Climate change is driving Switzerland towards drier and warmer weather with more rainfall but less snow. These are the scenarios unveiled on Tuesday by experts from MeteoSwiss, ETH Zurich and the University of Bern.
"We must prepare for and adapt to climate change," said Andreas Fischer, project manager for climate scenarios CH2018 at MeteoSwiss in Zurich. The climate forecasts form the basis of the federal climate change adaptation strategy.
These new scenarios confirm and clarify the image of climate change that we are already experiencing. The climate is expected to change in four major ways by mid-century if nothing is done globally: dry summers, tropical days, heavy rainfall and low snowfall winters.
In the long term, average rainfall amounts will decrease, leaving Swiss soil drier. During the summer, the average temperature will be 2.5 to 4.5 degrees higher than today. Droughts of about three weeks in summer are to be expected.
Maximum temperatures will trend upwards more dramatically than average temperatures. On the hottest days of summer, maximum temperatures could increase by 2 to 5.5 degrees compared with now.
Hot summers such as the ones Switzerland experienced in 2003 and 2018 could become the norm. Heat stress will hit densely populated, low-lying urban areas the hardest.
Experts predict that in the future heavy rainfall will be much more frequent and intense. The day with the highest annual rainfall will have on average about 10% more rain compared with the present day.
Winters will be much milder than today with a possible temperature increase of 2 to 3.5 degrees. There will be more precipitation, but in the form of rain. It will snow less and less frequently.
Decrease in snow-covered areas
In low-lying areas, snow cover will be about half as high as it is now. The isotherm of zero degrees could reach an altitude of 1,500 metres compared with 850 metres today. The snow-covered areas of the Alpine nation are likely to decrease, according to the experts.
The researchers calculated the Swiss climate for the next 100 years by considering two scenarios from the UN climate experts (IPCC): the first without climate protection and the second with measures that limit global warming to 2 degrees compared with the pre-industrial era.
"Significant climate protection would prevent almost half of all possible climate change in Switzerland by the middle of the 21st century and nearly two thirds of it by the end of the century," says Reto Knutti, a climate scientist at the ETH Zurich.
The CH2018 climate scenarios are the third of their kind after those of 2007 and 2011. With seven more years of data, trends can be discerned more accurately, according to Christoph Raible of the Oeschger Center for Climate Researchexternal link at the University of Bern.