Don't know that what you are trying to do would be easy to make. What level are we talking about here? High school? It would help to know if you are a 5th grader or a senior!
Scientific models take account of variables involved. In terms of food security, variables include but are not limited to: soil nutrients, rate of soil erosion, average precipitation, averaged frost free period, elevation above sea level, arable land per person, etc. A model will show how these (and other variables) are related and how changing one will affect the other. Good luck!