On a roundabout on the avenue lining the Mediterranean seafront at Palavas-les-Flots, a seaside holiday resort close to the town of Montpellier in southern France, a notice board sets out the local municipality’s rules for “better living together”.
These include the wearing of “correct” clothing in town, and notably shoes, the exhortation to not ride mopeds or motorbikes on the pavement, and to not indulge in loud behaviour – because “noise is a form of pollution and aggression”. But it makes no recommendation that holidaymakers leave their cars behind in favour of walking or using public transport, nor does it urge property developers to stop building on the remaining plots of land between the apartment buildings standing just a few metres from the seafront.
This major resort of the Languedoc region lies on a narrow sandy strip of land about 30 kilometres long that stands as a barrier between small lagoons to the north and the open Mediterranean Sea on its south side. Once a small fishing port, the permanent population of just more than 6,000 is bloated by tens of thousands of tourists during the summer months, largely accommodated in sprawling modern apartment buildings that overlook the beaches and a marina with more than 1,000 berths.
Nowhere along the avenue Saint-Maurice, which is one of the principal residential arteries of Palavas-les-Flots, is there any attempt to draw public attention to coastal erosion, nor to the issue of climate change. But already, in 1982, during an exceptional storm, the sea swept inland for a distance of about 50 metres from the beach. Now, finding passers-by to talk about the threat of flooding appeared to be a vain hope. It might be off-season, but the only pedestrian to be met along the avenue, alive with vehicles and motorbikes, was a Yorkshire Terrier, scurrying along with its head bowed.
But out on the jetty was a woman who said she remembered that last winter the seawater reached the roundabout on the main avenue. She pointed at the low walls made of wood that surround the entrances to the houses along the sandy seafront, still showing the stains of water.
In 2012, the French public agency for the management of surface and sub-surface resources and risks, the BRGM (or “French geological survey”, in English), carried out a study of the vulnerability to sea flooding of the coastline around Palavas-les-Flots. In their modelling projection of the effects on the town of rising sea levels, they notably took into account the events of 1982. They found that if greenhouse gas emissions continue at the current rate and, as a result, that global warming increases above a further 2°Celsius, the consequences for Palavas-les-Flots by 2100 will be considerable. These include saltwater pollution of coastal aquifers, land loss, the disappearance of the beaches (and the entire commercial activity dependent upon them), and a modification of the lagoons that lie behind the town.
“Palavas-les-Flots lies on a low-lying sandy base which has already encountered problems from coastal erosion, like a large part of the Languedoc region’s coast,” said Gonéri Le Cozannet, a BRGM engineer specialised in coastal erosion risks. “The vulnerability of these beaches to marine submersion is already high during storm conditions. Climate change will aggravate this.”
The rise in the sea level at Palavas-les-Flots currently averages three millimetres per year, a rate that is impossible to recognise with the naked eye. But it compares with an estimated average annual rise over the previous 6,000 years of one millimetre per year. This relative surge in sea levels accentuates the risk of erosion caused by heavy swells, notably during storms. The risk has become a major problem because of the recent artificial development of the natural coastline, and also the depletion of the amount of sediment that spills into the Mediterranean from the south-running Rhône river as a consequence of the construction of dams along its course.
“When one looks at the retreat of the Atlantic or Mediterranean coastlines, they suffer from the effects of erosion and storms,” said Éric Chaumillon, a researcher in coastal marine geology at the University of La Rochelle in south-west France. “The contribution made by the rise in the sea level is today very little with regard to the sedimentary dynamics. But in the long-term the effect is real. It is simply a question of timescale.”
The more global temperatures climb, the more the glaciers will melt into the oceans.Meanwhile, the more that beaches suffer from erosion, the lower they lie, and the more the sea rises the more the beaches erode. In Palavas-les-Flots, if the sea rises by 30 centimetres during a storm, the inland flooding will be significantly more extensive, while if the sea rises by a metre the whole of the town centre would be under water.
According to estimations produced by the Intergovernmental Panel on Climate Change, the scientific body that works under the auspices of the United Nations, sea levels will rise by 60 centimetres between now and the year 2100 if global warming increases during that period by an extra 2°C.
In Palavas-les-Flots and the neighbouring coastline, a scientific programme involving dozens of engineers, researchers and administrative officials with the local authorities of the Hérault département (county) is underway to monitor and counter the very real effects of coastal erosion: cameras have been set up to track the erosion of beaches, which is regularly measured, studies have been launched into the effects of storms, prospecting for new sand reserves is underway, along with modelling of the effects locally of climate change. While Palavas-les-Flots is not the most threatened site, it is strategically important because of its location within the surrounding lagoon- and lake-dotted Aigues-Mortes gulf which has a fragile eco-system.
But the scientific programme concerns the whole of the beaches lining the small towns in the same zone. “It is extremely important,” said Alexandre Richard, appointed by the Hérault local authorities to coordinate the coastal study. “The scale of the management of the natural environment dominates that of administrative management.”