Future sea level rise in municipal planning

A warmer climate leads to rising sea levels. Despite uncertainties about how rapid and substantial future sea level rise will be, society needs to prepare. In this report we examine how 33 coastal municipalities in southern Sweden plan for rising sea levels and what estimated future sea levels their planning is based on. We also analyse the responses in a number of interviews with individuals responsible for sea level planning at the studied municipalities, county administrative boards, the Swedish Civil Contingencies Agency (MSB), the Swedish Meteorological and Hydrological Institute (SMHI) and a consultancy firm. The greatest uncertainty in future sea level projections is how the inland ice sheets in Greenland and Antarctica will react to climate change. The reaction so far has been more rapid than previously thought. Recently, increasing levels have been mentioned in several articles published in scientific journals. In these articles, sea level rise is estimated to 1-2 metres by 2100 for the highest emissions scenarios. The sea will continue to rise for many centuries, even if greenhouse gas emissions cease completely. Local sea level rise differs from the global average and is affected by several factors. Our survey of municipal planning documents reveals that there are considerable gaps in current planning for future sea level rise. Almost one third of the municipalities studied have no estimates of future sea levels whatsoever in their planning. Among the municipalities that in fact estimate future sea levels, six out of ten lack clear sources for their estimates. SMHI is the dominant source for municipalities' estimates of future sea level rise. There is, however, considerable difference between the estimates of various municipalities. This illustrates the uncertainty that exists about what future sea level rise estimate is most reasonable to relate to. In recent years there is evidence of a trend that municipalities are using SMHI's estimate of a sea level rise of "around one metre" by 2100. Despite scientific studies indicating higher levels, most coastal municipalities in southern Sweden do not plan for sea level rise above one metre by the end of the 21st century. Currently planning for sea level rise beyond 2100 is lacking. SMHI, the County Administrative Board of Skåne and the municipality of Helsingborg emphasize the importance of planning more than 100 years into the future. However, few other municipalities plan for this time frame. This indicates that long-term planning for sea level rise needs to be improved. Our study reveals a lack of preparedness for more substantial sea level rise than estimated in current planning. The interviews show that even if several interviewees request planning for worst-case scenarios of future sea level rise, only MSB takes into account the worst possible outcome, as required by the European Union's Floods Directive. The study shows that municipalities and county administrative boards in southern Sweden demand increased clarity from the state, both in terms of concrete planning support and clear government guidelines for planning for sea level rise. Our study indicates a need for a government strategy for sea level planning in Sweden.