Resources & Climate

The Deep Blue Sea: Coastal Zones and Climate Change

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By David Michel – Coastal regions are on the front lines of climate change. Global warming’s projected impacts on coastal zones include rising sea levels, fiercer tropical cyclones, larger storm surges, increasing sea surface temperatures, and-as the oceans absorb more of the  carbon dioxide that human activities emit to the atmosphere-growing acidification of surface waters.

For coastal ecosystems and communities, the repercussions could be considerable, endangering the livelihoods, health, and welfare of millions of people. Stronger cyclones and higher storm surges may carry farther inland, inundating low-lying areas, destroying infrastructure, and displacing populations. Mounting sea levels can accelerate shoreline erosion and exacerbate saltwater intrusion into the rivers and aquifers that furnish fresh water to coastal settlements. Refugees fleeing coastal flooding may be driven into neighboring areas or even further afield.

The developing states are especially vulnerable to such coastal risks. According to a 2009 study of 84 developing countries, a 10% increase in the intensity of storm surges over the next 100 years would expose 24% of these nations’ combined coastal populations to flooding, enlarge the potential inundation zone to 25% of their coastal territory, and imperil more than 28% of their coastal GDP. Gradual sea level rise could prove similarly devastating. In Vietnam, for example, a one meter increase in sea level would submerge 10% of the country’s total population, 10% of its urban area, and 10% of its GDP. In Egypt, a one meter sea level rise would inundate 25% of the Nile Delta, swamp 13% of the nation’s agricultural land, and displace more than 10% of its 68 million people. Troublingly, the most recent analyses suggest global sea levels could rise 80 to 200 cm by the end of the century.

Establishing effective coastal management measures against climate change will impose substantial pressures on policy institutions in developing and developed nations alike. Coastal zones encompass diverse human activities and ecological processes in interconnected maritime and terrestrial spaces. Sustainable coastal policy planning consequently requires decision makers to integrate multiple uses and demands across political boundaries as well as across functional fields. At the same time, however, successful adaptation to emerging climate stresses must be site specific, appropriate to the diverse social contexts and the particular environments in which policies are enacted.

Yet much coastal management now falls well short of this ideal. Formulating holistic strategies balancing myriad actors and interests is no easy task. Policies suited for one geographic scale may conflict with objectives framed for other scales or sectors. Thus, coastal managers well know how inland rivers influence the seaboard. The water runoff, mineral sediments, and organic materials draining from upland basins continually renew and reconfigure shorelines and coastal deltas. Human interventions weigh heavily on these processes.

Globally, upstream dams and diversions now trap almost one third of all the sediment flow that would otherwise have reached the world’s coastal zones. Absent these sediments to replenish the land that river currents carry away, deltas will suffer greater relative sea level rise. One assessment found that this loss of river-borne sediment accounted for substantially more relative sea level rise than did mounting ocean levels in nearly 70 percent of 40 deltas surveyed around the world. Coastal managers and water policy makers contemplating climate change are keenly aware of these trends. Yet coastal zone and water resources management have developed as largely separate disciplines and are still rarely linked in planning or in practice.

At the other end of the scale, local communities frequently find themselves excluded from centralized, state-level policy processes. Current policymaking too often restricts public deliberation and decision to selected stakeholders and policy elites while ecosystem needs have no voice at all. So too, decision makers often simply do not have the detailed local information (e.g., fine-grained climate models to project local impacts, empirical time-series records of climate indicators, etc.) to accurately judge policy options.

Similarly, coastal managers frequently lack the financial and institutional resources and processes to aptly tailor or effectively monitor, evaluate, and revise national policies, much less local measures. Mechanisms for gathering and diffusing policy lessons and best practices between locales, countries, or regions remain largely to be developed.

Ultimately, the aim of developing and deploying broadly integrated coastal management policies may clash with the goal of crafting measures responsive to local specificities. Holistic approaches must necessarily assimilate myriad competing considerations, eventually muddying or compromising some in favor of others, departing from unique contexts, and abstracting local particularities. Locally targeted strategies, on the other hand, depend on context; they cannot be abstracted without losing their specificity.

Resolving these tensions will place significant demands on the financial, organizational, and human capacities of governing institutions. The organizing principles and architectures-local, national, regional, and global-of the governance structures required to meet this policy puzzle remain to be established. Surrendering to inertia, however, is not an option. Most coastal development, particularly urban infrastructure, is long lasting and immobile, making rapid redesign, reinforcement, relocation, or rebuilding against climate impacts complicated and costly. Once lost, vulnerable coastal ecosystems may not so easily be restored. Forging sustainable coastal management and adaptation policies in the face of climate change will likely prove devilishly difficult. But for many coastal communities and ecologies, the alternative is succumbing to the deep blue sea.

Susmita Dasgupta et al., “Climate Change and the Future Impacts of Storm-Surge Disasters in Developing Countries,” Working Paper 182 (Washington, DC: Center for Global Development, September 2009).

Susmita Dasgupta et al., “The Impact of Sea Level Rise on Developing Countries: A Comparative Analysis,” Climatic Change 93, Nos.3-4 (2009).

Charles J. Vörösmarty et al., “Battling to save the world’s river deltas,” Bulletin of the Atomic Scientists 65, no.2 (2009).




David Michel is a Research Fellow with the Stimson Center’s Regional Voices: Transnational Challenges project.

Picture: iStockphoto

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