How will corn production be affected by global warming?

An article by Timothy Telleen-Lawton, with the Wisconsin Environment Research & Policy Center, suggests some signifcant effects on corn yields by increases in temperature. Their numbers project a yearly damage in corn production of $1.4 billion, due to global warming.  Iowa is the most affected, with losses of $259 million annually. Follow this link- http://www.wisconsinenvironment.org/newsroom/global-warming/global-warming-news/global-warming-will-cost-millions-for-wisconsins-corn

However, there exists some skepticism over this report.  "A lot of the conclusions they draw really, really stretch the evidence," says Dr. Matt Roberts, Associate Professor in the Department of Agricultural, Environmental and Developmental Economics at Ohio State University. Roberts says the study portrays "an unfamiliarity with the way agriculture works. The conclusion that the University of Illinois looked came to is actually very benevolent weather, that in fact the last ten or twelve years we've seen some of the most peaceful weather we've seen in the last hundred years," says Roberts. "From an agricultural perspective, weather is getting better." You can read more here: http://www.wrn.com/gestalt/go.cfm?objectid=E8DAD98F-5056-B82A-375D43A0848AA492

So which point of view is accurate?  We probably won't know without the benefit of hindsight.  I believe that much of the increases in yield, are attributable to genetic improvements & crop breeding techniques.  But, as everyone associated with agriculture understands, Mother Nature holds the trump cards.