The Economic Impact of Sea-level Rise on Nonmarket Lands in Singapore Author(s): Wei-Shiuen Ng and Robert Mendelsohn Source: AMBIO: A Journal of the Human Environment, 35(6):289-296. 2006. Published By: Royal Swedish Academy of Sciences DOI: http://dx.doi.org/10.1579/05-A-076.1 URL: http://www.bioone.org/doi/full/10.1579/05-A-076.1 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Article Wei-Shiuen Ng and Robert Mendelsohn The Economic Impact of Sea-level Rise on Nonmarket Lands in Singapore such as beaches, marshes, and mangroves. Because they provide Sea-level rise, as a result of climate change, will likely pleasure to many people, they are often not traded on markets inflict considerable economic consequences on coastal and have no monetary market value. It is therefore not obvious regions, particularly low-lying island states like Singapore. how much should be spent to protect these resources from Although the literature has addressed the vulnerability of inundation. This study analyzes whether abandoning natural developed coastal lands, this is the first economic study to areas or protecting them is more efficient. Protection is advised address nonmarket lands, such as beaches, marshes and only if the benefits of protection are higher than the costs (11). mangrove estuaries. This travel cost and contingent We assess the benefits of protecting each coastal resource using valuation study reveals that consumers in Singapore a willingness-to-pay survey and a travel cost study. These attach considerable value to beaches. The contingent valuation study also attached high values to marshes and benefits are then compared with the costs of protection. mangroves but this result was not supported by the travel The next section describes the physical benefits associated cost study. Although protecting nonmarket land uses from with preserving beaches, marshes, and mangroves. The section sea-level rise is expensive, the study shows that at least following that describes the methodology used to value the highly valued resources, such as Singapore’s popular benefits of protecting these public resources. Results are beaches, should be protected. subsequently presented from the travel cost analysis and contingent valuation survey, and the last section describes the cost of protection for each resource. The paper concludes with policy recommendations for Singapore to address desirable INTRODUCTION AND LITERATURE REVIEW adaptation in natural areas to sea-level rise. The consequences of sea-level rise due to global climate change PHYSICAL BENEFITS have significant social and ecological impacts on coastal regions throughout the world. Global sea-level rise is caused primarily The shore zone has natural features that provide considerable by thermal expansion of seawater from rising ocean tempera- coastal protection. Sand and gravel beaches contribute as wave tures and also by melting of terrestrial ice, glaciers, and ice energy sinks, and barrier beaches act as natural breakwaters sheets (1, 2, 3, 4). Intergovernmental Panel on Climate Change (12). Coastal vegetation absorbs wind or wave energy, retarding (IPCC) has projected that sea levels will rise on average by five shoreline erosion. Marshes act as a sea defense (13), and mm per year over the next 100 years and could possibly rise mangroves are sediment traps (14) that act as a buffer zone even faster (5). These changes are important because they have between land and sea and play a significant role in protecting the potential to alter ecosystems and habitability in coastal both the coastal areas and coral reefs at the same time (7). If regions, which are home to an increasing percentage of the these ecological functions of the natural coastal systems are lost, world’s population, habitat for much of the world’s fisheries, coastal resilience would decline. As sea level rises, beach and vacation spots across the world (6). erosion, wetland displacement, and mangrove species inunda- Since the impact of sea-level rise varies among coastal regions, tion will occur, unless adaptation measures are implemented in it is important to assess each nation’s vulnerability to sea-level time. Beach erosion will move the shoreline, shifting the beach change (7). The degree of influence depends on the area that may profile closer inland (15). One method of preventing beach be inundated, the cost of potential adaptation measures, and the erosion is continual beach nourishment, which preserves ability to adopt such measures. Small island states are among beaches in their current conditions and discourages further some of the most vulnerable regions in the world to sea-level rise. erosion. Another approach is to build undersea seawalls and Climate change and sea-level rise will no doubt pose a serious backfill sand behind these hard structures. In both cases, the threat to small island states like Singapore (8). beach could continue to be used for recreational purposes. Global climate change and global sea-level rise are beyond Singapore has already installed hard undersea structures for Singapore’s control (9), but Singapore does have adaptation land reclamation (16). Beach protection is expensive, but it is a options that can reduce damages. IPCC 2001 argued that the feasible option. most serious considerations for some small island states is As for marshes and mangrove estuaries, natural inland whether they will have adequate potential to adapt to sea-level migration could be a protection measure. The impact of sea- rise within their own national boundaries (5). Singapore has the level rise on marshes and mangrove estuaries depends on financial capacity to protect its developed lands, and it will be vertical accretion rates and space for horizontal migration, able to carry out effective adaptation measures. In a recent because increasing sea level will destroy current habitats, hence, study, Ng and Mendelsohn (10) demonstrated that Singapore marsh and mangrove species would have to shift to new tidal should protect all of its market lands from inundation. The cost areas (5). Coastal ecosystems are threatened when marshes of protecting Singapore’s developed coast is much less than the drown because they do not accrete vertically fast enough (17). value of the potentially inundated land. They develop ponds as they drown and eventually can This study focuses on the economic impact of sea-level rise disappear entirely (6). The vertical accretion of the marsh on nonmarket lands in Singapore. Although the economic surface must occur at a rate at least equal to the rate of relative literature on sea-level rise has addressed developed lands, this is sea-level rise, in order to maintain an elevation for marsh the first study to address land that is not developed. Nonmarket vegetation to survive (17). Sea-level rise could thus easily alter lands are jointly consumed by many people and include areas marsh hydrology and affect the rate of net vertical accretion. Ambio Vol. 35, No. 6, September 2006 Ó Royal Swedish Academy of Sciences 2006 289 http://www.ambio.kva.se Z ‘ Mangroves go through similar processes when sea level rises. WTP ¼ VðtiÞdt: Eq: 3 When the rate of sea-level rise exceeds the rate of sedimentation, Ti substrate erosion, inundation stress, and increased salinity will where willingness to pay (WTP) is the annual value to the occur (18), mangrove species zones will migrate inland, and seaward margins will die back (7, 19). These events could individual of the site. The social value of a site is the sum of the happen to the mangrove estuaries on the western and northern consumer surplus values of all the individuals who visit that coasts of Singapore with increasing sea level (20). particular site (26). Coastal wetlands would naturally migrate inland in response to relative sea-level rise. However, in Singapore’s case, highly Contingent Valuation Method developed land behind the wetlands will prevent adequate sediment supply to the mangrove estuaries (20) and will inhibit The contingent valuation method (CVM) uses surveys of public the natural migration of mangroves as sea level rises. This opinion to estimate the nonmarket values associated with changes creates a complex problem, since protecting nonmarket lands in the environment. Numerous previous studies have applied will often imply sacrificing developed lands. Previous studies CVM in various valuations of natural resources (27, 28, 29, 30). have estimated that as more developed lands are protected, The contingent valuation method asks the sample population there will be a greater loss of wetlands (21, 22, 23, 24). The hypothetical questions about their willingness to pay for a site. extent of the impact of sea-level rise will depend on the decision Since this method could cover both use and nonuse values, it to either protect or modify the coastline, therefore allowing was chosen in this study to measure the nonmarket values of coastal wetlands to migrate inland (25). A tradeoff exists beaches, marshes, and mangroves in Singapore. The average between preserving nonmarket lands and protecting developed willingness to pay observed in the sample was then extrapolated lands, as human infrastructure will prevent coastal wetlands and to the entire adult population in Singapore to obtain an mangroves from migrating inland as sea level rises.