Precipitation

Without concerted efforts to mitigate climate change, by the middle of the century, an average summer could have up to 25% less precipitation. In terms of winter precipitation, an increase of up to 20% is possible. However, with a rapid and comprehensive reduction in global greenhouse gas emissions, the changes in precipitation could be moderated.

The further changes to the climate depend on the global emissions of greenhouse gases. The values listed below show how precipitation is projected to change with climate change mitigation (emission scenario RCP2.6) and without mitigation (RCP8.5) in the near future (2035), by the middle of the century (2060), and towards the end of the century (2085).

What do RCP2.6 and RCP8.5 mean? You can find an explanation of the emission scenarios here.

What does "the middle of the century" mean? You can find an explanation of the CH2018 time periods here.

Seasonal precipitation trends

Average precipitation tends to decrease in summer and increase in winter. Because most parts of Switzerland currently have more precipitation in summer than in winter, this would mean that precipitation levels even out over the year. In addition, precipitation in the winter months would tend to fall more often as rain because of the higher temperatures.

In the near future, the possible effects of climate change mitigation are not substantial, but these effects will increase progressively towards the end of the century. If greenhouse gas emissions continue to rise unabated (RCP8.5), summer precipitation towards the end of the century could be up to 39% lower than today. A rapid and global reduction in greenhouse gas emissions (RCP2.6) could effectively mitigate this decrease (-16% to +9%). Winter precipitation will continue to increase (+2% to +24%) without climate change mitigation (RCP8.5). Here, too, the upward trend could be mitigated. Precipitation is subject to large natural fluctuations, which is why the effects of climate change are less noticeable than with the temperature trend.

 

Change in winter precipitation (%)

Change in summer precipitation (%)

RCP2.6

RCP8.5

RCP2.6

RCP8.5

Possible in the near future

-6 to +18

-1 to +16

-16 to +6

-13 to +8

Possible from the middle of the century

-1 to +16

-3 to +21

-16 to +7

-25 to +9

Possible towards the end of the century

-3 to +19

+2 to +24

-15 to +9

-39 to +2

Possible range of changes around 2035, 2060, and 2085 in comparison to 1981–2010 with climate change mitigation (RCP2.6) and without (RCP8.5, simulation range). Typical 30-year averages across Switzerland.

Spatial pattern of precipitation change

The relative changes in seasonal precipitation up until the middle of this century (2060) are greatest in southern Ticino and in central Switzerland. In summer, we can expect a country-wide reduction in average precipitation. More details on regional variations in climate change in Switzerland can be found here.

The graph below shows the average seasonal precipitation for winter and summer and the expected relative change in these precipitation levels as a percentage for the period around 2060. Click on RCP2.6 or RCP8.5 to switch between the different Scenarios.

Last modification 15.11.2018

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