Impact of regional climate change on pest insects in oilseed rape.
Global and regional climate models are suitable tools to simulate the future climate. However, climate change projections are afflicted with different uncertainties, e.g. due to an incomplete coverage of all physical processes involved. A possible way to deal with these uncertainties related to model results is to analyze an ensemble of equally valid, possible realizations of regional climate model projections. Furthermore, the use of an ensemble of future climate projections leads to more accurate estimates of the potential future changes, because the effect of the internal variability can be more accurately addressed. Examples of multi model ensemble approaches in agriculture are discussed in the literature. Aside from effects on agricultural practice, possible impacts of global climate change are also expected on pest species in crop production, e.g. species distribution or shifting of crop invasion. Since 2009, an expert group of meteorologists, entomologists and modellers has been investigating the effect of regional climate change on pest species in oilseed crops for Luxembourg within the framework of several research projects. So far, projections have been done for the rape stem weevil, Ceutorhynchus napi (Gyll.), the cabbage stem weevil, Ceutorhynchus pallidactylus (Mrsh.) and the pod midge, Dasineura brassicae (Winn.). Based on an ensemble of 6 regional climate change projections, the bandwidths of possible change signals and the uncertainty associated with these projections were investigated for the near (2021-2050) and far future (2069-2098) in comparison to a reference time period (1961-1990). All projections were based on the Special Report on Emissions (SRES) A1B emission scenario of the Intergovernmental Panel on Climate Change (IPCC). This scenario describes anthropogenic emissions of a future world with rapid economic growth, an increasing global population until the middle of this century and a balanced use of fossil and non-fossil energy resources.