When we visit a web page or call someone with a smartphone, we use a network of submarine cables which are distributed all around the world. Although today 99% of telecommunications pass through these cables, allowing us to exchange data in a split second, the ever-growing amount of plastic that pollutes our oceans could disturb these communications and confront us to a thwarted daily use of the Internet. This would simultaneously question, in an unpredictable manner, the economic, social and geopolitical balances that have been established by the expansion of the network of networks over 30 years.
If we are not aware of the dangers of plastic pollution in the oceans, which would now involve the stakeholders of submarine cables and of the Internet, we are putting at risk the development of the network of networks and the way it shall be used by the young rising generation, our children, and future generations.
This is still little known but the incredible expansion of the Internet and mobile telephony would not have been possible without dropping off submarine cables over hundreds of thousands of kilometers at the bottom of the oceans. We chose cable data transmission rather than satellite transmission since the first one is faster and a lot cheaper than the latter.
Submarine cables are not new. The very first marine cable was pulled in the Channel between Calais (France) and Dover (England) in 1851 (1). At that time, it was used for telegraph communications. Five years later, in 1856, the first transatlantic telegraph cable was installed (2). It connected Ireland to Canada. It would then take only a few hours for a message to go from Europe to the North American continent while, before that, about ten days were necessary to cross the ocean by boat (3).
Even though telephone communications spread very fast with the invention of the telephone in 1876, the first telephone cable to cross the Atlantic Ocean was installed only in 1956. Indeed, unlike telegraph signals, telephone signals lose some of their intensity over the distance, and only later technological innovations improving signal amplification and cable sealing and insulation allowed us to solve this problem. In the meantime, we would favor radio transmission for long distance telephone communications.
Map of the telegraph cables in 1922 (A)
In 1988, a new page was turned: the first optical fiber cable was installed between France, England and the United States (1). Optical fiber, which offers a high capacity of data transmission, was about to replace gradually and then supplant completely former technologies such as copper and coaxial cables.
The number of active cables often changes due to the installation of new cables and the removal of old connections which have become economically obsolete (4). Globally, the number of cables increases every year. In 2014, there were 263 submarine cables (5) whereas in early 2018, there were approximately 448 cables around the globe for a total distance of 1.2 million kilometers (745,645 miles) (6). The shortest, called CeltixConnect-1, is 131-kilometer long (81 miles). It connects Ireland to the United Kingdom (7). The longest is called SEA-WE-ME-3 and covers a distance of 39,000 km (24,234 miles) (8). It interconnects South-East Asia, the Middle East and Western Europe. Here is an updated map that indexes all cables: www.submarinecablemap.com
Our unrestrained consumption of digital data on tablets, smartphones, personal computers, televisions, and now through connected devices, as well as the ever-growing number of Internet users around the world, suggests that the number of cables might never stop increasing. American company Cisco Systems, specialized in information technology and network, predicted in a 2018 report that the global Internet traffic should double between 2019 and 2022 (9). With this growing need for web communication, there is no other solution than to install more cables.
Almost every coastal country is connected to one or several cables. It might be risky, indeed, to use only one connection because cables can be exposed to accidental damage. They can be torn off by trawling nets or cut by a dropped anchor. Natural phenomena can also damage the cables: earthquakes, landslides, storms, erosion, abrasion and corrosion (10). When a cable has been so damaged that the data flow is interrupted, the connection can be restored by rerouting data through other available cables. Countries which can afford it divide their need on several cables in case one of them stops working.
View of a submarine cable from a cable ship (C)
Cross-section of a submarine cable. Optical fiber cables can be seen in the center (D)
Besides, telecommunication operators want to supply their users with a greater, faster and more reliable connectivity. Nowadays, as the digital world has become essential to the economies, submarine cables are considered by nations as well as private companies as a strategic investment of the highest importance. Installing submarine cables requires huge investments, rising up sometimes to hundreds of millions of euros for one connection. This is the reason why, for a long time, this installation was initiated by consortia gathering several stakeholders who then shared the cable’s capacity. However, for a few years now, giants of the Net like Facebook, Google, Amazon, or Microsoft do not hesitate to acquire their own cables, which they finance entirely (11).
While we were planning a marvelous and promising future for our telecommunications and data exchanges through submarine cables, we shaped in the meantime another story. A story which was also full of promises until recently, but then took a far less shiny turn: this is the story of plastic.
The story of plastic began a long time ago. It is generally said to date back to Antiquity. The first plastics to be produced by humans came from a natural source: tropical tree latex (12). This latex was used to make balls and figurines 1,600 years ago in South America. Later, other natural plastics were made from horn and tortoise shell (13). Then the very first synthetic plastics appeared: celluloid and bakelite. Invented in 1855, celluloid was initially supposed to replace ivory which started to become scarce in the field of arts and manufactures (for billiard balls and dice, for example) (14). Bakelite was invented in 1909 and was praised for its insulating and thermoresistive properties. It was used to make radio and phone cases, as an electrical insulator, as well as utensils, jewels and toys. Bakelite was the first plastic to be produced on a large scale: 175,000 tons of bakelite were produced in 1944 (15). Throughout the first half of the 20th century, new molecules were created to make the polymers we know and use widely today. We can mention for example polystyrene, polyethylene, polyvinyl chloride, and polycarbonate.
During the 1950s, mass consumption and diversification generated a boom in demands and reinforced the growth of the modern industry. Plastics were mainly produced by the petrochemical industry, from oil or natural gas. Uses of plastic were varied as it was introduced “in small objects of our everyday life” (16).
Since 1950, global plastic production and consumption increases every year consistently. From 1.5 million tons in 1950, the amount of plastic produced in all countries together has reached 348 million tons in 2017 (17). The European Union dedicates a major part of its production to packaging needs, which represent about 40% of all plastics produced inside European borders. This part is even higher in a country like France where it represents almost 46% (18).
Yet – it is assessed all over the globe – our plastics, once they have reached the end of their life, do not always find their way to the 2 traditional types of reuse that are incineration (to produce energy) and recycling.
A huge amount of plastics (sometimes insensitively abandoned by their user or stored in open-air landfill sites), once exposed to natural elements such as wind, rain and rivers, invades our oceans – if these plastics are not directly thrown into the sea.
Even though it has been known for decades, it took us a very long time to truly be aware of the phenomenon. In 1997, an event contributed to open our eyes a little wider. On his way back from a Los Angeles-Hawaii sailing race, passing through a rarely followed path, American sailor Charles Moore unexpectedly found what would be known as the greatest concentration of floating waste on the surface of the ocean – which mainly consists in plastic: the Great Pacific garbage patch, also known as the Pacific trash vortex. Almost as wide as six times France, it is also called in French the “7th continent” (19). Within this garbage patch, plastic represent 80% of the accumulated waste.
Great Pacific garbage patch (E)
From 2007 to 2013, no less than 24 expeditions were launched by various countries in order to identify other potential garbage patches on the surface of the oceans. They made a discovery that is both impressive and alarming: all oceanic basins contain a garbage vortex (the North and South Pacific Ocean, the North and South Atlantic Ocean, and the Indian Ocean) (20).
Because it floats, waste – especially plastic waste – is carried away by sea currents and drifts for years, slowly decomposed by the sun and waves. Sooner or later, it gets trapped in sea areas where circular currents, called “ocean gyres”, converge. These gyres form naturally when warm sea currents (getting away from the equator and heading towards the poles) and cold sea currents (going the other way round) meet. These currents, under the influence of the Earth’s rotation, curl clockwise in the Northern hemisphere and counterclockwise in the Southern hemisphere. “Sucked up” by the centripetal force, the plastic particles gather at the center of these giant vortices and accumulate down to 30 meters deep (21).
The 5 gyres or garbage vortices (F)
Today, between 8 and 12 million tons of plastic pour into the oceans every year (22). 8 million represent a garbage truck full of plastic discharged every minute in the planet’s waters (23).
A view of the North Pacific garbage patch (G)
Researchers have noticed that, in those vortices, garbage does not accumulate permanently. Garbage patches seems to be areas of transfer, transformation and redistribution of floating plastics (24).
Today, pollution invades every corner of the Earth. Traces of plastic were found in Arctic ice (25) and at the bottom of the ocean, including at the deepest point in the Earth’s crust: the Mariana Trench (26).
Plastic waste in the Mariana Trench (H)
So, on the one hand, there is this race to high-speed data leading to a multiplication of submarine cables, and on the other hand, an uncontrolled discharge of an ever-growing amount of plastic waste which pollutes both the surface and the bottom of the oceans all over the world.
We could tell ourselves that the oceans take up such a gigantic area on the Earth that there will always be a way to install cables where plastic pollution has not taken over all the space. We could also tell ourselves that this pollution does not pack so much as to form an insurmountable obstacle on the surface and a heap dense enough to worry the cable layers (the ships in charge of the installation of submarine cables and their removal in order to fix them). If these statements are true today, they might not be so tomorrow.
The cable ship “René Descartes” of the Orange telecommunication company (I)
What do we know about the oceans? Many things, certainly. Our knowledge increases every year, but it might still be poor compared to the complexity of the ocean ecosystems about which we still have a lot of unexpected discoveries to make (27). Moreover, these ecosystems might be affected by exogenous phenomena such as plastic pollution striking on every corner of the planet and in the depth of our oceans.
Let’s take the following points into consideration:
First: Garbage patches will grow significantly over the 10 years to come.
Global plastic production increases exponentially, currently doubling every 11 years. In concrete terms, between 2015 and 2026, we should produce the same amount of plastic as the one we have produced since the beginning of plastic production in 1950 (28). The volume of plastic waste that reaches the ocean is expected to follow the same tendency.
Indeed, the amount of plastic that is discharged in the oceans has been multiplied by a hundred since the 1970s, and it could be multiplied by ten in fifteen years according to biologist Jenna Jambeck from the University of Georgia, United States, going from 8 million tons per year since 2010 to 80 million tons in 2025 (29). The Great Pacific garbage patch alone would then be as wide as Europe.
Today, garbage patches are located away from fishing areas, commercial routes and recreational boating zones, but when their size increases, they might impinge on these seaways including those followed by cable ships. This could prevent them from installing and removing submarine cables. This is especially true given that garbage patches are not static. Indeed, the Great Pacific garbage patch moves about, and predicting its exact location is difficult (30).
What do we know about the behavior of a garbage patch that formed in the ocean and that would grow from a surface as wide as 6 times France to a size as large as Europe? What do we know about its impact on the ocean ecosystems, the currents and the seabed? What do we know about the repercussion of several garbage patches located in each ocean of a same planet, which would multiply their surface area in this way? Nothing. However, they will obviously have an even greater impact than the one they have today.
Secondly: A huge amount of plastic, even more impressive than the volume observed in the garbage patches, could be moving about in deep waters as well as in marine sediments.
We do not know exactly what happens to 99% of the plastic that ends up in the oceans (31). All plastic pollution on the surface of the oceans, including giant vortices, has been estimated to 269,000 tons in 2014 (24) (30). Yet, it is known that every year the oceans collect between 8 and 18 million tons of plastic. This means that millions and millions of tons remain invisible.
What we know without a doubt, however, is that sea animals ingest plastic because they mistake it for food. Every year, 100,000 tortoises and sea mammals (seals, dolphins, whales, sperm whales) and 1 million birds die from plastic ingestion (32). It has also been proven that fish and zooplankton (the first link in the food chain) swallow plastic (33). Does it mean that the invisible 99% of plastic are invisible because they have been ingested by the marine fauna?
Between the moment plastic waste is abandoned in the land or on the coast and the moment it dives into the ocean, it experiences a decomposition process. Due to sun exposure, rain, and rivers, this decomposition is more or less advanced depending on the distance traveled, and keeps going in the ocean when plastic is tossed around by the waves. It has been noted that many plastics present in the garbage patches are microplastics, which means that their size is inferior to 5 mm.
These microplastics are fragments of bigger plastic objects at an advanced stage of decomposition. And this decomposition process does not stop here. It goes on until plastic reaches the nanometer scale. After microplastics, come nanoplastics which are invisible to the naked eye.
In addition to being ingested by sea animals, plastic tends to sink in the ocean depths and does not stay on the surface.
Researchers have noticed that microplastics were abundantly present in the Mariana Trench. Located in the North-Western part of the Pacific Ocean, the Mariana Trench is the deepest ocean trench currently known and the deepest point in the Earth’s crust (-11,500 meters, or -37,730 feet) (34). The plastic concentration in the trench’s waters, especially at its deepest – the hadal zone (from – 6,000 m to more than – 11,000 m, from – 19,690 feet to – 36,090 feet) –, is several times higher than the plastic concentration on the surface of the ocean. The same account is true for the microplastic concentration in the hadal sediments of the trench. It is much higher than the microplastic concentration in marine sediments: it is twice as high as the one noted in the deep water sediments of the Atlantic Ocean and the Mediterranean Sea, and twenty times higher than in the deep water sediments of the South-Western Indian Ocean and the South Atlantic Ocean. Scientists think that a part of the “missing” microplastics in the ocean could have been deposited in the deep sea and that the hadal zone of the Mariana Trench is probably one of the greatest well of microplastic debris on Earth.
Yet, again, what do we know about the consequences of such a concentration of microplastics in deep waters and especially in sediments at the bottom of the ocean? We are still learning about the seabed and the Mariana Trench, and our current knowledge does not allow us to anticipate what could happen. Will the submarine cables, through which our communications pass and which are installed at the bottom of the ocean or buried down to 3 meters into the sedimentary stratum, be affected by plastic pollution on the seabed? It has been noted that frozen microplastics in the Arctic lowered the ice melting point, causing sea ice to disappear faster (35). Should we expect that plastic mixed with sea sediments might lead to more landslides at the bottom of the ocean and to an anarchical movement, or even to the rupture, of submarine cables?
Although their impact on submarine cables might seem less relevant, the 2 following points resulting from plastic pollution are worthy of attention:
Invasive species move and scatter around the world by traveling along with plastic on the surface of the ocean.
It has been noted that plastics can serve as rafts for micro-organisms and species: plastic allows them to travel very long distances out of the areas where they are usually confined. These displacements are likely to disrupt the ecological balance of the regions that are being colonized. A single 4-meter wide piece of plastic that came from Japan after the 2011 tsunami and washed up on the coast of Canada, brought 54 new species to the North-American ecosystems (36) (37).
Chemical pollutants attached to plastics on the ocean also move about.
As we have seen before, plastic, when exposed to a natural environment, fragments into microplastic and nanoplastic. Besides, it carries around pathogenic and invasive species. But there is more: plastic is able to absorb some chemical products such as PCB, DDT and phenols, which are then ingested by living organisms (tortoises and birds like fulmars and albatrosses, for example) and can contaminate the latter (22).
We can hope to see a virtuous scenario start as soon as possible through a preventive and informed understanding of the contradictions and threats that hang over the submarine cable industry (which is exposed to an invasive plastic pollution in the oceans), and through the deliberate willpower of this industry’s stakeholders to be involved in the future of plastic in our societies as much as the future of the Earth and the next generations. We could then witness a resorption of the amounts of plastic discharged in the oceans until they dry up entirely and permanently.
To this end, here are some approaches that the stakeholders of the submarine cable industry and the Internet can start doing immediately. I am willing to take action in collaboration with them:
1 – To help creating a precise global cartography of the sea areas polluted by plastic and of the plastic waste density in each of them.
Most of our knowledge about the amounts of plastic in the oceans and seas has been found through scientific expeditions – 24 in total – initiated between 2007 and 2013 and coordinated by the 5 Gyres Institute (38).
Estimating the volume of plastic in our oceans is a work which the stakeholders of the submarine cable industry can now contribute to. Their boats, called cable ships, often sail back and forth on the waters of the globe, giving them the opportunity to take notes and make observations that should be useful to those already involved in a better understanding of plastic pollution in the oceans, how far it extends and how it moves. These missions, of course, shall not get in the way of their primary goal of cable installation and removal, but shall rather be conducted in circumstances that could be defined in collaboration with researchers studying plastic pollution in the oceans, and that could allow the latter to know the phenomenon better. This action lead is also aimed at the stakeholders of the Internet who, since they are used to invest their skills in the development of innovative digital contents and services, could put some effort in the creation of numerical tools dedicated to a better handling of the ocean plastic phenomenon. Why not through artificial intelligence (AI), for example?
2 – To start eco-designing submarine cables.
Submarine cables are made of different materials, among which are plastics (polyethylene and polycarbonate). In order to eco-design the next submarine cables – we can mention here the Dunant project co-directed by Orange and Google (39) –, we should use recycled polyethylene and polycarbonate.
Cross-section of an optical fiber telecommunication submarine cable. 1. Polyethylene. 2. Mylar tape. 3. Stranded steel wires. 4. Aluminum water barrier. 5. Polycarbonate. 6. Aluminum or copper tube. 7. Petroleum jelly. 8. Optical fibers. (K)
The Orange Company, which is one of the main cable layers in the world, already began an environmental approach when it comes to removing submarine cables from the oceans, in order to reuse, destroy or recycle them (40). Their eco-design is yet to be launched.
3 – To have a daily well thought-out consumption of plastic and make it as exemplary as possible.
4 – To raise awareness among the users of submarine cables, meaning all Internet users, about the stakes of plastic pollution and about adopting a reasonable consumption of plastic.
2 – fr.wikipedia.org/wiki/TAT-1 (FR)
11 – news.microsoft.com/features/microsoft-facebook-telxius-complete-highest-capacity-subsea-cable-cross-atlantic/ www.numerama.com/tech/395610-google-va-tendre-son-propre-cable-transatlantique-entre-la-france-et-les-etats-unis.html
14 – fr.wikipedia.org/wiki/Parkesine (FR)
15 – fr.wikipedia.org/wiki/Bak%C3%A9lite (FR)
A – cartonumerique.blogspot.com/2018/04/les-cables-sous-marins-enjeu-majeur-de.html
B – www.submarinecablemap.com/
C – All rights reserved picture found on tinyurl.com/y4fhcj4q
D – Picture found through a Google search – Unknown original source / search in progress
E – Wikipedia image /NOAA : tinyurl.com/y4symz7h
F – Picture found on tinyurl.com/y2bbyjx5 – Unknown source / search in progress
G – Picture by Caroline Power found on tinyurl.com/y4aowszd
H – Picture found on www.sciencealert.com/plastic-bag-found-deepest-point-ocean-we-should-all-be-ashamed-mariana-trench-pollution
I – fr.wikipedia.org/wiki/Ren%C3%A9_Descartes_(c%C3%A2blier)#/media/File:France_Telecom_Marine_Rene_Descartes_p1150247.jpg
J – Picture found on www.leyton.com/blog-fr/?p=187-microplastiques-dans-lenvironnement-le-nouveau-defi-de-la-communaute-scientifique – Author research in progress
K – fr.wikipedia.org/wiki/C%C3%A2ble_sous-marin#/media/File:Submarine_cable_cross-section_3D_plain.svg