The Price of Procrastinating Coastal Adaptation to Sea-Level Rise

Abstract:

Sea-level rise is causing damages to coastal areas all around the world. Predictions of future sea-level rise are critical for planning future adaptation methods to mitigate damage to coastal areas. Two common types of adaptation are protecting the land by building seawalls or retreating further inland. In order to determine which method, and to what level of protection, is best for each coastal segment, we use a model for Coastal Adaptation and Impacts (CIAM). This model examines the sea-level rise, storm surge hazard, and other socioeconomic factors throughout the 21st century to determine which adaptation method will be the most economically-efficient for each individual coastal segment. Our model assumes the optimal adaptation method is implemented within the ten year time horizon, and that we have perfect information about sea-level rise on this time-frame. Here, we show the total costs associated with sea-level rise increase dramatically when the adaptation is delayed. We find that by the year 2050, the annual average cost when adapting optimally in the United States increases from $12.7 billion with no delay to $20 billion with a 10-year delay. With a 20-year delay, this increases to $25.3 billion in average annual costs. Our results demonstrate the importance of not delaying action to adapt to sea-level rise. Delaying adaptation now will only increase costs in the future.