Bioenergy crops are expected to play an important role in reducing greenhouse gas (GHG) emissions and in enhancing the security of energy supply. According to Sir David King, climate change is our most serious threat. This paper presents some new evidence on the way in which changes to the climate will affect winter wheat yield in Norfolk, England, and there are some surprising but vitally important outcomes. Winter wheat shows different dependence on climate parameters when the temperature is increased, rainfall increased or decreased, and carbon dioxide (CO2) levels increased. Model predictions showed that under many future climate scenarios winter wheat yield would increase with decrease in precipitation and in temperature ranging from +1.2oC to +3oC. However, increased temperature of up to +6oC resulted in yield decrease under both ambient and elevated levels of CO2.