A new study suggested that droughts and heat waves cleared roughly a tenth of the corn, rice, wheat, corn and other cereal crops in nations hit by extreme weather disasters in the period between 1964 and 2007.

Published on Wednesday in Nature, the paper has examined data on the effects, over 50 years, of extreme temperatures, droughts and floods on national crop harvests.

Navin Ramankutty, a geographer from the University of British Columbia and an author of the report, said, “People already knew that these extreme weather events had impacts on crop production. But we didn’t know by how much, and we didn’t have a basis for how that might change in the future”.

Dr. Ramankutty along with his team combined data from a disaster database with food production information from the United Nations Food and Agriculture Organization. They analyzed roughly 2,800 weather disasters, like the 1983-1984 drought in Ethiopia and the 2003 European heat wave, and also data on 16 distinct cereals, such as barley, rye, oats and maize that grow in 177 countries.

The researchers discovered that droughts reduce a nations crop production by 10%, and heat waves by 9%, but cold spells and floods have nil effects on agricultural production levels. They estimated a loss of over three billion tons of cereal production in the time period 1964 to 2007 due to droughts and heat waves.

Dr. Ramankutty said that they don’t think much about it, but over 50% of global calories belong to rice, wheat and maize solely. He mentioned that when these grain baskets are hit, it causes a hike in food prices, leading to increasing hunger.

With the increase in the global population, food production will be required to increase for feeding the extra mouths. Another author of the study Pedram Rowhani, a land-change scientist from the University of Sussex in Brighton, England, said however, if the world has to meet those demands, steps need to be taken efficiently and sustainably.