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Climate Change in Switzerland

The climate in Switzerland is characterised by large natural fluctuations. However, certain changes that have taken place since industrialisation can only be explained in terms of the increase in greenhouse gases. The average annual temperature has seen an increase of a good 2°C since 1864 (as by 2021), for the most part in the last few decades. Most notably, there has been significantly less snow since the 1980s, and some changes in precipitation are now becoming apparent. According to current climate scenarios, the warming will continue into the future. Summers are becoming drier, and extreme weather events are increasing

The weather and its statistical characteristics, the climate of Switzerland, have been systematically monitored and measured for over 150 years. These data and careful processing of them are essential for being able to better understand climatic fluctuations and climate change, and to develop models that can give us a picture of how the climate will change in the future. In collaboration with partners, MeteoSwiss develops future climate scenarios on a regular basis. This is indispensable to adapt and evaluate the risks and opportunities associated with climate change.

Historic climate: Natural fluctuations and climate change

Weather observations and measurements from around the world indicate that climate is characterised by large fluctuations. Until the beginning of the 20th century, these fluctuations were primarily due to natural causes. Later on, there are effects, in particular the temperature rise of the last few decades, that can only be explained in terms of the increasing greenhouse gas emissions (climate change). The long temperature data series from Basel since 1755 (Figure 1) illustrates this situation very clearly: Natural fluctuations dominate the temperature up to the beginning of the 20th century. The steep temperature rise in the last few decades, on the other hand, is a consequence of the increasing greenhouse gas emissions (climate change).

Observed trends for temperature, precipitation and sunshine

The effects of climate change are evidenced in numerous weather parameters - with the most obvious being temperature. The atmosphere close to the ground has warmed by around 2.1°C since measurements began in 1864. That is about twice the rise in the average global temperature of around 1.1°C (as of 2021). For around 30 years, there has not been one year that has been cooler than the average temperature between the period of 1961-1990. Nevertheless, the temperature fluctuates from year to year, as shown in figure 2.

Precipitation, too, has changed in some regions. The average winter precipitation over the last 150 years has risen in most regions in Switzerland (with the exception of the southern Alps and large areas of Grisons). So far, no changes have been evident in the average summer precipitation. There are clear indications, however, that heavy precipitation events are slowly changing, as the intensity as well as the frequency of heavy precipitation events (daily totals) have increased since 1901. Nowadays, primarily in the low-lying areas, there are significantly fewer days with snowfall, and smaller amounts of new snow falling than 30 to 40 years ago. The number of hours of sunshine dropped significantly between 1950 and 1980. Since 1980, however, the trend is positive, and hours of sunshine are similar today to what they were at the beginning of the 20th century.

More hot days and frost days, earlier vegetation, more drought?

The observed increase of a good 2°C is a figure that is difficult for people to conceptualise. It is easier to gain a sense of the changes through figures (so-called climate indicators) that everyone is familiar with. For example, everyone knows what a summer's day feels like. So, temperature indicators are already showing significant changes: Summer days and hot days (maximum temperature equal to or higher than 25°C/30°C respectively) have seen a huge increase, while ice and frost days (maximum temperature lower than 0°C/minimum temperature lower than 0°C) have dropped substantially. As a consequence of rising temperatures, spring and summer development of vegetation is occurring significantly earlier nowadays than several decades ago. Whether drought is on the increase is at present not yet conclusive.

The climate of the future: Change will continue

Together with research partners, MeteoSwiss has been developing national Climate Change Scenarios for more than 10 years. These show the future climate development for Switzerland and are based on the current state of scientific research. Climate change scenarios are calculated using complex physical climate models and modern statistical methods. The current Climate Change Scenarios (CH2018) show four primary changes:

  1. Drier summers
  2. Heavier precipitation
  3. More hot days
  4. Winters with little snow