In the deadly and destructive aftermath of Hurricane Sandy, the Northeastern United States is rethinking its strategy to reduce coastal vulnerability to future storms and natural disasters. This should become a global discussion, given the recent, large-scale disasters that have occurred worldwide: the December 2004 Indian Ocean Tsunami, the 2005 Hurricanes Katrina and Rita in the US Gulf Coast, the 2011 earthquake, tsunami and Fukushima nuclear disaster in Japan, and of course, last month’s Hurricane Sandy.
When major coastal storms strike, often the first question asked is whether global climate change is increasing the severity and frequency of such storms. With respect to Hurricane Sandy, that issue was raised just days after the event.
Hurricane Sandy may or may not alter the climate change conversation. Certainly, the relationship between changing global climate and coastal storms is difficult to verify scientifically. But this issue is much less important than addressing the increasing vulnerability of coastal populations to natural disasters, for several reasons.
First, coastal human population densities across the globe are nearly three times that of inland areas, and they are increasingly exponentially. Thus as the human population grows, we are packing more people into our coastlines than ever before.
Second, many estuarine, coastal and marine ecosystems naturally protect coastlines from storm surges, wind, flooding, erosion and other impacts of storms, but as coastal development and populations expand, these systems are disappearing rapidly. Their resulting loss and degradation due to human activities is intense and increasing, such that 50% of salt marshes, 35% of mangroves, 30% of coral reefs, and 29% of seagrasses are either lost or degraded worldwide. Such rapid decline and deterioration of these systems are making coastlines more vulnerable.
Third, across all the cities worldwide, about 40 million people are exposed to a one-in-100-year extreme coastal flooding event, and by 2070, it will be 150 million people. Consequently, because of the growth of urban populations generally, and cities in coastal areas specifically, more and more cities are facing the growing risks of major storm events, such as Hurricanes Sandy or Katrina.
Finally, the most vulnerable populations are likely to be in the poorest countries, and thus the least able to afford the risks and damages posed by coastal storms and floods. Around 14% of the population, and 21% of the urban dwellers in developing countries, live in low-elevation coastal zones that are exposed to these risks and damages.
Given these trends, there is an urgent need to develop a long-term strategy for investing in reducing the vulnerability of coastal populations to storm events. Such a strategy should have two primary features: protecting coastlines and populations to the risks posed by damaging storms, and restoring valuable coastal systems, such as salt marshes, coral reefs, mangroves, seagrasses and sand dunes.
Sadly, very few long-term coastal planning strategies are being conducted globally. One of the few exceptions is Louisiana’s 2012 Coastal Master Plan. Based on a total budget of $50 billion, the 2012 Plan will build between 580 to 800 mi2 of new land, much of it restored marsh, over the next 50 years to provide storm protection and other ecosystem benefits. Some restoration work in Louisiana predates the Plan. For example, dedicated dredging on the Barataria Basin Landbridge in Louisiana has already created 1,211 acres of intertidal marsh and nourished an additional 1,578 acres of marsh in 2010, at a total cost of $36.3 million. The Plan extends substantially these restoration efforts and also includes the building of levees and other flood protection structures that significantly reduce or eliminate risk from a 100 year storm. Overall, the Plan lowers the risk of damage from flooding throughout Louisiana’s coast by $5.3 billion to $18 billion annually.
As a result of the 2012 Master Plan, some ecosystem services, such as oyster fishing, may shift or decline along the Louisiana coast. But the Plan is likely to provide larger benefits from increases in alligator, freshwater fisheries and waterfowl habitat, while coastal wildlife, shrimp and saltwater fishery habitats are likely to stay at current levels. Freshwater availability could increase by 40%, and there will be significant increases in carbon sequestration and nutrient uptake. Nature-based tourism and suitable agricultural land will also rise slightly.
Louisiana is willing to spend $50 billion to reduce coastal vulnerability to future storms and to increase other ecosystem benefits over the next year. This seems a small price to pay for the health and safety of increasingly endangered coastlines.
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