Beach Erosion or Rising Sea Level?
Beach erosion is a huge problem worldwide, costing hundreds of millions of dollars for restoration projects each year. Increasingly, rising sea level is blamed, though this is mostly wrong. In the coming decades however, rising seas will make erosion even worse. It is important to understand each and how they will combine.
Beyond the cost of beach “re-nourishment”, real estate worth trillions is at risk. It is not just iconic Florida, or even the U.S. From Europe to Thailand and Australia to Africa, coastal beaches everywhere are heavily developed. Condominiums, homes, resorts, vacation clubs and commercial buildings have been proliferating like weeds in coastal areas over the last half century. All this development ignored a basic fact of coastal geology.
Beaches and coastlines have always migrated over centuries and millennia. Inexorably, yard by yard (meter by meter) there can be really huge movement of the shoreline. Even without abrupt storms, currents in the water move sand along the shoreline, with great cumulative effect. Often you can see this rolling movement, just by standing at the edge. It’s a part of nature and happens with or without human influence. The big change that “we” caused is to establish breakwaters, channels entrances, and groins that stick out from the beach and interrupt the normal flow of sand. At these “jetties” and other structures you will see the beach depleted on one side and MUCH wider on the other. That’s the result of interrupting the normal sand flow.
Huge pounding waves, often associated with winter storms, are another factor for beach erosion. Again, a normal phenomenon. Historically – a century ago – people did not build right up to the edge of the sea. Homes were set back a considerable distance and preferably on higher ground to avoid flooding. Fishing tents and even small summer cottages might be built closer but it was understood they could be moved or were expendable.
The problem began in the middle of the last century with larger, more expensive, more permanent structures, built as close to the beach as permitted. Often the protective sand dunes and natural vegetation were even removed to allow a better view. Understandably if someone wanted to live on the ocean they wanted to see it. This created more demand, developers kept wanting to push things further, larger, more expensive. Buyers and sellers acted as if beaches did not move.
Developer and buyers had a short-term mentality. They would be out in less than a decade if they needed to be. The risk would pass to someone else. Insurance was the tool that made it work. Particularly in the US, the riskier development was encouraged by federal programs like the National Flood Insurance and FEMA disaster relief.
It was a perfect storm: bigger, more permanent structures that would last fifty to a hundred years. Interrupting the natural flow of sand along the beach. Competitive insurance priced for the short term, with various government development incentives reducing the cost and perceived risk. Even without rising sea level, it would be a major problem.
Rising sea level will almost certainly make erosion worse in the decades ahead. When the base sea level is higher, sand movement along the shore and damage from waves will get better access to new terrain, and even to structures directly.
The other change factor that has been largely overlooked is a growing imbalance between demand and supply. The demand for quality sand for beach restoration is increasing dramatically, with limits on supply, driving up costs. When I was in the Netherlands recently, experts estimated that we had a few decades before we “hit the wall” where the costs to endlessly restore beaches, were no longer acceptable.
By mid century, erosion, the cost of beach restoration and rapidly increasing rising sea level will all challenge our concept of coastal development. The sooner we face that reality the better. New policies about coastal development and insurance will help to reduce the risk and ensure that we are developing assets that have a future. That can rise with the tide…