Estimating the cost of sea level rise

Sea level rise increases the flood risk in coastal communities throughout the world. Many studies have shown that enormous property values are at risk already this century. In particular under high emission scenarios. Protecting infrastructure from flooding is thus an important objective for coastal spatial planning, and planning activities are ongoing in states, counties and municipalities around the world. Current coastal spatial planning methods are, however, not well tailored for this task. Problems persist in how such plans can incorporate: uncertainties, time dependence and the interplay between sea level rise and sea level extremes. Here we demonstrate how these different components can be incorporated into a joint probabilistic framework, using Monte Carlo methods. A model called the sea level simulator is used together with a cost function that estimates the value of infrastructure as a function of its height above the current mean sea level, giving a comprehensive coupling between physical and economic risk. That is, between high sea levels and economic loss. The end result is a probabilistic estimate of flooding loss conditioned on user-defined emission scenario probabilities. The framework is well fit both as a decision support tool and as a tool for making uncertainty quantifications. The capabilities of the framework are demonstrated using examples from one of Sweden's oldest cities, the city of Kalmar. Examples are given showing how losses and their uncertainty depend on emission scenario, the length of the planning period and thresholds in the cost curve