Rotterdam, the Netherlands. The Dutch city is frequently subject to flooding conditions, and has implemented creative infrastructural developments to combat the problem 

A “sleeping giant” that could cost Australia’s economy $226bn in coastal infrastructure – this is how the Climate Council recently described the threat posed by rising sea levels. And with four out of every five Australians living on the coastline, it would appear that the millions of affected individuals can do little now but wait for their homes, schools and hospitals to succumb to the advancing waters.

“Rising sea levels increase the probability of flooding”, says Chris Zevenbergen, Professor of Flood Resilience of Urban Systems at UNESCO-IHE. “Rising sea levels is a continuous and natural process – and climate change is likely to accelerate this process.” Still, Australia’s losses pale in comparison to those in India, which, according to OECD estimates, will be the country worst hit by rising seas. By 2070, says the report, Calcutta’s 14 million people will be dealt $2trn in damages if emissions are allowed to go on unchecked, whereas Miami and Guangzhou are on track to lose $3.5trn and $3.4trn in that same year.

Escalating costs
Talk of the true extent of the damages has been gathering momentum now for some time, and so too has speculation on the financial ramifications rising sea levels could bring for the global economy. One such study, jointly compiled by World Bank economist Stephane Hallegatte and the OECD, forecasts that related losses of $6bn a year in 2005 could grow to $63bn by the midpoint of the 21st century, adding that many coastal cities run the risk of losing $1trn a year to flood damage. These are only estimates though, and exactly how much will be lost to the phenomenon is still an issue of fierce debate.

Even without the exact figures to hand, it’s clear that coastal cities around the world must work quickly to mobilise against the ever-potent threat of rising seas. And only by investing in infrastructure and patching up any vulnerabilities will they keep their heads above water and answer the prevailing 21st century question of climate change.

For example the Dutch delta-city of Rotterdam has laid down a high marker for cities like it designing creative infrastructure responses to the issue. Should the city’s vision materialise as planned, Rotterdam’s climate proofing strategy will shield the country’s second largest metropolis against billions of dollars in damages, and save its citizens from challenges ranging through inconvenience to homelessness.

As a low-lying seaport, Rotterdam is highly susceptible to any changes in sea level, no matter how slight, and without a strategy in place to alleviate the damages, residents and businesses could suffer huge consequences. Appropriately, rather than see water as a threat, city planners have utilised it as a resource by turning key city spaces into water storage and, in some instances, even turned the problem into profit. Now home to a plethora of green spaces, water plazas and underground basins, Rotterdam’s newly constructed water storage facilities put the resource to good use rather than flushing it back out into the sea.

“Current and new innovative infrastructure is the basis of our adaptation strategy on flood safety, because our system and strategy is based on prevention”, says Nick van Barneveld, a senior advisor working with the Rotterdam Office for Sustainability and Climate Change. The steps taken so far are among the most impressive worldwide, and Rotterdam’s water management system has laid down a benchmark for others to aspire.

By investing in infrastructure and taking the long view, the city is better prepared for any challenges it may face in the future as a result of rising sea levels. Yet the measures are not the exclusive work of government, and citizens have also been doing their bit to intercept any damages – namely by water proofing basements and keeping their valuables away from vulnerable spots.

All aboard
The work done to address the problem spans a multitude of projects, and currently the city is over a year into the construction of a floating neighbourhood, in keeping with a citywide vision to showcase the latest in flood-proofing technology and water management innovations.

The story of the area itself is an interesting one, even without the development: Once among Rotterdam’s most undesirable postcodes, Katendrecht is today an up-and-coming destination, replete with creative talent and trendy commercial outlets. However, ahead of the area’s redevelopment, the water residence project represents a crucial part of a much larger plan to prepare the city for a future changed by climate change.

“In Rotterdam we take the next step. We do not move away from the water, but we go on and into it”, wrote the PvdA politician Hamit Karakus in the project’s bid proposal, which later reads: “The current economic situation forces all parties involved to fundamentally rethink their roles. Old business models will need to be replaced with new ones. The way we invest in new activities shall continuously adapt to the changing developments. Each of us, whether public or private, will need to ask ourselves new questions to find new answers and forge new types of collaboration.”

The introduction here hints at one of the biggest questions in constructing flood defences; that is, who will foot the bill? The facts state that citizens, states and businesses alike will suffer as a result of rising sea levels, and so the responsibility should be shared between all parties if – as in Rotterdam’s case – the necessary infrastructural improvements are to be made. The solution then, is not to introduce ever-so-slight modifications to existing flood defences, but to implement a sustainable strategy that takes into account the long-term effects of environmental degradation.

Those following in the footsteps of Rotterdam, therefore, will be asked to stomach a huge infrastructure bill that, without public, government and business backing, could put the city in serious jeopardy. Today, the realisation that rising sea levels could bring huge financial losses marks a turning point, as coastal cities are left to weigh up the immediate costs of infrastructural development against the potential damages of rising seas in the future.

Boston sea party
For some cities, however, the scale of the damages is not at all unsurprising. Having experienced first hand the social and economic disadvantages a natural disaster can bring, Boston is today looking to the examples set forth by both Amsterdam and Venice, and flirting with the idea of one day becoming a canal city. Mayor Martin Walsh took to the stage on the second anniversary of Hurricane Sandy to warn that storms and rising sea levels pose a major threat to the city, and emphasised the importance of preparing for the dangers exacerbated by climate change. “I believe climate change is not a burden we take on, but an opportunity we embrace,” he said at the Architecture Boston Expo in October.

“Last year, the World Bank ranked Boston as the eighth most vulnerable city in the world in terms of overall cost of damage”, says Dennis Carlberg, Sustainability Director at Boston University. “Boston is a vibrant, thriving city, an economic engine for the region. There are billions of dollars of real estate and infrastructure at risk in the city, but the implications of flooding in the city are far reaching. The same holds true for costal cities around the world.” The realisation that Hurricane Sandy was a mere matter of hours away » from plunging low-lying areas of the city in up to six feet of water has been taken by local authorities as a warning sign (see Fig. 1). And the news that the city’s landmass is shrinking at a rate of approximately six inches per century, according to a City of Boston report entitled Climate ready Boston, means that rising sea levels are likely to encroach on the city sooner than most.

Now, city planners are beginning to envision a future whereby Boston’s streets are transformed into a network of canals, on the presumption that the Back Bay neighbourhood will be at least part submerged in water by the turn of the century. Alternatively, authorities could simply bolster their existing flood defences and shore up the areas most exposed to the city’s changing tides – though doing so would only prolong the inevitable damage.

“The biggest challenges are urban vitality, economic, policy, and the jurisdictional boundaries rising seas don’t respect. These are some of the challenges the Urban Land Institute is now exploring for a new report we plan to release in mid 2015”, of which Carlberg is co-chair for the institute’s Sustainability Council. “The cost of doing nothing will be far greater than investing in resilient and protective strategies – as long as we are able to reduce greenhouse gas emissions quickly.”

Rallied by studies into the spiralling costs of leaving flood defences unmanned and coastlines unchanged, public and private parties are placing a greater emphasis on protecting against rising sea levels in cities like Rotterdam, Boston and many more places like them. Without question, there is a growing consensus that water risk management merits a considerable chunk of public and private attention, though agreement on the exact form this should take varies from case-to-case.

In all cases, decisions are made on a benefit-cost analysis basis, though the problems come when incorrect assumptions are made about the exact nature of the problem cities are facing.

Making the wrong assumption
“Coastal defences reduce the risk of floods today, but they also attract population and assets in protected areas and thus put them at risk in case of the defence fails, or if an event overwhelms it”, says Stephane Hallegate, Senior Economist at the World Bank. “If they are not upgraded regularly and proactively as risk increases with climate change and subsidence, defences can magnify – not reduce – the vulnerability of some cities.” Essentially, the success of any solution is based on how accurately authorities can chart changing sea patterns, as well as any additional issues that extra defences might bring for those in the area.

In the case of Rotterdam, the city’s water management strategy is designed not simply to limit water damage, but to bring more investment, and therefore people, to the area. Here the benefits of the strategy are unclear, in that bringing more people to the fray could exasperate the issue further still. Already, the population stands at over 600,000, which has essentially ruled out the quick fix of closing problem sections of the city in times of storm, and the population growth born of the city’s water management strategy renders this already problematic solution nigh on impossible.

“Flood defences are inert systems and have a long lifetime which easily could exceed 50 years. It will take another 10 years to design and implement them. Hence, we have to look at least 60 years ahead and take all these changing drivers – such as sea level rise and economic growth which are associated with many uncertainties – into account in the design”, says Zevenbergen. “There is a risk of overinvesting [changes occur more slowly than assumed) and under investing (changes have been underestimated]. This means that these systems should be flexible and adaptable, which allow adjustments over time as new insights call for them. The biggest challenge is to build in flexibility into these systems in a cost-effective and attractive way. A major challenge for designers and engineers.”

The real skill in warding off the threat, therefore, is in ensuring that the solution does not create the illusion that so-called sustainable cities are invulnerable to rising seas. Obviously the issue, if left unchecked, is far greater than any amount of infrastructural development can hope to manage, though this shouldn’t stop cities from taking strides to reduce the damage. Cities such as Venice, Hamburg, Seoul and New Orleans offer an example of what can be done to stave off the damage. Though, as it stands, the solutions are too few and far between.

The decision to invest in coastal infrastructure is one that pertains to risk management above any-thing else, and by choosing not to invest, affected populations will be left dangerously exposed to the damages. We’re yet to see anything close to a concerted global effort to protect coastal cities from flooding, though we will likely see more in the future, as the danger increases and the damages spiral out of control.