Ocean

Living on the coast

More than 50% of the world’s population now lives less than 100 kilometres from the sea. By 2035, this figure could rise to 75%. This concentration along the coast is a sign of the very special relationship mankind has formed with the ocean. However, it also exerts immense pressure on the environment.

Upper East Side, Manhattan, New York, USA (40°46’ N - 73°57’ O). © Yann Arthus-Bertrand / Altitude

BEAUTIFUL COASTLINES

A growing number of people are moving to the coast. Although the socio-economic mechanisms are varied, the trend is general, but it is not recent. Coastal settlement has come down through the ages, as shown by the Mediterranean cities of Antiquity: Athens, Rome and Carthage; or those of the classical era: Venice, London, Constantinople/Istanbul and Seville, to name but a few. In America, Asia and Africa, colonisation has resulted in the development of large cities on the coasts: New York, Hong Kong and Cape Town, for example, are relatively recent cities. Today, Asia’s economic growth means that coastal cities are shooting up in China, Korea and Japan and overtaking global metropolises. In France, coastal communities house around 10% of the local population on only 4% of the land, with the density (281 pers./km²) two and a half times higher than the metropolitan average. In the United States, more than half the population lives in coastal regions, with a density three times greater than the national average (300 pers./km²), while coastal populations rose by 28% between 1980 and 2003, accounting for 33 million additional people. The vast deltas of the Nile, the Mekong and the Ganges are among the most densely populated areas in the world.

There are a number of reasons for this coastal concentration. History is one reason, though far from the only one. Now, as in the past, access to the ocean enables fishing and facilitates trade. In some areas, it encourages offshore exploitation, while in others it plays host to military installations. More and more frequently, it profits from an influx of tourists and boaters. All these activities provide jobs, income or simply subsistence for the local populations. However, that is not all. The coasts are attractive because of the way of life they offer their inhabitants, and while it is difficult to explain exactly why this is so, opinion polls show that coastal residents are happier and healthier than those living inland.

 RECLAIMING LAND FROM THE SEA

Beach resort near Arrecife, Canary Islands, Spain (Yann Arthus-Bertrand / Altitude)
Beach resort near Arrecife, Canary Islands, Spain © Yann Arthus-Bertrand / Altitude Paris

Demand is high, but space is in short supply. That is why some countries have reclaimed land from the sea. The idea is not a new one: the Netherlands created their polders by draining the water and establishing protective dykes. As a result, most of the country is now situated below sea level. In Western Europe, 15,000 square kilometres of polders have been reclaimed from the sea since the 17th century. Many countries are now using these techniques: Dubai, Singapore, Japan, etc.

Human population growth is accompanied by increasing land degradation. In some areas, particularly those popular with tourists, the coast has been marred by construction, e.g. on the Spanish Costa Blanca, which is the most urbanised section of the coastline in Spain, with almost 96% of it covered in concrete. Added to this are the problems of treating wastewater, often discharged directly into the sea, and the inevitable waste that comes with an influx of tourists.

The need for land for cultivation and building is particularly harmful to the important but fragile coastal ecosystems: the wetlands. The term refers to a group of ecosystems that are marshland to varying degrees and extremely important to biodiversity, i.e. mangroves, coastal marshes, dunes, lagoons, estuaries, etc. In metropolitan France, the wetlands play host to 25% of the biodiversity, but they are some of the most deteriorated ecosystems, with their surface area decreasing by 67% during the 20th century!

More and more pollution

Whether industrial or domestic, all land-based activities must take a share of the responsibility for marine pollution, starting with our consumption habits. Glass and plastic bottles, jam jars, shoes, discarded fishing nets, but also cigarette butts, cotton buds, lighters, etc.; there is an endless list of waste that washes up on the world’s beaches. According to the United Nations Environment Programme (UNEP), 80% of waste in the ocean originates inland, the rest being left on the beaches or thrown directly into the sea.

A yellow goby at the window of its shelter (a soda can), Honshu, Japan (Brian Skerry)
A yellow goby at the window of its shelter (a soda can), Honshu, Japan (Brian Skerry)

According to the United Nations, 60 to 90% of this “aquatic waste” is comprised of plastics. Each year, 6.5 billion kilos of plastic waste are discharged into the oceans, i.e. 206 kilos per second! Some of it is carried by the currents and forms concentrations like the Great Pacific Garbage Patch, also called the “plastic continent”, which lies between California and Hawaii over an area of 3.43 million square kilometres – one-third of Europe!

70% of the waste discharged into the oceans eventually sinks. It is then deposited on the seabed, where it forms a sort of carpet, which prevents exchanges between the seawater and the sediment, suffocating the environments in which much of the marine biodiversity is concentrated.

In many developing countries, 80 to 90% of wastewater goes directly into the ocean. Even in developed countries, the sewage treatment systems do not always prevent bacteria and chemical products from entering the marine environment. Toxic sludge, solvents, heavy metals, hydrocarbons, assorted types of acid and residues: every year, hundreds of tons of toxic industrial waste end up in the oceans after being discharged into the environment by some industries. Difficult to quantify by virtue of being generated beyond the confines of any inspections or legal framework, this waste can have a serious impact on the marine environment and human health. That is certainly the case with lead or even mercury, which are found with increasing frequency in fish intended for human consumption. Mercury can have a serious toxic effect on the nervous, digestive and immune systems and on the lungs, kidneys, skin and eyes. In Japan during the 1950s, in the small coastal village of Minamata, several thousand people died from a previously unknown illness. Only years later was it discovered that all the fish and shellfish from the bay, which constituted the main means of subsistence for the local population, had been contaminated by the discharge of methylmercury chloride from a nearby factory.

Coastlines that must be protected

It is therefore essential to protect the coastlines. In 1975, France created the Conservatoire national du littoral, the national coastal protection agency, a public institution responsible for acquiring land in order to protect it from the pressures of construction and urbanisation and to ensure that it remained in its natural wild state. Once acquired, the land becomes inalienable and is managed by the communes or by conservation agencies. Thanks to this arrangement, more than 12% of the French coastline is protected, i.e. 1,200 kilometres of coast covering an area of 150,000 hectares. The long-term objective is to have one-third of the coastline returned to a “wild” state by 2050.

Coastlines are also protected by international conventions, laws and government agencies. These include the 1971 Ramsar Convention concerning the protection of waterfowl, which evolved to include the protection of ecosystems specific to wetlands. More than 1,950 sites are featured on the Ramsar Convention List, including coastal areas where the depth of marine water at low tide does not exceed 6 metres, as well as peat bogs, marshes, mangroves and coral reefs. There are now more than 190 million hectares protected in this way.

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