Don't you think an ice age would be far more devastating than a warming trend?
AFAIK, global temperatures are still in the process of returning to normal after the retreat of the ice sheets that covered much of North America. So, global warming is going to happen whether we want it to or not. The question is: What caused the temperature to crash in the first place? Photosynthesis stops below 10 deg. Celsuis, but will persist all the way up to 45 deg. Celsius. So any event that comes anywhere near the freezing point of water would destroy our food supplies more surely than any predicted warming trend. For example, with sufficient water plants will grow in the Sahara, but nothing grows in the arctic.