Synopsis: Increased CO2 levels have dramatically improved agriculture crop yields, just the opposite of climate model predictions.
Source here. "The historical increase in the air’s CO2 content has improved human nutrition by raising crop yields during the past 150 years on the order of 70 percent for wheat, 28 percent for cereals, 33 percent for fruits and melons, 62 percent for legumes, 67 percent for root and tuber crops, and 51 percent for vegetables."