Snow and ice — snow, glaciers and ice sheets

The snowfall amount index reports precipitation falling as snow over the snow season, which was chosen here as November to April. Other definitions of the snow season can be adopted depending on the regional climate conditions.

Owing to the insufficient spatial resolution of current climate models, a single model grid cell may cover a wide altitude range with very different snow conditions, in particular in mountain regions with varied topography. Therefore, the figures shown here are based on data for 100-m-elevation bands for NUTS3 regions, which were retrieved from the Copernicus Climate Change Service (CS3) Climate Data Store (CDS) data set based on an ensemble of nine bias-adjusted EURO-CORDEX simulations. For illustration purposes, these data were then aggregated to determine snowfall amounts for two broader elevation ranges, of 500-1 400 m (low to medium elevation) and 1 500-2 400 m (medium to high elevation) using digital elevation data to weight the snowfall values of the narrower elevation bands using the model data.

Index factsheet (ETC/CCA Technical Paper): Snowfall amount

Relevance

The index indicates the overall availability of snow, which is relevant for various sectors, including winter sport and water management. Furthermore, excessive snow can be a hazard for buildings and transport infrastructure.

Past and projected changes

Available studies summarised by the Intergovernmental Panel on Climate Change show that annual snowfall has generally decreased across Europe due to increasing temperatures, especially at lower elevations (IPCC, 2019: High mountain areas).

Regions with large amounts of snowfall in Europe are concentrated in northern Europe, the Alps and — to a lesser degree — the Carpathians and mountain regions in southern Europe. Snowfall is projected to decrease substantially in central and southern Europe. In southern Europe, snowfall events could almost disappear by the end of the 21st century at lower elevations. In northern Europe, changes in snowfall depend on the balance between the overall amount of precipitation, which is projected to increase, and the proportion of precipitation falling as snow, which is projected to decrease, in particular at lower altitudes and under the highest emissions scenarios. Therefore, the direction of projected changes in these regions depends on the altitude level and the emissions scenario.

Further information (European Climate Data Explorer): Total winter snow, 2011-2099 

Notes:   The top panel shows the 1986-2005 mean values based on the median of historical model simulations. The central row shows the 15th and 85th percentiles of projected values for the near and far future. The projected changes compared with the 1986-2005 reference period are reported on the bottom row. Underlying data are aggregated into NUTS3 units. Empty areas correspond to units not containing the elevation range considered. Each unit displayed reports the weighted average of the values based on the fraction of the unit area covered by each 100-m-elevation step. The ensemble is composed of nine model simulations.

Source:  C3S CDS data set — Mountain tourism meteorological and snow indicators for Europe.

Current situation and projected changes in annual snowfall in Europe at medium to high elevation (1 500-2 400 m)

Notes:   The top panel shows the 1986-2005 mean values based on the median of historical model simulations. The central row shows the 15th and 85th percentiles of projected values for the near and far future. The projected changes compared with the 1986-2005 reference period are reported on the bottom row. Underlying data are aggregated into NUTS3 units. Empty areas correspond to units not containing the elevation range considered. Each unit displayed reports the weighted average of the values based on the fraction of unit area covered by each 100-m-elevation step. The ensemble is composed of nine model simulations.

Source:  C3S CDS data set — Mountain tourism meteorological and snow indicators for Europe for Europe from 1950 to 2100 derived from reanalysis and climate projections .

Definition

Definition

This index accounts for the total number of days in a year with the water equivalent of natural snow above a given threshold (here, 100 kg m², corresponding to a medium amount of snow). Alternatively, the index can be defined in terms of snow depth, depending on data availability. Moreover, different definitions of the snow season and different thresholds of snow cover can be adopted depending on the specific application and local climate.

Snow cover is generally computed using climate models, but the use of dedicated snowpack models is strongly recommended to assess past and projected changes. The index presented here was computed using the Crocus snowpack model driven by an ensemble of nine bias-adjusted EURO-CORDEX simulations. The original index values were provided for NUTS3 units in steps of 100-m elevations.

The figures below show the number of days per year with a medium amount of snow for the elevation ranges of 500-1 400 m (low to medium elevation) and 1 500-2 400 m (medium to high elevation). They were computed based on the values for the 100-m-elevation bands and the elevation distribution of each NUTS3 unit. Note that in northern Europe areas with an elevation below 500 m can also have a long snow season and be important for winter sport.

Index factsheet (ETC/CCA Technical Paper): Period with snow water equivalent above a threshold

Relevance

The index provides information on the amount of snow cover, which can be easily interpreted and used in various applications, especially those related to winter sport and water management.

Past and projected changes

Regions with a long snow season with (at least) medium snow levels are concentrated in northern Europe, the Alps and — to a lesser degree — the Carpathians.

Snow cover extent and snow water equivalent have decreased in recent decades across most of Europe. Furthermore, the snow seasons have become shorter in northern, western and eastern Europe, mainly driven by earlier snow melt in spring. Some increase in snow mass was observed at higher altitudes in northern Europe as a consequence of increasing winter precipitation.

The length of the snow season is projected to decrease substantially, with reductions of more than 100 days by the end of the century expected in some regions. The absolute shortening of the snow season is expected to be greater in regions where the current snow season is longer.

Further information (European Climate Data Explorer): Days with a high amount of natural snow, 2011-2099

Further information (EEA Indicator assessment): Snow cover

Notes:   The top panel shows the 1986-2005 mean values based on the median of historical model simulations. The central row shows the 15th and 85th percentiles of projected values for the near and far future. The projected changes compared with the 1986-2005 reference period are reported on the bottom row. Underlying data are aggregated into NUTS3 units. Empty areas correspond to units not containing the elevation range considered. Each unit displayed reports the weighted average of the values based on the fraction of unit area covered by each 100-m-elevation step. The ensemble is composed of nine model simulations.

Source:  C3S CDS data set — Mountain tourism meteorological and snow indicators for Europe for Europe from 1950 to 2100 derived from reanalysis and climate projections.

Current situation and projected changes in in days with medium amount of snow in Europe at medium to high elevation (1500-2400 m)

Notes:   The top panel shows the 1986-2005 mean values based on the median of historical model simulations. The central row shows the 15th and 85th percentiles of projected values for the near and far future. The projected changes compared with the 1986-2005 reference period are reported on the bottom row. Underlying data are aggregated into NUTS3 units. Empty areas correspond to units not containing the elevation range considered. Each unit displayed reports the weighted average of the values based on the fraction of unit area covered by each 100-m-elevation step. The ensemble is composed of nine model simulations.

Source:  C3S CDS data set of Mountain tourism meteorological and snow indicators for Europe for Europe from 1950 to 2100 derived from reanalysis and climate projections.