EFFECT OF USING DIFFERENT METHODS IN THE CONSTRUCTION OF CLIMATE-CHANGE SCENARIOS - EXAMPLES FROM EUROPE

To investigate the impacts of future climate change on agriculture in Europe and to aid the development of agricultural adaptation strategie s, several scenarios of climate change were constructed and provided a s input to crop-climate models at both broad and site-specific scales. These scenarios were based on results from a number of global climate model (GCM) experiments, including both equilibrium and transient cli mate change experiments. All GCMs provide 'internally consistent' scen arios of climate change, but at coarse horizontal spatial resolutions. Results from equilibrium experiments give no indication of the rate o f climate change, whereas transient experiments simulate time-dependen t climate change. Broad-scale climate change scenarios for Europe were constructed at 0.5 degrees latitude/longitude resolution using a Gaus sian space-filtering routine. Site-specific scenarios at the daily tim escale required by crop-growth simulation models were constructed usin g a stochastic weather generator in conjunction with GCM-derived infor mation about possible future climate change. A regression technique to downscale broad-scale changes in temperature and precipitation means to specific sites was carried out at 2 European sites, Rothamsted, UK, and Seville, Spain. At other European sites, where crop-climate model s were being run, the GCM-derived grid-box changes were used without d ownscaling. Use of a weather generator also enabled GCM-derived change s in climate variability to be incorporated into the scenarios by usin g the grid-box changes in the means and variances of the climate varia bles to perturb the parameters of the stochastic weather generator dir ectly. The implications of using these different methods of climate ch ange scenario construction for the resulting scenarios are discussed.