How We Can Save Cities From Rising Sea Levels

How We Can Save Cities From Rising Sea Levels Raise the (Thames) Barriers! diamond geezer/Flickr, CC BY-NC-ND

Extreme storms and rising sea levels will threaten the existence of coastal cities worldwide, unless preventative action is undertaken. With population growth and sea-level rise set to continue, research has estimated that by 2050, we can expect more than US$1 trillion worth of damages per year to be incurred by 136 of the world’s largest cities, if there is no attempt to adapt.

The game changer came in 2005, when we saw one of the most active hurricane seasons in US history. Hurricane Katrina, the fifth hurricane of that season, resulted in nearly 1,600 deaths. Almost half of these fatalities occurred in New Orleans: 80% of the city was flooded, at a cost of US$40 billion. When the water subsided, so did the population: ten years on, the city that used to house 500,000 is now home to only 300,000 people.

There are a number of ways to go about changing cities to account for rising sea levels: we can raise coastal defences, build houses on stilts, or simply move cities and their populations away from the coast. Which of these strategies works best was one of many questions set out in Climate Change: A Risk Assessment – a new report led by Sir David King and the Foreign and Commonwealth Office.

Constant threat

Globally, sea levels have been remarkably stable since civilisation started to develop several thousand years ago. During the 20th century, sea levels rose about 17cm, at an average rate of 1.8mm per year. Over the past few decades, that rate has doubled to more than 3mm per year. This trend is expected to continue and accelerate. According to the latest Intergovernmental Panel on Climate Change report, the sea level is projected to rise up to 1m by 2100. If the large ice sheets of Greenland and Antarctica melted, even higher rises are considered possible, albeit highly uncertain.

Importantly, if carbon emissions are stabilised, or even decrease, the sea level will continue to rise for many centuries, as the deep ocean slowly warms and the large ice sheets reach a new equilibrium. Simply put, sea-level rise is here to stay. It is likely to lead to greater flooding, salinisation (the build up of salt in surface and groundwater) and erosion in coastal areas, affecting millions of people worldwide and costing billions of dollars of damage.

How We Can Save Cities From Rising Sea Levels The devastation of Typhoon Haiyan. EU Humanitarian Aid and Civil Protection/Flickr, CC BY-ND

The high costs of economic damage and loss of life are becoming less acceptable in a world where extreme weather events can be accurately forecast and coastal protection is possible. In many parts of the world, damages and loss of life remain high, as seen during Typhoon Haiyan, which hit the Philippines in 2013. Preparing coastal cities for extreme events and adapting them to cope with sea-level rise remains challenging: King’s report highlights the engineering, financial and socio-political limits of the adaptation challenge.

But cities are starting to embrace these challenges. For example, last year, Boston put forward the bold, novel idea of becoming an American Venice – a city full of canals to hold water as sea levels rise. New York has considered building a barrier to keep water out, in light of the fact that, with a 1m rise in the sea level, a 1-in-100 year event (that is, a severe storm one would expect to occur once every 100 years) could become 200 times more likely to occur.

London has also developed a range of flexible options that would protect the Thames Estuary against up to 5m of sea-level rise. These include raising defences, implementing flood storage and constructing a new and bigger Thames Barrier further downstream.

Developing better cities

In developing countries, few cities are preparing for sea-level rise, despite the awareness that this is a long-term hazard. Developing cities also frequently have rapid population growth. In Shanghai and Kolkata more than 400,000 people live less than 2m above the present-day sea level. A rise of 1m will increase the frequency of a current 1-in-100 year event by 40 times in Shanghai, and about 1,000 times in Kolkata.

Local ground subsidence is another factor to worry about. This involves the sinking of the land relative to the sea due to natural and sometimes human processes (such as groundwater withdrawal). Local ground subsidence will worsen conditions in about a quarter of coastal cities – namely, those built on susceptible deltaic soils (those at the mouth of a river).

How We Can Save Cities From Rising Sea Levels Malé’s protective tetrapods. Sally Brown, Author provided

Small islands and their cities are also under serious threat from sea-level rise as they are low-lying, remote and dispersed in their territories, and often have limited financial resources. Far from being a green, spacious island, Malé – the capital of the Maldives – is one of the world’s most densely populated cities. Building protective structures is one way of reducing the impacts of extreme events: Malé is surrounded by a sea wall and giant tetrapods (a four-pronged concentrate structure about 2m high). But a lack of space limits future coastal protection.

To overcome this, a new island has been constructed, Hulhumalé, with sea-level rise also in mind. The solution to sea-level rise is simply to build upwards: The island was raised to 2m above present day sea level to protect against storms. This buys time, but moving into the late 21st or early 22nd century this may not be enough. Other Maldivian islands are following suit, with the Safer Islands programme selectively raising parts of islands. This may help the parts of the country, but clearly much more work is required to ensure the long-term prospects of this fragile island nation.

Ultimately, these case studies show us that there’s no one-size-fits-all approach to adapting cities to rising sea levels. Rather, the best bet for cities to adapt against rising sea levels is to dare to be different. Both engineering design, government authorities and social attitudes must acknowledge that change needs to occur, if we’re to avoid disaster.The Conversation

About The Author

Sally Brown, Research Fellow, University of Southampton; Ivan Haigh, Lecturer in Coastal Oceanography, University of Southampton, and Robert Nicholls, Professor of Coastal Engineering, University of Southampton

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Related Books

Life After Carbon: The Next Global Transformation of Cities

by Peter Plastrik , John Cleveland
1610918495The future of our cities is not what it used to be. The modern-city model that took hold globally in the twentieth century has outlived its usefulness. It cannot solve the problems it helped to create—especially global warming. Fortunately, a new model for urban development is emerging in cities to aggressively tackle the realities of climate change. It transforms the way cities design and use physical space, generate economic wealth, consume and dispose of resources, exploit and sustain the natural ecosystems, and prepare for the future. Available On Amazon

The Sixth Extinction: An Unnatural History

by Elizabeth Kolbert
1250062187Over the last half-billion years, there have been Five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists around the world are currently monitoring the sixth extinction, predicted to be the most devastating extinction event since the asteroid impact that wiped out the dinosaurs. This time around, the cataclysm is us. In prose that is at once frank, entertaining, and deeply informed, New Yorker writer Elizabeth Kolbert tells us why and how human beings have altered life on the planet in a way no species has before. Interweaving research in half a dozen disciplines, descriptions of the fascinating species that have already been lost, and the history of extinction as a concept, Kolbert provides a moving and comprehensive account of the disappearances occurring before our very eyes. She shows that the sixth extinction is likely to be mankind's most lasting legacy, compelling us to rethink the fundamental question of what it means to be human. Available On Amazon

Climate Wars: The Fight for Survival as the World Overheats

by Gwynne Dyer
1851687181Waves of climate refugees. Dozens of failed states. All-out war. From one of the world’s great geopolitical analysts comes a terrifying glimpse of the strategic realities of the near future, when climate change drives the world’s powers towards the cut-throat politics of survival. Prescient and unflinching, Climate Wars will be one of the most important books of the coming years. Read it and find out what we’re heading for. Available On Amazon

From The Publisher:
Purchases on Amazon go to defray the cost of bringing you InnerSelf.comelf.com, MightyNatural.com, and ClimateImpactNews.com at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.

 

enafarzh-CNzh-TWdanltlfifrdeiwhihuiditjakomsnofaplptruesswsvthtrukurvi

follow InnerSelf on

facebook-icontwitter-iconrss-icon

 Get The Latest By Email

{emailcloak=off}

LATEST VIDEOS

To Reach Zero Emissions Government Must Address Hurdles Putting People Off Electric Cars
To Reach Zero Emissions Government Must Address Hurdles Putting People Off Electric Cars
by Swapnesh Masrani
Ambitious targets have been set by the UK and Scottish governments to become net-zero carbon economies by 2050 and 2045…
Spring Is Arriving Earlier Across The US, And That's Not Always Good News
Spring Is Arriving Earlier Across The US, And That's Not Always Good News
by Theresa Crimmins
Across much of the United States, a warming climate has advanced the arrival of spring. This year is no exception.
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
by Alan N Williams, et al
The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that without a substantial decrease…
A Georgia Town Gets Half Of Its Electricity From President Jimmy Carter's Solar Farm
A Georgia Town Gets Half Of Its Electricity From President Jimmy Carter's Solar Farm
by Johnna Crider
Plains, Georgia, is a small town that is just south of Columbus, Macon, and Atlanta and north of Albany. It is the…
Majority of US Adults Believe Climate Change Is Most Important Issue Today
by American Psychological Association
As the effects of climate change become more evident, more than half of U.S. adults (56%) say climate change is the…
How These Three Financial Firms Could Change The Direction Of The Climate Crisis
How These Three Financial Firms Could Change The Direction Of The Climate Crisis
by Mangulina Jan Fichtner, et al
A silent revolution is happening in investing. It is a paradigm shift that will have a profound impact on corporations,…
Investing In Climate Change
by Goldman Sachs
“Top of Mind at Goldman Sachs” Podcast – In this episode, we dig into what may be the most important issue of our time:…
Climate Change: Briefings from Southern Africa
by SABC Digital News
Climate change affects us all, but it can be a confusing business. Three leading South African scientists who have…

LATEST ARTICLES

5 Ways To Teach Children About Climate Change
5 Ways To Teach Children About Climate Change
by William Finnegan
Climate change is an interdisciplinary subject that both school children and adults think is important. And as we deal…
This Is The Arctic's Recent Carbon Emissions We Should Fear For Climate Change
This Is The Arctic's Recent Carbon Emissions We Should Fear For Climate Change
by Joshua Dean
The Arctic is predicted to warm faster than anywhere else in the world this century, perhaps by as much as 7°C.
Why This Is A Once In A Lifetime Chance To Reshape How We Travel
Why This Is A Once In A Lifetime Chance To Reshape How We Travel
by Marcus Enoch and James Warren
This isn’t a normal period of disruption, which is usually caused by failures in supply such as road accidents or…
Why A Better World Needs Better Economics
Why A Better World Needs Better Economics
by David Korten
Science warns us that the 2020s will be humanity’s last opportunity to save itself from a climate catastrophe.
How Plants And Animals Share Response To Climate Change
How Plants And Animals Share Response To Climate Change
by Daniel Stolte
Plants and animals are remarkably similar in their responses to changing environmental conditions across the globe,…
Why Poorer Suburbs Are More At Risk In Warming Cities
Why Poorer Suburbs Are More At Risk In Warming Cities
by Jason Byrne and Tony Matthews
The many reasons for this include urban densification policies, climate change and social trends such as bigger houses…
A Second Us Dust Bowl Would Hit World Food Stocks
A Second Us Dust Bowl Would Hit World Food Stocks
by Tim Radford
When the US Great Plains are hit again by sustained drought, the world’s food stocks will feel the heat.
Rising Seas: To Keep Humans Safe, Let Nature Shape The Coast
Rising Seas: To Keep Humans Safe, Let Nature Shape The Coast
by Iris Möller
Even under the most conservative climate change scenarios, sea levels 30cm higher than at present seem all but certain…