April 16, 2012
Some Thoughts on Coastal Land Loss
A few weekends ago I had the pleasure of participating in the Louisiana Law Review's Coastal Land Loss symposium at the LSU Law Center, along with many fantastic colleagues. I thought I would share a few thoughts I presented to the attendees on the issue (and I apologize in advance for the length), which affects Louisiana in a significant way, of course, but which is also an increasingly menacing issue of global concern (see the plight of the Maldives as just one example).
In Homer’s epic Odyssey the hero Odysseus faces a terrible choice. He must guide his men through a narrow strait and either pass close to Charybdis, a sea monster that spewed forth water three times a day with disastrous consequence, or pass close to Scylla, a beastly monster on the coast. Odysseus ultimately chose the latter fate, accepting the loss of some of his men by crashing into the coast, but calculating that he would lose far fewer men than if he took on the raging sea. U.S. citizens and policy-makers face a similarly costly choice―that of either grappling directly with increasingly menacing and encroaching seas rising due to climate change or undergoing the socially and economically disruptive, but potentially less devastating, transition to further inland.
In this way, Scylla and Charybdis provide an accurate metaphor of choosing between the perils of the sea and the threats looming on the coast. The modern conception of this choice regards how we allocate priority on either mitigation OR rather adaptation as the primary response to coastal land loss - that’s assuming, of course, that we do not wish to take the third option of doing nothing and allowing our ship to sink. I should note that I use mitigation and adaptation differently here than they are typically used in the climate change context. In the climate change discussion more generally we use mitigation to refer to curbing carbon emissions in order to slow global warming and associated sea level rise, while adaptation typically means accepting these threats and engaging in policies aimed at reducing the harms of climate change and sea level rise.
But when we are talking about mitigating coastal land loss specifically, we have a choice to confront Charybdis in an attempt to keep the sea at bay: to design policies and invest billions of dollars to restore wetlands, to rebuild coastal lands and barrier islands through dredging and other large-scale engineering projects, or to create man-made structures such as sea walls and other mechanisms of tide and flood control, to name a few examples (all things that might be considered adaptation approaches in the more general climate change context). With adaptation of coastal land loss we have a choice to run upon Scylla and endure the hardship of, at first, slowing the rapid economic development, land development, and population boom in high risk areas of our coastal zone, and second, transitioning from already existing development and infrastructure in these areas to higher ground inland. These two options are obviously not mutually exclusive, and as the International Panel on Climate Change has noted, policies aimed at both will likely be necessary to manage climate change generally, and coastal land loss specifically. Yet the relative emphasis on either mitigation or adaptation will have drastic ramifications for not only the effectiveness of the coastal land loss response, but also for the amount and allocation of local, state, and federal financial resources. In other words, though both mitigation and adaptation are likely to be used in different areas along the coast, a great risk lies in striking the balance between the two that places too much emphasis on one or the other, potentially resulting in years of wasted effort, billions of dollars that would have been better utilized elsewhere, and a greater degree of social disruption than necessary.
A confluence of events has given rise to coastal land loss around the world, the first driver being population growth. The Low Elevation Coastal Zone is the contiguous area along the coast that is less than 10 meters above sea level. Though this area covers only 2 percent of the world’s land area, it contains 10 percent of the world’s population and 13 percent of global urban population. In 2003, approximately 153 million people in the U.S., or 53 percent of the population, lived in coastal counties. As a result, over half the U.S. population lives within the 17 percent of land that is coastal, with some states maintaining over half their population in the coastal zone. Coastal counties as a general matter average 300 persons per square mile, far more than the national average of 98 persons per square mile. Furthermore, the population density in coastal counties has been increasing at a rate that far outpaces the rate of increased density in non coastal counties. In other words, the rate of population growth in coastal counties is disproportionate to the growth of U.S. population. Coastal population increased between 1980 and 2003 by 33 million, accounting for nearly half of the U.S.’s total population growth during that time period. Coastal population is expected to increase by another 27 million by 2017, accounting this time for more than half of the nation’s total population increase. The rate of population growth in coastal counties outpacing that of the country as a whole creates a dramatic increase in population density along the coast.
And, of course, population growth has increased the demand for land development. Developed land in the U.S. as a whole increased by 25 million acres (34 percent) between 1982 and 1997 - an amount that startlingly accounts for more than one-fourth of all of the land developed for urban uses since European settlement (in only 15 years). Though developed land grew by 34 percent, corresponding population growth was only 15 percent, demonstrating that land consumption occurred at a rate more than twice the underlying rate of population growth. Furthermore, the gap between the two rates is growing. Between 1982 and 1992, land was developed at 1.8 times the rate of population growth. During the period between 1992 and 1997, that multiple had grown to 2.5. As described by the Pew Oceans Commission,“[i]f the relationship between land use and population in the last decade continues, there will be 68 million more acres of developed land in the contiguous U.S. than there are today . . . This newly developed acreage—equivalent to the land area of Wyoming—will almost match the amount of land developed from the founding of the country until 1983.”
Population growth and increased development make any choice between land loss mitigation or adaptation policies, and any attempt to actually implement them, exceedingly difficult. The amount of investment needed to implement mitigation policies will continue to rise, as there are more people to protect from geologic land loss caused by the encroaching seas, there is more wealth to protect in the form of residential and commercial development, jobs, and infrastructure tied directly to inland economic welfare, and more natural capital is lost to development exacerbating artificial land loss. In the same way, adaptation policies must grapple with the fact that there are more people to move out of high risk coastal areas, more wealth accumulation and investment to forestall in order to prevent development of new high risk areas, and increased economic and social inertia that makes it difficult to slow down coastal zone growth in the first instance, much less steer already anchored economic and social systems further inland.
The second driver is vanishing wetlands. Over the last century, development has claimed over half of the wetlands in North America. The loss of important ecosystem services provided by wetlands can increase disaster risk and the negative impacts of climate change. These ecosystem services are important to both human well-being and the maintenance of coastal land—not only the physical maintenance of coastal land, but also the maintenance of its functionality. Wetlands provide a key buffer system that protects against storm surge caused by hurricanes and other weather events, dissipates and absorbs flood waters and stormwater runoff, thus protecting local communities and saving municipalities flood control expenditures. Wetlands act as an anchor for preserving coastal lands by dispersing coast-building sediment and forestalling coastal erosion, provide water filtration services that clean coastal waters, act as a major carbon sink that helps regulate the climate, provide habitat for coastal species, among a variety of other services.
Vanishing wetlands are directly tied to rising sea levels as well as increasing populations and associated development. In some U.S. states, like Louisiana, the disappearance of wetlands has compounded coastal land loss and has further synergized with rising sea levels to exacerbate disaster events seared into the collective national consciousness—Hurricane Katrina being the most recent example, of course, causing by some estimates $81 billion in damages.
The state of Louisiana is losing 6,600 acres of coastal wetlands per year. Some of this loss is naturally occurring, but the primary causes are human-made and include commercial and residential development, levees, navigational channels, and oil-and-gas infrastructure. The diversion of the Mississippi River for human-made development has diverted land-building sediment that now empties into the Gulf as far as the outer continental shelf where it cannot form important barrier islands. Other coastal states face a similarly staggering amount of wetland loss. For example, in only the last fifteen years Florida has lost 84,000 acres of wetlands to urban development—a rate of 5,600 acres a year.
The third driver of coastal land loss is sea level rise, which is perhaps the most obvious threat to coastal lands—it is the Charybdis which we must either flee by adapting or fight by mitigating to the extent possible. Unlike most disasters however, the harmful land loss threats of sea-level rise are not immediately obvious, since its observable impacts play out incrementally over human lifetimes. This makes sea level rise arguably even more dangerous than other threats to coastal lands, at least in the sense of spurring human action. The full magnitude of harm is apparent only when temporally aggregated over periods of time exceeding any one generation’s life span. Thus it is especially difficult to forge collective action among individuals, policy-makers, and governments to avoid the disaster.
Though sea level rose .17 meters over the past century, a rate of roughly 1.7 mm/year, satellite imagery demonstrates that the rate increased to 3.1 mm/year between 1993 and 2003. In other words, the rate of sea level rise is accelerating. Since this increased rate corresponds with increases in atmospheric concentrations of greenhouse gases and temperatures over the same time period, the future impact of a changing climate on sea levels is highly variable and uncertain. Approximately 58,000 square kilometers of coastline along the Atlantic seaboard and Gulf of Mexico are less than 1.5 meters above sea level, with more than eighty percent of this coastline in the states of Louisiana, Florida, Texas, and North Carolina. North Carolina alone maintains as much land within one meter of sea level as the Netherlands. Approximately 1,600 square kilometers of land in eighty-five eastern seaboard counties lie less than a meter above current sea levels, potentially threatening approximately 4,800 kilometers of roads and 388,000 people. Over the next fifty years coastal erosion is estimated to threaten nearly 87,000 homes along U.S. coasts. On the other side of the country in California, a mere .3 meter rise in sea level would cause what were once 100-year-storm surge flood events to become ten year events.
So, given the confluence of these factors, what about mitigation or adaptation as a response? A good example of mitigation is the recently released Louisiana’s Comprehensive Master Plan for a Sustainable Coast aimed at investing $50 billion over upcoming decades to restore the Louisiana coast and attempt to mitigate coastal land loss by fighting the encroaching sea - metaphorically taking on Charybdis with full force. The Master Plan calls for a variety of actions to achieve the goal of curbing coastal land loss and actually increasing coastal land acreage, most of which are matters of human engineering aimed at either creating man-made structures to manage coastal land loss, or restoring natural processes to do so. These include projects aimed at protective levee building, bank stabilization, barrier island restoration, channel realignment, hydrological restoration, marsh creation, bioengineered oyster barrier reef creation, ridge restoration, sediment diversion via the Mississippi River and shoreline protection projects. These mitigation measures will involve the construction of numerous types of structures, such as earthen levees, concrete walls, floodgates, and increased use of pumps.
Adaptation provides a much more simple recipe for coastal land loss, though one that is just as difficult, and in the short term likely more difficult, than mitigation – develop policies aimed at steering new development away from areas likely to be lost, and then as areas become lost or increasingly under threat of loss, retreat to higher ground. This has the potential, over the longer term, to be far less costly than investing billions in mitigating land loss in areas likely to become inundated regardless.
So, as between coastal land loss mitigation or adaptation, which should receive the greater focus? There are three reasons why we should approach mitigation in particular with caution. The first is the uncertainty regarding the effectiveness of certain mitigation actions over the long term. Take wetlands restoration, for example. Though wetlands restoration has become increasingly utilized of late, some scientists have argued that restoring wetlands often falls far short of replacing wetland functionality. Instead, they argue, we all to often use restoration and mitigation banking as justification for destroying natural wetlands that will never be recovered, leading to continued global loss of wetlands. Despite this research, in North America alone over the last 20 years over $70 billion has been spent restoring over 7 million acres of wetlands.
There are further mitigation uncertainties regarding changes in sea level rise, rates of subsidence, and effectiveness of sediment diversion projects, to name a few mitigation measures. We should proceed with caution regarding mitigation because it is an unknown quantity compared with adaptation. At least we know adaptation will be disruptive, can better pinpoint just how disruptive, and we also know that it will allow us to retreat from harm’s way. With mitigation the response will be more complex, and billions of dollars invested could over the longer term do little good.
The second reason we should proceed with caution on mitigation is the tempting political expediency that may drive policy-makers’ choice to implement mitigation policies. The Louisiana Master Plan conducted a poll and determined that 85% of Louisianans “believe it is smart to invest dollars in risk reduction and coastal restoration.” This demonstrates the intuitive appeal to the legislator for proposing and supporting mitigation policies aimed at restoring and saving the coast. On the other hand, how well-received might the legislator be who says “we need to dramatically re-think and re-structure how and where we undertake new development and we need to transition current infrastructure to lower risk areas”? Given the long time scales – relative to human lifespans – that a policy-maker’s decision takes to be proven correct or incorrect, one might say it would always be in their best interest to propose mitigation, as the upside political and governance benefits is large since you both please the populous and you likely would not be around to witness the downside if mitigation policies ultimately fail. But none of these governance and political considerations give us any qualitative indication about whether adaptation or either mitigation policies are indeed the best option for a given area. And that should be what drives decision-making, not political expediency.
The third and final reason we should approach mitigation policies with caution is the fact that failure to adapt past land use activities in the coastal zone is one of the reasons that mitigation and adaptation policies are now needed, lending support that adaptation now can avoid both costly mitigation policies as well as pre-empt the need to adapt or mitigate in the future. We are now living in a world where people build in floodplains purposefully, anticipating mitigation policies in the form of government subsidized insurance, levees and other structural solutions to bail them out of potential flooding events. These decisions result in us later being forced to make the difficult cost-benefit decision to flood one city because it would cause less damage than flooding another city – which happened recently along the Mississippi. The same holds true for the coastal zone, where we have exacerbated vanishing wetlands and rising seas by refusing to adapt to their existence and structure society around those resources, and instead have replaced natural capital with human-built capital and have subsequently sought to mitigate risks that we ourselves created. So, while adaptation may be the harder call for us to make today, our descendants would much prefer that we adapted rather than continued a cycle of mitigating risks that we ourselves create.
Ultimately, a balance of adaptation and mitigation will necessarily be a part of our response to coastal land loss. But as we weigh those respective options, we should do so honestly, with consideration to future generations, and with regard to costs and benefits over long time scales, because in some circumstances it may very well be better to run upon Scylla in order to avoid Charybdis. Especially since we know that, despite advertisers' best efforts, coastal land loss won't be as glorious as this:
April 16, 2012 | Permalink
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