The International Food Policy Research Institute has written several reports that analyze the impact of climate change on agriculture. They are worth reading and excellent sources of in depth regional information and data. One of the most compelling and frightening conclusions they arrive at is that hunger and malnutrition will eventually be suffered by over 25 million children in the poorest of countries - all of it directly due to climate change. Africa and Asia not surprisingly, would be the hardest hit.
Global food prices for staples such as rice and maze have already seen staggering increases over the last few years, which contributed to an international food crisis that has been largely ignored here in the US. Lower yields from harvests due to environmental damage will certainly not help.