Climate change will also affect Switzerland

Five Swiss nationals are among the experts who contributed to the Intergovernmental Panel on Climate Change (IPCC) study released today. In conjunction with the global submission taking place in Geneva, the report was also commented on in Bern by the Swiss Academy of Natural Sciences.

«It is to be expected that extreme weather events, such as those that have recently occurred in Switzerland and Germany or are occurring in southern Europe, will rise in the future. These events will become more frequent and more intense, the first part of the IPCC’s sixth assessment report states.

A team of 234 scientists from 66 countries has assessed the state of knowledge on a scientific basis. With more data, a greater understanding of physical processes, and improved models, the certainty of many findings has increased significantly since the last report in 2013.

Since that time, greenhouse gases in the atmosphere have continued to increase. Between 2013 and 2019, the average concentrations of CO2 increased by nearly 5 %, methane by 3.5 %, and Nitrous Oxide (N2O) by 2.5 %. «The report shows that the atmospheric CO2 baseline concentrations in 2019 were 47% higher than at the beginning of the industrial era and overall higher than at any time in the last two million years,« said Gian-Kasper Plattner of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), author of the IPCC report. The global surface temperature between 2011 and 2020 has averaged about 1.1 degrees Celsius higher than in the pre-industrial era (1850 to 1900). The frequency and the intensity of heat waves and extreme precipitation events have increased since 1950.

Man-made origins

According to the IPCC, the main cause of these evolutions is human-induced climate change. «It is extremely unlikely that some of the heat waves observed recently could have occurred without human influences,« says Sonia Seneviratne, a professor at ETH Zurich who is in charge of the chapter on weather and climate extremes.

Global temperatures will continue to rise until mid-century. The extent of the increase will depend on new emissions. Erich Fischer, another author of the report, who is also an expert at ETH Zurich, adds that «global warming can still be limited to less than 1.6 degrees Celsius with more than 50 percent probability, and most likely to less than 2 degrees, only if carbon dioxide emissions decrease rapidly in the coming years and are reduced to zero by 2050.