Economic Value of Salt Marshes under Uncertainty of Sea Level Rise: A Case Study of the Narragansett Bay

Abstract

Salt marshes are an integral part of coastal ecosystems that are changing rapidly with sea level rise (SLR). Because marshes provide important ecosystem services, such as carbon sequestration and shoreline protection, it is critical to understand how their economic benefit values are likely to be affected by SLR. Such change, however, depends on the capacity of marshes to adapt to flooding by migrating inland. This study provides the economic value of changes in carbon and non-carbon benefits using predicted changes in salt marsh coverage in Narragansett Bay, Rhode Island under three SLR scenarios and two marsh adaptation conditions. We apply regional carbon prices and a value function transfer approach to value other salt marsh service values. Results indicate an average annual value of $1,863/acre for carbon and $2,537/acre for non-carbon ecosystem services. This yields a mean discounted value of $592 million (M) (+14% compared to no change) over 90 years. We discuss alternative management strategies to enhance marshes’ capacity to migrate inland, which may accrue as much as $659 M.