Introduction
World Food Summit defines food security as: “Food security exists when all people, at all times, have physical and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life”. (World Food Summit, 1996) On the contrary, the food insecurity means the situation people who are lack of food or nutrition. A person who lives in such situation for a very long time cannot access enough nutritious food to be healthy. Additionally, food insecurity can be chronic, seasonal or transitory (FAO, 2000). At present, the problem has been more and more serious and it has caused a series of problems. In some areas where food is abundant, the nation feel adequately secured about food. However, there are still over 925 million people (20%) suffering the chronic hunger in the developing counties in 2010 (FAO, 2010). In the graph below, it show the trend of the number of undernourished people in the world, and in 2009 it reached a peak of over 1000 million. Even though the population of hunger decreased in 2010, it is still a difficulty issue for around the world.
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In general, there are many causes of food insecurity, for instance, the unavailability of food, insufficient purchasing power, inappropriate distribution, or inadequate use of food at the household level (FAO, 2000). However, all these reasons contribute to one same result, undernourishment. As far as I see, these reasons can be related in two main causes: the short supply of grain and people cannot access enough food to keep a healthy life individually.
On one hand, the production of grain is easily affected by natural factors. Firstly, the global food output is facing a huge challenge because of climate change. It is thought that global warming is a important reason for decreasing