In the aftermath of Hurricanes Katrina in New Orleans and Sandy in New York, an awareness of the vulnerability of major first-world cities to violent storm events has given rise to any number of proposals to make the world’s cities safer from the effects of global climate change and sea level rise. This article makes a case that empowered and well-resourced cities could be the best first line of defense in an uncertain and rapidly changing world.

Despite what they think in North Carolina, sea level rise cannot be legislated away.

By the time the Inquisition forced Galileo to recant his belief in the heliocentric theory of the solar system, it really didn’t matter anymore. Any fool with a telescope could see that Earth did indeed circle the Sun and not vice versa.

Today, regardless of how much some might want to wish away sea level rise or declare it heresy, anyone with a Smartphone can access one of many credible observational platforms and see for themselves that sea level has risen measurably over the past few decades and continues to do so.

Although we must ultimately arrest and hopefully reverse the “disease” of global warming, we cannot afford to ignore its symptoms while finding and implementing a cure. Without disputing for a moment the desirability of reducing GHG emissions, it is questionable that even drastic action to control them in the short term can meaningfully reduce atmospheric concentrations of CO₂, lessen the number and intensity of extreme weather events, or prevent sea level from continuing to rise. The actions we take in the near term to address the effects of global warming, while reducing the risk to people and property, are a critical step to ensuring that future generations will inherit a productive and sustainable world.

If global warming were a disease we would not let patients die while we searched for a cure.The increasing consumption of electricity globally, but particularly in the developing world, will be a major impediment to reducing GHG emissions in the near term.

Currently two-thirds of global electricity is generated from relatively inexpensive fossil fuels and as the developing world strives to improve economically, the likelihood of shifting a meaningful portion of global electric power generation from fossil fuels to non-emitting sources such as nuclear and renewables is remote.

Current technologies for solar, wind, hydro-, and geothermal power simply cannot scale to levels necessary to achieve emission reductions that would meaningfully impact atmospheric CO₂ levels in the near term.  Commercial nuclear power for most of the developing world is neither affordable nor manageable.

Cities in the developed as well as the developing world are vulnerable to sea level rise and storm surge.

Vulnerability to natural hazards was once thought to be solely the scourge of the developing world. Hurricane Sandy probably laid that myth to rest forever. Cities like Miami, New York, Shanghai, and Tokyo are every bit as vulnerable to sea level rise and storm surge as Kolkata, Bangkok, Ho Chi Minh City, and Mumbai. However, given the great differences in resources and capabilities for action between the developed and less developed world, fortune will likely favor cities in wealthier nations.

Narrowing the vulnerability gap between the have-more and have-less nations should be a fundamental goal of global climate change policy.

Making cities less vulnerable to the effects of climate change is a global challenge; one in which rich as well as poor nations will struggle to make their way. Obviously, to the extent that wealthy cities and nations have the resources to address issues of monumental scope and scale, they will have an advantage. However, although many nations in the developing world are particularly vulnerable to climate change effects because of geography, their rapid pace of urbanization, limited resources, and large numbers of poor people, technology can help cities to narrow this vulnerability gap.

We now have sophisticated physical models and high-performance computers on which to run them that can precisely delineate flood-prone areas with an accuracy and precision undreamed of just a few years ago. Coupling these models to regulatory processes under local control such as land use planning, zoning, and building codes could foster development patterns where less of the population, building stock, and supporting infrastructure were located in vulnerable locations. Homes, public facilities, and infrastructure could be better located using these models and as facilities age and major reconstruction becomes warranted, they can be relocated to elevations above expected flood levels.

• Had the emergency electrical generators at the Fukushima Daiichi nuclear plant been located above the tsunami inundation zone, much of the resultant radiological disaster would likely not have occurred.

• Similarly, had the lowest-lying entry points to the New York City subway system been equipped with water-tight barriers, costly flooding during Hurricane Sandy could have been prevented.

Engineering design practice cannot assume that the earth of the future will behave as it has in the past.

Traditionally, we have attempted to defend ourselves from various hazards by planning for a “design basis event” that connotes the worst that is likely to occur given what is known regarding a particular hazard or threat. Although it is compelling to believe that designing for some maximum probable event fully addresses the risk from natural hazards, history is littered with accounts of protective strategies that failed spectacularly in practice.

A recent case in point is Miyako City in Japan that constructed a 10 m tsunami barrier in 1958 which was overtopped in 2011. Although designed for what was believed to be a ”worst case” scenario, the actual event was worse still—with disastrous consequences. To a large extent, engineering design practice for “natural” hazards assumes that the earth of the future will behave much as it has in the past but this is probably no longer true.

How can cities like New York best be protected?

In the aftermath of Hurricane Sandy, flood gates that would seal off New York harbor from the sea during extreme weather events are currently being contemplated. These proposals must be examined very critically!

Physical flood defenses create a dependency from which it is difficult or impossible to deviate. For example, New Orleans and the entire Mississippi River Basin in the U.S. are now hostage to decisions made at the national level nearly 100 years ago to install massive levees and flood walls. These structures require constant care (which is often not funded), increase vulnerability outside the protected zone, and also have the undesirable effect of luring new development into these  “protected” areas. Cities and other local governments need to be informed and active participants in how today’s decision-making can affect the realization of a sustainable long-term future.

Obviously, cities such as New York, Tokyo or Shanghai must and will be protected. The key questions are how should this be done and by whom. Should there be a top down imperative to construct massive floodworks where there is a single chance to get it right or through a locally-implemented flood defense strategy that is flexible and scalable so that it can be modified as conditions change and we (and future generations) learn how to better address evolving conditions?

Overdevelopment of vulnerable coastal areas is probably the major contributing factor to the uptick in property damage from storm events.

Losses from storm events have increased dramatically in recent years. This is due less to the increased violence of the storms than to the value of the built assets that have been placed in their path. Abandoning vulnerable coastal areas and allowing them to return to a natural state is seen by some as a preferable alternative to physical flood defenses. However attractive this option may appear from the perspective of national governance, its practical application would have enormous impacts at the local level on property owners and communities.

Over and above the very real social and legal issues involved, most of the revenue generated by local governments in the U.S. is derived from property taxes based on valuation. A decision at the national level to declare tens to hundreds of billions of dollars worth of property to be of substantially less value would have a cataclysmic economic impact on these communities and the services they provide. A balance can be struck between sustainable development practices and the needs and rights of property owners.

Toward More Resilient Communities

As climate change adds to the uncertainty of what we think we know about how the natural world will behave, prevention and preparation for hazards such as coastal and lowland flooding will become far more challenging. Although physical defenses are appropriate in some circumstances, they are expensive to build and maintain and relatively inflexible to changing conditions. Because of the great uncertainty in predicting the magnitude of specific hazard events at specific locations, resilience, the ability to absorb and recover from unanticipated shocks, should be the guiding principle of disaster risk management.

The bulk of the task of improving urban resilience to climate change and sea level rise will ultimately fall to the cities themselves. Although national governments can set broad policy direction and provide financial assistance, the world’s major cities must have access to the information, tools, and resources necessary to develop and implement geographic and culturally appropriate strategies that will work at the local level.

City governments should be empowered to partner with groups that can leverage all available resources, such as:

• Universities and government laboratories to conduct research and develop and test alternative solutions to development patterns and construction techniques
• Business groups and private utilities to protect critical infrastructure and ensure the continuation of vital services
• Civil society organizations to educate the public on best to protect themselves and their property and how to aid in recovery operations.

Urban managers must also learn new skill sets appropriate to the challenges that will accompany climate change. For vulnerable communities such skills will not be optional and cannot be outsourced or delegated away.

It is obvious that climate change will affect the global risk profile for decades to come but much of what needs to be done to reduce the risk to people and property is actually independent of it. How well cities anticipate and prepare for these changes and their impacts will have a profound effect on the lives and economic well-being of hundreds of millions of people both now and in the future.

Finally, we should not take it solely upon ourselves to “fix” a problem that has already been 200 years in the making. This ignores the ability (or desire) of future generations to have any role in their own welfare and develop time-appropriate solutions of their own based on what will have been learned in the intervening years as well as technological advances that we cannot as yet foresee in regard to power generation, atmospheric cleansing, or geo-engineering.

Imagine if those at the dawn of the Industrial Age had limited our choices to their best science to address the effects of combustion!