Category Archives: Articles & Dossiers

Green And Golden Seaweed Tides On The Rise, By Victor Smetacek & Adriana Zingone

By Victor Smetacek & Adriana Zingone

Originally published in © Nature Magazine , December 5, 2013. Copyright. All text and images courtesy of © Victor Smetacek & Adriana Zingone. All rights reserved.

Sudden beaching of huge seaweed masses smother the coastline and form rotting piles on the shore. The number of reports of these events in previously unaffected areas has increased worldwide in recent years. These ‘seaweed tides’ can harm tourism-based economies, smother aquaculture operations or disrupt traditional artisanal fisheries. Coastal eutrophication is the obvious, ultimate explanation for the increase in seaweed biomass, but the proximate processes that are responsible for individual beaching events are complex and require dedicated study to develop effective mitigation strategies. Harvesting the macroalgae, a valuable raw material, before they beach could well be developed into an effective solution.

Green, brown and red seaweeds lying on the beach are part and parcel of life in many coastal regions. The amount of beached seaweed biomass started to increase along the shores of industrialized countries in the 1970s, and by the 1990s had become a nuisance along many beaches (1,2) when mass-stranding events of macroalgae became known as green tides. During the 2000s the number of reports from new locations all over the world increased further, as did the magnitude of the beaching events (3). Although non-toxic to humans, seaweed tides harm shore-based activities by virtue of their sheer physical mass. Tonnes of seaweed smothering the shoreline deter tourists and the dense, drifting seaweeds can prevent swimmers and small boats from accessing the sea (Fig. 1); if not removed in time, the algae can turn into a stinking morass, which can produce toxic hydrogen sulphide (H2S) from its anoxic interior1,3, and have major detrimental effects on the affected coastal ecosystems (1,2,4–6.)

Surprisingly, the extensive seaweed tides are mainly the result of only a few genera of macroalgae. Two genera are especially prominent. Species of the genus Ulva, which now includes the former genus Enteromorpha (7), are mainly responsible for green tides. The thallus (vegetative body) is only one or two cells thick but the shapes vary even within spe- cies and can be sheet-like, tubular or fern-shaped (8).

Sargassum — from which the Sargasso Sea takes its name — is the other genus; and we suggest the term ‘golden tide’ to describe the massive shoaling events it is responsible for (after the apt description of floating Sargassum as “The golden floating rainforest of the Atlantic Ocean” (9).

The Sargassum thallus is leathery, tough and differentiated into features that resemble leaves and a stem, and has well-developed gas bladders for flotation. Both Ulva and Sargassum are cosmopolitan, exceptionally species- rich genera and increase their growth rate in response to nutrients (10,11). Whereas most species will only grow when attached to a hard substrate, a few can substantially increase their biomass in a free-floating state, either by increasing the size of the thalli and their fragments, or by making new floating thalli. This is crucial (discussed later) because it is the unattached forms that, by invading new space (the water column), are able to increase their nutrient supply, free themselves from competition for limited hard substrates and avoid their many benthic grazers. As a result, unattached forms can build up large biomasses, forming the massive seaweed tides we discuss in this Perspective. Green tides have occurred all over the world, whereas golden tides have been restricted to beaches between the Gulf of Mexico and Bermuda; however, they significantly increased their range during a spectacular 2011 event.

Ulva green tides

The increase in Ulva biomass on European and US beaches that began (1) in the 1970s was linked to coastal eutrophication. As the many harmful effects became evident, the countries affected took measures to reduce nutrient input to the sea from agricultural sources and sewage. A decline in nutrient concentrations resulted in abatement of the prob- lem in the southern North Sea (12). In other regions, particularly along the popular tourist beaches of Brittany, the magnitude of green tides has been increasing since the 1970s (13).

“The occurrence and magnitude of green tides often vary both annually and seasonally…”
— Victor Smetacek & Adriana Zingone

Beached seaweed has traditionally been collected and used as fertilizer by local farmers, but by the 1990s it had to be taken away by the truckload (Fig. 1). In 2009, H2S gas from Ulva rotting on a Brittany beach caused the death of a horse, and, in 2011, the death of around 30 wild boars. Both incidents were widely reported in the press with some headlines giving the impression that the algae were toxic. The resulting effect on tourism caused severe losses to the local economy, in addition to the costs of removing and disposing the 100,000 tonnes of beached algae (estimated to be US$10–150 per tone) (13).

Increases in the accumulation of Ulva biomass coincided with the expansion of factory livestock farming in Brittany. The consensus among the scientific community seems to be that eutrophication from the effluents of intensive stock rearing is the cause of the increase in number and magnitude of green tides since the 1990s (13). The meat- producing and tourist industries are both mainstays of the provincial economy, and, following the animal deaths, confrontation between the two increased (14).

Brittany is a wet region overloaded with nutrients released by the high density of animals — equivalent to those from 50 million people13 — and so eutrophication is inevitable because the manure is not being shipped back to the animal feed producers outside the province. In efforts to make the best out of a situation that is unlikely to change soon, Ulva biomass has been used as a raw material for biogas production, organic fertiliser and as an additive to animal and human food. However, the value barely meets the costs of current methods of algal collection and processing (13).

In 2008, a spectacular green tide invaded, without warning, the beaches of Qingdao — the venue for the sailing events of the Beijing Olympics. Masses of Ulva floated in from the open water of the Yellow Sea and beached a few weeks before the competition was due to start, ensuring prominent coverage by the international media (Fig. 1). A 30-km-long boom was deployed to keep the masses of floating algae out of the bay, and the removal of more than a million tonnes of algae from the beaches involved 10,000 people at an estimated cost to the province of $30 million (15). In addition, aquaculture operations along the shore suffered losses of $100 million (3).

Given the novelty of the phenomenon, the origin, genesis and relationship to eutrophication of the green tide was traced with exemplary speed (16). Analysis of satellite images of the Yellow Sea in 2008 revealed that in total 3,500 km2 were covered with floating algae in patches spread over 84,000 km2. The high nitrate concentrations in the Yellow Sea could explain the high growth rates (21.9% per day) of the floating algal patches (15–17). These patches were subsequently driven inshore by winds, hitting a 140 km stretch of coastline, which included Qingdao. The species responsible, Ulva prolifera, was subsequently shown to proliferate rapidly by sporulation of cells of fragmented thalli; these grew into new thalli by attaching to the parent thallus, with 1–2-mm diameter fragments having the highest sporulation rate (18).

The pelagic seaweed bloom, as well as those in subsequent years, could be traced in satellite images to the coastline some 200 km south of Qingdao where aquaculture of the edible red alga Porphyra yezoensis, which is grown on rafts along the intertidal zone, has expanded rapidly since 2004 (refs 17, 19). Because Ulva prolifera grows profusely on the rafts, thallus fragments dislodged and discarded in the sea during harvesting of Porphyra in spring are the most likely seed source of the mid-summer green tide. If this seeding hypothesis is correct, then collecting and using Ulva as a by-product would mitigate the magnitude of the green tide.

It is estimated that 500 tonnes of Ulva thalli, discarded from the Porphyra rafts, grow into one million tonnes in 6 weeks (15). Another hypothesis based on genetic signatures (5S rDNA spacer sequences), suggests that the Ulva strain responsible for the green tide could be overwintering on the sediment surface south of the Yellow Sea as frag- ments that stem from the summer surface bloom20. The hypotheses are not necessarily mutually exclusive, as the swarm of seeding fragments moving northward from the Porphyra rafts could be augmented by thalli fragments rising to the surface from shallow sediments (Fig. 2). Whatever the source of seeding thalli, green tides along the coasts of the Yellow Sea are recurrent, with the 2013 event reportedly reaching a record level (21).

Managing green tides

The case for a direct connection between spreading coastal eutrophication and the worldwide upsurge in the incidence of green tides is compelling (1,2). However, curbing eutrophication requires significant investment in infrastructure and agricultural practices in the catchment area and can take years to implement, and even longer to take effect. Thus, although water quality in Tokyo Bay has improved, Ulva green tides have increased; the species responsible overwinters as unattached thalli drifting at the sediment surface of shallow waters (22). The notorious Ulva blooms of Venice in the late 1980s, however, are no longer such a nuisance (23,24) even though nutrient concentrations — in particular nitrate — have not significantly diminished in the subsequent decades (24). As biomass accumulation is a function of the seed population multiplied by its growth rate, spreading seed banks of overwintering, free-floating strains of local Ulva could obviate the effects of reducing eutrophication because they are protected from the many Ulva grazers (such as snails and crustaceans) that live on the sea floor (25,26). Thus, green tides have been a chronic problem in the eutrophied northern Baltic since the 1970s — unattached Ulva intestinalis thalli overwinter in shallow, ice-covered waters and rise in the water column, commencing growth in spring (27). Free-floating Ulva species generally persist from spring until autumn in a growth state, after which they transfer the sequestered nutrients to the sediments. In shallow, enclosed seas and fjords these are returned to the surface by vertical mixing (that is, retained within the system) (13). Thus, in favorable topographical and hydrological environments, free-floating macroalgae are likely to continue to proliferate and maintain the eutrophic state that is favourable for their perpetuation.

The occurrence and magnitude of green tides often vary both annually and seasonally, hence the planning of mitigation measures will require interdisciplinary investigation of the life-cycle strategies of the species involved in relation to the physical and chemical setting of the environment: topography, circulation, wind patterns and the nutrient regime, exemplified by the work done on the Yellow Sea green tides (3,15– 20,28–30). An obvious mitigation target would be the overwintering and early spring growing stages. The costs of collecting and disposing of Ulva masses in spring would have to be weighed against their nuisance ‘value’ in the summer.

“During 2011, there was an ocean-scale build-up of Sargassum that at its peak extended across the Atlantic and resulted in massive golden tides along the west African coast, from Sierra Leone to Ghana, and, on the other side of the Atlantic, from Trinidad to the Dominican Republic…”
— Victor Smetacek & Adriana Zingone

In the Yellow Sea, the profit from Porphyra aquaculture amounts to $53 million, whereas the cost of removing Ulva from the beaches is estimated to be $30 million15. As elsewhere, the overburdened local governing bodies are responsible for keeping their beaches clean. In Brittany, the tourism industry ($5.1 billion) and the farming sector ($11.6 billion) have been pitted against each other (31,32). Recently, policy makers at national and European Union levels have passed measures to curb factory farming practices, which has led to closures, lay-offs and protests in the area (33). Similar tensions have begun to arise in China between the Jiangsu province, home to Porphyra aquaculture, and Shandong province, whose coasts have been affected by green tides (34).

Sargassum golden tides

Golden tides due to the beaching of floating Sargassum occur regularly in summer along the coasts of the Gulf of Mexico and are often a nuisance on tourist beaches (35). An increase in golden tides during the 1980s and 1990s has been linked to higher nutrient loads of the Mississippi river (10). However, compared with Sargassum in the Sargasso Sea — often referred to as “the only sea without a coastline” (9) — little is known about Sargassum in the Gulf of Mexico. Analysis of satellite images from 2002 to 2008 revealed that floating Sargassum originated in the north-western Gulf of Mexico each spring and was exported to the Sargasso Sea where it accumulated in the summer months and by winter had disappeared36, presumably because aged thalli sank to the deep sea (37). From satellite images, an estimated one million tonnes wet weight of Sargassum is exported to the Atlantic each year (36). For comparison, about the same mass of Ulva was collected and disposed of on land during the green tide of the 2008 Olympics (3), and a similar amount was estimated to have accumulated in the Venice lagoon during the peak outbreak (23).

Floating Sargassum, represented by the two species Sargassum natans and Sargassum fluitans, is deemed a valuable and unique habitat that harbours many highly adapted, and even endemic animal species that depend on Sargassum for food (9). If Sargassum is imported to the Sargasso Sea each year, it is hard to imagine how the dependent animal species, which beach with the Sargassum, could have evolved with such a ‘one-way’ seasonal life cycle. Nevertheless, the satellite observations are supported by ship-based reports of the seasonal cycle of floating Sargassum (36). Thus, the processes maintaining the floating Sargassum habitat through the winter and the specific properties of the north- western Gulf that allow rapid growth of new thalli during spring, warrant investigation.
S. natans and S. fluitans are considered to be the only holopelagic macroalgae, so why is a specific geographical seeding site part of their life cycle? This question gains importance because of the commercial interest in Sargassum biomass; patents have been filed for growing and harvesting Sargassum in the Sargasso Sea. Furthermore, an international alliance of scientists has recently been formed to protect and manage the Sargasso Sea (9).

During 2011, there was an ocean-scale build-up of Sargassum that at its peak extended across the Atlantic and resulted in massive golden tides along the west African coast, from Sierra Leone to Ghana, and, on the other side of the Atlantic, from Trinidad to the Dominican Republic (Fig. 3) (38). The peak biomass during the 2011 event was 200- fold higher than the previous 8 years’ average biomass peak recorded in the region (39). According to eyewitnesses, beached Sargassum was unknown in northwest Africa before 2011, so the event came as a shock to the many afflicted fishing villages, and has been attributed to the effects of offshore oil production that had started at the time (40). The afflicted southern Caribbean islands had never, within living memory, experienced an event of this magnitude (38). Satellite images showed that the algal rafts had developed along the northern coast of Brazil, north of the mouth of the Amazon, from where they moved east and west, eventually stretching from shore to shore (Fig. 3) (36). The effects on the beaches were substantial; however, because no popular tourist beaches or big cities were affected the African events were only reported in regional media. Along the western coast of Ghana a blanket of Sargassum extended for kilometres offshore, clogging fishing nets and impeding the passage of small boats. This resulted in food shortages for people living in villages dependent on artisanal fisheries for their livelihood (41). In the Caribbean, tourism was affected because of the closure of beaches and bays (Fig. 1).

Unfortunately, the satellite sensor from which the images in Fig. 3 were produced (MERIS) went out of service in early 2012 (ref. 39). We could not find any reports of unusually large golden tides in subsequent years from either the southern Caribbean islands or the west coast of Africa.

Explaining the unprecedented, ocean-scale build-up of Sargassum biomass in 2011 will require much detective work by physical, chemical and biological oceanographers because its occurrence challenges the current concept that the Sargasso Sea is a closed system (9).

Indeed, an unanswered question raised in the 1970s asked why there are five subtropical ocean gyres (STG) but only one, the North Atlantic, harbours the Sargasso Sea. The circulation pattern of all STGs is essentially similar and all impinge on extensive coastlines along their western flanks. The long, unbroken evolutionary history of floating Sargassum is evidenced by the many adaptations, in particular perfect camouflage, that various animal classes have evolved in response to life in this floating habitat.The highly specialized sargassum fish (Histriohistrio) has a pan-tropical distribution (including the west African coast) (42), prompting the questions: does Sargassum exist in large enough quantities to provide a habitat for specialized species in other STGs and how could this change in the future. Was the 2011 Sargassum bloom a freak event caused by a unique collection of non-linear environmental factors impinging on each other to create an environment in which Sargassum thrived? Or does it represent a symptom of an ocean-wide response to increasing pressure on the biosphere from anthropogenic waste, and hence an indication of what is to come?

Establishing an international consortium

Blooms of noxious phytoplankton (unicellular microalgae), known as red tides and later as harmful algal blooms (HABs), occur in coastal regions worldwide. In most cases, the harmful effects are caused by phytoplankton species that render seafood toxic, result in the mass death of marine animals or affect aquaculture operations. High-biomass phy- toplankton blooms can also be a nuisance on beaches by discolouring the water (red and brown tides) or forming scums and foams (43). Their biomass is low compared with green tides, but they can also cause anoxic events, albeit in deeper water. HAB research has substantially increased over the past decades, greatly profiting from international organisations such as the Global Ecology and Oceanography of Harmful Algal Blooms programme (IOC–SCOR GEOHAB) (44). The seaweed blooms discussed in this Perspective are very different (2) and only have two features in common with microalgal HABs: they grow in a free-floating state (that is, they compete with phytoplankton for nutrients) and cause harm to the affected coastlines. Because they are essentially benthic organisms that live a planktonic existence, the investigation of free-floating macroalgae will need to combine established research methods from both fields, and apply new techniques for surveying, sampling and modelling them. It would be advisable to develop such a dedicated, interdisciplinary research programme at an international level.

The focus of this scientific network could be the comparatively few species of macroalgae that can all increase biomass in a free-floating stage, either drifting above the bottom in shallow waters, or floating at the surface further out at sea. Most green-tide species belong to the former category (1,2) and, to our knowledge, the latter has only been reported in the Yellow Sea. The surface-floating Ulva prolifera strain has been shown to differ from attached Ulva species of the Yellow Sea coastline (15).

“…in-depth understanding of the growth dynamics of massive seaweed tide species is not only a prerequisite for developing cost-effective mitigation strategies, but it could also provide the basic knowledge required to manage free-floating algae as a potentially valuable resource.”
— Victor Smetacek & Adriana Zingone

Is this surface-floating form a new genotype that can only attain massive biomass in settings with the hydrographic features and wind patterns of the Yellow Sea? Or are other shallow seas, such as the North Sea, susceptible to invasion by a surface-floating form of Ulva? This could happen either by evolution within the local species pool or by inadvertent introduction of the Yellow Sea form. Among the questions that need to be addressed is the buoyancy regulation mechanism of free-floating Ulva, which allows thalli to stay suspended in the water column or rise to the surface. Furthermore, life cycles also need to be studied in situ. The ability to produce new thalli on the surface of the parent thallus (18) suggests the absence of chemical deterrents, which are known to exist for the thallus surface of other Ulva species (45,46). In the case of Sargassum, the factors necessary for large-scale spring regeneration of thalli require elucidation, as well as hindcasting for the factors that allowed the 2011 Sargassum event. Finally, the fact that surface-floating Ulva and Sargassum rafts were able to proliferate in the open sea indicates their ability to compete with phytoplankton for nutrients. Biomass build-up of dense macroalgal clumps, in contrast to diffuse phytoplankton, is presumably enabled by wind energy pushing the rafts through the water, which can vastly increase their nutrient supply. One wonders why evolution of this surface-floating macroalgal life form in the open sea is restricted to so few genera.

Mitigation or amelioration?

An in-depth understanding of the growth dynamics of massive seaweed tide species is not only a prerequisite for developing cost-effective mitigation strategies, but it could also provide the basic knowledge required to manage free-floating algae as a potentially valuable resource.

Ulva biomass contains a number of compounds of interest to the food-additive industry, and a biorefinery plant to process the Ulva biomass collected from the beach or shallow water has recently been established in the region of Brittany plagued by green tides (47). One of the aims is to provide an alternative food additive to the fish-meal-based one currently given to farmed fish. In order for this to work, the costs of collecting Ulva need to be similar to those of collecting fish used to make fish meal. In the case of surface-floating Ulva, ‘catching’ the algae at sea by making use of ships from the current fishing fleet, which are already equipped with the facilities required to preserve the catch, should be competitive in terms of cost. Patches of floating rafts located by aerial surveys could be concentrated with booms similar to those used for containing oil spills, and the thalli pumped on deck and collected on nets and filters of decreasing mesh size (to collect fragments). If carried out in the early stages of the bloom, this technique could mitigate the magnitude of the beaching events.

In other regions, techniques to collect Ulva masses in shallow water from special ships by rakes, nets or suction pipes could be developed and one technique is already in operation in the Venice lagoon (23). Transporting the Ulva biomass to processing factories from harbours should be much cheaper and easier than using rakes and tractors on beaches; the quality of the raw material will also be superior because it will be fresher and contain less sand. Price depends on demand, so encouraging the establishment of Ulva-processing factories will raise the price of the raw material — and could well make floating rafts of Ulva an interesting target for a new, summer fishery. In the case of Sargassum, also a valuable raw material, harvesting by ship is already regulated in the western Atlantic (48). Needless to say, harvesting floating macroalgae is the logical and ultimate (49) step in the process known as “fishing down marine food webs”.

It should also be pointed out that the carbon-to-nitrogen ratio of oceanic Sargassum is around 50:1 (ref. 10) and the alga’s tendency to rapidly sink to the deep-sea floor makes it a much more efficient vehicle to artificially sequester carbon in the oceans than phytoplankton, which have carbon-to-nitrogen ratios of less than 10:1.

The future impact of green and golden tides could be very different if they become regarded as potential crops rather than harmful weeds.


References

  • 1. Fletcher, R. T. in Marine Benthic Vegetation – Recent Changes and the Effects of Eutrophication (eds Schramm, W. & Nienhuis, P. H.) 7–43 (Springer, 1996).
  • 2. Valiela, I. et al. Macroalgal blooms in shallow estuaries: controls and ecophysiological and ecosystem consequences. Limnol. Oceanogr. 42, 1105–1118 (1997).
  • 3. Ye, N. H. et al. ‘Green tides’ are overwhelming the coastline of our blue planet: taking the world’s largest example. Ecol. Res. 26, 477–485 (2011).
  • 4. Norkko, A. & Bonsdorff, E. Population responses of coastal zoobenthos to stress induced by drifting algal mats. Mar. Ecol. Prog. Ser. 140, 141–151 (1996).
  • 5. Norkko, A. & Bonsdorff, E. Rapid zoobenthic community responses to accumulations of drifting algae. Mar. Ecol. Prog. Ser. 131, 143–157 (1996).
  • 6. Arroyo, N. L., Aarnio, K., Mäensivu, M. & Bonsdorff, E. Drifting filamentous algal mats disturb sediment fauna: Impacts on macro–meiofaunal interactions. J. Exp. Mar. Biol. Ecol. 420–421, 77–90 (2012).
  • 7. Hayden, H. S. et al. Linnaeus was right all along: Ulva and Enteromorpha are not distinct genera. Eur. J. Phycol. 38, 277–294 (2003).
  • 8. Blomster, J. et al. Novel morphology in Enteromorpha (Ulvophyceae) forming green tides. Am. J. Bot. 89, 1756–1763 (2002).
  • 9. Laffoley, D. A. et al. The Protection and Management of the Sargasso Sea: The Golden Floating Rainforest of the Atlantic Ocean 1–44 (Washington, 2011).
  • 10. Lapointe,B.E.A comparison of nutrient-limited productivity in Sargassum natans from neritic vs. oceanic waters of the western North Atlantic Ocean. Limnol. Oceanogr. 40, 625–633 (1995).
  • 11. Teichberg,M.etal. Eutrophication and macroalgal blooms intemperate and tropical coastal waters: nutrient enrichment experiments with Ulva spp. Glob. Change Biol. 16, 2624–2637 (2010).
  • 12. van Beusekom,J.E. E.etal. Quality Status Report 2009. Wadden Sea Ecosystem No. 25 (eds Marencic, H. & de Vlas, J.) 1–21 (Common Wadden Sea Secretariat, Trilateral Monitoring and Assessment Group, 2009).
  • 13. Charlier,R.H.,Morand,P.&Finkl,C.W.How Brittany and Florida coast scope with green tides. Int. J. Environ. Stud. 65, 191–208 (2008).
  • 14. Saltmarsh,M. A battle between economic mainstays in Brittany. (New York Times, 2010).
  • 15. Liu, D.etal. The world’s largest macroalgal bloom in the Yellow Sea,China: formation and implications. Estuar. Coast. Shelf Sci. 129, 2–10 (2013).
  • 16. Sun,S.etal. Emerging challenges: Massive green algae blooms in the Yellow Sea. Nature Preced.(2008).
  • 17. Keesing,J.K.,Liu,D.,Fearns,P.& Garcia,R.Inter-andintra-annual patterns of
    Ulva prolifera green tides in the Yellow Sea during 2007–2009, their origin and relationship to the expansion of coastal seaweed aquaculture in China. Mar. Pollut. Bull. 62, 1169–1182 (2011).
  • 18. Gao,S.etal.A strategy for the proliferation of Ulva prolifera, main causative species of green tides, with formation of sporangia by fragmentation. PLoS ONE 5, e8571 (2010).
  • 19. Hu, C. et al. On the recurrent Ulva prolifera blooms in the Yellow Sea and East China Sea. J. Geophys. Res. 115, C05017 (2010).
  • 20. Liu, F. et al. Understanding the recurrent large-scale green tide in the Yellow Sea: temporal and spatial correlations between multiple geographical, aquacultural and biological factors. Mar. Environ. Res. 83, 38–47 (2013).
  • 21. Jacobs, A. With surf like turf, huge algae bloom befouls China coast. (New York Times, 2013).
  • 22. Yabe,T.etal.Green tide formed by free-floating Ulva spp.at Yatsu tidal flat,
    Japan. Limnology 10, 239–245 (2009).
  • 23. Sfriso, A. & Marcomini, A. Decline of Ulva growth in the lagoon of Venice.
    Bioresour. Technol. 58, 299–307 (1996).
  • 24. Facca,C.,Pellegrino,N.,Ceoldo,S.,Tibaldo, M.&S friso,A. Trophic conditions in
    the waters of the Venice lagoon (Northern Adriatic Sea, Italy). Open Oceanogr. J.
    5, 1–13 (2011).
  • 25. Geertz-Hansen,O.,Sand-Jensen,K.,Hansen,D.F.&Christiansen,A.Growth
    and grazing control of abundance of the marine macroalga, Ulva lactuca L. in a
    eutrophic Danish estuary. Aquat. Bot. 46, 101–109 (1993).
  • 26. Kamermans,P.etal.Effect of grazing by isopods and amphipods in growth of
    Ulva spp. (Chlorophyta). Aquat. Ecol. 36, 425–433 (2002).
  • 27. Bäck,S.,Lehvo,A.&Blomster,J.Mass occurrence of unattached Enteromorpha
    intestinalis on the Finnish Baltic Sea coast. Ann. Bot. Fenn. 37, 155–161 (2000).
  • 28. Lin,H.Z.etal. Genetic and marine cyclonicaldy analyses on the largest
    macroalgal bloom in the world. Environ. Sci. Technol. 45, 5996–6002 (2011).
  • 29. Zhang, X. W. et al. Somatic cells serve as a potential propagule bank of
    Enteromorpha prolifera forming a green tide in the Yellow Sea, China. J. Appl.
    Phycol. 22, 173–180 (2010).
  • 30. Zhang, J. H. et al. Growth characteristics and reproductive capability of green
    tide algae in Rudong coast, China. J. Appl. Phycol. 25, 795–803 (2013).
  • 31. Viscusi, G.
    Fear of noxious ‘green tides’ drives tourists from beaches of Brittany(Boston Globe, 2011).
  • 32. Diaz,M., Darnhofer,I., Darrot,C.& Beuret,J.-E.Green tides in Brittany: What
    can we learn about niche–regime interactions? Environ. Innov. Soc. Transitions 8,
    62–75 (2013).
  • 33. Samuel,H.
    French protesters say Brittany will be François Hollande’s‘cemetery’ (The Telegraph, 2013).
  • 34. Jing,L. Seaweed farming linked to Qingdao’s green tide of algae (South China Morning Post, 2013).
  • 35. Williams, A.& Feagin,R.Sargassum as a natural solution to enhance dune plant growth. Environ. Manage. 46, 738–747 (2010).
  • 36. Gower,J.& King,S.Distribution of floating Sargassum in the Gulf of Mexico and the Atlantic Ocean mapped using MERIS. Int. J. Remote Sens. 32, 1917–1929 (2011).
  • 37. Johnson,D.L.& Richardson,P.L.On the wind-induced sinking of Sargassum. J. Exp. Mar. Biol. Ecol. 28, 255–267 (1977).
  • 38. Hemphill,A. Change is in the air–seaweed, seaweed everywhere! (Arlo Hemphill, 2013).
  • 39. Gower,J.,Young,E.&King,S.Satellite images suggest a new Sargassum source region in 2011. Remote Sens. Lett. 4, 764–773 (2013).
  • 40. Ackah-Baidoo,A.Fishing in troubled waters: oil production, seaweed and community-level grievances in the Western Region of Ghana. Community Dev. J. 48, 406–420 (2013).
  • 41. McDiarmid,J.Western Ghana’s fisher folk starve amid algae infestation (IPS, 2011).
  • 42. Froese,R.&Pauly,D.(eds). FishBase.(Fishbase, 2013).
  • 43. Anderson,D.M.,Cembella,A.D.&Hallegraeff,G.M.Progress in understanding harmful algal blooms: paradigm shifts and new technologies for research, monitoring, and management. Annu. Rev. Mar. Sci. 4, 143–176 (2012).
  • 44. GEOHAB.Global Ecology and Oceanography of Harmful Algal Blooms (SCORand IOC, 2001).
  • 45. Nelson,T.A.,Lee,D.J.& Smith,B.C. Are “green tides” harmful algal blooms? Toxic properties of water-soluble extracts from two bloom-forming macroalgae, Ulva fenestrata and Ulvaria obscura (Ulvophyceae). J. Phycol. 39, 874–879 (2003).
  • 46. Harder,T., Dobretsov,S.&Qian,P.-Y.Water born epolarmacromoleculesact as algal antifoulants in the seaweed Ulva reticulata. Mar. Ecol. Prog. Ser. 274, 133–141 (2004).
  • 47. Algae Industry Magazine. Olmix opens algae biorefinery in Brittany(Algae Industry Magazine, 2013).
  • 48. South Atlantic Fishery Management Council. Fishery Management Plan For Pelagic Sargassum Habitat Of The South Atlantic Region(NOAA, 2002).
  • 49. Pauly,D.,Christensen,V.,Dalsgaard,J.,Froese,R.&Torres,F.Fishingdown marine food webs. Science 279, 860–863 (1998).

A Beach Project Built on Sand; By Robert S. Young, PhD

beach-re-nourishment
Photo source: ©© U. S. Fish and Wildlife Service – Northeast Region

Excerpts;

“Earlier this month, Gov. Andrew M. Cuomo announced a $207 million plan to dredge millions of tons of sand off the south shore of Long Island and spread it along the beaches and dunes. The Army Corps of Engineers, which will direct the federally financed project, says it will stabilize Fire Island and reduce the storm surge hazard for the mainland.

In fact, the project will do neither. It is a colossal waste of money and another consequence of the nation’s failure to develop a coherent plan to address the risks from storms faced by states along the eastern seaboard and gulf coast…”—Robert S. Young, Director, Program for the Study of Developed Shorelines, Professor, Coastal Geology, Western Carolina University

Read Full Article, By Robert S. Young, PhD, in The New York Times

A New Frontier for Fracking: Drilling Near the Arctic Circle

alaska-child-thumbnail
Shishmaref, Alaska. Photo source: ©© Angela

Excerpts;

Hydraulic fracturing is about to move into the Canadian Arctic, with companies exploring the region’s rich shale oil deposits.

But many indigenous people and conservationists have serious concerns about the impact of fracking in more fragile northern environments…

Read Full Article, Yale E 360

“El Expolio De La Arena”

El Expolio De La Arena

By Cristina Sáez

Originally published in © La Vanguardia Magazine , August 8, 2014. All text and images courtesy of © La Vanguardia Magazine; Copyright © La Vanguardia Magazine. All rights reserved.

En estas fechas, muchos deben de estar en la playa. Es el destino turístico por excelencia, elegido por una de cada tres personas para su asueto estival. Si usted, lector, es una de ellas, ¡aproveche! Porque, desgraciadamente, dentro de poco puede que no quede ni una sola playa en todo el planeta. “Ah, ¡el cambio climático!”, tal vez esté pensando. En parte tiene razón, pero el motivo principal de la desaparición de este bello ecosistema natural no será ese, sino que se acabará la arena.

“Vamos a la playa, ponemos la toalla, tomamos el sol, tal vez hacemos un castillo de arena con nuestros hijos. Y nos vamos tan contentos, sin plantearnos nada. Pero, el 75% de las playas del planeta está desapareciendo. En el 2100, de seguir así, no quedará ni una sola. Hay mafias que matan por conseguir arena, hay contrabando. Y si la voracidad de ciertos países continúa, acabaremos viendo a indonesios, indios malasios defendiendo a tiros sus costas a no tardar”. Quien así habla es Denis Delestrac, un realizador de documentales francés que investigó a fondo durante tres años qué estaba ocurriendo con este recurso natural.

En el 2013 estrenó un documental sobre el tema, Sand Wars, guerras de arena, en el que denuncia la sobreexplotación de esta materia y las gravísimas consecuencias que acarrea para el planeta. Su filme ha sido premiado en numerosos festivales e incluso ha propiciado que las Naciones Unidas (ONU), en el marco de su programa de medio ambiente (UNEP), hayan publicado un informe, basado en su investigación, titulado Arena, más escasa de lo que pensamos, en el que alerta sobre la situación, que califica de “emergencia”.

Una de cada cuatro playas del planeta ya muestra los efectos de la extracción masiva de arena. Paradójicamente, el impacto global de este fenómeno pasa inadvertido para la mayoría de las oenegés, gobiernos, científicos y medios de comunicación. La extracción de arena, en muchos sitios, ha resultado en la destrucción de playas y ecosistemas enteros, y ha tenido gran impacto en el turismo de esas zonas y el medio de vida de muchos pescadores.

La Nueva Fiebre Del Oro

Vamos a la playa y se suele dar por sentado que la arena va a estar ahí, se ven grandes extensiones doradas, parece un recurso inacabable, infinito. Pero tiene los días contados porque se ha colado en todos los rincones de nuestra vida.

Se estima que cada año, el tráfico mundial de este material es de cerca de 18.000 millones de toneladas, según un informe de la International Union of Geological Sciences. Esta cantidad es seis veces superior al consumo de petróleo, de unos 3.400 millones de toneladas.

“Al ser un material a priori tan abundante, se ha utilizado tradicionalmente en muchos procesos industriales. Se usa para hacer desde pasta de dientes, pintura y productos de limpieza del hogar hasta alimentos deshidratados, vidrio… Y por las capacidades semiconductoras del silicio, el elemento principal de la arena, también se emplea para fabricar chips, ordenadores, móviles”, explica Joan Poch, profesor de Geología de la Universitat Autònoma de Barcelona.

Aunque los sectores que más cantidad devoran son la construcción y el turismo. El primero lo hace de forma muy voraz: el 80% de las autopistas, puentes, edificios y otras obras pú- blicas están hechas con ingentes cantidades de arena. Esto se debe a que desde hace medio siglo se usa el hormigón armado como material de construcción, sumamente eficiente y de bajo coste. “Construcciones como parkings subterráneos o bloques de muchas plantas o rascacielos sólo son posibles gracias a este material”, indica Albert Cuchí, arquitecto y profesor de la Universitat Politècnica de Catalunya.

“El tráfico mundial de arena se ha estimado en unos 18.000 millones de
toneladas al año, casi seis veces más que el consumo de
petróleo.”
— Cristina Sáez

El hormigón se elabora con agua, cemento y gravas y arena, que en España procede de canteras en montañas (también alteran el entorno), porque la ley de Costas prohíbe que se obtenga del litoral. Pero en otros países se extrae del fondo marino y de las playas. El problema es que las cantidades que se necesitan para edificar o hacer puentes o carreteras son astronómicas. “Si cogiésemos un edificio recién construido, lo arrancásemos con los cimientos y lo pesáramos, tendríamos más de dos toneladas de material por metro cuadrado. Y más de la mitad sería arena y gravas”, señala Cuchí.

Singapur es uno de los países que más arena consumen delplaneta –quizás el que más–. Es una de las naciones más ricas pese a su reducido tamaño. “Para mantener su estatus de hub financiero internacional desde los años 60 ha aumentado un 20% su superficie. ¿Cómo? Echando tierra al mar. Y para ello ha importado arena de Indonesia, Vietnam, Malasia”, denuncia Megan MacInnes, responsable de campaña de la oenegé británica Global Witness.

Primero, explica, usaron legalmente la arena importada de sus vecinos, hasta que estos se percataron de que sus costas estaban devastadas y prohibieron la exportación. Singapur empezó a ir más lejos a com- prarla. Y también, entonces, comenzó el tráfico ilegal.

“Hay ladrones que van por la noche a playas paradisiacas de Malasia o Indonesia y se llevan toneladas de arena de la costa en pequeñas barcas. Luego van al puerto de Singapur, donde la venden, sin que la policía los intercepte”, asegura el realizador Denis Delestrac. O hay barcos que anclan en la costa y dragan grandes cantidades de arena a la superficie, lo que tiene igualmente consecuencias devastadoras al acabar con el ecosistema del fondo del mar, afectar a la pesca tradicional y poner en jaque la subsistencia de muchas familias.

Indonesia es seguramente el país que más ha sufrido la avaricia singapurense. Las autoridades locales afirman que han desaparecido ya 24 pequeñas islas de su litoral, y Greenpeace Indonesia alerta de que muchas más de las 83 islas que conforman la costa norte del país podrían ser engullidas por el mar en la próxima década debido al robo de arena.

“El daño que se está produciendo en la costa es irreparable. Y resulta irónico, porque Singapur tiene un marco legal muy avanzado para la protección del medio ambiente, pero claro, dentro de sus fronteras. Lo que les ocurre a otros países no parece importarle demasiado”, acusa Megan MacInnes.

“Las extracciones de arena ya han hecho desaparecer 24 pequeñas islas de Indonesia, y muchas de su costa norte están amenazadas; países como Singapur o Dubái son grandes consumidores
de arena.”
— Cristina Sáez

Que islas enteras desaparezcan dragadas resulta catastrófico para la seguridad de Indonesia, porque las pequeñas actúan de escudos de las más grandes y habitadas ante tormentas y tsunamis. “En algunas comunidades del océano Índico los efectos del terremoto y posterior tsunami en el 2004 fueron peores por la extracción de arena”, señala Claire Le Guern, directora de Santa Aguila Foundation-Coastal Care, una entidad norteamericana que lleva 10 años alertando sobre los peligros de la extracción de arena.

Dubái, en los Emiratos Árabes, es otro voraz consumidor de arena. El minúsculo país vive un boom por construir rascacielos. Cuenta con cerca de 200, entre ellos el Torre Jalifa, el más alto del mundo. Y hay previstos casi medio millar más que, de llegarse a edificar, la convertirán en la ciudad del mundo con más construcciones de este tipo. Y para ello, claro, se necesita más y más arena.

El país desarrolló además dos proyectos –tildados de estrambóticos por algunos– de islas artificiales. Uno, The World, un archipiélago de 300 islas que forman un mapa del mundo, se ha abandonado. Y otro es The Palm Jumeira, una isla artificial con forma de palmera.

¿Imagina los millones de toneladas de arena que se necesitaron para crear esas islas? Cerca está el desierto, pero no se puede usar su arena. “El grano de la del desierto está muy erosionado por la acción del viento y es muy redondo y pulido, no se une a otro. En cambio, el de playa es más rugoso, desigual y funciona muy bien para construir”, explica Joan Poch.

La Mafia De La Arena

India es uno de los principales suministradores de arena de Dubái. En el país del sur de Asia, la mafia de la arena es la organización más poderosa; empresas de construcción y material, así como policías y políticos corruptos están detrás del robo de playas enteras, afirma Delestrac. “Hay crimen organizado, con conexiones con las más altas esferas políticas; un sistema bien organizado que va desde la extracción hasta la venta y la construcción. Y las personas que se ven obligadas a excavar la arena son muy pobres, una especie de esclavos, a quienes amenazan con matar a sus familias si no lo hacen”, cuenta.

También en Africa Coastal Care tiene noticia de organizaciones criminales que matan y extorsionan para hacerse con este recurso. De hecho, la oenegé ha documentado la devastación de las playas marroquíes del norte. “Antes estas playas eran muy largas, podías casi recorrer toda la costa por ellas. Y eran bellísimas, con enormes dunas. Constituían uno de los principales atractivos turísticos del país. Y vimos con nuestros propios ojos cómo se las llevaban día y noche. Hombres, incluso niños, cogían la arena con palas, la cargaban en burros para meterla en camiones. Ahora esa zona es paisaje lunar. Da muchísima pena”, cuenta Le Guern.

Marruecos tiene como despensa el Sáhara. El país exporta cada año unas 50.000 toneladas de arena procedente de territorios ocupados, por lo que la ONU ha dictado que el comercio de este recurso es ilegal, aunque continúa, denuncia la oenegé Western Sahara Resource Watch. Y afirma que entre los principales compradores está España, que desde hace 30 años importa arena del desierto para rellenar playas canarias.

¡Vamos A La Playa!

Además de la construcción, el otro agujero negro de la arena es el turismo. Es una industria muy potente de la que muchos países dependen económicamente por la actividad que genera, desde alojamiento hasta restauración y ocio. De ahí que todos quieran ofrecer playas anchas y bonitas, aunque eso implique prácticas como robar arena de los vecinos.

En Cancún, en el 2009, se registró el caso de un hotel que había vaciado una playa de otra zona turística para rellenar su propia playa. Y no hace falta ir tan lejos: en Cádiz, el año pasado, Ecologistas en Acción denunció el robo de arena de la playa de Valdevaqueros que fue vendida a Gibraltar, que la usó para crear playas artificiales.

En España y otros países es muy habitual extraer arena del fondo del mar, de la costa, para rellenar las playas. Poco antes de comenzar la temporada de baño, es frecuente ver enormes barcos anclados frente a la costa dragando arena para luego verterla en la zona en que pondremos la toalla meses después.

“Ya apenas quedan playas naturales en el mundo. Casi todas son artificiales, porque si no las rellenásemos cada cierto tiempo, desaparecerían”, explica Jorge Guillén, geólogo marino del Instituto de Ciencias del Mar-CSIC (ICM-CSIC).

La extracción de arena del fondo marino no es inocua. Muchos microorganismos y pequeños animales y algas viven en esa arena y constituyen la base de la cadena alimenticia marina. Si ellos desaparecen, peces mayores no tienen con qué alimentarse. Y así hasta llegar a nosotros, los humanos. Además, rellenar las playas es un parche temporal, porque esa arena se vuelve a perder. ¿Y eso por qué?

Las playas son ecosistemas muy dinámicos que cambian con cada estación. En invierno apenas se ve arena, y en verano, en cambio, aparecen grandes franjas doradas. Esos cambios en el aspecto de la playa no implican modificaciones de volumen, sino de distribución de la arena. Es un proceso que de manera natural funciona a la perfección, en el que no se pierde ni se gana un solo grano. En geología, a este equilibrio se le llama balance sedimentario.

Los problemas empiezan cuando ese balance es negativo. “La pérdida de arena de las playas tiene que ver con la intervención del ser humano”, señala Joan Poch. La mayoría de los granos de arena de la playa procede de la erosión de las montañas y tarda decenas de miles de años en llegar a la costa. Son transportados por el viento y, sobre todo, por los ríos. No obstante, la mayoría de los ríos están ahora regulados mediante presas, que detienen el agua y asimismo el aporte de sedimentos al mar.

“Las playas pierden hoy arena porque los ríos ya depositan menos sedimento, por la edificación en primera línea de mar y la construcción de puertos y por el aumento del nivel del mar”
— Cristina Sáez

“En España, se calcula que, antes de construir las presas, el río Ebro, por ejemplo, aportaba unos 20 millones de toneladas de sedimentos al mar. Ahora puede que lleguen apenas unas 150.000 toneladas”, señala Jorge Guillén. Esto, sumado a la edificación en primera línea de mar, sin respetar la forma de la playa y sus dunas; a la construcción de puertos por toda la costa, que desvían las corrientes submarinas que antes distribuían la arena, y al avance del nivel del mar por el cambio climático, “hace que la gravedad de la situación vaya en aumento; las playas ejercen de amortiguadores entre el océano y la tierra. Sin esa protección y con el aumento del nivel del mar, las olas están invadiendo la tierra, salinizando la capa freática y contaminando el agua que bebemos y que usamos para la agricultura. Es un auténtico desastre”, alerta Claire Le Guern.

Vidrio Reciclado

Pero ¿qué se puede hacer para evitarlo? Porque el problema, coinciden en señalar todos los expertos, irá al alza. La arena es un recurso natural finito, la demanda seguirá aumentando, continuarán las mafias, el contrabando y los desastres naturales. “Una solución puede ser reciclar lo que ya tenemos. Dedicar más recursos y energías, e inversiones tecnológicas a investigar las posibilidades del reciclaje”, señala la directiva de la organización Coastal Care.

En este sentido, en Florida, en Estados Unidos, están regenerando las playas con vidrio reciclado. En esa zona del país, la costa es clave para la economía, puesto que es el principal reclamo turístico: aguas prístinas, buen clima, arena fina. No obstante, como en tantos otros lugares, aquí también han construido en primera línea de mar, las playas se han erosionado, y llevan décadas teniendo que rellenarlas. Y hace un tiempo se quedaron sin arena.

Entonces se les ocurrió una solución ingeniosa. Al parecer, una tercera parte del vidrio es imposible de recuperar, y en Florida han cogido esa parte, la han machado hasta pulverizarla y la han puesto de nuevo en as playas. “Se comporta exactamente igual que la arena. No hay turistas por ahí con los pies cortados”, bromea Le Guern. Debe de ser muy similar porque incluso las tortugas han regresado a esas playas a poner sus huevos.

Donde más tienen que cambiar las cosas es en la construcción. Para Sonia Hernández -Montaño, arquitecta experta en bioconstrucción y fundadora del estudio Arquitectura Sana, “podemos optar por una solución parche y seguir construyendo con hormigón armado, aunque buscando alternativas para no tener que seguir reventando montañas o vaciando playas”. En España, cuenta esta arquitecta, se ha llevado a cabo algún experimento con autopistas, en las que se han usado escorias de la industria metalúrgica que no se podían reciclar.

“Ya existen algunas experiencias de uso de materiales reciclados en la construcción, y en Florida se ha usado vidrio reciclado para rellenar las playas; los expertos abogan también por recuperar materiales naturales de cada zona.”
— Cristina Sáez

En Sant Cugat, cerca de Barcelona, la planta de Unión Transmóvil, dedicada al reciclaje de residuos de la construcción, recoge los escombros de obras de reforma y de derribos, los somete a un proceso de limpieza y así consigue recuperar material apto para volver a construir.

Ya se emplea en carreteras, drenajes, canalizaciones. “Los vertederos son el negocio tradicional, adonde van a parar todos los residuos de la construcción, pero eso contamina, crea canteras y desaprovecha recursos. Hay muchos residuos susceptibles de convertirse en productos para abastecer el mercado. ¿Por qué usar solamente materiales nuevos?”, se pregunta Roger Domènech, gerente de la citada planta.

Otra opción es introducir más materiales naturales, como la madera laminada, usada en Austria y Alemania, aunque tiene un límite constructivo: no se pueden superar las cuatro o cinco plantas.

Para el arquitecto y profesor Albert Cuchí, “la construcción del futuro tendrá que se más a la rehabilitación y no tanto a la nueva construcción. También tenemos que repensar el modelo de ciudad, sólo así podremos utilizar otros sistemas de construcción. ¿Hace falta que más de la mitad de la población mundial viva en la costa?”.

Igualmente, habrá que reflexionar sobre el modelo de arquitectura. Ahora está globalizada, se construye igual en Dubái que en Finlandia, dice Hernández-Montaño, “los arquitectos deberíamos tratar de repensar cuál es la arquitectura tradicional de cada lugar y usar los materiales de la zona. No tiene sentido hacer los mismos edificios en todas partes, cuando el clima es distinto”.

Como civilización no podemos detener el mundo que tenemos en marcha, pero tampoco podemos seguir haciendo las cosas igual que hace 50 años, porque la situación en el planeta ha cambiado. La población ha aumentado, los recursos naturales menguan y el cambio climático avanza. “Tenemos que hallar nuevas maneras sostenibles de adaptarnos a las nuevas situaciones. Necesitamos invertir en nuevo pensamiento. De otra forma, ¿qué Tierra vamos a dejar a los que vienen detrás?”, se pregunta Claire Le Guern, de Coastal Care.

City of Santa Barbara Sea-Level Rise Vulnerability Assessment: A summary Report

By Nicole L. Russell and Gary B. Griggs, Department of Earth and Planetary Sciences, Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz,

ABSTRACT

In 2010, the California Resources Agency funded a project to develop a guide for assisting local governments in sea-level rise adaptation planning: “Adapting to Sea- Level Rise: A Guide for California’s Coastal Communities” (Russell and Griggs 2012). An assessment of the vulnerability of the city of Santa Barbara to future sea- level rise (by the years 2050 and 2100) and related coastal hazards served as a case study for the development of the adaptation guide.

Historically damaging events, shoreline topography and development, and exposure to sea-level rise and wave attack were evaluated for Santa Barbara, as were the likely impacts of potential future coastal hazards to specific areas of the city, risk levels, the city’s ability to respond, and potential adaptation measures.

The case study finds that the risk of wave damage to shoreline development and infrastructure in Santa Barbara will be high by 2050 and very high by 2100. Choices are limited and adaptive capacity will be moderate, with retreat as the most viable long-term option. By 2050, flooding and inundation of low-lying coastal areas will present a moderate risk to the city, which will have a moderate capacity for adaptation. The risks are expected to be very high and adaptive capacity will be low by 2100.

Cliff erosion has taken place for decades, threatening public and private property in the Mesa area. The risk of increased cliff erosion rates will be moderate by 2050 and very high by 2100. Because armoring is ineffective along the Mesa and retreat would necessitate the relocation of structures, adaptive capacity will be low. Inundation of beaches presents a low threat to the city by 2050 but a high threat by 2100.

The city faces a dilemma: Protect oceanfront development and infrastructure or remove barriers and let beaches migrate inland. By 2100, structures will have to be moved if beaches are to be maintained.

Gobal sea level is rising. As a result, many coastal communities will face tough choices for adapting to the future conditions and/or dealing with the consequences. Although the precise rate of future sea-level rise is impossible to predict because of the uncertainties in the factors that affect future climate and thus sea level, a 2011 survey of California’s coastal professionals suggests that most are well aware that sea level is changing and will continue to change well into the future (Finzi Hart et al. 2012).

Participants in the assessment also indicated that adaptation to sea-level rise is a high priority for coastal communities. Fortunately, the state of California is supporting their cause. The California Coastal Commission recently announced that it will award a total of $1 million in grants in early 2014 to local governments that successfully apply for assistance to update their Local Coastal Programs, with special consideration for updates that address the effects of climate change.

Tide gage records indicate that the average rate of global sea-level rise was 0.8 to 2.2 mm/yr (Figure 1). From Cape Mendocino to the Canadian border, the coastline lies above a subduction zone, where accumulating stress tends to raise the land. While there are some regional tectonic differences along this nearly 1,000-km (600-mi) stretch of coastline, tide gage data show that local rates of sea-level rise are generally lower than the global average and in some cases, local sea level is dropping because the rate of uplift outpaces the rate of sea-level rise. These phenomena suggest that coastal communities must tailor sea-level rise adaptation plans to fit the unique needs of their own localities.

Relative to the year 2000, sea level is projected to rise along the California coast south of Cape Mendocino by 5-30 cm (2-12 in) by the year 2030, 13-61 cm (5-24 in) by 2050, and 43-168 cm (17-66 in) by 2100. From Cape Mendocino to Puget Sound (Washington) in the north, sea level is projected to change by -5 to +23 cm (-2 to +9 in) by 2030, -3 to +48 cm (-1 to +19 in) by 2050, and 10-142 cm (4-56 in) by 2100 (NRC 2012). (These projections have ranges due to the con- sideration of multiple climate models.) However, these figures do not account for the next great Cascadia Subduction Zone earthquake, which would likely cause much of the region north of Cape Mendocino to immediately subside and local sea level to suddenly rise by at least 1 m (3.3 ft) (NRC 2012).

The ocean’s gradual advance upon low-lying shorelines will lead to the eventual permanent inundation or erosion of beaches that are backed by development or barriers, such as seawalls, roads, parking lots, and other structures. While permanent inundation is expected to occur gradually over the long-term, the most significant threats to California’s shoreline over the next few decades will continue to be short-term episodic events, such as storms. Storm waves and associated storm surges that arrive during high tides are especially damaging when sea level is elevated during strong El Niño winters (NRC 2012). However, a rising sea level is expected to increase the frequency and severity of these and other short-term events that coastal communities are used to experiencing, such as occasional storm flooding (Figure 2) and cliff or bluff erosion (Figure 3). Additionally, floodwaters and waves can be expected to reach higher elevations and move further inland than they have in the recent past. This will threaten private homes, businesses, and public property, including critical low-lying infrastructure, such as highways, bridges, power plants, and sewage treatment facilities along the coastline, many of which have already been threatened, damaged, or destroyed by storms in past years.

It is likely that sea-level rise will have a significant impact on California’s economy. A 2011 state-commissioned study (King et al.) uses sea-level rise projections to estimate the potential economic losses due to flooding and beach erosion or five California beach communities. A 1.4-m (55-in) rise in sea level by the year 2100 could lead to a total loss (i.e. total accumulated loss between now and the year 2100) of at least $440 million in tourism spending and tax revenue at Venice Beach alone (King et al. 2011). This estimate is likely conservative because it assumes that population and income will not grow after the year 2010.

Adaptation planning is still in its early stages and there is a need for technical assistance and the ongoing translation of scientific information into forms that are readily understood by coastal planners and managers (Finzi Hart et al. 2012). Given this insight and the fact that each community is unique in terms of land motion (and thus rate of local sea-level change), topography, demographics, poli- tics, etc., California’s Resources Agency funded an effort to develop a guide for assisting local governments in their preparations for future sea-level rise.

While there are many existing documents about climate change vulnerability and adaptation, it appears that none of them are focused specifically on local sea-level rise. “Adapting to Sea-Level Rise: A Guide for California’s Coastal Communities” provides scientific background information about sea-level rise and walks users through the processes of performing local sea-level rise vulnerability assessments, risk analyses, and formulating and implementing sea-level rise adaptation plans (Russell and Griggs 2012). This guide is now available online, courtesy of the California Ocean Science Trust.

The methods presented in this guide were developed in part through our assessment of the vulnerability of the city of Santa Barbara, California to sea-level rise and related coastal hazards, which can serve as an example for other coastal communities (Griggs and Russell 2012). See: “City of Santa Barbara Sea-Level Rise Vulnerability Study.”

SEA-LEVEL RISE AND THE CITY OF SANTA BARBARA

The city of Santa Barbara is located along the central California coast, about 145 km (90 mi) northwest of Los An- geles. Its approximately 8-km (5-mi) east-west trending coastline faces south and includes cliffs, bluffs, and beaches (Figures 4 and 5). The low-lying Santa Barbara Airport is also part of the city, although it is located about 5 km (3 mi) west of the city proper. The “City of Santa Barbara Sea-Level Rise Vulner- ability Study” (Griggs and Russell 2012) evaluates the vulnerability and adaptive capacity of the city of Santa Barbara to sea-level rise by the years 2050 and 2100. Sea-level rise is expected to increase the magnitude of coastal hazards and loss of resources from storm damage, flooding, sea cliff and bluff erosion, and shoreline erosion. A variety of physical, ecological,economic, and social consequences can be expected to result from these changes. The vulnerability study qualitatively assesses risks to the city, emphasizing the potential consequences for public property and infrastructure, as well as private property and development along the coastline.

Materials and methods

This project was initiated while the city of Santa Barbara was completing a general plan revision and an environmental impact report (EIR) that included a climate change component. At the beginning, we met with relevant city departments to explain the project’s objectives, ask for information and suggestions, and find out what kinds of information were desirable to city staff. Follow-ups provid- ed useful information and photographs of historical coastal storm damage, flooding, and cliff erosion.

Historical aerial photographs from the California Coastal Records Project proved to be very useful for evaluating conditions and development along the city’s coastline. In addition, the city’s revised general plan and EIR highlighted areas that were historically and/or are currently vulnerable to coastal storms, flooding, and erosion, as well as the areas that will likely be vulnerable to coastal impacts associated with future sea-level rise. We used the state of California’s sea-level rise projections to assess haz- ards: 25-43 cm (10-17 in) by 2050 and 1-1.4 m (3.3-4.6 ft) by 2100 (projections relative to the year 2000). (These values were recommended in 2010, prior to the release of the 2012 NRC report.) City department staff reviewed draft versions of the vulnerability assessment and adaptation recommendations.

For adaptation to future changes, a coastal community must have an understanding of both its vulnerability to the expected changes and its risk, as adaptation to sea-level rise is a risk management strategy for an uncertain future. For the purposes of this study, vulnerability is defined as the degree of exposure to a relatively high sea level or to the com- bined effects of an elevated sea level plus a major coastal storm and/or high tide. On the other hand, risk includes both the probability that a future event (i.e. coastal flooding, inundation, or increased cliff erosion) is likely to occur, as well as the magnitude (or level of severity) of the event. Thus, a vulnerability assessment should include an evaluation of the level of a community’s exposure to coastal hazards, as well as the potential magnitudes of the damages or losses from events that are known to elevate sea level significantly, such as large El Niño storms or storm surges.

Finally, adaptive capacity must be evaluated. Adaptation is defined as the adjustment of natural or human systems in response to actual or expected events and their effects, such that losses are minimized. Thus, a coastal community’s adaptive capacity is defined by its ability to respond to sea-level rise and its associated impacts, including the avoidance, reduction, or moderation of potential damages, as well as its ability to cope with the expected or predicted consequences of such impacts.

Conducting the assessment

Several types of coastal processes have the potential to affect communities like Santa Barbara. Each of the following needs to be evaluated and considered in planning efforts:

  • Sea-level rise
  • Coastal storm damage
  • Runoff and flooding
  • Cliff or bluff retreat
  • Shoreline or beach retreat

It is also important to understand that the effects of these individual processes can be cumulative and any combination can be more severe or damaging than a single event. The city of Santa Barbara has been damaged during such events in the past and will experience them again in the future, most likely with an increased frequency under rising sea levels. The impacts of those events are also expected to increase in magnitude as a result of sea-level rise.

“ The city faces a dilemma: Protect oceanfront development and infrastructure or remove barriers and let beaches migrate inland. By 2100, structures will have to be moved if beaches are to be maintained.”
— Nicole L. Russell & Gary B. Griggs

The first step in conducting a sea-level rise and coastal hazards vulnerability assessment is to collect information about a community’s historical vulnerability to coastal hazards using reports, maps, surveys, photographs, newspaper archives, interviews, etc. that detail past damages. This will help to delineate historically eroded, flooded, or damaged areas and, therefore, the areas that are most likely to be affected again in the future. Because future rates of erosion are expected to be at least as high as historic rates, a community will need to obtain data for historic cliff, bluff, dune, and beach erosion rates. It is also important to look for informa- tion about previous short-term increases in sea level and exposure to El Niño events. Potential adaptation responses can then be recommended for reducing exposure to future hazards. In this study, specific areas of the city of Santa Barbara were analyzed in order to determine the likely impacts of sea-level rise, the risks that are posed by these hazards, and the city’s ability to respond to them.

The second step is to obtain historic sea-level rise rates using the nearest tide gage or gages, as these can serve as a community’s baseline data. The National Oceanographic and Atmospheric Ad- ministration (NOAA) is a good resource for this information. This step is necessary because rates of sea-level rise vary by tectonic setting along the 1,770-km (1,100-mi) length of California’s coastline.

The third step is to obtain the most recent sea-level rise projections for different future dates (e.g. 2050 and 2100). The estimates provided in the latest NRC report are the standards that were recently adopted by the California state agencies that must consider sea-level rise adaptation measures. It makes sense for local communities to use the same values, although adaptation plans should be adjusted as new sea-level rise projec- tions become available. As previously stated, the Santa Barbara study uses the state of California’s 2010 sea-level rise projections of 25-43 cm (10-17 in) by the year 2050 and 1-1.4 m (40-55 in) by 2100 (relative to sea level of the year 2000), as the NRC’s 2012 values (13-61 cm or 5-24 inches by 2050 and 43-168 cm or 17-66 inches by 2100), were not yet available prior to this study’s completion.

The final step in assessing vulnerability is to identify and map the areas that are likely to undergo flooding in the future, given the most recent sea-level rise projections (for 2050 and 2100). It is best to use the latest high-resolution land surface elevation data, such as Li- DAR data, which can be obtained from NOAA’s Digital Coast website, although utilization of this data requires experience in GIS.

For the latest analysis of Santa Barbara’s potential future flood elevations, 2010 LiDAR data were obtained as digi- tal elevation models from NOAA’s 2009- 2011 CA Coastal Conservancy Coastal LiDAR Project (2011). The horizontal positional accuracy of these data is 51 cm (20 in) or better and the vertical accuracy is 18 cm (7 in) or better (NOAA 2011). Contour lines representing (a) the 1.35 m (4.43 ft) mean high water level (from Hapke et al. 2006), (b) the 100-year flood (0.9 m or 3 ft flood) level on top of mean high water plus 60 cm (2 ft) of sea-level rise (the highest projected sea-level rise by 2050, from NRC 2012), and (c) the 100-year flood level (0.9 m flood) on top of mean high water plus 1.7 m (5.5 ft) of sea-level rise (the highest projected sea- level rise by 2100, from NRC 2012) were added using ArcGIS software. Contour layers were exported as shapefiles and then converted to KML format for use in Google Earth.

The next course of action is to complete a risk assessment for different endpoints in time (e.g. 2050 and 2100) by evaluating the likelihood that impacts from each sea-level rise-related hazard or process from the vulnerability assess- ment will occur in the future, as well as the magnitudes of the consequences of those events. An assessment of risk also includes an evaluation of adaptive capacity, or the ability of a community to respond to, adapt to, or recover from the changes associated with sea-level rise at different future time periods (NOAA 2010). For this study, we considered the future threats of concern along the city’s coastline (e.g. flooding, cliff and bluff erosion, inundation, and beach loss), the economic importance and value of public facilities and infrastructure, and the value and importance of residential development. Additionally, we assessed the magnitudes of the impacts of future hazardous events, the timing and frequency of such events, and the certainty of occurrences to the degrees that they can be projected (e.g. given that sea level reaches a particular elevation, certain structures will be flooded during storms of a given magnitude). The future risks from hazards that are associated with sea-level rise were evaluated for both a short to intermediate timeframe (2012- 2050) and an intermediate to long-term timeframe (2050-2100). We used three different levels for the magnitude of impact: low, moderate, and high; and four different levels for the probability or likelihood of occurrence: low, moderate, high, and very high. Although the terms “low, moderate, high, and very high” are based upon the sea-level rise scenarios that were originally suggested for use by California’s state agencies, they are used qualitatively in the Santa Barbara report.

Finally, we used the vulnerability and risk assessments to identify adaptation options for each projected hazard. Communities should consider overall effectiveness, general cost-effectiveness, and ease of design and implementation of various strategies. Adaptation to sea- level rise is a relatively new concept and most coastal communities have limited resources for dealing with the consequences of climate change. Ideally, a city or county would determine the economic/historic/cultural, etc. values of all of its coastal infrastructure, development, recreational areas, etc., for the purpose of ranking their relative levels of vulnerability and importance to the com- munity. Planning staff could then focus upon the critical areas, such as facilities and development that are sited at the lowest elevations, infrastructure that is critical for meeting the needs of the community (e.g. sewage transmission lines, pumping stations, or treatment plants), and structures or infrastructure that are closest to the edges of eroding cliffs or bluffs. In this way, a community could stagger its adaptive efforts in phases, rather than attempting to tackle all areas simultaneously.

We utilized a ranking system for various risks to the city of Santa Barbara’s coastline by 2050 and 2100 using California’s 2010 projections for sea-level rise and emphasized the effects of anticipated future sea-level rise on public property and infrastructure, as well as private property (Tables 1 and 2). Suggested adaptation measures include a broad range of approaches: future planning for hazard avoidance, engineering (including retrofitting, rebuilding, construction, and protection), and retreat or relocation.

RESULTS AND DISCUSSION

Flooding

Santa Barbara has a NOAA tide gauge (established in 1973) but, due to displacement during various construction projects, the record is discontinuous and of limited value (Figure 6). However, if the tide gage remains stationary in the future, the record should become reliable and over time it will provide a long-term indication of local sea-level rise rate. The study recommends that all precautions be taken in order to protect the existing NOAA tide gauge at the breakwater from future construction or disturbance, such that a long-term record of local sea level change can be established.

As sea level rises, there will be an increased number of extreme high water events, which tend to occur when high tides coincide with winter storms and their associated high winds, storm surges, and wave run-up. Santa Barbara has suffered the effects of such events in the past. While sea level is temporarily elevated for several months during El Niño years, a particularly devastating storm during the 1983 El Niño was also accompanied by high tides, large waves, and storm surge, which eroded portions of the beachfront park facilities, damaged the yacht club and harbormaster’s office, and reached almost to Shoreline Drive (Figures 7-9; Figure 4 shows location of Shoreline Drive). Waves also carried debris onto Cabrillo Boulevard at Palm Park along East Beach (Figure 10; Figure 5 shows location of Cabrillo Boulevard).

Where streams meet the coast, back- water conditions can occur as elevated sea levels (from high tides, storm surges, or, over the long-term, from rising sea levels) prevent floodwaters from draining rapidly, causing streams to back up or slow down, which can lead to upstream flooding. Currently, flooding occurs dur- ing high tides and major storm events but these problems will be exacerbated in the future with increasing sea levels.

“ Retreat, or gradual relocation of the cliff-top homes or infrastructure, is the most effective long-term approach.”
— Nicole L. Russell & Gary B. Griggs

The city’s 2009 coastal flood hazard map was updated using NOAA’s (2011) LiDAR data, which has improved surface elevations. The new images show contour lines for the present mean high water level and for the potential future extent of 100- year flooding, based on the NRC’s 2012 sea-level rise projections for 2050 and 2100. The images were created using ArcGIS and Google Earth in order to produce maps with easily identifiable geographic features (Figures 11A-B). Both the 2009 city map and the new maps are limited in that the areas highlighted as being subject to flooding include all areas that are lower than the critical elevations, even though some of those areas are inland and not directly connected to the shoreline.

An increase in the number of extreme high water events will likely accelerate rates of cliff retreat and increase damage to public and private oceanfront properties and development, including city infrastructure. These types of events pose the greatest threats to the Santa Barbara coastline for the near-term future (until about 2050). Historically, damage to shoreline structures and infrastructure has been moderate but this is expected to increase to high in the near-term (by 2050) with 36 cm (14 in) of sea-level rise (pre-NRC 2012 value) because damage is already happening at present-day sea level (Table 1). The magnitude of damage will increase to very high by the year 2100 if sea level rises by 1.2 or more meters (at least 3.9 ft; pre-NRC 2012 value) above the year 2000 sea level (Table 2). Park facilities, parking lots, development at the harbor, the municipal wharf, Shoreline Drive, Cabrillo Boulevard, and associated infrastructure and development that serve visitors along Cabrillo Boulevard will all eventually be at risk from wave attack.

There are limited adaptive measures for the city’s low-lying shoreline areas: beach sand nourishment, armor to pro- tect in place, or relocation of facilities (retreat). Although Leadbetter Beach (Figure 4) was widened by hundreds of feet following breakwater construction in the late 1920s, significant damage still occurred landward of the beach during the 1983 El Niño winter. West and East Beaches (Figure 5) are now nourished by the discharge of sand dredged from the harbor entrance. Without increasing the height and length of the breakwa- ter, additional sand will probably not solve the challenges that are posed by a significant increase in sea level by 2050.

Furthermore, it is unclear whether there is a source of sand that would be large enough for such a project. While a seawall can help to buffer or protect oceanfront development from wave attack over the short to intermediate-term (until 2050), this may require significant investment in the Leadbetter, harbor, West, and East Beach areas. Over the long-term (from 2050-2100), if 0.9-1.2 m (3-4 ft) of sea-level rise were to occur and the city beaches were greatly reduced in width or eliminated as buffers for the winter months, a seawall would need to be of substantial height. The lifetime of the structure, the protection that would be offered by it, and its potential costs and benefits would need to be carefully weighed against a gradual retreat, which might be the only long-term option as sea level continues to rise.

In addition, rising sea levels and a high water table could begin to interfere with wastewater discharge and/or potentially increase flood hazards at treatment plants in low-lying areas (CCC 2009). The city’s El Estero Wastewater Treatment Plant is located within 400 m (0.25 mi) of the shoreline, at a ground elevation of about 3.6-4.2 m (12-14 ft) above historic mean sea level. While it does not appear likely that the plant could be subject to flooding with a modest increase in sea level, projections show that the facility would be increasingly vulnerable over time to a 100-year flood event with 1.4 m (4.6 ft) of sea-level rise. Thus, sea-level rise may necessitate the modification of plant facilities or operations in the com- ing decades.

Airport flooding and inundation

The Santa Barbara Municipal Airport, located about 13 km (8 mi) west of down- town Santa Barbara, is the largest com- mercial service airport on the California coast between San Jose and Los Angeles, providing a major economic benefit to the South Coast. The airport was originally built on artificial fill within and upon the margins of the Goleta Slough. As such, it is located only a few feet above sea level, much like the San Francisco and Oakland International Airports, as well as many other airports in coastal cities around the world. Because it lies in an area where five streams converge, the airport has historically been subject to flooding. In 1969, water completely surrounded the main terminal (Figures 2 and 12). In 1995 and 1998, all three runways were flooded, closing the airport for several days (Figure 13). Public buildings and structures are threatened by inundation during heavy rains and runway flooding poses a safety hazard, preventing planes from taking off and landing.

Even without sea-level rise, flooding will occur during intense and prolonged rainfall, which will increase runoff from the streams that drain into the Goleta Slough and combine with high tides. With a rising sea level, the frequency and magnitude of flooding in the area can be expected to increase. NOAA (2011) LiDAR data were used to update the city’s 2009 flood map for the airport area. With 61 cm (24 in) of sea-level rise by 2050, a 100-year flood could reach the runways and get close to the terminals (Figure 14). By 2100, 1.7 m (5.6 ft) of sea-level rise would allow 100-year floodwaters to extend across the entire airport (Figure 14).

Thus, the probability of airport flood- ing is high in the short to intermediate- term (to 2050). If sea-level rise ap- proaches or exceeds 1.2 m (3.9 ft) by 2100, the probability of flooding, with some permanent inundation of the site, will be very high. There are two areas of concern regarding short-term flooding and permanent inundation: 1) the airport terminal and parking areas, and 2) the runways and associated areas for air- planes. While temporary flooding of the runways and airport parking areas will be short-term inconveniences, as they have been in the past, permanent inundation presents an unacceptable risk. The adaptive capacity of the Santa Barbara Airport to future flooding and inundation in the short to intermediate-term is believed to be moderate. It seems possible, although very expensive, to raise the runways in order to accommodate the 100-year flood conditions for the projected high sea level of 2050. However, it appears that neither the terminal nor the runways can easily be adapted to the 100-year flood conditions of 2100 with high projected sea-level rise.

Cliff and bluff retreat

There are 6.4 km (4 mi) of coastal cliffs within Santa Barbara’s city limits. Monterey Shale, capped by unconsoli- dated marine terrace deposits, comprises the majority of these cliffs, which are 15- 30 m (49-98 ft) high. They are susceptible to erosion from both wave attack and terrestrial runoff and they are also prone to landslides and slumps. The bedrock has been deformed and tilted throughout this area and in some places, bedding dips (tilts) towards the beach. This is highly conducive to bluff failure, in which slid- ing occurs along exposed bedding planes. The cliffs at both ends of the city are experiencing active erosion and retreat. Historic aerial photographs were used to determine average long-term erosion rates, which range from about 15 to 30 cm/yr (6 to 12 in/yr) (Griggs et al. 2005). Hapke and Reid (2007) completed a statewide assessment that compares cliff edge position on aerial photographs from the 1930s with LiDAR data from 1998 (approximately a 70-year period) and obtained similar values: an average of 10-46 cm/yr (4-18 in/yr) for the Mesa area in the west (Figure 4) and about 15 cm/yr (6 in/ yr) for the Clarke Estate/Cemetery cliffs in the east. The range in erosion rates is a product of local variations in bedrock strength, bedding plane orientation, and the effects of development and human interference, including the placement of protective riprap on the fronting beaches. However, the overall linear trend of the bluff edge along the Mesa indicates that long-term rates of cliff retreat are fairly uniform alongshore.

Cliffs may appear to go unchanged for years until the right combination of groundwater saturation, tidal height, wave attack, and/or seismic shaking, causes episodic failure. The loss of two homes on the Mesa in 1978 illustrates how landsliding along the bluff edge can result in the nearly instantaneous loss of oceanfront property and structures. The winter of 1978 saw the first large El Niño event in years, and rainfall was heavy in Santa Barbara for several weeks prior to the slide. The Mesa failure was a typical rotational slump on a curved failure (rupture) surface, with a nearly vertical head scarp.

Google Earth was used to measure distances from the cliff edge to homes along the Mesa. There are about 98 cliff-front dwellings along the Mesa and nearly half of these are within 30 m (98 ft) of the cliff edge, while eight of them are within 15 m (49 ft). These homes were constructed at different times and setback distances from the cliff edges vary. Some homes or their additions (such as decks, patios, and other accessory structures) are located immediately adjacent to or within 5-10 m (16-33 ft) of the cliff edge (Figures 15 and 16). The proximity of a large number of homes and their additions to the cliff edge, combined with the cliff’s general instability and long-term retreat rates, results in a moderately high vulnerability to future cliff retreat and accelerated ero- sion due to a rising sea level.

On 25 January 2008, Shoreline Park (on the Mesa) suffered a landslide that extended 20 m along the cliff and moved the cliff edge inland by as much as 12 m (39 ft) (Figure 17). Since the park’s construction in the late 1960s, different sections of the cliff at the park have retreated intermittently. As erosion has occurred, walkways, picnic tables, and fencing have been relocated inland. Progressive retreat of the cliff fronting Shoreline Park is expected to continue, possibly by an increased rate, in the future.

The cliffs that front the Clarke Estate and the adjacent cemetery on the city’s east side are also subject to landsliding (Figure 3). Riprap was placed at the base of the bluff below the estate in the 1980s. This has reduced wave impact but it has not halted the failure of overlying materials, which appears to proceed primarily due to terrestrial processes. Below the cemetery, on the east end of the bluffs, an old con- crete seawall gradually deteriorated, so riprap and some cliff-top retaining walls were constructed in its place in an attempt to slow erosion. Many years ago, several groins were built in this area in order to trap littoral drift and widen the beach but these have also deteriorated over time and are no longer effective. Some of the gravesites that were once closest to the cliff edge have been moved back over time.

A continued rise in sea level will allow waves to attack the bases of cliffs and bluffs with an increased frequency, which will increase erosion. With average his- toric retreat rates between 15-30 cm/yr (6 to 12 in/yr), a loss of at least 3-6 m (10-20 ft) can be expected over the 20-year lifes- pan (by 2030) of Plan Santa Barbara. Total retreat could be higher than that in places where uncontrolled drainage, historic landslides, or adverse bedding planes exist (AMEC 2010). Over the short to intermediate-term (2012-2050), the probability of significantly increased cliff erosion rates is considered to be moderate (Table 1). However, the prob- ability is likely to increase substantially to high or very high over the intermediate to long-term (2050-2100; Table 2). If cliff erosion rates on the Mesa remain close to their historical values or double (to 30-60 cm/yr or 12-24 in/yr), the cliff edge could retreat by 12-24 m (39-79 ft) by 2050. Such retreat would directly threaten 30 or more homes, as well as a number of secondary structures. With increased ero- sion rates, Santa Barbara can expect to see 24-50 m (79-164 ft) of erosion from the present cliff edge by 2100. This will affect oceanfront walkways, trails, a play- ground, picnic areas, and two restrooms at Shoreline Park that are located within 15 m (49 ft) of the present cliff edge.

This magnitude of retreat would threaten or necessitate the relocation or removal of about 67 cliff-top homes on the city’s west side. If erosion rates increase in the future, the number of affected homes will also increase. With nearly all of the oceanfront Mesa-area homes likely to be affected by 2100, this is deemed to have a high impact over the intermediate to long-term timeframe (Table 2). A conservative prediction here and in other similar areas is that the rate of cliff erosion will increase in the future and the rate of increase will be related to the extent of sea-level rise, as well as any changes in wave climate. The study recommends the establishment of a cliff edge monitoring program with a set of surveyed transects that can be regularly re-measured in order to document and track rates of retreat along all sea cliffs within city limits.

There are two basic approaches for adapting to cliff or bluff erosion within the city of Santa Barbara or elsewhere: armor or retreat.

Because of the height of the cliffs and the typical failure mechanisms (large slumps or landslides), armoring is not likely to be an effective long-term solution. The situation along the cliffs below the Clarke Estate and the cemetery is similar to that of the Mesa. Although scattered riprap has been placed there over the years, it has been ineffective in halting cliff erosion because failure is occurring high on the cliff, as a result of terrestrial processes. While beach-level armoring is unlikely to be an effective mechanism for halting cliff erosion in this location, the land at the Clarke Estate and the cemetery is not highly developed, so retreat is a relatively easy option.

Retreat, or gradual relocation of the cliff-top homes or infrastructure, is the most effective long-term approach. The overall capacity of the city to adapt to the hazards of increased cliff retreat is low because there is no buffer zone or physical space to allow for retreat without relocation of structures.

Inundation of beaches

The likelihood of the inundation of city beaches (i.e. passive erosion or permanent coverage by seawater) will de- pend upon beach widths and elevations, as well as the future rate(s) of sea-level rise. Inundation, as opposed to short-term flooding, is defined as an essentially permanent condition. Leadbetter (Figure 4), West, and East beaches (Figure 5) have all eroded or flooded temporarily in the past, with waves reaching Cabrillo Boulevard under severe storm conditions (Figures 9 and 18). Over short to interme- diate timeframes (i.e. 2012 to 2050), there is a low probability of the permanent loss of city beaches under the 36-cm (14-in) sea-level rise scenario (Table 1). There may be some beach narrowing by 2050 but this is not likely to be very noticeable. An El Niño event will likely cause more beach flooding than will gradual sea- level rise, but the former is a short-term phenomenon lasting only a few days or weeks. Over the long-term (2050-2100), sea-level rise will gradually begin to cover low-lying areas that are fixed by back-beach barriers (such as seawalls, parking lots, buildings, etc.), which will eventually include all of the shoreline and beach areas closest to sea level. Seawater will reach further inland as sea-level rise continues, permanently covering previously dry land. For instance, areas that would have formerly only been tempo- rarily flooded or submerged during very high tides or El Niño conditions, such as freeway underpasses, will gradually begin to be submerged permanently.

“ All city beaches could potentially narrow and gradually disappear, and be replaced by shallow water or wet sand at low tide by 2100.”
— Nicole L. Russell & Gary B. Griggs

All city beaches could potentially narrow and gradually disappear, and be replaced by shallow water or wet sand at low tide by 2100. This would negatively affect tourism, beach use, and recreation. Any narrowing or loss of beaches would pro- gressively expose public facilities, such as the coastal bike trail, public parking lots, restrooms, and development at the Santa Barbara Harbor, Stearns Wharf, and along shoreline streets, to periodic flooding and/or increased damage from wave action. The study recommends the establishment of a set of beach profiles along the city shoreline and a set of winter and summer profiles from Cabrillo Boulevard to the shoreline to be surveyed annually, with profile spacing of about 500 ft (150 m). This would track both seasonal and long-term changes.

The ability to adapt to the potential inundation or loss of Santa Barbara’s beaches is low to moderate, depending on the particular beach in question. Allowing beaches to migrate inland and the shoreline to retreat as sea level gradually rises presents challenges for the city be- cause there is valuable development and infrastructure along the entire back edge of the beaches, from Leadbetter to East Beach.

Ultimately, park facilities and parking lots could be abandoned and the structures could be removed in order to allow the beach to migrate inland across the former shoreline. By the time that the ocean reaches Shoreline Drive, a major thoroughfare, projections for sea-level rise in the decades between 2050 and 2100 will likely have improved, such that the risks and options for adaptation can be assessed more accurately than they can be today. If Santa Barbara’s beaches are to be maintained, adaptation may ultimately require removal or relocation of the facilities between the shoreline and Cabrillo Boulevard. Adaptive capacity is deemed moderate because most of these facilities are potentially movable.

CONCLUSIONS

Sea-level rise is becoming an increasingly significant concern to many U.S. coastal communities and state and federal agencies, especially in light of the recent devastation caused by Hurricane Sandy. A rising sea level is expected to exacerbate the effects of all coastal storms, increasing the frequency and magnitude of coastal flooding, as well as the extent and rate of cliff, bluff, and beach erosion, with associated damage to shoreline infrastructure and development. Adaptation to sea-level rise is one important local approach to minimizing future risks and damages to coastal communities.

Sea-level rise adaptation is still an emergent concept, so there are few case studies and scarce information for city planners and coastal managers who want to begin the processes of assessing local vulnerability, performing risk analyses, and formulating and implementing their own adaptation plans.

Adapting to Sea- Level Rise: A Guide for California’s Coastal Communities (Russell and Griggs 2012) is a resource that should aid coastal communities both in and outside of California during the organization and management stages of their efforts to plan for sea-level rise.

The city of Santa Barbara has taken a critical first step towards sea-level rise adaptation by addressing these issues in its 2011 General Plan update and Environmental Impact Report, as well as in its 2012 Climate Action Plan, which incorporates data collection and adaptation planning recommendations from the City of Santa Barbara Sea-Level Rise Vulnerability Study. Furthermore, the city has applied for the California Coastal Commission’s Local Coastal Program Assistance Grant Program to update its Local Coastal Program to reflect the expected impacts of climate change, including sea-level rise.

It will be very useful for Santa Bar- bara and other coastal communities to publicize the results of their adaptation planning and to share them not only with local government staff, elected officials, and the public but also with other coastal communities, which face common issues related to sea-level rise and could benefit from the experience and insight.


REFERENCES:

  • AMEC Earth and Environmental Inc. 2010. “Pro- posed Final Program Environmental Impact Report for the Plan Santa Barbara General Plan Update.”
  • California Climate Change Center (CCC) 2009. “The impacts of sea level rise on the Califor- nia coast.” 99 p. www.pacinst.org/reports/ sea_level?rise/report.pdf.
  • Committee on Sea Level Rise in California, Oregon, and Washington, Board on Earth Sciences and Resources, Ocean Studies Board, Division on Earth and Life Studies, National Research Council (NRC) 2012. Sea-Level Rise for the Coasts of California, Oregon, and Washing- ton: Past, Present, and Future. The National Academies Press, 275 p. http://www.nap.edu/ catalog.php?record_id=13389.
  • Department of Commerce, National Oceanic and Atmospheric Administration, National Ocean Service, Coastal Services Center (CSC) 2011. “2009-2011 CA Coastal Conservancy Coastal Lidar Project.” NOAA’s Ocean Service, Coastal Services Center.
  • Finzi Hart, J.A., P.M. Grifman, S.C. Moser, A. Abeles, M.R. Myers, S.C. Schlosser, and J.A. Ekstrom 2012. Rising to the Challenge: Re- sults of the 2011 Coastal California Adapta- tion Needs Assessment. USCSG-TR-01-2012.
  • Griggs, G.B., 2010. Introduction to California’s Coast and Beaches. University of California Press, 311 p.
  • Griggs, G.B., K. B. Patsch, and L.E. Savoy 2005.
    Living with the Changing California Coast.
    University of California Press, Berkeley, CA, 540 p.
  • Griggs, G.B., and N.L. Russell, 2012. City of Santa Barbara Sea-Level Rise Vulnerability Study. California Energy Commission Public Interest Energy Research Program, 87 p.
  • Hapke, C.J., D. Reid, B.M. Richmond, P. Ruggiero, and J. List 2006. National assessment of shoreline change: Part 3: Historical shoreline changes and associated coastal land loss along the sandy shorelines of the California coast. U.S. Geological Survey Open-file Re- port 2006-1219: 79 p. http://pubs.usgs.gov/ of/2006/1219/of2006-1219.pdf.
  • Hapke, C.J., and D. Reid 2007. National Assess- ment of Shoreline Change, Part 4: Historical Coastal Cliff Retreat along the California Coast. U.S. Geological Survey Open File Report 2007-1133: 51 p. http://pubs.usgs.gov/ of/2007/1133/of2007-1133.pdf.
  • King, P.G., A.R. McGregor, and J.D. Whittet 2011. The economic costs of sea-level rise to California beach communities. California Department of Boating and Waterways and San Francisco State University, 97 p, http:// www.dbw.ca.gov/PDF/Reports/CalifSea- LevelRise.pdf.
  • National Oceanic and Atmospheric Administra- tion 2010. Adapting to Climate Change: A Planning Guide for State Coastal Managers. 138 p. http://coastalmanagement.noaa.gov/ climate/docs/adaptationguide.pdf.
  • Russell, N.L. and G.B. Griggs 2012. Adapting to Sea Level Rise: A Guide for California’s Coastal Communities. California Energy Commission Public Interest Energy Research Program, 52 p.

Why Wave Power Has Lagged Far Behind as Energy Source

wave-sumba
Photograph: © SAF – Coastal Care

Excerpts;

Researchers have long contended that power from ocean waves could make a major contribution as a renewable energy source.

But a host of challenges, including the difficulty of designing a device to capture the energy of waves, have stymied efforts to generate electricity from the sea…

Read Full Article,Yale E360

Call Climate Change What It Is: Violence

climate-change-canvas
Climate change canvas.
“My painting reflects the cycles of change, brought on by pollution and climate, that are severely affecting the Wiradjuri nation – one of the largest Aboriginal nations in Australia…” Artists from around the world have painted canvases illustrating the human impact of climate change in their countries. Captions and Photo source: ©© OXFAM International

Excerpts;

Climate change is anthropogenic, Climate change is violence.

So, If we want to talk about violence and climate change, and we are talking about it, after last week’s horrifying report from the world’s top climate scientists, then let’s talk about climate change as violence.

Climate change is global-scale violence, against places and species as well as against human beings. Once we call it by name, we can start having a real conversation about our priorities and values…

Read Full Article, Guardian UK

Temperature and Violence, Nature Climate Change

Coastal Barrier Resources System: Testimony of Robert S. Young, PhD

bull-island-south-carolina
Bull island, Cape Romain National Wildlife Refuge, South Carolina. Photo source: ©© Hunter Desportes
“Barrier islands are predictably hazardous locations on which to develop, invest, or maintain infrastructure. They are subject to long-term shoreline erosion, significant and devastating storm impacts, and rapid changes along inlet–adjacent shorelines.”—Robert Young.

By Robert S. Young, PhD,
Director, Program for the Study of Developed Shorelines, Professor, Coastal Geology, Western Carolina University

“The Us Congress will hold a hearing tomorrow on 9 separate bills that would remove properties and lands from the Coastal Barrier Resources System. CBRA was established to prevent federal funds from flowing into vulnerable barrier islands that were undeveloped in 1982. Several bills before committee would remove areas of North Carolina, South Carolina, and Florida from the system allowing them to access federal flood insurance, beach nourishment funding, etc. Following are the hearing notice and my testimony which I will present before Congress tomorrow.”

Testimony of Robert S. Young, PhD, PG

In regards to several bills proposed to revise boundaries of the John H. Chafee Coastal Barrier Resources System;

Before the House Committee on Natural Resources Subcommittee on Fisheries, Wildlife, Oceans and Insular Affairs;

April 8, 2014, Room 1324 Longworth House Office Building.

(b) The Congress declares that it is the purpose of this chapter to minimize the loss of human life, wasteful expenditure of Federal revenues, and the damage to fish, wildlife, and other natural resources associated with the coastal barriers along the Atlantic and Gulf coasts and along the shore areas of the Great Lakes by restricting future Federal expenditures and financial assistance which have the effect of encouraging development of coastal barriers, by establishing the John H. Chafee Coastal Barrier Resources System, and by considering the means and measures by which the long-term conservation of these fish, wildlife, and other natural resources may be achieved.—Coastal Barrier Resources Act, 1982

The 1982 Coastal Barrier Resources Act included a solid combination of science- based policy making with a conservative, free-market approach to risk reduction and environmental conservation. The science is clear. Barrier islands are predictably hazardous locations on which to develop, invest, or maintain infrastructure. They are subject to long-term shoreline erosion, significant and devastating storm impacts, and rapid changes along inlet–adjacent shorelines. Many of this nation’s barrier islands have been completely inundated by storm waters multiple times over the last three decades.

“ We simply cannot afford to continue to hold hundreds of miles of shorelines in place with federal dollars… ”
— Robert S. Young

In addition, these hazards will only increase over the coming years as shoreline erosion continues. Coastal hazards on these low-lying, sandy shorelines are different than other hazards like tornadoes or wildfires in that they have a significantly higher recurrence interval and we can, from a scientific perspective, precisely identify the areas that will experience repeat impacts.

Dauphin Island, Alabama, for example, has suffered significant storm impacts 11 times since 1979 receiving 7 Presidential disaster declarations. Tornadoes do not destroy the same community multiple times in a period of 10 to 20 years, but coastal storms do, and barrier island communities bear the brunt of these storms. I can tell you with near certainty that we will be rebuilding the west end of Dauphin Island again at some point in the next ten years, probably sooner, rather than later. As a scientist, and hazards specialist, I cannot possibly pinpoint, with the same level of certainty, that any particular locality will experience tornado impact during this same timeframe.

The federal government invests millions to billions (depending on the year) of dollars annually in storm protection projects, erosion mitigation projects, and storm damage recovery projects to support the economies and property values on these barrier island communities. Federal and state taxpayers subsidize this investment with a dizzying array of mechanisms.

The Federal Flood Insurance Program, administered by the Federal Emergency Management Agency (FEMA), provides vulnerable properties access to flood insurance that would not be available in private markets. Many states have government-managed “wind pools” to keep the rates for non-flood property insurance artificially low. The largest insurer of coastal property in Florida is the State of Florida through its Citizen’s Property Insurance Corporation. Finally, private losses not covered by insurance are often written off at tax time, an indirect federal subsidy of risky development. Since 1988, residents of Dauphin Island have paid $9.3 million in flood insurance premiums to the federal government, but they have received $72.2 million in payouts for their damaged homes.

Community and state level funds for post-storm rebuilding come largely through the public assistance sections of the 1988 Stafford Act. This law created the federal system of emergency response that we are all so familiar with and works in tandem with congressional emergency appropriations bills to distribute aid to coastal communities following storms. The Stafford Act permits the rebuilding of the infrastructure that allows the investment property to exist: roads, utilities, even beaches and golf courses. Flood insurance may help put some homes back, but the Stafford Act permits the rebuilding of the infrastructure connected to those homes.
Finally, federal and state taxpayers have spent billions of dollars over the last four decades pumping up beaches in front of coastal properties (beach nourishment) and constructing coastal protection projects. Following Hurricane Sandy, the United States Army Corps of Engineers will be spending $4-5 billion building beaches, dunes, and storm protection primarily in New Jersey and New York. $700 million is being proposed for one nourishment project along Fire Island, which is made up almost entirely of parks. Even more mind-boggling is the fact that FEMA treats beach nourishment projects as infrastructure. If a storm washes away your beach, taxpayers will put it back. Make no mistake, these beach building projects are designed primarily to protect property, and where federal dollars are used, they are a federal subsidy to that coastal resort community.

“ The Coastal Barrier Resources Act was the ideal compromise. The Act did not ban the development of any coastal area. But, it did recognize the scientifically verifiable vulnerability of sandy, barrier island shorelines. ”
— Robert S. Young

Incredibly, some communities have even accessed federally backed loans to support beach nourishment projects through the United States Department of Agriculture’s loan program aimed at economic development in rural communities. In short, the federal government subsidizes the economy of, and investments in, coastal barrier island communities to a very large degree.
Please also keep in mind that the homes on most barrier island resort communities are largely investment properties, typically owned by LLCs, Trusts, or like entities. Our data show that along the oceanfront of North Carolina’s barrier islands, more than 90% of the properties are investment or rental properties.

It is frequently suggested that this enormous federal investment is justified because the “coastal economy” is so robust and powerful, generating significant jobs and local tax dollars, that we cannot possibly walk away. This is a very strange argument. If the coastal economy of barrier island resort communities is so powerful, it should be self-sustaining. It should not require massive federal investment, nor should it require manipulation of property insurance markets.

The Coastal Barrier Resources Act was the ideal compromise. The Act did not ban the development of any coastal area. But, it did recognize the scientifically verifiable vulnerability of sandy, barrier island shorelines. CBRA was a market- based experiment. If it makes economic sense to develop a particular area, then the development will move forward. But, those who stand to benefit from the development need to include the risk of that investment in their calculus. And, on low-lying, eroding, barrier islands, that risk is substantial, and growing.

I understand that Congress has a responsibility under the Act to consider errors made in creating the original maps designating CBRA properties. I will not comment on the legitimacy of any claims made in the bills before you today. However, I urge you to be judicious in the changes you agree to make. We should be reducing the exposure of federal taxpayers to the tremendous risks associated with coastal development, and allowing market forces to drive decision-making. Any substantial reduction in the size of the Coastal Barrier Resource System would be a costly mistake, and it would send a terrible message.

In fact, I urge you to consider a mechanism for expanding, rather than contracting CBRA. We simply cannot afford to continue to hold hundreds of miles of shorelines in place with federal dollars. And, we cannot continue to support multi- billion dollar emergency appropriations bills that routinely put oceanfront property back in place after a storm. I suggest that we expand the Coastal Barrier Resource System to include communities that receive multiple disaster declarations. Starting now, two or three more strikes, and you are out. Or, I should say, “in”. You are now in CBRA.

We can give these highly vulnerable communities plenty of warning, and a few chances, but ultimately they will need to account for the investment risk themselves. You can stay, but if you stay, you pay. Many people have heard the Dauphin Island story and exclaimed to me, “those people must be crazy to rebuild those homes over and over again.” In fact, they are not crazy. They are making a perfectly sensible economic decision based on the level of federal subsidy they receive for their investment. It is we who are crazy for assuming all the risk. The Coastal Barrier Resources Act was an effort to address that craziness. I urge you to maintain the integrity of the system and protect the spirit of the Act.”

New UN Report Is Cautious On Making Climate Predictions

venice-italy
Acqua alta, Venezia, Italia. Photo source: ©© Roberto Trm
The IPCC draft report lays out eight “key risks”: sea level rise and storm surges in coastal areas are amongst them, and could affect “hundreds of millions… by 2100.”

Excerpts;

The draft of the latest report from the Intergovernmental Panel on Climate Change warns that the world faces serious risks from warming and that the poor are especially vulnerable. But it avoids the kinds of specific forecasts that have sparked controversy in the past…

Read Full Article, Yale E 360