protein, iron, and zinc compared to current atmospheric conditions1. According to research by Samual Myers at the Harvard T.H. Chan School of Public Health, the protein content of rice, wheat, barley, and potatoes decreased by 7.6%, 7.8%, 14.1%, and 6.4% respectively under elevated atmospheric carbon dioxide levels2.  The decreased nutritional value of these crops can be explained by a shift in the plant’s internal chemistry, which causes the plant to retain fewer essential micronutrients.

The decrease of micronutrients in our food could result in 122 million people becoming protein deficient and 175 million people becoming zinc deficient by 20501. The dietary iron intake of approximately 1.4 billion people could significantly decrease, increasing their risk of anaemia and other related diseases3. In addition, billions of people that currently live with nutritional deficiencies could see their conditions worsen. Moreover, for a majority of the world’s population, most dietary protein intake comes from the consumption of plants, as meat is difficult to source and is rarely consumed. A decrease in the nutritional value of crops would lead to populations across the world, specifically those that primarily rely on plants for their nutrient intake, suffering an increased risk of health problems.

Addressing the root causes of climate change is crucial to improving this situation. A multifaceted approach is required to decrease carbon emissions globally. Specifically, it is important to recognize the carbon footprint involved in food production. Currently, the global food production system creates about 25%-30% of total greenhouse gas emissions each year4. To combat this, the food production industry needs to shift to a process that is more sustainable. Moving away from livestock, which requires high volumes of water and produces high volumes of carbon and methane, to a more plant-based diet could help decrease the output of greenhouse gases. Growing and selling crops locally, instead of transporting them long distances, could also help reduce the carbon footprint associated with food production. Also, replacing livestock with plants would increase the number of plants growing each year, which can act as a carbon sink to further reduce atmospheric carbon dioxide emissions.

Increasing atmospheric carbon dioxide isn’t only causing global warming. It is already beginning to significantly affect food and health. Currently, more than 2 billion people globally are malnourished; about 30% of the global population5. That number will continue to grow if staple crops lose nutrients due to rising carbon dioxide emissions.


  1. Sweeney, Chris. “As Carbon Dioxide Levels Climb, Millions at Risk of Nutritional Deficiencies.” News, Harvard T.H. Chan School of Public Health, 27 Mar. 2019,
  1. Medek, Danielle E., et al. “Estimated Effects of Future Atmospheric CO2 Concentrations on Protein Intake and the Risk of Protein Deficiency by Country and Region.” Environmental Health Perspectives, vol. 125, no. 8, 2017, p. 087002.,
  2. Smith, M. R., et al. “Potential Rise in Iron Deficiency Due to Future Anthropogenic Carbon Dioxide Emissions.” GeoHealth, vol. 1, no. 6, May 2017, pp. 248–257.,
  3. Xu, X., Sharma, P., Shu, S. et al. Global greenhouse gas emissions from animal-based foods are twice those of plant-based foods. Nat Food 2, 724–732, 2021.
  4. World Health Organization (WHO). “Preventing and Controlling Micronutrient Deficiencies in Populations Affected by an Emergency.” WHO, 2007,

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