Science Mag (August 14, 3015) In 2007, drought struck the bread baskets of Europe, Russia, Canada, and Australia. Global grain stocks were already scant, so wheat prices began to rise rapidly. When countries put up trade barriers to keep their own harvests from being exported, prices doubled, according to an index of the Food and Agriculture Organization of the United Nations. Just 3 years later, another spike in food prices contributed to the Arab Spring uprisings.