THE jewel in Louisiana’s coast is almost glittering again. With 10 kilometres of beach, great fishing and a small-town atmosphere, Grand Isle is the ideal refuge for those seeking a second home or a break from the intensity of city life. It is hard to believe that two years ago this week, hurricane Katrina swept across the island. The rebuilding may not quite be done, but tourists are back. “We are open and ready for your visit,” proclaims the island’s website.
For those who study coastal development, however, Grand Isle symbolises not hope, but government folly. The island is regularly hit by severe storms, yet federal building subsidies continue to pour in. By one estimate, over $1 million of public money has been spent for each of Grand Isle’s 600 or so permanent residents over the four decades up to the 1990s. After Katrina, more government money poured in. “It’s welfare for the wealthy,” says Oliver Houck, an environmental lawyer at Tulane University in New Orleans. “We’re paying for people to live in the hit zone.”
“Government money that poured in after Katrina is welfare for the wealthy. We are paying for people to live in the hit zone”
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The situation on Grand Isle may be extreme, but it is part of a much wider trend. Governments around the world know that coastal homes are at risk of storm damage, yet they continue to subsidise such developments. To make matters worse, engineering projects designed to help protect residents can do just the reverse.
While the problem is known, the full cost of these contradictory policies is only now becoming clear. A series of economic and environmental assessments published last month has detailed the billions of dollars involved. Although the studies show that an urgent rethink is needed, plans for the rebuilding of New Orleans suggest that politicians – in the US at least – are not listening.
“It’s a crazy situation”, says Robert Bea, an environmental engineer at the University of California, Berkeley. “Katrina should have taught us that.”
The passage of Katrina, which formed on 23 August 2005 and hit New Orleans six days later, was echoed in macabre fashion last week by hurricane Dean, the first major storm of 2007. Although Dean missed densely populated areas as it passed through the Caribbean and Gulf of Mexico, it did harm local biodiversity (see Hurricane Dean decimated Mexican ecosystems). The storm season is due to peak over the next two months, and major hurricanes strike the US coast in two out of every three years. Some scientists also believe that storms are becoming more intense and frequent as the world warms. With such threats looming, no wonder economists are asking just how long society can justify its love of coastal living.
In the case of Katrina, the accounts are still being finalised, and insurance companies are expected to pay out hundreds of billions of dollars in total. Yet as huge as it is, the figure omits other costs of coastal disasters, says Erica Gaddis, an environmental scientist at the University of Vermont in Burlington. The environmental cost of 25 million litres of oil spilled during the storm may be impossible to calculate, for example, as might the social cost incurred when Louisiana authorities had to cut local services to finance the recovery programme, or the economic cost of over 200,000 volunteers putting life on hold to help the American Red Cross.
Gaddis, whose is one of several on coastal issues in a special edition of (vol 63, p 307), says government must consider these costs when drawing up policies for coastal development. In contrast, US governments over the past 50 years have encouraged building in disaster-prone areas. Coastal towns have grown in line with the rest of the nation and now house 50 per cent more people than in 1970. These areas are also getting richer: the wealth of the 177 coastal counties in the US is increasing by 4 per cent every year, meaning that ever more expensive property is sitting in the path of destruction.
Higher insurance costs could have put a brake on this development, but when the cost of flood premiums rose in the 1960s the government simply introduced a state-backed scheme that now provides protection for 20,000 coastal communities. No one has put a figure on how many new properties the scheme has made possible, but a review by Kenneth Bagstad, also at the University of Vermont, concludes that high-risk areas might not be covered at all if the issue were left to market forces alone ().
Then there is the issue of how much protection engineering projects really provide. Parts of New Orleans are inhabited only thanks to a series of levees built by the government to corral the waters of the Mississippi after hurricane Betsy flooded the city in 1965. In California, meanwhile, engineering has been vital for the development of agriculture and infrastructure, with over 1500 kilometres of defences on the Sacramento-San Joaquin delta helping protect pumping plants that supply two-thirds of the state’s drinking water. As sea level rises, so does the risk of a levee breach. A major failure could halt supplies of water to southern California, potentially causing over $10 billion of damage, according to a in 2006 by the University of California, Berkeley.
“New Orleans was a dress rehearsal for this,” predicts Bea, who was part of an independent team drawn from institutions including the University of California, Berkeley, and the American Society of Civil Engineers among others that studied why flood defences failed during Katrina.
With the density of coastal populations in the US predicted to increase by 11 per cent between 2003 and 2015, Bea and others say it is time to scale back the twin policies of subsidies and engineering fixes. Ending cheap insurance would prove extremely unpopular, however. Coastal residents are already feeling the effect of hikes in insurance premiums. Some firms are ending cover for high-risk areas, and many residents of New Orleans have said they cannot get the cover they need to rebuild. Politicians facing such complaints are seeking to boost federal protection, not scale it back. For example, a bill that would allow residents to buy subsidised wind as well as flood insurance from the government cleared the House Financial Services Committee last month.
Making the case for less engineering may be easier, though, since it is clear that levee failures played a major part in the devastation of New Orleans. Levees have also depleted the supply of sediments and nutrients from the Mississippi that nourished the wetlands that surround New Orleans. Around 65 square kilometres were lost every year over the last century (see graphic). Had these grasses and cypress trees survived they might well have held back some of the water: anecdotal evidence from hurricane Andrew in 1992 suggests that each kilometre of marsh buffer zone reduced the surge by almost 5 centimetres, says Robert Costanza, an environmental economist at the University of Vermont.
In an unpublished analysis of 34 hurricanes that have hit the US since 1980, Costanza has put a price on that lost protection: losing just 1 square kilometre of wetland increases the economic impact of a hurricane by an average of over $3 million, he concludes. What wetland remains helps prevent $23 billion of damage every year.
The US Army Corps of Engineers, which builds and maintains the levees, says it is aware of the economic value of wetlands and plans to reverse the destruction by diverting rivers to restore marshes, and using sand to rebuild islands, which form another natural barrier. However, progress has been slow. Whereas the federal government has already committed almost $15 billion to a scheme to rebuild engineering defences by 2011, the wetlands plan is not due to go before Congress until December.
Before 1965, Bea says he too would have backed a solution based on levees and flood walls. Bea was living in New Orleans when hurricane Betsy swept through, and lost his house and possessions. However, that made him realise that flood defences involve working with nature, not against it. It is, he says, “a marriage, not a battle”.
The world’s coasts under threat
The US is far from being the only place where growing coastal populations are creating a human and ecological crisis.
In 1990, just under a third of the world’s population lived on the coast. By 2002, that figure had risen to 41 per cent, and coastal populations are now growing at four times the global average, according to Maria MartĂnez of the Institute of Ecology in Xalapa, Mexico, and her colleagues. Some of the fastest-growing megacities, such as Lagos in Nigeria, are also on the coast. That is going to create problems, predicts MartĂnez, since coastal areas provide over three-quarters of all “ecosystem services”, such as fresh water (, vol 63, p 254).
Rising population levels can also leave coastal communities more vulnerable than they need be. Many mangrove trees in Asia have been cut down to improve access to water, for example. Satellite images of the Indian coastline taken before and after the 2004 Asian tsunami reveal that some villages survived because they were sheltered by mangroves, while others nearby without protection did not.
“People are attracted to the coasts because of the high density of ecosystem services, but then the concentration of population has the side effect of depleting those same services,” says Robert Costanza, an economist at the University of Vermont in Burlington. “It’s like tourism: people are attracted to gorgeous natural settings until they become so full of people that the attraction is destroyed.”
