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New research by Harvard University warns that ris­ing car­bon diox­ide lev­els that con­tribute to global warm­ing could dras­ti­cally reduce the nutri­tional con­tent of sta­ple crops.

Researchers from Harvard’s T.H. Chan School of Public Health who con­ducted the study have con­cluded that if car­bon diox­ide lev­els con­tinue to rise, the nutri­tional value of crops like wheat, rice, bar­ley and pota­toes will be reduced. This would put the pop­u­la­tions of 18 coun­tries around the world at risk of los­ing more than five per­cent of the dietary pro­tein avail­able to them by 2050.

In con­crete num­bers, this amounts to 150 mil­lion peo­ple. The researchers arrived at this fig­ure by study­ing the results of exper­i­ments con­ducted on crops by expos­ing them to high car­bon diox­ide lev­els and exam­in­ing global dietary infor­ma­tion, demo­graph­i­cal data and fig­ures mea­sur­ing income inequal­ity.

The study, pub­lished in Environmental Health Perspectives, revealed that when exposed to high lev­els of car­bon diox­ide, the pro­tein con­tent of rice decreased by 7.6 per­cent, 7.8 per­cent for wheat, 14.1 per­cent for bar­ley and by 6.4 per­cent for pota­toes. This also presents a risk of decline in the min­eral con­tent of these foods, like zinc, iron and sele­nium, all of which are essen­tial for human health.

According to the study, 76 per­cent of the world’s pop­u­la­tion gets its pro­tein from plants. The regions high­lighted as the most vul­ner­a­ble include Sub-Saharan Africa where pro­tein defi­ciency is already a dilemma and South Asian coun­tries like India where rice and wheat are sta­ples and the main pro­tein source.

In India, 5.3 per­cent of the pro­tein con­tent of crops could be lost, affect­ing 53 mil­lion peo­ple.

In a Harvard University press release, Samuel Myers, senior research sci­en­tist at the Department of Environmental Health stressed that action needs to be taken: ​“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,” he said.

“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.”

Carbon diox­ide is one of the heat-trap­ping green­house gases that con­tribute to cli­mate change. This was the first study to quan­tify the impacts of ris­ing car­bon diox­ide lev­els as a result global warm­ing on the pro­tein con­tent of sta­ple crops.

The researchers point out that adding more fer­til­izer to crops does not mit­i­gate the neg­a­tive effects of car­bon diox­ide on plant pro­tein, with fer­til­izer pro­duc­tion and uti­liza­tion actu­ally being a con­trib­u­tor to green­house gas emis­sions.

Replacing plant pro­tein with ani­mal pro­tein is not pre­sented as a solu­tion either because of the resource-inten­sive nature of live­stock farm­ing. Instead, more resilient crops like legumes could be an alter­na­tive, as well as mea­sures address­ing more equi­table food dis­tri­b­u­tion and poverty reduc­tion.

• Harvard T.H. Chan School of Public Health


• Environmental Health Perspectives