Socio-economic systems are complex: they are non-linear, disruptive, have feedback loops and tipping points, and their development is highly uncertain. This is why science-based scenarios on possible future socio-economic developments is a key tool for forward-looking policy and action planning. The future cannot be predicted, but thinking in terms of "if-then" developments allows policy decisions to be better aligned with possible developments. A scenario is not a prediction or a forecast, but a plausible and simplified description of how the future might unfold based on a coherent and consistent set of assumptions about the main driving factors. Switzerland has a long tradition of scenario work and trend analyses to support policy, including climate scenarios, energy perspectives, transportation perspectives, population scenarios, GDP and industry scenarios, long-term perspectives for public finances, as well as the prospective work of the Federal Chancellery regarding analyses of the situation and contexts.

Against this background, we have developed Shared Socio-economic Pathways for Switzerland (SSPs-CH - socio-economic scenarios) and Shared Policy Assumptions (SPAs - packages of climate policy instruments), in reference with the global SSPs of the IPCC. These Switzerland-specific scenarios complement the existing scenario work mentioned above in several respects: Firstly, they consider a longer time horizon up to the year 2100. Secondly, the SSP-CH take into account an unusually broad spectrum of possible, very different future developments. This mainly concerns changes in society, the economy and technology. Thirdly, against the background of these changes, the SPAs explicitly allow the impact of climate policies to be analyzed.

The Socio-economic Scenarios for Switzerland SSP-CH project consists of three components:

1. The Shared Socioeconomic Pathways for Switzerland  (SSPs-CH - socio-economic scenarios)

2. The Shared Policy Assumptions (SPAs - climate policy instrument packages)

3. Greenhouse gas and land-use modelling