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Wet and dry — mean precipitation

Page Last modified 19 Nov 2021
3 min read
So much of life — and people’s livelihoods — depends on rain falling at the right time and in the right amount. Too much or too little can be devastating. Precipitation is vital to natural and managed ecosystems and to water supply, energy production and of course farming. Low rainfall at the wrong time in the growing season can severely affect crops, groundwater recharge and soil quality. Decreases in rainfall could aggravate local or regional conflicts among the different water users (agriculture, energy production, industry, households and tourism).

Key messages


  • Annual precipitation has been increasing in northern Europe and decreasing in the south, with no discernible trend either way in central Europe; these trends are likely to continue in the future.
  • Summer rains — so vital to natural ecosystems and agriculture — show signs of decreasing in central and southern Europe, with no change projected for northern Europe.

Total precipitation

 

Definition

The total precipitation index represents the total amount of precipitation over a given period (e.g. a whole year or a season).

Index factsheet (ETC/CCA Technical Paper): Total precipitation

Relevance

The simple definition of this index enables it to be easily applied and interpreted for a wide range of purposes and sectors, including water management, agriculture and hydropower production.

Past and projected changes

Annual precipitation at the pan-European level shows substantial interannual variability, but a significant trend cannot be detected, neither in recent decades nor in projections. At the regional level, however, an increase in annual precipitation has been observed in and projected for northern Europe, a decrease has been observed in and projected for southern Europe, and no significant trend has been observed in or projected for central Europe.

Projections for precipitation during the summer, which is particularly important for natural ecosystems and agriculture, suggest that precipitation will decrease in central Europe, as well as in southern Europe, whereas no change is projected for northern Europe.

Winter precipitation is expected to increase in northern and central Europe, especially under the high-emissions scenario (representative concentration pathway (RCP)8.5).

Further information (European Climate Data Explorer): Precipitation sum, 2011-2099


 Annual precipitation for the European land area and sub-regions

Annual precipitation

Notes:   The black lines show the annual values for 1950-2020 from reanalysis data, and the dashed horizontal lines show the means over 1986-2005. Solid grey, blue, yellow and red lines represent the ensemble medians of model simulations for the historical period and under low-, medium- and high-emissions scenarios (RCP2.6, RCP4.5 and RCP8.5, respectively) (smoothed by a 20-year moving average). Shaded areas show the 15th and 85th percentile ranges of the model ensembles. The size of the model ensemble used for each scenario is shown in the top right corner.

Source:  ERA5 and bias-adjusted CMIP5 data.

Summer precipitation for the European land area and sub-regions

Summer precipitation

Notes:   The black lines show the annual values for 1950-2020 from reanalysis data, and the dashed horizontal lines show the means over 1986-2005. Solid grey, blue, yellow and red lines represent the ensemble medians of model simulations for the historical period and under low-, medium- and high-emissions scenarios (RCP2.6, RCP4.5 and RCP8.5, respectively) (smoothed by a 20-year moving average). Shaded areas show the 15th and 85th percentile ranges of the model ensembles. The size of the model ensemble used for each scenario is shown in the top right corner.

Source:  ERA5 and bias-adjusted CMIP5 data.

Current situation and projected changes in annual precipitation in Europe 


Notes:   The top panel shows the 1986-2005 mean values based on the reanalysis. The central row and bottom row show the projected values and the projected changes, respectively, of the 15th and 85th percentiles for the near and far future. The size of the model ensemble used for each scenario is reported in the time-series figure above.

Source:  ERA5 and bias-adjusted CMIP5 data.

Current situation and projected changes in summer precipitation in Europe

Notes:   The top panel shows the 1986-2005 mean values based on the reanalysis. The central row and bottom row show the projected values and the projected changes, respectively, of the 15th and 85th percentiles for the near and far future. The size of the model ensemble used for each scenario is reported in the time-series figure above.

Source:  ERA5 and bias-adjusted CMIP5 data.

Chapters of the Europe's changing climate hazards report

  1. Heat and cold

  2. Wet and dry

  3. Wind

  4. Snow and ice

  5. Coastal

  6. Open ocean

                                                                               

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