Implications of changes in rainfall and temperature variability for Swiss and European maize production

Climate change is expected to dramatically alter crop yield in Europe until the end-of-century. Corn in particular is a C4 plant, which, although it uses water efficiently, will experience both positive (earlier sowing) and negative (longer drought) effects of global warming. Many process-based models have identified the importance of various climatic factors in corn growth and how climate change will alter yields. However, few studies have estimated yield shifts on the continental scale. In this work, regions having similar climates are first delineated using a K-Mean algorithm applied on four metrics, derived from temperature and rainfall daily time series of two years: 2000 and 2100. The observed distribution of rainfed maize yield in year 2000 in each region is the result of the interactions between the four climate variables. The method is first developed with Swiss data, then extended to Europe. In a warming continent under RCP 8.5, the boundaries of climatic regions will shift significantly. This shift is found to increase the rainfed yield by 35 % in the main producing Swiss region, the Plateau. On the other hand, cultivating rainfed maize at the same latitudes as today in Europe is projected to result in yield reductions of up to 80%. This decline occurs in areas where Mediterranean climate is expected to replace Atlantic and Continental climates. Mediterranean climate in Europe covering currently 19.0 % of the continent will extend to 41.6 %. Nothern Europe is the only area benefiting from climate change for maize growth. This work has led to the creation of a very simple method, based on freeely available data, and with low computation costs, that can provide an overview of the consequences of climate change on food security in Europe