Urban designers are facing a daunting challenge. With data indicating a dramatic increase in sea levels over the coming years, designers must determine how to create something today that can withstand the risk and uncertainty of tomorrow. How much will the climate change? What do we design for?
Even as we face the need to address a growing demand for coastal flood resilience, the design process remains rooted in knowledge, customs and standards drawn from history – not from what might happen in the future. So, we are faced with the question of whether to design with an eye on what is customary, or an ear on what science is telling us.
Since 1921, the National Oceanic and Atmospheric Administration (NOAA) has collected data on sea levels in Boston. It tells us the local sea levels have risen 10 inches over 100 years – with the rate of change in the last decade nearly double the average of the past century. And, scientists report changing climate conditions will cause the rate to accelerate to as many as six feet above current levels by the turn of the next century.
Despite the hard data, designers have yet to adopt a systematic method to evaluate trends over time and project future realities. We continue looking backward at data not very different from what was used to layout old-fashioned neighborhoods and buildings – without careful analysis of water conditions. We have continued to respond to extreme weather and storm surges reactively, instead of developing new standards and practices to help us avoid disaster losses and costly recovery in the first place.
Only recently have cities around the world begun to consider the potential impacts of rising seas but, even as they recognize the threats, there remains a disconnect with regard to updating and altering design standards. Consider the plan New York City Mayor Michael Bloomberg developed after Hurricane Sandy for improving resilience, which still bases building codes on Federal Emergency Management Agency (FEMA) flood maps. Even the brand new FEMA advisory maps are crafted using past information rather than projected future conditions. That means the calculated risk level – one percent per year – may be accurate on day one, but would quickly be outdated after factoring in future flood risk due to climate change.
Rising Flood Insurance Premiums
The Biggert-Waters Act of 2012, which initiated sweeping changes to the National Flood Insurance Program connected to FEMA maps, calls for premiums to increase steeply. And, that trend will continue until true risk-based pricing is achieved, eliminating subsidies and dis-incentivizing vulnerable development in flood prone areas.
When Sandy struck New York City almost one year ago, high tide crested ten feet above normal, monstrous waves over 30-feet tall broke previous records measured at buoys and water reached many densely settled neighborhoods from scenic barrier islands to the globally critical financial district. Disruptions to the power grid, liquid fuel supplies and even natural gas pipelines left hundreds of thousands of people in the dark for weeks. The financial impact of Sandy – estimated at $100 billion in the days after the storm – is not fully tallied, but represents a staggering amount of insured losses, federal disaster relief, and unrecovered losses to private and public owners and business owners who experienced everything from short interruptions to total failure.
To avoid similar disasters with increasing frequency, we must shift the paradigm and plan for a future where change is the new normal. Conventional statistical analysis that only looks at past data will fail to capture trends we need to account for. But what should the new design criteria be? How can we intelligently address the uncertainty of projections?
We can look to New Orleans, the city devastated by Hurricane Katrina in 2005, which recently completed a $14 billion rapidly engineered and constructed infrastructure program based on forward-looking engineering design criteria. Rather than past data alone, the criteria relied on computer models of multiple possible future scenarios while accounting for climate change and other projected trends, using a probabilistic risk-based approach. When Hurricane Isaac struck in 2012, the freshly built floodwalls, closure gates, and storm surge barrier – the world’s largest – functioned seamlessly and prevented flood damage estimated at twice the cost of construction. An impressive ROI indeed.
Such methods illustrate a path forward. The challenge for regulators, planners and designers is to develop design criteria and frameworks that account for the uncertainties so we can prepare for climate risks and avoid continually responding to larger and costlier climate-related emergencies.
Wendi Goldsmith is CEO of Bioengineering Group. Dennis Carlberg is sustainability director for Boston University and co-chair of the Urban Land Institute Boston Sustainability Council and Sea Level Rise Committee.
