Drought

• The biggest cause of world hunger is drought or under-irrigation of crops. Cities and factories are consuming bigger and bigger shares of water resources, thus depriving farms of water. Additionally, weather patterns may shift and not rain on valuable cropland. Many third-world countries depend solely on rain to water their crops due to a lack of irrigation infrastructure. Even if the land gets some water, the crop yield may be significantly diminished and not be able to feed everyone.
  
  

Starvation

• The biggest effect of world hunger is starvation. Depending on your size, you needs a certain minimum amount of calories to survive. Additionally, even if you receive all the needed calories, you could still starve if you are lacking necessary vitamins and proteins. If farmers are starving, the effect will be cyclical as they will be too weak to farm as much. Unfortunately, starvation also encourages hoarding, even during good times, as people will fear another period of famine.
  
  

Conflict

• Conflict is both a cause and an effect of world hunger. Conflict, be it tribal conflict or even full scale war, can destroy farmland, drive off farmers and prevent access to cities that need food. Additionally, the fighters can raid food storage buildings for food and keep it for themselves. On the effect side, starving people may start stealing or even kill for food. Historically, most wars have been over farmland. Egypt was invaded by the Greeks, Romans and the Carthaginians because of the Nile Delta, which was the best farmland in the ancient world.
  
  

Refugees

• Refugees create both a cause and effect of world hunger. When people are starving, they often leave the affected area for one that is not experiencing famine. However, these refugees impose a greater burden on the new area and may trigger another famine. Additionally, by leaving the old area, the refugees become harder to find and feed by international aid organizations.