Global sea level rise coupled with a city that is subsiding on its’ own foundations is a dangerous combination. Nowhere do you see the effects of this trend known as “sinking cities” more than in the heavily populated coastal cities around the world.
Sinking cities is now a widespread phenomenon and unless serious steps are taken to combat this growing problem, the results would be devastating.
Cause and effect
Coastal cities such as Jakarta, Dhaka, Bangkok, and Miami are at constant risk of exposure to coastal flooding, high tides, and storm surges. Global warming and melting of glacial ice caps are the main causes of these rising sea levels. Most sources predict that oceans will rise between 0.3 to 2.5 meters (1’-8’) by 2100. In New York City, for example, this means that 725 square kilometers (280 square miles) of urban land will be lost. In addition, coastal cities are also subsiding for a number of reasons including groundwater extraction, depletion of oil wells, geological factors, or just the sheer weight of the skyscrapers. In less than 100 years, some of the world’s major cities might literally find themselves underwater.
The search for sustainable solutions
Although the picture may look bleak, most cities and their respective governments are taking action to protect their coastlines from this imminent threat. In cities such as Bangkok and Tokyo, there are new regulations regarding groundwater extraction that is both reducing the rate of subsidence and restoring groundwater levels. Solutions also include updating infrastructure, creating new zoning regulations, and coastal defense systems to protect itself from rising sea levels and superstorms. Hurricane Sandy that hit the Atlantic seaboard in 2012 is just one example of the devastation that storm surges can cost a coastal city. After $70 Billion in damage and loss of life and property, the coastal cities hit by this superstorm are still recovering.
Rebuild By Design
In the United States, the search is on for sustainable solutions that will protect the city against the next storm surge and rising tides. After Superstorm Sandy’s devastation, the federal government has launched Rebuild By Design (RBD), a competition for groups of experts to offer solutions on how to prepare for the next big storm. This competition resulted in 7 projects that will protect the coastlines of NYC and NJ. This initiative became a model to help create research-based, collaborative processes that prepare communities and regions for future challenges. One of these plans is the Resilient by Design | Bay Area Challenge that was launched in early 2017.
The premise of the Resilient by Design Bay Area Challenge was both simple and audacious. As flood risks increase due to intensified severe storms and sea level rise, organizers asked the question – can the Bay Area come together to shift its course and build a more resilient region before a big disaster hits, and can we address other regional challenges along the way? Since then, 10 design concepts were selected, meant to inspire, catalyze action, and push the area along the path to a more resilient future.
Courtesy of SCAPE Landscape Architecture DPC.
Livin’ on the edge
Nearly half of worlds’ population resides along coastal areas, ranging from megacities to small islands. The effects of climate change – including sea level rise, increased storminess, ocean warming and acidification – are negatively impacting these communities’ lives and livelihoods. In cities and elsewhere, communities already face regular flooding due to higher tides, some see more frequent natural disasters, and others see tourist-attracting coral reefs or surfing fade.
New Orleans’s catastrophic experience with Hurricane Katrina in 2005 caused hundreds of thousands of people to leave the metro area—often those with the fewest resources and the most flood-prone homes. Investing $14.5 billion in levees has left residents, that had no choice but coming back to their devastated homes, only slightly better off than they were pre-Katrina.
Five years ago, Superstorm Sandy struck New York, bringing record-breaking wind gusts and deadly flooding. In New York City, 53 people died – nearly half of them were from Staten Island. Recent hurricanes Harvey, Irma, and Maria have all raised the same question: What is to be done with the dozens of towns and cities that have developed infrastructure and neighborhoods on vulnerable flood-prone land that routinely requires massive cleanup and rebuilding efforts after each disastrous storm? Altogether, the recent storms could cost up to nearly $400 billion in damages. But some communities and local leaders are starting to realize that this model won’t break the cycle. In Ocean Breeze, a Staten Island community, instead of rebuilding on vulnerable flood plains, some residents have chosen to leave old neighborhoods behind and let nature take its course.
However, in most places, whether it’s from livelihood or lifestyle related reasons, people still prefer to leave close to the coastlines, putting themselves and their families at flood risk.
Harnessing nature for resilient coastlines
Part of the solution for coastal flooding lays in restoring historical coastal habitats like oyster reefs, tidal wetlands, and mangrove forests, that serve as natural coastal protection.
In Staten Island, the Living Breakwaters project is a breath of fresh air. This neckless of 9 breakwaters is aimed at protecting the southern tip of Staten Island by reducing the height of waves hitting the shore and as a result extending the width of the sandy beach, providing additional protection. However, these breakwaters, as stated in their name, are “Living” infrastructure designed not only for risk reduction but also for the ecological enhancement of the local marine environment. The ecologically designed breakwaters alongside the use of bio-enhancing materials will help reestablish habitat complexity and mimic the functionality of natural oyster reefs that historically dominated the area. These reefs are known to create and maintain a complex underwater habitat and act as a keystone species and ecosystem engineer, whose loss from the area is associated with changes in biological and physical processes.
Sinking cities, rising sea levels, and storm surges in the wake of global warming are our new reality. It is up to us to find creative solutions in which to adapt and survive while protecting our environment, as doing nothing is the biggest risk of all.
Weeks after Hurricane Florence ravaged the Carolinas, and on the sixth anniversary of Superstorm Sandy in New York, the four-part series examines how cities are preparing for the real-time effects of climate change.