“We want to know where the line is”: comparing current planning for future sea-level rise with three core principles of robust decision support approaches

Figures & data

Table 1. Decision processes studied and their organisations.

Main organisation and level of operation	Decision process studied and location	Description	Date of decision
Swedish Nuclear Fuel and Waste Management Co. (SKB). National level.	Designing a repository for the final storage of short-lived radioactive waste in Forsmark. South East Sweden.	The repository is associated with extremely high safety requirements and is located by the sea. It will be built in 20 years and be open for another 80 years, during which it will be vulnerable to flooding.	In progress
City of Gothenburg, 557,000 inhabitants. Local level.	Producing a detailed plan for new housing. Western Sweden.	The City of Gothenburg has developed several local plans for new buildings in the central area of the town. One of these areas, Götaverksgatan, is threatened both by flooding from the river Göta Älv and by rising sea levels.	2014
Swedish Transport Administration. Regional level.	Producing a plan for a railway connection in a tunnel. Western Sweden.	The West Link is a railway connection in a tunnel under the center of Gothenburg. The tunnel is estimated to be brought into operation in 2026 and is constructed to be safe from flooding during its 120-year lifespan. There has been a planning process to prevent the tunnel from being flooded.	2016
Nacka municipality, 100,000 inhabitants. Local level.	Producing a new comprehensive plan. Eastern Sweden.	Nacka is situated in the greater Stockholm area and has a long and highly exploited coastline that will be further developed. The newest comprehensive plan contains some guidelines for coping with rising sea levels when exploiting the coastline.	2012
Haninge municipality, 85,000 inhabitants. Local level.	Producing a new comprehensive plan. Eastern Sweden.	The same decision context as for Nacka municipality.	2016

Table 2. Summary of findings.

Organisation	How uncertainties were handled	The use of bottom-up approaches	The use of static versus flexible solutions
The Swedish Transport Administration	The administration made an assumption of a reasonable sea level rise by 2100 based on SMHI´s estimate and added an “uncertainty margin” to this level.	A top-down approach was used in which the future climate was a starting point in the planning process. In the next step, possible consequences of the future climate were described for the infrastructure studied. Finally, possible adaption measures were identified.	Flexible solutions were chosen with measures identified for three different levels of the sea. Future measures were prepared, for example by reservation of land when needed.
Swedish Nuclear Fuel and Waste Management Company	The company made its own assessment of a maximum global sea level rise by 2100 and did not rely only on information from SMHI.	Same as above.	A static solution was chosen on where to lay the foundation level of the surface facility. It was planned at such a height that it can handle the most extreme scenario of future sea level rise.
City of Gothenburg	The municipality acted much in the same way as the Swedish Transport Administration by making its own estimation of sea level rise based on scientific literature and by adding a security margin.	Same as above.	The city has a planning directive for the lowest level of the grounds of new buildings. Besides that, flexible solutions were chosen, such as preparing to raise the street level and the floor of the buildings in case of need in the future. Also, solutions on a larger scale were planned for long-term management of flood risks.
Haninge municipality	The municipality asked for, and was provided with, one planning level describing a reasonable future sea level rise. No uncertainties in this level were considered.	Same as above.	Static solutions were chosen on where to locate new houses. That means that new houses should not be built less than 2.7 meters below the present sea level. No further adaptation measure were thought to be needed.
Nacka municipality	Same as above.	Same as above.	Same as above.