An elevated CO2 concentration in the atmosphere accelerates growth and improves yields of agricultural crops. (defyccc.com)
On average, adaptation improves yields by the equivalent of ~ 15 - 18 % of current yields, but the effectiveness of adaptation is highly variable (medium confidence). (dotearth.blogs.nytimes.com)
It could also greatly improve yields in existing corn - growing regions of the world where food security remains a major problem. (scientificamerican.com)