Replenishing eroded beaches may prevent cities from properly adapting to climate change

Sunny Isle. The beaches of South Florida are already being replenished by the authorities. Image: Getty.

Coastal communities around the world are struggling to adapt to rising sea levels and increasingly severe coastal storms. In the United States, local governments are making investments to reduce those risks, such as protecting shorelines with seawalls, “nourishing” eroded beaches by adding sand and rerouting or redesigning roads and bridges.

In the short run, spending public money this way is economically rational. But in the long run, many people who live near coastlines will probably have to relocate as seas continue to rise.

We have studied this problem by combining insights from our work in economics, coastal geomorphology and engineering. As we have explained elsewhere, short-term actions to adapt to coastal flooding can actually increase risks to lives and property. By raising the value of coastal properties, these steps encourage people to stay in place and delay decisions about more drastic solutions, such as moving inland.

Keeping millions in harm’s way

According to recent estimates, a one-foot increase in sea levels will put about 1m people in the United States at risk, and 3 feet will threaten about 4m people. Global sea levels currently are projected to rise 0.5 to 2.1 feet by 2050 and 1.0 to 8.2 feet by 2100.

As we see it, market forces and public risk reduction policies interact in unexpected ways, reducing incentives for communities to make long-term plans for retreating from the shore. Nourishing beaches and building seawalls signal to individuals and businesses that their risks are lower. This makes them more likely to build long-lasting structures in risky areas and renovate and maintain existing structures. As a result, their property values increase, which reinforces economic and political arguments for more risk-reduction engineering.

To illustrate this pattern, we compared a sample of houses in Nags Head and Kitty Hawk, North Carolina, two popular beach towns less than 10 miles apart on North Carolina’s Outer Banks. When we consulted county tax appraisal values, Nags Head beaches had routinely received sand from beach nourishment, whereas Kitty Hawk beaches had not. On average, homes in our Nags Head sample were worth over $1m, while homes in the Kitty Hawk sample were worth about $200,000.

Other researchers have found that in some locations, the threat of rising seas is eroding coastal property values. But this tends to be true for properties that are viewed as highly vulnerable – for example, homes that have already flooded. In contrast, homes that are elevated or have other flood-proofing features tend to have much higher values, so they are perceived as assets.


Subsidising risky choices

Some amount of risk reduction makes sense. If people who benefited paid its full cost, and everyone involved understood how imminent the risk was and how much engineering solutions would cost, then market forces would likely produce reasonably efficient solutions.

As an example, flood-prone Norfolk, Virginia recently adopted an ordinance requiring almost all new homes and many major renovations to be elevated and include other flood-proofing features. This approach will help to price flood protection into the cost of homes and will tend to reduce demands to directly subsidise protective engineering, flood insurance and post-disaster assistance.

In our view, such solutions are a move in the right direction. But they will not break the positive feedback loop we describe as long as other public policies continue to skew perceptions of the long-term viability of coastal communities.

Engineering projects to slow shoreline retreat and reduce flooding generally receive smaller subsidies now than in past decades, but many communities still benefit. For example, beach nourishment in Ocean City, Maryland is cost-shared between the federal government, which pays about half, and state and local agencies. The Federal Emergency Management Agency helps pay to rebuild homes and public buildings damaged in major disasters. And allowing people to deduct local taxes on their federal tax forms partly subsidises local tax financing for risk reduction.

Beach nourishment started at New York’s Coney Island a century ago. But with the sheer volume of sand needed to keep up with sea level rise, its costs could outweigh its benefits within a few decades.

Inaccurate perceptions of risk

Information and uncertainty are larger problems. Many coastal residents do not perceive medium- and long-term climate risk to be as serious as the scientific consensus suggests. Moreover, scientists are still analysing how fast sea levels are likely to rise. Future storm frequency is uncertain, and could be affected by changes in global greenhouse gas emission trends.

On the positive side, engineering innovations such as designing storm-resistant homes could become more effective. But existing approaches like beach nourishment are likely to become more expensive as sand resources diminish and more communities compete for them. And growing uncertainty is likely to increase near-term demand for risk reduction engineering.

The most critical time for adaptation decisions is immediately after a storm or flood. Faced with expensive repairs or rebuilding, property owners face higher costs to return to the status quo. But if homeowners expect that public resources will be spent to protect them against future disasters, they are less likely to consider making big changes.

Federal or state financial rebuilding assistance creates a similar bias. If that money were used to subsidise relocation or other drastic adaptive actions, rebuilding patterns would be different. So far, however, programs for buying out flood-damaged properties have been largely unsuccessful. Many factors, including residents’ level of experience with disaster recovery and financial concerns, can make people unwilling to consider relocating.

Incentives to think long-term

There is no perfect formula for balancing near-term climate-proofing against more drastic steps to move people away from the coasts. But we believe that when communities focus excessively on reducing near-term threats, they risk inhibiting the successful adaptation that they are trying to promote.

We have three suggestions for breaking this cycle. First, local land use policies could be designed to discourage rebuilding homes to similar or higher property values after damage from storms. Second, communities could put increasing emphasis on adaptive engineering and large-scale planning practices – for example, sunsetting beach nourishment projects when sea level rise reaches some preannounced level.


Finally, adaptation decisions could be planned and implemented at a multi-jurisdictional level, rather than town by town. This approach would help to avoid “rich towns get richer” dynamics that can develop when wealthier jurisdictions deploy sand resources and other protective measures in a way that reduces their own risk while ignoring or heightening threats to nearby locations.

Change is coming to coasts around the world. We believe that broader understanding of how markets and public policy interact is essential to minimise the social and economic costs of this change.

The Conversation

Andrew G. Keeler, Professor of Economics and Program Head, Public Policy and Coastal Sustainability, UNC Coastal Studies Institute, East Carolina University; Dylan McNamara, Professor of Physics and Physical Oceanography, University of North Carolina Wilmington, and Jennifer Irish, Professor of Civil and Environmental Engineering, Virginia Tech.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

A helpful and informative guide to London, for the benefit of the New York Times editorial board

The sun rises over quaint old London town. Image: Getty.

It’s like with family members you hate: it’s fine for you to slag them off, but if anyone else has, you’re up in muted, backhanded arms about it.

Yesterday, the world’s number one London fan the New York Times tweeted a request for experiences of petty crime in the city. This was met by a deluge of predictably on-brand snark, like “Sometimes people scuff my leg and only apologise once”, and “Dicks who stand on the left-hand-side of tube escalators”. This served the dual purpose of uniting a divided London, and proving to the NYT that we are exactly the kind of chippy bastards who deserve to constantly lose their phones and wallets to petty crime.

By way of thanks for that brief endorphin rush, and in hopes of leading things in a more positive direction, I’d like to offer the Times this uplifting guide to London, by me, a Londoner.

I take my London like I take my coffee: on foot. If you are with someone special, or like me, like to reimagine your life in the format of Netflix dramady as you walk alone on Sundays, I can highly recommend the Thames Path as a place to start.

Kick things off next to Westminster, where we keep our national mace in the House of Commons. Useful though the mace might prove in instances of street theft, it is critical that it is never moved from the House. It acts as a power source for our elected representatives, who, if the mace is moved, become trapped in endless cycles of pointless and excruciatingly slow voting.

Cross Westminster Bridge to the Southbank, where in the manner of a spoiled 2018 Oliver Twist, you can beg for a hot chocolate or cup of chestnuts at the Christmas market for less that £8. Remember to hold your nose, the mutton vats are pungent. Doff your cap to the porridge vendor. (LOL, as if we make muttons in vats anymore. Box your own ears for your foolishness.) Then buy some hemp milk porridge, sprinkle with frankincense and myrrh, and throw it at the pigeons. There are thousands.

In the spring, head a little further south through Waterloo station. If you pass through the other side without getting ABBA stuck in your head, Napoleon’s ghost will appear to grant you three wishes.

Proceed to the Vaults, which is like the rabbit warrens in Watership Down, but for actors and comedians. No-one knows the correct way in, so expect to spend at least 45 minutes negotiating a series of increasingly neon graffiti tunnels. Regret not going to art school, and reward yourself upon your eventual entry with a drink at the bar. Browse the unintelligible show programme, and in no circumstances speak to any actors or comedians.

When you emerge from the Vaults three days later, turn back towards the river and head east. Enjoy the lights along the Thames while you pick at the spray paint stains on your coat. 


After about 20 minutes, you will reach the Tate Modern, which stands opposite St Paul’s Cathedral. Close to sunset, the sky, water, and cathedral might turn a warm peach colour. The Tate remains grey, coldly confident that for all its brutalist outline, it was still fantastically expensive to build. Feel grateful for that loose knit jumper you stole from the Vaults, and go inside.

Spend two minutes absorbing the largest and most accessible art, which is in the turbine hall, then a further hour in the museum shop, which is next to it. Buy three postcards featuring the upstairs art you skipped, and place them in your bag. They will never see the light of day again.

Head further east by way of Borough Market. Measure your strength of character by seeing how many free samples you are prepared to take from the stalls without buying anything. Leave disappointed. Continue east.

At Tower Bridge, pause and take 6,000 photos of the Tower of London and the view west towards parliament, so that people know. Your phone is snatched! Tut, resolve to take the embarrassment with you to your grave rather than shame Her Majesty's capital, and cross the river.

On the other side of the Bridge, you could opt to head north and slightly east to Shoreditch/Brick Lane/Whitechapel, where you can pay to enjoy walking tours describing how some pervert murdered innocent women over a century ago.

Don’t do that.

Instead, head west and north. through the City, until you reach Postman’s Park, which is a little north of St Paul’s, next to St Bartholomew's hospital. Go in, and find the wall at the far end. The wall is covered in plaques commemorating acts of extraordinary and selfless bravery by the city’s inhabitants. Read all of them and fail to hold back tears.

Then tweet about it.