Oceans, lungs of the planet

Covering around 71% of the earth’s surface, oceans play a major role in how our planet functions. They regulate the climate, store CO2 and also represent an indispensable asset for mankind. Food, medicine, cosmetics, raw materials, renewable energy sources, jobs… they provide us with so many benefits. At the very heart of our existence and yet incessantly abused – pollution, overfishing, acidification, global warming – the oceans are a resource which needs to be preserved to ensure the future of humanity. Overview.


Oceans represent the largest reserve of water and heat on the planet. They are capable of absorbing, transporting and reproducing heat. How is this done? Thanks to a permanent exchange of water between the four large reservoirs formed by the seas and oceans, surface and ground water, the atmosphere and the biosphere. The sun, thanks to its thermal energy, constantly activates and maintains moving water masses. This is known as the water cycle. The phenomenon is simple: seawater evaporates thanks to the action of the sun, subsequently amalgamating to form clouds and finally falling in the form of rain and snow to join the rivers and streams and end up back in the sea.

Source CNRS

Another major asset: the oceans enable us to breathe by recycling CO2 and producing oxygen. More than 50% of oxygen comes from the sea. Often invisible to the naked eye, marine phytoplankton release more oxygen into the air than all the forests in the world! True fonts of carbon, containing almost 60 times more CO2 than that found in the atmosphere. The oceans therefore also contribute to limiting global warming, in the sense that no significant acidification is caused.


The sea is the biotype (or biological environment) containing the highest number of plant and animal species. In today’s world, the oceans feed almost 3.5 billion human beings, i.e. half of the population. However, whilst the stock of fish is important, equally so is that of molecules. This is an extraordinary reality when you consider that numerous substances of pharmacological interest have been identified this way. One example of this is squalamine. Found in sharks, this molecule is a powerful inhibitor of neoangiogenesis which contributes to the growth of cancerous tumours: a discovery which should very soon offer new alternatives in cancer treatment.

Finally, from an economic standpoint, our oceans offer real opportunities. Regions located near the coast are the source of 40% of the wealth generated within the European community thanks to combined income provided by fishing, tourism, transport, industry, renewable energy sources and trade. In France, there are more than 300,000 jobs (excluding coastal tourism) related to the sea, representing an overall turnover of more than €50 billion. This is without forgetting the sea beds which are incredible reserves for raw materials: the vast majority of the world’s reserves of ores and rare metals – copper, cobalt, zinc – can be found there.


The survival of the human race depends on our oceans and yet man is constantly harming them by damaging these fragile ecosystems. According to the Food and Agriculture Organization of the United Nations (FAO), 30% of the world’s fish reserves are overexploited. Overfishing, as well as pollution and acidification of the oceans, are threatening the planet’s equilibrium. Currently, two-thirds of all human beings live within 80 kilometres of the sea. This dense population produces waste, a portion of which finds its way into the sea. According to a study published on 30 June 2014 in the United States in the journal of the American academy of sciences, plastic waste floating in the oceans may represent between 7,000 and 35,000 tonnes, with a higher concentration in the North Pacific. Another study into a pollution phenomenon, conducted in May 2014 in the North Atlantic by the Expédition 7ème Continent (the 7th Continent Expedition), reached the same conclusion: micro-waste from the deterioration of macro-waste encourages the colonisation of micro-organisms and contaminates the food chain.

In 2015, the 7th Continent Expedition continues its work with the support of SUEZ. Two expeditions are planned for between 15 May and 15 June 2015 in the North Atlantic and the end of 2015 in the South Atlantic, bringing together expertise in science, teaching and media, structured around a common commitment to action.