Rising CO2 levels could push ‘hundreds of millions’ into malnutrition by 2050

Carbon Brief, DAISY DUNNE, 27 August 2018

An additional 290 million people could face malnutrition by 2050 if little is done to stop the rise of greenhouse gas emissions, a study finds.

The increased presence of CO2 in the atmosphere could cause staple crops to produce smaller amounts of nutrients such as zinc, iron and protein, the researchers say.

Using international datasets of food consumption, the study estimates that these changes could cause an additional 175 million people to be zinc deficient and an additional 122 million people to be protein deficient by 2050.

The findings show that malnutrition is most likely to affect parts of the world that are already grappling with food insecurity, such as India, parts of North Africa and the Middle East, the lead author tells Carbon Brief.

Growing problems

Climate change is known to threaten food security by increasing the chances of extreme weather events such as heatwaves and drought – which can cause crop failures.

However, climate change could also threaten food security by worsening malnutrition.

Across the world, humans get the majority of the key nutrients they need from plants. Crops, including cereals, grains and beans, provide humans with 63% of their protein, which is needed to build new body tissue.

Plants also provide humans with 81% of their iron, a nutrient that facilitates the flow of blood around the body, and 63% of their zinc, a nutrient that helps fight off disease. (Other sources of these nutrients include meat and dairy.)

However, recent experiments show that, when food crops are exposed to high levels of CO2, they tend to produce lower amounts of these three key nutrients.

The reason why this happens is still not well understood, says Dr Matthew Smith, a researcher in environmental health from Harvard University and lead author of the new study published in Nature Climate Change. He tells Carbon Brief:

“The prevailing theory for many years has been that higher CO2 causes a faster growth rate[in crops] – which favours carbohydrates rather than other nutrients important for human health that cannot be taken up quickly enough by the roots.”

However, there is also evidence that suggests not all nutrients decrease under higher CO2, notes Smith, meaning the extent of the impact is still an “open question”.

Under pressure

For the new study, the researchers estimated how global levels of malnutrition would be affected when the average concentration of CO2 in the atmosphere reaches 550 parts per million (ppm). He tells Carbon Brief:

However, there is also evidence that suggests not all nutrients decrease under higher CO2, notes Smith, meaning the extent of the impact is still an “open question”.

Under pressure

For the new study, the researchers estimated how global levels of malnutrition would be affected when the average concentration of CO2 in the atmosphere reaches 550 parts per million (ppm)…….

The results show that India faces the largest malnutrition increases out of any country. By 2050, an additional 50 million people in India could become zinc deficient, while an additional 502 million women and children under five could face anemia as a result of iron deficiencies.

Other high-risk countries include Algeria, Iraq and Yemen – three countries which are already grappling with higher-than-average rates of malnutrition, Smith says:

“Hundreds of millions of people could become newly deficient in these nutrients – primarily in Africa, southeast Asia, India and the Middle East – potentially contributing to a range of health effects: anemia, wasting, stunting, susceptibility to infectious disease, and complications for mothers and newborns.”

Curbing CO2

Despite the stark findings, there are “many steps that can be taken” to reduce the impact of rising CO2 levels on malnutrition, Smith says:…..

The findings add to previous research showing “the potential health consequences” of rising CO2 levels, says Prof Kristie Ebi, a researcher in public health and climate change from the University of Washington, who was not involved in the study. She tells Carbon Brief:

“The growing body of literature on the impacts of rising CO2 concentrations on the nutritional quality of our food indicates the health consequences could be significant, particularly for poorer populations in Africa and Asia – although everyone could be affected.” https://www.carbonbrief.org/rising-co2-levels-could-push-hundreds-of-millions-into-malnutrition-by-2050