Klimawandelbedingte Ertragsveränderungen und Flächennutzung (KlimErtrag)

We provide an overview of the state of knowledge on the climate change impacts on German crop production and generate model-based, quantitative and spatially differentiated simulations of the yield changes of the most important German arable crops, up to the middle of the century. To simulate yields, we use several agro-ecosystem models and provide a meta-analysis of the related scientific literature. In addition, we consider the effects of specific weather conditions such as heat and drought periods on yields in the past. In order to assess the future development, we use the data of different climate projections . On average, with regional differences, the simulations show no decline in yields until the middle of the century and no increase in yield variability. We observe a decrease in the effectiveness of the CO2 fertilization effect for yield increases of winter wheat over time. The yields of silage maize benefit the least from CO2 fertilization. For the past, we identify yield losses due to extreme summer and spring drought for almost all crops as well as due to heat events for winter wheat and partly for oilseed rape. Heat-related yield losses increase for winter wheat with increasing CO2 concentrations. However, we cannot identify an unambiguous increase in yield losses due to extreme drought or waterlogging in the future. Uncertainties in the results exist, amongst other reasons, due to a wide range of future precipitation development in the underlying climate models, in particular with regard to the reliability of the precipitation projection in spring. The simulations do not consider adaptation of production to climate change as well as negative yield effects due to potential increase in storms, hail storms, heavy rain or harmful organisms.