Costs of sea level rise on the example of North Carolina

A distinctive feature of the east coast of the United States, especially its southern part, are shoals that cut off coastal waters from the open ocean. To some extent, this resembles the situation of the Polish part of the Baltic Sea.

Salinity level vs. cost-effectiveness of treatment

In our country, shoals usually cut off the reservoir completely, except for the riverbed, forming coastal lakes. In the US, the situation is usually different – open lagoons are more common, and spits are not peninsulas, but barrier islands. Either way, lagoons are less salty than the open ocean, more enclosed lakes – almost freshwater, and more open lagoons – only brackish. In European water policy jargon, they are referred to as transitional waters.

The salinity of lagoons and coastal lakes is low enough to make it profitable to treat their resources for consumption. Interestingly, the only large intake of such waters located on a lake in Poland concerns Miedwia, a facility that is not a classic spit lake, but is located near marine waters and its salinity, although not on a par with, for example, Gardno, is higher than average (conductivity exceeds 500 µS/cm).

In the Atlantic resorts of the US, water from sweetened lagoons is the primary source feeding the water supply. Near the ocean, its undercurrents make groundwater more saline and make it even more expensive to treat.

How does terrain affect water prices?

Spits are formations related to coastal dunes and revetments. They are elongated, but narrow and low. During storms, waves can easily pour through them, bringing salty water into the lagoon. With a long-term change in ocean level, their height, shaped by waves and wind, will eventually adjust to it, but before that happens, they can rise and disappear. The current rise in ocean levels is causing lagoons to become more exposed to ocean water inflow.

For North Carolina beaches, the current sea level rise is 2-5 mm per year, and forecasts by the US National Oceanic and Atmospheric Administration predict an acceleration of this trend. This means an increase in the salinity of the lagoons and, consequently, the expense of treating drinking water. The process is a trade-off between the cost of obtaining perfectly fresh water and consumers’ tolerance for some salinity. As a result, tourists visiting resorts in the future will have to pay more for treated tap water or put up with its higher salinity, or perhaps both.

Summary of survey results

Accordingly, a group of economists from North Carolina and Georgia decided to estimate the preferences of potential tourists in relation to these projections. To do this, they used classic (though modernized compared to the 1970s approach) methods of estimating the value of ecosystem services by surveying those who use them about actual and acceptable expenditures. The survey was conducted among people who not only declare a desire to spend their vacation at the seaside, but also have previously purchased at least one night at the coast, and thus confirmed their desire with deeds.

The survey focused on beach vacationing only in North Carolina, and surveyed residents of that state who do not own waterfront property. This excluded those who have invested so much in vacationing at a particular beach that a minor inconvenience would not cause them to change their plans. Owners of summer cottages are more likely to spend their vacation in the place where they bought the property. Residents of farther-away states are less likely to interrupt their vacation than those who can return home and go somewhere else within a few hours.

Tourists were asked a series of questions about both their recent vacations to the seaside and their plans for the next. They were also asked to declare what degree of difficulties would discourage them from repeating their stay in the same place. The average respondent (or rather, respondent, since women slightly outnumbered men among the responses) has been on almost 3 overnight trips to the sea over the past year, and spent $749 on the last one. (the survey was conducted in 2021).

Besides, he was prepared to spend $879 next time. Not surprisingly, therefore, when asked whether a $100 increase in cost would cause him to change his plans, no one answered in the affirmative. As one might guess, as the potential cost increased, the percentage of those discouraged grew. For an increase of 1,000. dollars. Only 60 percent of respondents would already agree.

Another series of questions concerned the quality of tap water, specifically its salinity. Light to moderate salinity would not deter most tourists. For that, you would need significant salinity or a combination of salinity and cost. A number of those surveyed would not care at all, relying on water brought from home or bottled water purchased locally. Those who would give up their planned vacation, however, would be most likely to swap it for a trip to another beach in the same state, but with better conditions. Worse, if it turned out to be the same everywhere.

Financial consequences of sea level rise

The numbers resulting from the survey were substituted by economists into models and estimated what losses in the tourism industry could result from the expected rise in ocean levels and salinization of drinking water sources. In the most pessimistic scenario, they would amount to $232 million, $193 million and $402 million in 2040, 2060 and 2080, respectively.

Sea level rise and the thawing of spits are not just a matter of cost and drinking water quality. Even this group of tourists, who will not be deterred by these problems, may have less recreational space available to them when it is swallowed up by the ocean. A few years ago, the cost of losing ocean fishing spots in North Carolina was estimated at $430 million, and the decline in coastal property values at $7 billion. These sums may not come down to every cent, but they provide a glimpse that climate change is a concrete financial problem.

Naturalistic losses in coastal habitats have not been calculated. Many naturalists criticize estimates of the value of ecosystem services used in economics, believing that they include only a slice of the real value. They point out that it is immeasurable, and it is absurd to consider the existence of a species or habitat worth a specific amount.

Source: doi 10.1029/2023WR036440