Ozone and higher temperatures can combine to reduce crop yields, but effects will vary by region.
Many studies have shown the potential for global climate change to cut food supplies. But these studies have, for the most part, ignored the interactions between increasing temperature and air pollution — specifically ozone pollution, which is known to damage crops.
A new study involving researchers at MIT shows that these interactions can be quite significant, suggesting that policymakers need to take both warming and air pollution into account in addressing food security.
The study looked in detail at global production of four leading food crops — rice, wheat, corn, and soy — that account for more than half the calories humans consume worldwide. It predicts that effects will vary considerably from region to region, and that some of the crops are much more strongly affected by one or the other of the factors: For example, wheat is very sensitive to ozone exposure, while corn is much more adversely affected by heat.
The research was carried out by Colette Heald, an associate professor of civil and environmental engineering (CEE) at MIT, former CEE postdoc Amos Tai, and Maria van Martin at Colorado State University. Their work is described this week in the journal Nature Climate Change.
Overall, with all other factors being equal, warming may reduce crop yields globally by about 10 percent by 2050, the study found. But the effects of ozone pollution are more complex — some crops are more strongly affected by it than others — which suggests that pollution-control measures could play a major role in determining outcomes. Ozone pollution can also be tricky to identify, Heald says, because its damage can resemble other plant illnesses, producing flecks on leaves and discoloration.
Potential reductions in crop yields are worrisome: The world is expected to need about 50 percent more food by 2050, the authors say, due to population growth and changing dietary trends in the developing world. So any yield reductions come against a backdrop of an overall need to increase production significantly through improved crop selections and farming methods, as well as expansion of farmland.