Expected Change of the Key Agrometeorological Parameters in Central Europe by 2050 Trnka M. 1,3, Štěpánek P. 2, Dubrovský M. 3, Semerádová D. 1,3, Eitzinger J. 4, Formayer H. 4, Žalud Z. 1,3, Možný M. 2 (1) Institute for Agrosystems and Bioclimatology, Mendel University of Agriculture and Forestry Brno, Czech Republic, (2) Czech Hydrometeorological Institute, Brno, Czech Republic (3) Institute of Atmospheric Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic (4) Institute for Meteorology, University of Natural Resources and Applied Life Sciences (BOKU), Vienna, Austria Change in the length of growing season Change in the timing of agromet. periods Figure 3: Present ( ) mean duration of growing season in the Czech Republic. [days]. Figure 4: Expected length of growing season in the same region by 2050 (HadCM based scenario in combination with A2 SRES is considered). Results: Introduction: Growth and development of field crops are strongly affected by the climate conditions as well as by extreme weather events.These may have severe consequences both for crops directly and for key field operations (i.e. sowing and harvest timing). Farming will remain weather-dependent activity even under changed climate conditions and thus many studies have addressed possible consequences of change in meteorological variables and crop yields (or other parameters e.g. quality). However most studies paid only limited attention to changes in the frequency of potentially damaging events (e.g. frost damage) or overall suitability of weather conditions for farming that always was and will be highly significant in determining profitability of a given season (e.g. field workability during sowing or harvest). The study focused on the expected change of following agrometeorogical parameters in the region of interest (Figure 1ab): Length of growing season and sum of effective temperatures; Potential water balance on the field level (Rainfall vs. ET0); Quality of the snow cover and probability of occurrence of late/early frosts; Number days suitable for sowing during and harvesting during appropriate time in the season. In order to estimate the uncertainty in the future characteristics of the growing season a range of GCMs provided for the Fourth Assessment Report (4AR) was used, (ECHAM, HadCM, NCAR-PCM and CSIRO). For simplicity only results for HadCM in combination with A2 SRES scenario and high sensitivity of climate system are presented. REFERENCES: Running, S.W., Coughlan, J.C., A general model of forest ecosystem processes for regional applications. I. Hydrological balance, canopy gas exchange and primary production processes. Ecol. Model. 42, 125–154. Climate change might have following consequences for agrometeorological parameters in Central Europe (assuming SRES A2 world at 2050): Prolongation of the vegetation season by days. The rate of the change will be 30-50% higher in cooler sites with altitudes over 500 m. The prolongation of the season will be more less symmetrical at both ends (i.e. spring and fall). Increase of the mean sum of effective temperatures over 5°C by °C and by °C in case of effective temperatures over 10°C. This corresponds to change of elevation by m in terms of temperature gradient under present climate. The rate of change will be comparatively higher at lowland sites. Shortening of the period with snow cover occurrence and risk of frost by days. However the frequency of frosts during the early and late vegetation period is likely to increase due to longer nights even under overall warming of the climate. Significant increase of water deficit even at cold climate region with marked change during key period for crop development (i.e. April – June). The deficit within this period will increase by 30 and 40 mm with more pronounced change in the cold region. Decrease of number of days with full snow cover by 40-50% with more pronounced change at lowland sites. The occurrence of days with high potential for the frost damage (i.e. no snow cover and TMIN < -10°C or -15°C) will decrease at cool region and increase in cold region. No significant change of the risk is expected for the warm region. Number of days suitable for sowing on medium soils will increase by 10-15% during fall and 4-12% during spring. Early sowing will be enhanced especially in warm region whilst cool and cold region will have to still rely on later sowing dates. Proportion of days suitable for harvesting during June-September will increase especially in case of cold region (6-10%). The June weather will remain relatively unfavorable for harvest as the number of suitable days will not change in warm and cool regions. This might pose a potential problem for farmers under the changed climate due to expected shifts of harvest dates to earlier terms i.e. mid June-early July. Figure 1a The overview of the main area of interest with points visualizing the set of weather stations used in the study. Figure 1b The set of stations used for the spatial analysis at selected figures. Conclusions: Acknowledgements: This study was conducted with support of the 6th FP EU research project CECILIA (no GOCE ). The development of modelling tools and methodology was supported by COST 734 (Impact of Climate Change and Climate Variability on European Agriculture) and by OC187project supporting research activities within COST 734 in the Czech Republic. Change in the sum of effective temperatures a) b) Figure 5: Present ( ) mean annual sum of effective temperatures higher than 5°C (main vegetation season). Figure 6: Expected mean annual sum of effective temperatures > 5°C by 2050 (HadCM based scenario in combination with A2 SRES is considered). Figure 7: Indicates change in the start/end and duration of vegetation season, mean period of frost risk and mean snow cover period in the „warm“ climate region (Mean annual temperature > 9.5 °C). Figure 8: Indicates change in the start/end and duration of vegetation season, mean period of frost risk and mean snow cover period in the „cool“ climate region (Mean annual temperature <7.0 °C). Shifts in the field scale water balance Figure 10: Change of the field scale potential water balance over various agriculturaly important periods for three types of climate regions. Mofication of snow cover and frost risk Change of sowing and harvesting condtions Figure 11: Change in the maximum, mean and minimum number of snow days (i.e. days with continous snow cover) at three types of Central European regions. Figure 12: Maximum number of days with critical TMIN during winter periods without adequate snow cover – days with potential frost damage. Figure 13: Change in the proportion of days with suitable contionds for sowing during fall ( JD); early spring ( JD) and late spring ( JD). Figure 14: Change in the proportion of days with suitable contionds for harvesting with heavy machinery. Figure 9: Change in the field scale potential water balance (Rainfall – Reference Evapotranspiration) over the Czech Republic between conditions of the baseli ne climate ( ) and conditions expected in 2050 according to HadCM3 and A2 SRES scenario.