Sea to the left, cities on the right
The beach squeeze
Door Alex Torres
By Alex Torres
Alex Torres
Ten steps. That is all that it takes to get from the crashing waves of the Wadden Sea at Huisduinen, near Den Helder, to the nearest man-made construction. We already know that sea levels are rising, but how many of us have given any thought to what’s happening on the other side of the beach?
‘This is where the real problem is’, says Eva Lansu, while sipping her lemon tea at a cafe directly adjoining the beach. In the past, beach ecosystems could simply adjust, usually by retreating inland. But now, cities, roads, and other structures are leaving them with nowhere to go. This could lead to a third of the world’s beaches disappearing within the next 75 years, according to her study published earlier this year in Nature Communications.
Natural defence
Sandy coasts are quite unique. For one, they are many people’s favourite summer destinations, and highly sought-after spots for recreation. They are also home to a variety of plants and wildlife, such as seals, birds, crabs, and dune grasses. But, perhaps more importantly, sandy dunes help us by acting as natural flood defences and drinking water reservoirs.
A hundred metres, that’s really not enough space
This is why it’s important that these ecosystems are able to adapt to rising tides. Back in 2021, UG researcher Lansu – who also works for the Royal Netherlands Institute for Sea Research (NIOZ) – was interested in finding out exactly how much space is left for that. ‘We realised no one had looked at that before’, she says, ‘so my team and I wanted to take measurements at different sandy coasts around the Netherlands.’
But Covid had other plans. ‘We couldn’t really go out, so we had to find another way to get data’, Lansu says. ‘Which turned out to be quite simple!’
They just downloaded information about streets and buildings using OpenStreetMap. All of a sudden, what was meant to be a study of only the Dutch coast turned into a comprehensive overview of the entire world’s sandy shores.
Dire situation
With this data, Lansu and her team could easily measure the distance between the sea and the nearest infrastructure. What they saw was dire. Approximately a third of all sandy shores in the world have buildings or roads built within the first hundred metres from the sea.
‘That’s really not enough space’, Lansu says. According to new data she collected on site from over forty-seven dune areas in the Netherlands and in Florida, coastal dune ecosystems need at least one to two kilometres of infrastructure-free space in order to adapt to rising sea levels and erosion.
The situation is particularly bad in Europe, where sandy coastlines have a median width of only 130 metres. Here, in Huisduinen, it’s even worse. To get to the beach, Lansu has to climb up and down the dyke that encloses the seafront like a wall. ‘It’s a seaside village that can’t look at the sea’, she says and she counts the steps to get from the sea to the dyke. ‘Ten! An entire ecosystem has been shrunken to ten paces.’
Beach crisis
There are thousands of places just like this. That means that, according to the worst projections, Europe may be in for a serious beach crisis. Other regions of the world, such as Australia and parts of Africa, are better prepared for the rising sea levels, boasting sandy coasts that are several kilometres wide.
It will become harder and more expensive to get enough sand for the beaches
‘It has to do with population density and the gross domestic product (GDP)’, Lansu explains. ‘When there’s more people and money in a region, there’s more infrastructure close to the coast.’ Both Europe’s population and GDP are projected to grow in the coming years, further increasing the pressure on the sandy coastlines.
But before we wave goodbye to the French Riviera or Portugal’s sunny surf spots, there are ways to fight this situation. All around the world, governments dump extra sand on beaches to fend off the sea, in a process known as sand nourishment. Along the Dutch coast, for example, ten million cubic metres of sand is deposited every year.
Commodity
However, this strategy can quickly become unsustainable. ‘Sand isn’t infinite’, Lansu says. ‘It will become harder and more expensive to get enough sand to keep this going all over the world. At some point, countries will start to trade sand, like it’s a commodity.’
Another, more drastic option would be to give land back to the dunes. ‘If we get rid of the roads and buildings in those areas, it would buy us time’, says Lansu. ‘That would allow the dunes to retreat inland, preserving those ecosystems, along with all their benefits.’
Lansu is not confident, however, that such a measure would garner strong public support. ‘It isn’t very realistic from an economic perspective, but from an ecological perspective, I’d say it’s essential.’
Protected zones
A more pragmatic approach is to conserve the dune systems we still have. In her study, she saw that protected coastal zones, where building is illegal, allow for much more space for the dunes to thrive. In such areas, infrastructures tend to be around four times farther away from the sea than in non-protected areas.
This issue won’t become a priority until something goes really wrong
This solution would still require very strong coast-friendly policies, and possibly quite a bit of international cooperation. As Lansu states in her study, only 16 percent of the world’s sandy shores are protected, so there would still be much work to do. And this measure would not necessarily fix the problem, but only prevent it from getting worse.
‘It all just makes me sad,’ says Lansu. ‘Because it seems like this issue won’t become a priority until something goes really wrong.’
‘It’s especially disappointing in the case of the Netherlands’, she believes. ‘We’re known for being a country that’s very good at urban planning. But we’re really not thinking ahead in this matter. Also, when you think of climate change in general, we are really not at the front lines of these fights.’
Still, Lansu will continue mapping out the consequences of this coastal squeeze. Along with her team, she has just submitted a study on the effects of lack of space on dune biodiversity. With this, she hopes to provide a clearer picture of what’s at stake and inspire policymakers to think about the other side of the beach.