How high will seas rise?

Pacific and Indian Ocean atoll nations are already being abandoned because of the direct and indirect effects of sea level rise, such as saltwater intrusion into groundwater. In the Marshall Islands, some crops are being grown in abandoned 55-gallon oil drums because the ground is now too salty for planting. New Zealand is accepting, on a gradual basis, all of the inhabitants of the Tuvalu atolls. Inhabitants of Carteret Atoll have all moved to Papua New Guinea. The forward-looking government of the Maldives recently held a cabinet meeting underwater to highlight the ultimate fate of their small island nation.

The world’s major coastal cities will undoubtedly receive most of the attention as sea level rise threatens infrastructure. Miami tops the list of most endangered cities in the world, as measured by the value of property that would be threatened by a three-foot rise. This would flood all of Miami Beach and leave downtown Miami sitting as an island of water, disconnected from the rest of Florida. Other threatened U.S. cities include New York/Newark, New Orleans, Boston, Washington, Philadelphia, Tampa-St Petersburg, and San Francisco. Osaka/Kobe, Tokyo, Rotterdam, Amsterdam, and Nagoya are among the most threatened major cities outside of North America.

Preserving coastal cities will require huge public expenditures, leaving smaller coastal resort communities to fend for themselves. Manhattan, for example, is likely to beat out Nags Head, North Carolina for federal funds, a fact that recreational beach communities must recognise when planning a response to sea level rise.

Twelve per cent of the world’s open ocean shorelines are fronted by barrier islands, and a three-foot sea level rise will spell doom for development on most of them - save for those completely surrounded by massive seawalls. Impacts in the United States, with a 3,500-mile long barrier island shoreline extending from Montauk Point on Long Island to the Mexican border, will be huge. The only way to preserve the barrier islands themselves will be to abandon them so that they may respond naturally to rising sea level. Yet, most coastal states continue to allow massive, irresponsible development of the low-lying coast.

Ironically, low-elevation Florida is probably the least prepared of all coastal states. Hundreds of miles of high rises line the state’s shoreline, and more are built every year. The state pours subsidies into coastal development through state-run insurance and funding for coastal protection. If a portion of those funds were spent adapting to sea level rise rather than ignoring it, Florida might be ready to meet the challenge of the next century. Let’s hope the state rises to the challenge.

Despite the dire facts, the next century of rising sea level need not be an economic disaster. Thoughtful planning can lead to a measured retreat from vulnerable coastal lowlands. We recommend the following:

Immediately prohibit the construction of high-rise buildings and major infrastructure in areas vulnerable to future sea level rise. Buildings placed in future hazardous zones should be small and movable - or disposable.

Relocation of buildings and infrastructure should be a guiding philosophy. Instead of making major repairs on infrastructure such as bridges, water supply, and sewer and drainage systems, when major maintenance is needed, go the extra mile and place them out of reach of the sea. In our view, no new sewer and water lines should be introduced to zones that will be adversely affected by sea level rise in the next 50 years. Relocation of some beach buildings could be implemented after severe storms or with financial incentives.

Stop government assistance for oceanfront rebuilding. The guarantee of recovery is perhaps the biggest obstacle to a sensible response to sea level rise. The goal in the past has always been to restore conditions to what they were before a storm or flood. In the United States, hurricanes have become urban renewal programs. The replacement houses become larger and larger and even more costly to replace again in the future. Those who invest in vulnerable coastal areas need to assume responsibility for that decision. If you stay, you pay.

Get the Corps off the shore. The US Army Corps of Engineers, more or less by default, is the government agency in charge of much of the planning and the funding for the nation’s response to sea level rise. It is an agency ill-suited to the job. Part of the problem is that the engineers’ “we can fix it” mentality is the wrong mindset for a sensible approach to responding to changing sea level.

Local governments cannot be expected to take the lead. The problems created by sea level rise are international and national, not local, in scope. Local governments of coastal towns (understandably) follow the self-interests of coastal property owners and developers, so preservation of buildings and maintaining tax base is inevitably a very high priority. In addition, the resources needed to respond to sea level rise will be far beyond those available to local communities.

Responding to long-term sea level rise will pose unprecedented challenges to the international community. Economic and humanitarian disasters can be avoided, but only through wise, forward-looking planning. Tough decisions will need to be made regarding the allocation of resources and response to natural disasters. Let us hope that our political leadership can provide the bold vision and strong leadership that will be required to implement a reasoned response.