SOüETAL RESPONSES TO REGIOI{AL CLIMATIC CHAh{GE Forecasting by Analogy SOCIEI'AL REST'ONSES T-O RI.]GIONAI, CLIMATTC CHANGE F'orecasting by Analogy edited by Michael H. Glantz The hc¡t. dry summer of 1988 in North America has once again drawn attention to the prospects of an unprecedented warming of the earth's atmosphere. Whether the droughts and high temperatures prove to be the first signs of a global warming (popularly relbrred to as the greenhouse eftèct) is of less importance than the need to improve our understanding of the interrelationships between climate and society. In this book the contributors identify potential regional societal responses to a possible climatic change, taking a close look at several regional scenarios based on actual. prolonged, outlying climatic events that have occurred recently in North America. 1'he case studies identify actors at the local. regional. or federal lerels and assess their perceptions and responses, identifying the rigidities and flexibilities of various communities in dealing with climatic '- ¡ ^t -r lt- edited by Michael H. Glantz- change. ì The book also reviews the regional scenario approach and its policy implications, the use of analogies. and the role of extreme events in climate impact assessment. Michael H. Glantz is head of the Environmental and Societal lmpacts Group and senior scientist at the National Center fbr Atmospheric Research in Boulder. Colorado. For order and other information. please write to: WESTVIEW PRESS 5500 Central Avenue Boulder, Colorado 8030 I rsBN n-81,33-?t3r-'{ I Future Sea-Level Rise and Its Implicatíons for Charlestori, South Carolina Margaret A. Davidson and T.'W. Kana INTRODUCTION It is becoming increasingly accepted that there will likely be a doubling of atmospheric COz in the next century, which would raise the earth's temperature by L.5'-4.5"C (3'-8"F). A global warming of even a few degrees translates into an increase in sea level because increasing atmospheric temperatures would cause to warm and expand. Mountain glaciers, which have retreated in the last century, could melt more rapidly. Glaciers in Antarctica and Greenland could melt along the fringes, and portions of them could disintegrate and slide into the oceans (Meier, seawater 1e84). In 1983, a report from the National Researc.h Council estimated that worldwide sea level would rise 70 cm (2$ ft) in the next century (NRC, 1983), while a report from the U.S. Environmental Margaret A. Daaid,son is the Executiue Di,rector of the South Cørolina Sea Grønt Consortium. As ø løwyer ønd, a sc'ience rn&na4er, she i,s interested, in lhe reløt'i,onship between science anil d,eci,s'ionmølc'i,ng, pørti,culørly øt the stq,te and local leael. She ltøs organ'ized ønd pørticipateil in seaera,I worlcshops and, symposiø concerned, wi,th sea-leael rise. T.W. Køna'is presid,ent of Coøslul Science ønd, Eng'ineering, Inc. After recei,ui,ng a Ph.D. from Johns Hopkins Aniaersity, he tøught coasta,l geology at the Aniaersily of South Carolina. Among his møny coøstøI projects and, publicøtions øre two U.S. EPA-sponsored, projects on sea-leuel ri,se. 198 Protection Agency (EPA) stated that uncertainties regarding the factors that could influence sea-level rise were so numerous that a single estimate of sea-level rise was impossible and instead developed high, medium, and low scenarios (Hoffman et al., L983). The EPA report estimated that sea level would rise between 38 and 2I2 crn by the year 2075, with the likely range falling between 9L and 136 cm (3 and 5 ft), compared with a global rise in the last L00 years of 10 to 15 cm (4 to 6 in). Sea-level rise along the Atlantic coast of the United States has been L5 to 20 cm per century higher than the worldwide av€rag€r due to a subsidence trend that is expected to continue into the future. Although predicting the actual process of global warming requires an international effort, it is at the local level that some basic reactions to this phenomenon will take place. The will and the ability of individiral communities to respond to the range of effects engendered by global change is highly variable. Communities cannot prevent global warming; they can, however, aggravate or mitigate its impacts. Communities can pursue various land development patterns, construct physical barriers, or otherwise make adaptations to sea-level rise. To meet the challenge of a global warming, society will need credible as well as reliable information concerning the likely effects of sea-level rise. Unfortunatel¡ local areas generally do not have access to adequate information nor are they capable of anticipating and planning for long-term events like the localized impacts of a global warming of the atmosphere. So while the international and national communities debate and negotiate global responses to global warming, the effort at the state or local level is more fragmented. Places like Charleston, South Carolina-the focal point of this chapter-are among those low-lying communities that stand to lose the most if strategic planning is ignored, or delayed too long. Fortunatel¡ the rate of global warming and its pending impacts provide some lead time for planning. The question is what scenario is required to drive the planning process. 199 OVERVIE\A¡ OF THE CHARLESTON, SOUTH CAROLINA, REGION The Charleston region encompasses a variety of topographic features and settlement patterns that would be affected by sea-level rise. The historic and tourist areas-dating from 1"670 and including downtown Charleston-are located on a peninsula at the confluence of the Ashley and Cooper Rivers, which combine to form Charleston Harbor (which, in turn, forms the Atlantic Ocean, according to local legend) (Figure 1). Much of the peninsular city is built over former marsh areas that were filled in the nineteenth and early twentieth centuries; more than one-third of the structures on the peninsula are on ground less than five feet above mean sea level (Basilchuk, L986). The tip of the peninsula which contains the city's historic houses and most expensive residential real estate is protected by a seawall, built in the mid-1800s, and known as The Battery. During the present century, The Battery has been topped by waves associated with hurricanes. The metropolitan Charleston area, with a population of approximately 500,000, spreads across several rivers and some distance inland; it also includes resideniial a¡¡d resort development on a number of barrier islands. Elevation for much of this area averages approximately three meters (i0 ft) above mean sea level (Michel et al., 1983), and the region's topography is cha¡acterized by a number of tidal rivers and creeks, expansive marsh resources, and large areas of freshwater wetlands (hence the name "Lowcountry," by which much of coastal South Carolina is known). Over the past 20 years, rapid suburban development has been concentrated in the high ground and waterfront/marshfront locations within close (roadway) proximity to the peninsula, and development trends project both expansion and in-filling of the metropolitan area, mostly at low to moderate densities. Population and employment in the a¡ea are expected to grow by 16-28 percent within the next L2 years. \Materfront development is va¡ied. The Cooper River side of the peninsula, extending inland to the City of North Charleston, is primarily devoted to port activities and an extensive naval base, the third largest of the U.S. fleet. The Ashley River side of the 200 ciarbstnn è o ç Þ o d Johm ls. A t¡ Aft Figure l\o SCALE 1.5O I 2 æt 1 5 O 1 Skllomtor3 2m¡l€6 L peninsula includes a major arterial, a college, and residential development, while the side of the river opposite includes a state park, historic gardens, and substantial residential development. Additional waterfront development along the region's tidal rivers and creeks is predominately residential or recreational, or still undeveloped, but also includes commercial fishing berths, marinas, and shipyard operations. In addition to low topographic relief, ihe area has a tidal range of. 1..8-2.4 m (6-8 ft), with seasonal highs. As a result, the region is prone to flooding during periods of heavy rainfallparticularly when rainfall events coincide with high tides or strong easterly winds. There have also been several recent and notable winter storms with marked flooding and beach erosion. Historical trend analysis has shown that the inner estuarine marshes in the area have been accreting since 1939 (Michel et al., 1983). The stability of the barrier island beaches varies--some are 20L highly erosional, while others a¡e stable or accretional. Human activities have influenceil those trends. Computer modeling indicates that most of the region's barrier islands would be completely inundated by a moderately severe hurricane (winds exceeding 100 mph) hitting at high tide. Drainage systems are inadequate in many areas. For instance, the peninsula city's gravity-based drainage system dates from the 1800s. A 1984 plan proposed the expenditure of $130 million to upgrade the system and install a series of pumps, but to date adequate funding has not been forthcoming. As for wastewater treatment, there are four major treatment systems and a number of small ones in the region. The city of Charleston's system, which serves the city and a substantial suburban area, is based on an island in the Ashley River at 4.9 m (16 ft) above mea,n sea ievel. Due to an aging collection system, there is significant infiltration of floodwaters into the city's sewer system. Through intensive local efforts and federal investment over the past decade, most urban and suburban portions of the region are currently served by sewer lines or will be in the next few years. 'Water service is provided to most of the region by the city of Charleston (Commissioners of Public'Works) via a distribution system originating inland. The Back River Reservoir, located approximately 30 miles up the Cooper River and the site of the region's major new industries, provides a secondary but increasingly important source of raw water for the city's system. The recent completion of the U.S. Army Corps of Engineers' Cooper River rediversion project, transferring flows out of the Cooper River in order to reduce siltation in the harbor, has created the need to monitor and manage salinity in the Cooper River and Back River Reservoir, to ensure that the tidal salt wedge moving up the Cooper River is balanced by sufrcient freshwater flow to protect the reservoir. POSSIBLE IMPACTS OF SEA.LEVEL RISE Global sea-level rise produces direct impacts along coastal areas as well as some less obvious, indirect'impacts. These include flooding, erosion, saltwater intrusion, and habitat alteration. But the role played by sea-level changes is often difficult to distinguish 202 from other processes which overshadow the ocean's general rise over short time scales. For example, Charleston experiences daily tide changes of more than 1.5 m (5 ft), certainly a fluctuation that is hundreds of times greater than the yearly rise in sea level for the area. Storm tides occasionally raise water levels more than 3.0 m (10 ft) above mean sea level. The relevance of sea-level rise is that each of these phenomena is superimposed on the global, mean water level. Should sea level rise at a faster rate, new land areas and habitats will become exposed to tidal and storm surge processes. Much of the planning that must take place in the next few decades will necessarily begin with the baseline conditions existing today. For Charleston, water leveis effectively control development, habitat type and various infrastructure or administrative functions. These range from the "normal" limit of tidal imrndation, which delineates critical and protected wetland habitat or marshes, to the predicted 100year tidal flood elevation, which establishes minimum elevations for habitable structures (Figure 2). Sea-level rise changes the baseline; it raises the height of normal and storm tides. hnportantly, it exposes new areas to tidal inundation or it increases the frequency and duration of flooding in presently vulnerable areas. PREDICTED TIDES & STORM SURGE LEVELS CHARLESTON IBATTERYI S.C. 12,0 1 00 Year Slorm Surge +9.0 Seawall +6.0 10 Year Storm Surge 1 Mean Spring H¡gh Water +2.7 Mean High Water 0 Mean Sea Level -2.7 Mean Low Water Figure 2. 203 Increøseil Flood,ing Generally, increased property damage from periodic flooding is possible in low-lying areas. Up to one-half of the area could be frequently flooded if there are no anticipatory responses to sea-level rise (Kana et al., 1984). Expanded stormwater runoff management (mainly retrofitting existing developed areas) will be necessary in some residential areas. The potential for storm flooding and periodic tidal inundation of certain key transportation arteries (including the causeways to the barrier islands) will be increased (Kana et al., 1984). The scope of this problem includes periodic inundation, resulting traffi.c inconveniences, enhanced degeneration of streets and the interruption of emergency service delivery, and episodic but potentially catastrophic reduction in evacuation capability from barrier islands and low-lying areas. lV'aterfront properties will experience increased flooding as a result of normal tidal inundation, as well as increased risk of catastrophic flooding from episodic storms (hurricanes and northeasters). Data indicate that the present division between transition tide levels and "high" ground is approximately 2.1 m (7 ft) above mean sea level for Cha¡leston (Kana and Baca, 1986). Properties at elevations of 2.1-3.0 m (7-10 ft) will be the first to experience the effects of rising sea level. of Waterþont Property ønd, Actiuities Higher water levels will produce higher wave action. As a result, i.mprovements may be needed in coastal structures ranging from minimal repair and upkeep to complete reconstruction, depending on exposure. It is generally accepted that the technology is available to provide structural solutions to sea-level rise. The question is what property value is sufficient to justify the very Desta,bilizq,tion large cost of structural protection. If a structural response is not economically or environmentaily feasible, property abandonment may be necessary. The determination of which avenue to pursue will be dictated primarily by the frequency and severity of inr¡ndation. Sparsely developed areas susceptible to frequent inundation are more likely to be abandoned because of the economics of protection. 204 Activities will also become destabilized with a rising sea level. For example, the need for maintenance dredging of ship channels may be lessened by a moderately rising sea level. However, given that some ships currently have only a two-foot clearance under the Cooper River bridges at low tide, the utility of port and naval facilities may be diminished if a rising sea level prevents passage of some vessels to existing port facilities. Increa.seil Rislc from Hurri.ca,nes Hurricanes generally produce the highest water ievels in coastal areas. Damages from hurricanes occur because of the combination of high rrir'aves, strong winds, and high water levels. The vulnerability of the Charleston region to hurricane damage is likely to be increased under any scenario of sea-level rise. Because much of the area is already subject to flooding and hurricane surges, higher sea level is likely to increase surge and flood heights, placing more areas at risk and exposing structures which are row higher than "baseline" surge heights to the possibility of wave-related damage. Perhaps the greatest impact of sea-level rise in the context of hurricanes would be the reduction in evacuation time as a result of causeway flooding. The causeways to both Folly Beach and Sullir¡ans Island have low spots at 1.8 m (6 ft) above mean sea level, and general elevations of. 2.L-2.4 m (7-8 ft). Higher mean sea level would reduce the available time in advance of hurricane arrir¡al that these causeu¡ays would be passable. This potential effect may be mitigated through highway construction that elevates the causeways. The final impact may be increased cost. The higher and the more rapidly that sea level rises, the greater the potential for increased hurricane damage, and the prospects that such episodic risk may generate changes in land use and activity patterns. The range of these changes would be largely dependent upon the investment that public and private interests are willing to make to protect existing uses and activities. The scope of these investments is significant and includes moving electric generators at the area's numerous hospitals (most of which are located on the ground floor) and flood-proofing both active and inactive hazardous waste management facilities on the Charleston peninsula. Increased atmospheric warming will also increase the frequency of hurricanes in the area (Titus and Barth, 1984). 205 Increased, Beuch Erosion A rise in sea level would cause shorelines to retreat (i.e., move inland) in two ways. First, they would retreat through simple inundation of the land presently at the margins of tide and wave action. Additionally, they would retreat through accelerated erosion of dunes which occurs in response to higher wave action associated with higher water levels. scientists have shown that a rise in sea level of one foot could cause some beaches in the Charleston area to erode one to several hundred feet (Michel et al., 1983). The rate will depend upon the magnitude of sea-level rise as well as other factors not related to sea-level rise. The increased height of tidal crests associated with full- and new-Inoon tides is likely to increase erosional impacts on barrier island beaches. Islands which are currently erosional, such as Folly Beach: may see increased rates of erosion. Islands that a¡e accreting, such as Sullivans Island, will see that rate reduced, and possibly reversed, as sea level rises. Stable islands such as the Isle of Palms or Kiawah Island may begin to experience erosion. In addition, the episodic phasing of high tides and northeasters is likely to cause greater erosion and island flooding than presently occurs. Choices will have to be made between abandoning some property or replenishing eroded beaches. Marsh Destruction 'Wetlands in the Charleston area have been able to keep pace wiih the recent historical rise in sea level. Sea level during this century has risen an aveïage of 3.6 mrtfyr (Hicks and Crosb¡ 1974). This is equal to the approximate sedimentation rate in South Carolina marshes (Sharma et al., 1987). Thus, salt marshes have been accumulating sediment at a rate equal to sea-level rise, while migrating slowly inland over terrestrial soils' There is no evidence that the total area of salt marsh has expanded, so the rate of inland migration is probably balanced by erosion on the seaward boundary. The success with which coastal wetlands adjust to rising sea level in the future will depend upon the abiiity of wetland sedimentary processes to keep pace with an accelerating rate of sea-level rise and the extent to which human activities prevent new ma¡shes from forming as inland areas âre flooded. Most of the marshes in 206 to subtidal estuarine habitat if to rise 1.5 m (5 ft) and walls were built to protect existing development (Figure 3). In fact, even a conservative estiCharleston would be tra,nsformed sea level were mate of sea-level rise could permanently inundate coastal wetlands, because local salt marshes vegetated with Spartina øIterniflor(r extend upward only to about 70 cm (2.3 ft) above mean sea level and down as low perhaps as mean sea level (J.T. Morris, unpublished data). Increased development along an estuary's fringe enhances the probability that bulkheads or dikes will be buili to protect investments, which in turn increases the likelihood that estuarine ma¡shes will be inundated and prevented from migrating inland (Titus, 19S6). The other threat to coastal wetlands is that they may not be able to rise as quickly as sea level may in the future. It is difficult to imagine that coastal wetlands could trap sediment at a rate three to five times greater than at present, which is what will be required if they are to keep up with rising sea level. A three- to five-foãt rise in the next century would almost certainiy upset these ecosystems in a fashion simila¡ to that occurring in Louisiana, which every year loses over 100 square kilometers to the sea. There, freshwater wetlands are dying as a consequence of saltwater intrusion, which results in greater subsidence, erosion, and an accelerating rate of destruction (see Meo, this volume). south carolina's rivàrs have extensive tidal and nontidal freshwater wetlands that would be threatened by saltwater intrusion associated with rising sea level. Much of the sediment entering into the Charleston area is derived from suspended sediment originating primarily from the Cooper River which, since 1940, has carried the diverted flow of the-Santee River (U.S. Army Corps of Engineers, unpublished general design memorandum). However, the Army Corps of Engineers has recently rediverted much of the cooper River flow back into the santee River. This will reduce sediment input, possibly reducing the rate of marsh accretion in the future, which would accelerate the loss of coastal wetlands (I(ana and Baca, 1986). Lying between the sea and the land, tidal wetlands will experience theãirect effects of-changing sea levels, tidal inundation, and storm surges. 'We can project several ecological as well as economic ãoor"quences of these losses. For example, the destruction of riverine wetlands would mean the loss of important wildlife habitats and would destabilize sediments. Mobilization of sediments will have LOW MÀRSH HIGHLAND 2015 ,16* 20?5 2% 20'15 2% 2075 5g WAIER ÎIDAL FLAT 2075 12X 2075 33f suasfa^ÌE +30 EI 2016 MSL ----------*- aw8lR^lC aR7"8.,Uf,L 1980 Íusl. EIISTre igao 12% Figure B. r980 27 Conceptual model of the shift in wetlands zonation along a shoreline profile if sea-level rise exceeds sedimentation rates (using U.S. EPA scenarios). In general,-the response will be a landward shift and altered .ràd dirttibution of each habitat because of variable slopes at each elevation interval. t9 o \¡ 208 a negative impact on navigable waterways and could release trace metals and other substances trapped in sediments. Finally, the productivity of several important fisheries, like shrimp, that depend upon wetlands will decrease. It is possible, however, that man-induced alterations to estuarine dynamics, such as depositing dredge spoil material (from harbor maintenance dredging) along the edge of fortification in order to raise bottom heighis sufficiently to support marsh communities, could be available to manage some of the potential impacts on habitat and vegetative communities. Creation of an artificially high sedimentation rate through the use of dredge spoil has promise, but changes in sediment chemistry brought about by this method may not support marsh vegetation. FRAMEWORI( FOR RESPONSE As the magnitude of the effects of sea-level rise increase, the likelihood of national and state regulatory agency involvement also increases. These levels of government possess both greater fiscal resources and the necessary political jurisdiction to deal with complex environmental issues, i/ they choose to use them. Local governments, however, have the tools available to set their own policy directions regarding the effects of sea-level rise. These include zoning ordinances, building codes, and local prop_ erty tax structures. Moreover, local jurisdictions must be arr\¡are that in the face of pervasive sea-level rise impacts, state and federal agencies may be unable to address many local impacts, or to address them in the ways most responsive to local interests. This is especially true in south carolina, where there is littre or no centralized planning. To a large extent, fiscal constraints dictate the substance of the responses. Local governments will have to take a pragmatic approach in deciding their range of commitments in the allocation of scarce resources. Pri''¿te sector investment will play a rarge part in the decisionmaking process as it will dictate to a large extent the development patterns that occur once the impacts of sea-level rise begin to appear. Political constraints will also play an important role. A mul_ tiplicity of local jurisdictions complicates a coordinated. planning 209 effort. In the Charleston region, there are more than 44 local government units and special purpose districts. The vulnerable temrre in office of local decisionmakers adds to this complexity. Typicall¡ those who make governmental decisions and financial commitments at the local level are in office for no longer than ten years. It seems difficult enough to gain consensus on policy decisions concerning events in the next decade, let aione the next century. The sophistication of information provided by the scientific community thus will play an important role in determining how and when local comrnunities will prepare for and respond to the impacts associated with sea-level rise. FACTORS AFFECTING LOCAL RESPONSES TO SEA-LEVEL RISE In the absence of perceived manifestations of sea-level rise, the scientific community must provide local policymakers with detailed a"rird logical projections that are good enough to give assurance that the phenomenon and its anticipated impacts are real. If coastal impacts are localized, as would occur under low sea-level rise, local policymakers need information on exactly how physical impacts are likely to be manifested. For example, increased flooding potential would be addressed quite differently if the manifestation is periodic flooding, as opposed to a theoretical, episodic increase in the height of a hurricane storm surge. To the extent that certainty cannot be provided, and translated to inexpert and untrained decisionmakers, societal respor¡ses to the impacts of sea-level rise are likely to be postponed. In addition to reliable projections, decisionmakers need comparative information, that is, a baseline. Local policymakers need documentation to show (1) that the phenomenon is actually,happening, and (2) that very localized effects a,re occurring. Moreover, projections must be refined based upon observed conditions, before policymakers can be expected to make major decisions that are often irreversible in the short term. Projections of and responses to the impacts of sea-level rise involve a variety of different time frames, which must be identified and coordinated as a precondition to meaningful local response. These time frames include: to moderate projections of 210 o Rate of sea-level rise and related cha,nge o Useful life of structures and infrastructure o Financial life of structures and infrastructure r Political tenure of decisionmakers o Technological life a,nd technological changes RECENT PERCEPTIONS AND RESPONSES The Sea-Ièael Bise Forum i,n Chørleston In the early 1980s, popular media coverage of a global warming was still sporadic. In South Carolina, there was minimal awareness and discussion of this issue outside the academic community. However, EPA initiated studies of the potential physical and economic impacts of sea-level rise on Charleston, South Carolina, and Galveston, Texas, and then convened a national conference in VVashington, DC, in March 1983, where these studies v¡ere presented. Subsequentl¡ a symposium on sea-level rise was held in Charleston during February 1984. This symposium featured a diversity of speakers from federal and state resource agencies, local government, and local economic development and real estate interests. There was advance publicitg and the meeting was attended by more than 100 people, many of whom had little prior awareness of global warming and sea-level rise. Shortly before the meeting, there was considerable presswe by local development interests upon the local sponsors to cancel the meeting. Their concerns r¡vere based on apprehensions that hightighting the EPA case study woutrd have a profound negative impact on residential and commercial developrnent in the area. During the course of the meeting itself, local public and private interests demonstrated the strongest resistance to being concerned about impacts associated with sea-level rise. In contrast, the representative from the state's coastal management agency (South Carolina Coastal Council) demonstrated the greatest reflection about sea-level rise effects and potential responses. Nonetheless, the general consensus of most local officials at that meeting was that the possibility and range of impacts from sea-level rise was too vague and too remote to affect any near-term planning (unpublished transcript of symposium, South Carolina Sea Grant Consortium). ztl Associated, B each Eroston This localized resistance began to change, however, over the next few years as the state's beaches were adversely impacted by short-term meteorological phenomena. The natural, balancing processes of erosion and accretion were accentuated during a series of severely erosional winter storms. The combination of accelerated erosion and imprudent development along parts of the South Carolina coast set the stage for major erosion damages during a storm on New Year's Day 1987 (Kana, 1988). This storm caused considerable damage all along the eastern seaboa¡d and received extensive coverage in national media, including USA Toilay, Ti,me, ar.d Newsweek. The highty erosive effects were the result of a rare planetary alignment coupled with a winter northeastern storm. Marked erosion occurred throughout the South Carolina coast: residential and commercial structures were threatened and, in a number of places, toppled. Public interest in these natural processes and their societal and environmental impacts increased rapidly. Concomitantl¡ coastal residents began to notice the increased media coverage of global warming and sea-level rise. Local communities began to discuss more openly the impacts of both short- and long-term natural processes on the beaches that contribute substantially to the state's $3 billion tourism industry. A statewide BIue Ribbon Committee on Beachfront Management was established by the South Carolina Coastal Council to address the complexity of issues affecting the coast: sea-level rise was recognized in the Committee's final report as a significant factor affecting erosion. Instituti o nal Resp ons e : B eachfr o nt Legisløtio n The report of this Blue Ribbon Committee then was craf,ted proposed state legislation which emphasized a retreat policy into accompanied by a restriction on nevr' erosion control devices such as seawalls. The bill that finally passed South Carolina's General Assembly maintained a commitment to a retreat policy but differed from the original bill which began its journey through the legislature in Jarruary 1988. The bill was subjected to compromise and extended debate as it made its way through the legislative process a,nd finally to 2L2 Conference Committee. The struggle over the passage of the legislation pitted members of the environmental community against lobbyists representing the lending industry and coastal property orvners. Much of the debate focused on the establishment of a minimum setback line and what reconstruction, if an¡ should be permitted in front of that line. The lending community felt that mortgages they held might be devalued by the passage of a bill that adopted a strong "retreat" policy. Another point of debate centered on the requirement to renourish the beach whenever a damaged or destroyed "erosion control device" is repaired or replaced. The requirement is the yearly renourishment of the beach in front of the property by the property owner. The amount of sand added to the beach cannot be less "than one and one-half times the yearly volume lost due to erosion." This may prove to be a cumbersome and expensive requirement in the face of accelerated erosion rates associated with sea-level rise. The legislation also prohibits the rebuilding of vertical seawalls if damaged by more than 50 percent. The legislation mandates that all vertical seawalls be replaced with an approved erosion control device 30 years after the effective date of the legislation. Other provisions of the Beach Protection Act of 1988 require the South Carolina Coastal Council to create a "long-range and comprehensive beach management plan" for the South Carolina coast, provide guidance on the distribution of renourishment funds, and stipulates that within two years of the effective date of the legislation, local governments must also prepare iocal beachfront management plans in coordination with the South Carolina Coastal Council. Thus, it seems likely that local interests in understanding and planning for sea-level rise will now increase as a result of impacts not necessarily caused by a CA2ltrace gases-induced global warming. SUMMARY It appears reasonable to conclude that a three- to five-foot rise in sea level could seriously impact Charleston, South Carolina. Even if it is too early for local government to take many (if any) specific actions in anticipation of future sea-level rise, it is not too 273 early to prepare for the time when specific, proactive decisions will need to be made. As such, more detailed and less variable projections are needed (including very localized impact assessments) in order to give policymakers the information they need to make responsible decisions about sea-level rise. While the scientific and the climate-related impacts communities are refining their projects, the interested public should be kept informed-but not alarmedabout the likely time frames when actions will be needed, and about the magnitude of impending impacts. Ultimately, the local responses to the impacts of sea-level rise will involve decisions about fundamental priorities and the allocation of funding to preserve elements of local land use, lifestyie, and activities. Just as sea level is projected to rise graduall¡ local responses will be made over time, in reliance upon the developing products provided by the scientific communit¡ and in hope that the measures implemented in response to sea-level rise will be sufficient to protect the economically developed coast and its residents' ways of life. Substantial environmental and economic resources can be saved if better predictions become available soon, easily justifying the cost (though substantial) of developing them (Titus et a1., 1983). However, deferring policy planning until all remaining uncertainties are resolved is unwise. The knowledge that has been accumulated in the last 25 years has provided a more solid foundation for expecting sea level to rise in the future. Nevertheless, most environmental policies assume that coastal ecosystems are static. Incorporating into our environmental research the notion that ecosystems as well as social systems are dynamic need not wait until the day when we can accurately predict the magnitude of the future environmental changes. REFERENCES Basilchuk, N., 1986: Charleston's troubling sea change. Neuts and Courier, Sundag 24 August. Hicks, S.D., and J.E. Crosb¡ 1974: Trend,s and, Vøri,ability of Yeørly Mean Seø Leael, 1893-1972. NOAA Technical Memorandum NOS-13, COM-74.11,012. Rockville, MD: NOAA. 2t4 Hoffman, J.S., D. Keyes, and J.G. Titus, 1983: Project'i,ng Future Sea Leael Rise: Meth'od,ology, Estirnates to the Yeør 2100, and, Reseørch Need,s. EPA 230-09-007. \Mashington, DC: U.S. Environmental Protection Agency. Kana, T.W., 1988 Beach Eros'i,on in South Carolina. Charleston, SC: South Carolina Sea Grant Consortium. Kana, T.\M., and B.J. Baca, 1-986: Potenti'al Impøcts of Sea Leael Rise on Wetland,s around, Charleston, South Cøroli'na. EPA 'Washington, DC: U.S. Environmental Pro230-10-85-014. tection Agency. Kana, T.W., J. Michel, M.O. Hayes, and J.R. Jensen, 1984: The physical impact of sea level rise in the area of Charleston, South Carolina. In M.C. Barth and J'G. Titus (Eds.), Greenltouse Effect anil Sea Leael Ri'se' New York, NY: Van Nostrand Reinhold Co., 105-50. Meier, M.F., 1984: Contributions of small glaciers to sea level. S cience, 226 (4681), 141'8-21. Michel, J., T.'W. Kana, M.O. Hayes, and J.P. Jensen' L983: Ilypotheti,cal Shoreli'ne Cltønges Assoc'i'o'teil uith Vørious Sea Leuel Rise Scenari,os for lhe Ani,ted' Støtes, Case Stuily: Charleston, South Co'rolina. Prepared by ICF, Inc., under contract to U.S. Environmental Protection Agency. Columbia, SC: Research Planning Institute, Inc. National Research Council, 1,983: Chøngi,ng Cli,mate. Report of the Carbon Dioxide Assessment Committee, Board on At'Washington, DC: National mospheric Sciences and Climate. Academy Press. Sha,rma, P., L.R. Gardner, W.S. Moore, and M.S. Bollinger, 1987: Sedimentation and bioturbation in a salt ma¡sh as revealed by 210Pb, tttCr, and ?Be studies. Lirnnol. Oceønography, 32,313-26. Titus, J.G., 1986: Greenhouse effect, sea level rise, and coastal zone management. Coastal Zone Management Journo,l, lf, 3,147-72. Titus, J.G., and M.C. Barth, 1984: An overview of causes and effects of sea level rise. In M.C. Barth and J.G. Titus (Eds.), Greenhouse Effect o,nil Seø Leuel R'ise. New York, NY: Van Nostrand Reinhold Co., L-56.