Considering the direct effect of higher atmospheric concentrations of CO2, models using the Intergovernmental Panel on Climate Change's (IPCC) A2 emission scenario suggest that by 2080, crop yield changes will range from reductions of 20 percent to 30 percent in such countries as Bolivia, Mexico, Peru, and Venezuela, to increases of up to 5 percent in Argentina (Cline 2007; Parry and others 2004).