Winter wheat yields in the UK: uncertainties in climate and management impacts

Winter wheat is an important UK cereal, suited to the current climate. However, recent climate projections show changes in temperature and precipitation are likely, potentially affecting UK crop yields. Assessments of future yields contain several sources of uncertainty including those associated with climate and potential adaptation. Here we address these uncertainties using the CERES-Wheat model fed with an ensemble of regional model projections and different sowing dates and fertiliser regimes. In all of the 13 administrative regions in the UK Climate Projections (UKCP09), increases in temperature accelerated the development rate of wheat, a result that was robust across the ensemble. This generally leads to positive impacts on yield and a northward shift in cultivation, with some decreases in the south. Uncertainties in yield became greater towards 2100, a result of corresponding increases in the uncertainty of climate changes. Sensitivity analysis suggests that CO2 fertilisation could compensate for yield losses due to changes in temperature and precipitation in most regions. Earlier sowings appear to be more beneficial in the future over the UK, whilst later sowings increase the risk of yield losses. In a warmer climate, increasing the amount of fertiliser did not improve yields and in fact increased the risk to productivity. Critically, adjustments to sowing date and fertiliser addition did not mitigate the loss of yield experienced in southern regions, suggesting limited adaptation potential in this case. We propose that regional yield changes may not be critical for wheat production in the UK as a whole, as losses in some regions are more than compensated for by gains in others.