Carbon dioxide emissions will result in millions of people facing the prospect of protein deficiency by 2050, according to a by Harvard T.H. Chan School of Public Health.

The study, which is published today in the journal Environmental Health Perspectives, found that the populations of 47 countries will lose over 5% of their dietary protein if projected rises in carbon dioxide emissions come to pass, as increased CO₂ reduces the nutritional value of dietary staples such as wheat and rice.

Some of the affected countries already face significant protein deficiency problems, such as countries in Sub Saharan Africa, but the projected rise is set to bring to issue to an additional 150 million people. Protein deficiency can cause, among its symptoms, muscle wasting, infections and delayed wound healing, potentially leading to a host of additional health issues.

“This study highlights the need for countries that are most at risk to actively monitor their populations’ nutritional sufficiency, and, more fundamentally, the need for countries to curb human-caused CO₂ emissions,” said Samuel Myers, senior research scientist in the Department of Environmental Health.

It was already known that a greater quantity of atmospheric CO₂ results in plants producing less protein as they grow, however this study is the first to quantify the extent.

The researchers found that under the elevated CO₂ concentrations projected to occur in the atmosphere by 2050, rice, wheat, barley and potatoes would see a drop in protein content by 7.6%, 7.8%, 14.1% and 6.4% respectively.

An additional study by Myers, which is also published today in the journal GeoHealth, found that CO₂ are also set to cause a drop in iron found in nutritional staples, increasing the chances of iron deficiency.

Add the findings of a 2015 study where Myers and colleagues found that the same elevated emissions are set to put 200 million people at risk of a zinc deficiency, and it is clear that in many parts of the world there is a serious risk to people’s health as a result of atmospheric CO₂.

The obvious solution to this is to make increased efforts to limit CO₂ emissions, however with many countries remaining sluggish in acting on climate change-related issues, it is doubtful as to whether this will be achieved.

However, it will also be important to focus dietary strategies on the affected countries, meaning primarily focusing on South Asia, Sub Saharan Africa and India, where 53 million people will be affected.

“Strategies to maintain adequate diets need to focus on the most vulnerable countries and populations, and thought must be given to reducing vulnerability to nutrient deficiencies through supporting more diverse and nutritious diets, enriching the nutritional content of staple crops, and breeding crops less sensitive to these CO₂ effects,” Myers said. “And, of course, we need to dramatically reduce global CO₂ emissions as quickly as possible.”