The world is headed for a potentially crippling famine by 2050 triggered by growing populations and unabated global warming.

And there's a mounting and little known threat to the world's food supply: ozone pollution.

The world will need 50 percent more food by 2050, mainly because of more people, said a study published in Nature Climate Change, a monthly peer-reviewed scientific journal in the UK.

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The world's ability to produce food, however, may be degraded by climate and air quality changes.

Researchers from MIT and Colorado State University that did the study reported that if everything else stays as it is today, global warming may reduce world crop yields by about 10 percent by 2050.

Their study focused on four major crops: soybeans, rice, maize, and wheat that make up half the calories people consume worldwide.

Ozone pollution is also a grave and rising threat to the world's food supply.  The threat to crops comes from ozone precursors, a group of pollutants mostly emitted during the burning of fossil fuels such as coal.

Agricultural production is '"very sensitive to ozone pollution," said Colette Heald, an author of the study and associate professor of civil and environmental engineering at MIT.

This shows how important it is "to think about the agricultural implications of air-quality regulations. Ozone is something that we understand the causes of, and the steps that need to be taken to improve air quality."

She noted that ozone pollution can also be tricky to identify because its damage can resemble other plant illnesses, producing flecks on leaves and discoloration.

The research team calculated that 46 percent of damage to soybean crops on very hot days previously been attributed to heat is actually caused by ozone.

They compared the world in the year 2000 with the world as it is projected to be in 2050.They developed a statistical model of crop yields based on the historical climate and crop data.

The researchers used national crop data from 1960-2000, thereby making a model based on the observed relationships.

In some scenarios, the researchers discovered that pollution-control measures could prevent the worst of the expected crop reductions.

Ozone reduction could reduce a predicted global drop in food production to nine percent from the original 15 percent prediction.

They said implementing regulations limiting ozone emissions might prove to be a practical and preferable alternative to help secure global food production and increase food security.

Long-term exposure to ozone has also been shown to increase risk of death from respiratory illnesses in humans.