August 22, 2019

Climate Change and Food Quality

How a changing climate impacts the nutritional value of food
Experts have long warned that climate change will have a negative impact on the quantity of food we can produce worldwide. But now research is showing us that climate change will have a profound and negative impact on food quality and nutrient content as well.

In October 2018 the Intergovernmental Panel on Climate Change (IPCC) issued a special report that clearly indicates it’s time to sound the alarm when it comes to global warming. Based on the degree of warming we are presently experiencing, by 2040 it’s predicted that we will be in the midst of extreme weather events, rapidly rising sea levels, extinction of certain species, as well as significantly reduced food production.1 To some degree, we are already experiencing many of these issues.

When we think of climate change, we often think of its influence on the weather and the environment. We may also equate climate change with reduced food quantity. Both of these factors, as well as others outlined in the IPCC report, are definitely cause for concern. But we are also now learning that climate change will have a profound and negative impact on food quality and nutrient content.

The authors of a 2014 paper published in JAMA concluded that “Health is inextricably linked to climate change. It is important for clinicians to understand this relationship in order to discuss associated health risks with their patients and to inform public policy.”2

Climate change refers to overall climate changes that take place over a long period of time.3 This can include temperature, precipitation, and wind. Global warming on the other hand only pertains to hotter temperatures caused by increased greenhouse gases in the atmosphere—in particular carbon dioxide (CO2).

Decreased food production due to climate change is certainly a key concern. According to the IPCC, in 2014 it was estimated that global food production will decrease by 2% per decade while demand will increase by 14%.4 At the same time, compelling research indicates that the nutrient content of food will also decline. While much has been written about food quantity as it relates to climate change, we are only now hearing about the food quality issue.

Declining Food Quality

Before 2015, studies to gauge the impact of increased CO2 greenhouse gases on nutrient content of foods used artificial growing conditions that emulated what is predicted for the middle of this century.5 But new research technology known as free-air CO2 enrichment (FACE) allows for crops to be exposed to ambient and elevated CO2 in normal field conditions. This new technology provides an even more accurate assessment of the CO2 impact on food quality.

A 2015 paper published in Scientific Data that used the FACE technology collected data across three continents that represented more than 10 times the data from previously published studies and found that elevated CO2 led to a decrease in zinc, iron, and sometimes protein concentrations in various foods.6

It’s true that CO2 actually stimulates plant photosynthesis and growth, which should positively impact food production; however, research now shows that increased CO2 creates plants with higher carbohydrate concentrations and reductions in protein and mineral content.7

Research now shows that increased CO2 creates plants with higher carbohydrate concentrations and reductions in protein and mineral content.

According to a 2018 paper by Ebi and Ziska, reduced zinc and iron concentrations in food could lead to “a greater burden of infectious diseases, diarrhea, and anemia.”8 Ebi and colleagues also published a paper in 2018 that used FACE technology to evaluate rice—a primary food source for more than 2 billion people worldwide. In addition to declines in protein, iron, and zinc, the researchers also found consistent declines in vitamins B1, B2, B5, and B9.9

Listen now to our audio interview with Kristie Ebi, PhD, a researcher with the Center for Health and the Global Environment with the University of Washington.

Declines in food quality also negatively impact food quantity. A 2019 paper showed similar nutrient declines in grains of non-legume crops. This paper also found lower harvest yields in the foods lacking these key nutrients. The researchers concluded that “low nutrient concentrations in grains also constrain seed germination and seedling establishment, leading to low yields at harvest. A number of studies have demonstrated that seed nutrient concentrations can strongly affect seedling vigour and development.”10

A 2018 meta-analysis of 57 articles looking at elevated CO2 and the nutritional content of vegetables found decreased concentrations of protein, zinc, and iron, as well as magnesium.11 Similar to other research, this analysis showed that there was also an increase in carbohydrates such as glucose, fructose, and sucrose with these altered environmental conditions. Several researchers speculate that these changes in the protein to carbohydrate ratio caused by elevated CO2 could worsen an already out of control obesity epidemic.12

A 2018 meta-analysis of 37 studies that was published in Molecular Nutrition & Food Research found that increased CO2 decreased plant carotenoid concentrations by 15%.13 It’s well established that carotenoids in foods have valuable health benefits.

The human race relies on the nutrient content of food to help fend off illness and achieve optimal wellness. The obvious concern is that such significant declines in key nutrients will lead to increased micronutrient deficiencies that will lead to increased illness.

Micronutrient Deficiency

Climate change could exacerbate the already growing issue of micronutrient deficiencies and the associated symptoms, diseases, and health issues. The World Health Organization estimates that 2 billion people have micronutrient deficiencies worldwide, with zinc and iron deficiency among the most common.14

In an article published on the Our World Data website, Ritchie and Roser explain that there are 3 key strategies that can be employed to help address existing and expected micronutrient deficiencies:14

  1. Supplementation
  2. Food fortification
  3. Biofortification

The authors of a paper published in the journal Nature Climate Change agree that supplementation, fortification, and biofortification are solid strategies to help ameliorate the possibility of dangerous levels of micronutrient deficiency around the world. The authors conclude, “Many people around the world rely on vegetal sources for nutrients that are critical to their health and are likely to suffer nutritional insufficiency in the coming decades as those food crops become nutritionally impoverished as a result of anthropogenic CO2 emissions.”15

The scientific evidence suggests that increasing CO2 levels can negatively impact the nutrient quality of many foods. And when nutritional value declines, micronutrient deficiencies increase. Along with those deficiencies comes a long list of symptoms and corresponding illnesses such as anemia, cognitive decline, birth defects, osteoporosis, cardiovascular disease, and more. Obviously, something needs to be done. And perhaps the best place to start is to collectively take proactive steps to reduce CO2 emissions one household at a time.

Empowering Patients

In addition to monitoring and preventing potential patient micronutrient deficiencies, healthcare practitioners are in a unique position to inform patients that climate change needs to be addressed. The US Environmental Protection Agency reminds us that there are many ways we all can help reduce CO2 emissions including:16

  • Replace frequently used light fixtures and lightbulbs
  • Buy ENERGY STAR products
  • Change furnace air filters regularly
  • Reduce, reuse, recycle
  • Don’t waste water
  • Compost when you can
  • Spread the word

We can also reduce CO2 emissions by bicycling and walking more, using public transportation, carpooling, buying an energy efficient automobile, avoiding car idling, and making sure car tires are filled to the recommended pressure.

Climate change is real. And it will have dangerous ramifications to human health if we don’t become proactive now.

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  2. Patz JA, Frumpkin H, Holloway T, et al. Climate change: challenges and opportunities for global health. JAMA. 2014:312(15):1565-1580.
  3. US Geological Survey. What is the difference between global warming and climate change? Accessed August 22, 2019.
  4. Intergovernmental Panel on Climate Change. Climate Change 2014: Impacts, Adaptation, and Vulnerability. New York, NY: Cambridge University Press; 2014.
  5. Myers SS, Zanobetti A, Kloog I, et al. Increasing CO2 threatens human nutrition. Nature. 2014;510:139-142.
  6. Dietterich LH, Zanobetti A, Kloog I, et al. Impacts of elevated atmospheric CO2 on nutrient content of important food crops. Scientific Data. 2015:36.
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  9. Zhu C, Kobayashi K, Loladze I, et al. Carbon dioxide (CO2) levels this century will alter the protein, micronutrients, and vitamin content of rice grains with potential health consequences for the poorest rice-dependent countries. Science Advances. 2018;4.
  10. Jin J, Armstrong R, Tang C. Impact of elevated CO2 on grain nutrient concentration varies with crops and soils — a long-term FACE study. Science and the Total Environment. 2019;651:2641-2647.
  11. Dong J, Gruda N, Lam SK, et al. Effects of elevated CO2 on nutritional quality of vegetables: a review. Frontiers in Plant Sciences. 2018;9:924.
  12. Weigel HJ. Crops and climate change: plant quality declines as CO2 levels rise. eLIFE. 2014:3.
  13. Loladze I, Nolan JM, Ziska LH, Knobble AR. Rising atmospheric CO2 lowers concentrations of plant carotenoids essential to human health: meta-analysis. Molecular Nutrition & Food Research. 2019;June 28.
  14. Ritchie H, Roser M. Micronutrient deficiency. Our World Data. 2017;August.
  15. Smith MR, Myers SS. Impact of anthropogenic CO2 emissions on global human nutrition. Nature Climate Change. 2018;8:834-839.
  16. United States Environmental Protection Agency. Climate change: what you can do at home. Accessed August 22, 2019.