Sometimes I think it's the "either-or" thinking that's going to do us in.
New Scientist magazine cites research by Schlenker and Roberts of North Carolina State University that suggests that yields of three crucial crops (maize, cotton, and soybeans) in the United States would fall catastrophically by the end of the century if we don't cut greenhouse emissions.
Maize yeilds, for example, would plummet 82% if nothing changes, and would still drop by 30-45% even if we cut our emissions by half.
In the same article, David Pimentel of Cornell is quoted as saying that curbing biofuel production would solve hunger and high food prices faster than reducing greenhouse gas emissions. SO: accept lower yields and make it up in volume??
Of course, the answer is both: we need to make biofuels that don't use food crops or food-crop-suitable land AND reduce our greenhouse emissions. That way everybody wins.