Long-term climatic variability in Calabria and effects on drought and agrometeorological parameters

In recent decades a general change in climate has been documented in several
locations over the world. Such changes could have significant effects on various environmental
scenarios, including water resource management, agriculture, hydrology and ecosystems.
The complex topography and coastlines of Mediterranean regions influences the
climatic regime exhibiting substantial fine-scale spatial variability. In Italy, the climate is
generally becoming warmer and drier, with quite large differences depending on the site and
data treatment. In this study a historical set of meteorological data (110 precipitation and 28
temperature series), collected over 1921–2007 in the Calabria region (Southern Italy) was
analysed. Several meteorological and agrometeorological indices were selected for whether
they could evaluate the potential effects of climate change on water availability for natural
vegetation and cultivated plants. The significance of the analysed time series (monthly,
seasonal and annual time scales) was evaluated by using statistical trend analysis (Mann-
Kendall and t-test). Moreover, the intensities of drought events were determined using the
Standardized Precipitation Index (SPI) for the time scales of 3 and 6 months. The analysis
highlighted a general decrease in annual precipitation and an increase in drought intensity.
At a regional level, yearly precipitation decreased by almost 318 mm/100 years (representing
almost 30 % of the yearly mean precipitation in the region). Temperature changes were
more complex. On a regional scale, yearly mean minimum temperatures increased by 0.9 °C/
100 years and maximum and mean temperatures decreased by 1 °C/100 years and 0.8 °C/
100 years, respectively. Due to the asymmetric behaviour of temperatures, there was a
decreasing impact on evapotranspiration.