The latest UN report on climate change emphasises food supply effects: Climate change.
The report argues that climate change has negatively affected wheat and maize yields both regionally and on a global basis. The effects of climate change on two other important food crops, rice and soya beans, have been smaller in the most important producing countries. There may be some positive effects on crops in cooler climates in future. However, the overall outlook for wheat, rice and maize production in tropical and temperate regions is expected to be more negative than positive.
The last assessment by the UN's Intergovernmental Panel on Climate Change in 2007 was more sanguine about how climate change was impacting on food production. Unfortunately, the suggestion that the CAP might incorporate a climate change pillar was rapidly dropped in the last set of reform negotiations.