A 200-year climate record in Central Europe: implications for agriculture

Abstract

The close links of climate, soil conditions, and agricultural productivity have been used in Central Europe for taxation purposes since the eighteenth century. Since agroclimatic conditions are variable, their fluctuations in the past centuries can provide a valuable context for analyzing changes expected in the coming decades. Here, historical agroclimatic conditions and future projections were constructed for key agricultural regions in Central Europe. The agroclimatic zoning method used in this study incorporates (1) the sum of temperatures for days with a mean temperature above 10°C during the frost-free period, (2) the water deficit during the summer period from June to August, defined as the difference between precipitation and reference evapotranspiration, and (3) information regarding the suitability of soil and terrain for agriculture production based on twentieth century soil surveys. Changes in selected agroclimatological indices were also analyzed. To produce a weather series representing climate conditions between 1803 and 2008 over the study area, we used a stochastic weather generator trained on high-quality daily observations from 52 representative meteorological stations during the baseline period from 1961 to 1990. To estimate the extent of agroclimatic zones and the values of selected agroclimatic indices, the parameters of the weather generator were perturbed by the deviations of the temperature and precipitation means from the baseline using a long-term climate series from 1803 to 2008, from Brno. To generate a weather series representing the climate in 2050, we used an approach known as “pattern-scaling” in combination with outputs of three general circulation models. To our knowledge, this is the first study analyzing both continuous fluctuations in agroclimatic conditions over the past 200 years and expected shifts in the coming decades over Central Europe.

In the study region, our results demonstrate that changes in climate factors since the second half of the twentieth century have favored the expansion of warmer and drier agroclimatic conditions in the most fertile areas, progressively endangering the sustainability of rain-fed agriculture. Conversely, the agroclimatic conditions of regions at higher elevations have improved over the past six decades, as witnessed by increases in maize production areas but also an influx of previously absent pests, e.g., the European corn borer. The length of the vegetation summer has been increasing and shows daily average temperature exceeding 15°C. The mean number of days with snow cover has decreased by up to 30 days since a peak in the late nineteenth century. In lowland areas, the date of the last frost, with a 20-year return period, has moved closer to beginning of the season. Our results show that the predicted rate of change is unprecedented in available agroclimatic records; thus, adaptation cannot rely on past. Consequently, agricultural producers in the region will be forced to significantly bolster their adaptive capacity and develop flexible procedures that reflect the rapidly changing agroclimatic conditions.