Which of the following is NOT mentioned as pressure on food supplies?

An international aid group is calling for an overhaul of the world’s food system, saying prices for staples such as corn will double in the next 20 years. London-based Oxfam released a report Tuesday saying demand for food is expected to rise 70 percent by 2030, as climate change, lower crop yields and rising energy prices pressure food supplies.
    The group says those hardest hit will be the poor, who spend as much as 80 percent of their income on food. The report recommends addressing the problem by boosting food reserves, ending the use of food crops in biofuels, and ending speculation in worldwide food markets. It also calls for a shift away from large-scale commercial food producers to smaller local growers.