The Swiss climate scenarios describe the possible future development of the climate in Switzerland. Researchers have used a variety of climate simulations to estimate the future climate. These climate simulations are based on assumptions about how the world could develop in the future in terms of various socio-economic aspects, which in turn influences how much energy is consumed and how much greenhouse gases are emitted. These possible development paths are referred to as emissions scenarios and are internationally defined scenarios.

The emissions scenarios consist of two components: the Shared Socioeconomic Pathways (SSPs) and the Representative Concentration Pathways (RCPs).

Shared Socioeconomic Pathways

The SSPs describe possible future economic and social developments such as population, gross domestic product and urbanisation. There are five different SSPs (SSP1 to SSP5). Depending on socio-economic development, there are different possible greenhouse gas emissions and thus greenhouse gas concentrations. These possible development paths of greenhouse gas concentrations in the atmosphere are referred to as RCPs.

Representative Concentration Pathways

The RCPs describe possible future greenhouse gas concentrations, which in turn determine the extent of future warming. The IPCC has defined six representative development pathways: RCP1.9, RCP2.6, RCP4.5, RCP7.0 and RCP8.5. The numbers refer to the additional anthropogenic radiative forcing in W/m² towards the end of the 21st century compared to 1850. The RCP2.6 scenario assumes an additional radiative forcing of 2.6 watts per square metre by the end of the 21st century, while the RCP8.5 scenario assumes 8.5 watts per square metre. The greater the radiative forcing, the stronger the global warming.

Emissions scenarios (SSP-RCP) used in the Swiss climate scenarios

Three different SSP-RCPs are used in the Swiss climate scenarios: SSP1-RCP2.6, SSP2-RCP4.5 and SSP5-RCP8.5.

The 2-degree path (SSP1-RCP2.6)

The SSP1-RCP2.6 scenario represents a sustainable development path. In this scenario, rapid and global climate mitigation measures are taken in line with the Paris Agreement. Global warming is limited to less than 2 °C compared to pre-industrial levels.

The “middle ground” (SSP2-RCP4.5)

In the SSP2-RCP4.5 scenario, current developments (as of 2022) continue into the future. Limited climate mitigation measures are implemented, and economic development continues to rely in part on fossil fuels. The challenges of adapting to climate-related risks are growing.

The fossil fuel path (SSP5-RCP8.5)

In the SSP5-RCP8.5 scenario, fossil fuels are actively and increasingly used, and energy consumption is high. Very few climate mitigation measures are implemented. The climate is changing drastically. The very high challenges of climate change adaptation are addressed through international cooperation.

The climate scenarios describe the local impacts that may result from different emissions scenarios. Which of these developments occur depends on future social, economic and political decisions. Appropriate measures can therefore limit the severity of the impacts of climate change.