Martin Dubrovsky

Impacts of climate change and alternative adaptation options on winter wheat yield and water productivity in a dry climate in Central Europe

The main objective of the present crop simulation study was to determine the impact of climate change on the winter wheat production of a dry area situated in north-east Austria (Marchfeld region) based on the CERES-Wheat crop-growth simulation model associated with global circulation models (GCMs). The effects of some of the feasible regional- and farm-based adaptation measures (management options) on crop yield and water and nitrogen (N) balance under the climate scenarios were simulated. Climate scenarios were defined based on the ECHAM5, HadCM3 and NCAR PCM GCM simulations for future conditions (2021–50) as described in the Special Report on Emission Scenarios A1B (Nakicenovic & Swart 2000 ). The potential development, yield, water demand and soil N leaching were estimated for winter wheat and all of the defined climates (including rising CO 2 levels) and management scenarios (soil cultivation, windbreaks and irrigation). The results showed that a warming of 2°C in the air temperature would shorten the crop-growing period by up to 20 days and would decrease the potential winter wheat yield on nearly all of the soil types in the region. Particularly, high-yield reductions were projected for light-textured soils such as Parachernozems. A change from ploughing to minimum tillage within the future scenario would lead to an increase of up to 8% of the mean yield of winter wheat. This effect mainly resulted from improved water supply to the crop, associated with higher soil water storage capacity and decrease of unproductive water losses. Hedgerows, which reduce the wind speed, were predicted to have particularly positive effects on medium and moderately fine-textured soils such as Chernozems and Fluvisols. With both management changes, regional mean-yield level can be expected to be +4% in comparison with no management changes in the future conditions. Compared with the baseline period, water demand for the potential yield of winter wheat would require 6–37 mm more water per crop season (area-weighted average). The highest water demand would be on medium-textured soils, which make up the largest amount of area in the study region. Additionally, the effects of snow accumulation near hedgerows would further increase the yield, but would also lead to higher N leaching rates. However, specific management options, such as minimum tillage and hedgerows, could contribute towards reducing the increasing water demand.

Developing a reduced-form ensemble of climate change scenarios for Europe and its application to selected impact indicators

This paper presents a method for identifying a representative subset of global climate models (GCMs) for use in large-scale climate impact research. Based on objective criteria (GCM performance in reproducing the seasonal cycle of temperature and precipitation, and a subset ability to represent future inter-GCM variability), two candidate subsets are selected from a reference set of 16 GCMs. An additional subset based on subjective expert judgement is also analysed. The representativeness of the three subsets is validated (with respect to the reference set) and compared for future changes in temperature, precipitation and Palmer drought index Z (direct validation), and occurrence of the European corn borer and snow-cover characteristics implemented in the CLIMSAVE Integrated Assessment Platform (indirect validation).The direct validation indicates that one of the objective-based subsets (ECHAM5/MPI-OM, CSIRO-Mk3.0, HadGEM1, GFDL-CM2.1 and IPSL-CM4 models) provides the best choice for the Europe-wide climate change impact study. Its performance is balanced between regions, seasons and validation statistics. However, the expert-judgement-based subset achieved slightly better results in the indirect validation. The differences between the subsets and the reference set are generally much lower for the impact indices compared to their mean (across all GCMs in the subset) changes due to projected climate change. The ranking of the candidate subsets differs between regions, climatic characteristics and seasons, demonstrating that the subset suitability for a specific impact study depends on the target region and the roles of individual seasons and/or climatic variables on the processes being studied.

Climate Change Impacts on Czech Agriculture

Chapter summarizes the major impacts of changing climatic conditions in the Czech agriculture. Specific case studies are performed for the whole country (arable land) and are processed through GIS in the spatial grid 500 x 500 m respectively 1 x 1 km if middle Europe is considered. Contribution presents the impacts of climate change on the production of two major field crops (winter wheat and spring barley) in the Czech Republic for different future time horizons (2030, 2050 and 2100). The yield study includes not only the effect of climatic conditions but also the fertilization effect of carbon dioxide. Study is completed by effects of rising temperatures on the spread of temperature-depending biotic factors (selected pests) and changes in agroclimatic conditions for field crops. The basic data which are needed and used are long-term database of the national meteorological service and agricultural organizations which was used for evaluation of growth models (e.g. CERES). Other used tools are models which allow describe the evolution of pests in new climate conditions (e.g. CLIMEX or ECAMON) and various meteorological indieces. Description of expected weather conditions are based on two emission scenarios, according to the IPCC (mostly SRES-A2 and -B1) and three GCM models (NCAR-PCM, ECHAM5 and HadCM3). Their open access monthly outputs are published for the individual time horizons (e.g. 2030, 2050 and 2100) and are prepared in the daily time step by stochastic weather generator. The impacts of climate change are determined by comparing the current and expected state observed phenomena.