Oceans cover 71% of the earth’s surface and provide an estimated 2.5 trillion dollars of revenue per year, according to WWF. Impacted by global warming and human activities, they are under greater and greater threat. Yet solutions exist.

Oceans on the brink of depletion

Two thirds of the oxygen we breathe is produced by ocean phytoplankton. They also absorb about 30% of human-generated CO2, mitigating the terrestrial impact of global warming. But “how long will this ability to regulate the climate last?” asks CNRS researcher Françoise Gaill. According to her, this buffer effect comes at a high cost: it is not known to what extent the ocean can stock ever more CO2 because that causes acidification of the ecosystem, with great consequences on biodiversity.



Ocean temperature rise is indeed more worrisome because its consequences are serious. Notably, it contributes to a drop in oxygen content. Today there are four times more ocean dead zones (deprived of oxygen, or hypoxic) than there were 50 years ago. The number of low-oxygen coastal marine areas has increased tenfold since 1950. Life is getting scarcer and bacteria are multiplying, feeding on human-caused pollution (wastewater and agricultural runoff). Marine creatures are thus leaving these areas to avoid asphyxiation, exposing them to predators in other marine areas and to fishing. Moreover, fishing itself has quadrupled since 1950 and resources are being depleted: world capture fisheries production is estimated to 82 million tonnes from marine waters, more than 50% of oceans are exploited by large industrial trawlers, and fish consumption in developed countries is increasing and their imports are growing. At the other end of the chain, millions of people depend on fish for protein, with no possible alternative, according to WWF.

As for water pollution, take the example of plastics, which recently received front-page coverage in the media and only worsens the state of ecosystems: in 2014, 269,000 tons of plastic were floating in the world’s waters. This variably-sized waste is drawn to the heart of ocean gyres by converging currents and forms veritable continents of plastic. Macroplastics are genuine traps for sea animals – 90% of sea birds are said to have already ingested some plastic, whereas microplastics are ingested by marine organisms and contaminate the entire food chain, right up to our dinner plates.


Saving the oceans: an international goal

The oceans and their resources are by nature shared, as are the risks and consequences of their degradation. Therefore solutions must be jointly determined. So important is this global stake that one of the Sustainable Development Goals was dedicated to it in September 2015. SDG 14 seeks to “conserve and sustainably use the oceans, seas and marine resources for sustainable development.

Marine Protected Areas (MPAs), created by the Convention on Biological Diversity (CBD) in 1992 at the Rio Summit, are havens of biodiversity where fishing and exploitation are managed or forbidden with the aim of preserving and restoring marine ecosystems. An international study on their impact has just been completed: it has been found that MPAs can effectively contribute to mitigating the ongoing upheavals.

In these protected areas, life has returned to normal and the entire ecosystem benefits, from phytoplankton to people near MPAs whose living depends on fishing. For several conservation NGOs and according to scientific studies on their impacts, MPAs should be considered a societal investment which benefits economic actors.



Today there are more than 15,000 MPAs in the world, covering more than 7% of the ocean’s surface. CBD’s goal is to protect 10% of the ocean’s surface by 2020. Isabelle Autissier, a WWF activist and former yachtswoman, reiterates that the NGO is striving for a goal of 30% MPA ocean coverage by 2050 and estimates that 850 billion euros would be saved annually.

According to Dan Laffoley, Vice Chair of the World Commission on Protected Areas in the International Union for Conservation of Nature, shifts in the ocean are occurring “1.5 to five times as fast as anything we are seeing on the ground. This highlights the urgent need to act, but the ratio has a silver lining: the effects of rectification will be seen quickly.


Discover each month on ID4D the “Development News”, with a brief overview of a topical issue, and the “Press review”, with a selection of web articles, reflections and analyses.

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