Evapotranspiration plays an essential role in estimating water balance, runoff and effective precipitation. To determine historical and projected water availability for Europe, we contribute high‐resolution (1 km) estimates of monthly and annual potential evapotranspiration (ET0) and actual evapotranspiration (AET0). In the ET0 calculation, the monthly and annual heat index I and annual α parameter were estimated following the Thornthwaite method, and AET0 was calculated using the Budyko approach. The variables were estimated for a climate normal period that largely precedes an anthropogenic warming signal (1961–1990), and for two CMIP5 multi‐model future projections (2011–2040 and 2041–2070). We project widespread and relatively uniform ET0 increases of around 50–100 mm by the 2020s and 75–125 mm by the 2050s for most of Europe. These values imply important changes that may affect runoff and groundwater recharge. AET0 was identified as important driver of water availability with more regional variability. Spatial mapping of changes relative to the normal baseline imply that all except northern parts of Europe are vulnerable to water deficits, with pronounced decrease expected in southern Europe. We provide high‐resolution maps and data as an important tool for future natural resources management and climate change mitigation planning.

The spatial distribution of precipitation, temperature and climate indices has been represented in the Emilia‐Romagna region with an aim to characterize its climate. The Johansson Continentality Index, the Kerner Oceanity Index, the De Martonne Aridity Index and the Pinna Combinative Index are the climate indices used in the present report based on data from 21 meteorological stations located in Emilia‐Romagna and its surroundings. The analysed climate data are from the 1961–1990 period. Monthly precipitation and temperature diagrams from the Borgo Panigale station were computed for use in agricultural fields, hydrological sciences and climatology applications. Based on the findings of the climate analysis, the spatial variation of climate indices was estimated using the Kriging ordinary function, available in ArcGIS 10.2.2 environment.

Evapotranspiration and water availability are driven by changing climate and land cover parameters. In the present study, climatological records and land cover data were analysed simultaneously to accomplish the spatial distributions of climate change effects on water resources in Varanasi district, north India. Humidity–aridity was assessed by Lang's rain factor and De Martonne's aridity index, based on mean monthly rainfall and air temperature from seven meteorological stations. The climate change effect on water resources was evaluated using a 5 × 5 matrix that includes water availability and the aridity index by considering two time periods: 1941–1970 (1950s) and 1971–2000 (1980s). The methodology is based on seasonal crop evapotranspiration (ET_c) (initial, mid‐season, end season and cold season) and annual water availability calculations. The high values (≤ 1,045 mm) of ET_c were identified during the mid‐season stage. Water availability indicates decreases in the maximums from 718 to 636 mm during the two analysed periods, with a negative impact at the spatial scale. Lang's rain factor (< 40) indicates an arid climate in the northwest, west, east and central parts of the district and a humid climate (Lang's rain factor > 40) in the south. De Martonne's aridity index indicates rapid aridization from south to north (28.3 in the 1950s and 25.6 in the 1980s). The high and very high climate effects on water resources in Varanasi district were found mainly in the crop lands, while in the urban areas the climate effect is low. The much affected area by climate change and land cover was depicted during the recent period (1980s). This statement was proved also by the Mann and Kendall test, which indicates a negative trend for annual precipitation at all stations (for the period 1941–2000), while the mean annual temperature had a positive trend for four stations. These findings suggest that climate change had a negative effect on water resources during the last 60 years in the study area.

The impact of climate on crop evapotranspiration (ET_c) was assessed in the Pannonian basin for the present (1991–2020) and future (2021–2050). Annual temperature, annual precipitation and monthly potential evapotranspiration are the main climate data used in the present study. The European land cover database was used for the spatial recognition of terrain vegetation of the countries which are found in the Pannonian basin. A difference of maximum annual temperature from 19.9 to 20.8 °C was observed in the investigated area between 1991–2020 and 2021–2050. Precipitation rates decrease from west (1800 mm) to east (below 400 mm), and the potential evapotranspiration varies from 500 to 800 mm. Four stages of crop growth were identified and for each stage the crop co‐efficients were assessed. For present projections of climate data, the annual crop evapotranspiration variability is from 105 to 1087 mm and records the highest values in mid‐season stage, over 630 mm. Future projections indicate that in the central and southern part of the Pannonian basin the annual crop evapotranspiration will increase. For both present and future projections, the lowest crop evapotranspiration was found in the cold season, because of lack of heat and lower values of the crop co‐efficient.

The impact of climate change on groundwater vulnerability has been assessed in the Pannonian basin over 1961–2070. High-resolution climate models, aquifers composition, land cover, and digital elevation model were the main factors which served to perform the spatial analysis using Geographical Information Systems. The analysis reported here is focused on the long-term period, including three temporal time sets: the past period of 1961–1990 (1990s), the present period of 2011–2040 (2020s), and the future period of 2041–2070 (2050s). During the 1990s, the high and very high areas of groundwater vulnerability were identified in all the central, western, eastern, southeastern, and northern sides of the Pannonian basin. In these areas, the water availability is lower and the pollution load index is high, due to the agricultural activities. The low and very low vulnerability class was depicted in the South-West part of the basin and in few locations from the peripheral areas, mainly in the North and West. The medium groundwater vulnerability spreads over the Pannonian basin, but it is more concentrated in the central, South, and South-West. The most affected territory is Hungary, while the territories of Slovenia, Croatia, and Bosnia and Herzegovina are less affected. In the present and future periods, the very high groundwater vulnerability increased in areas by 0.74% and 0.87%, respectively. The low class area decreased between the 1990s and the 2020s by 2.33% and it is expected to decrease up to 2.97% in the 2050s. Based on this analysis and the groundwater vulnerability maps, the Pannonian basin appears more vulnerable to climate change in the present and future. These findings demonstrate that the aquifers from Pannonian basin experience high negative effect under climate conditions. In addition, the land cover contributes to this negative status of groundwater resources. The original maps of groundwater vulnerability represent an instrument for water management planning and for research.