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Five facts to help understand the interdependence between oceans and human activity


World Oceans Day on 8 June is an annual event that began in 1992 to raise public awareness on ways to better manage oceans and their resources. For this event, open_resource provides five facts to help understand the interdependence between oceans and human activity.


Pollution in oceans, particularly by plastic, is a huge challenge.
Estimates show that 269,000 tonnes of plastic waste now floats in our oceans.
This waste is 80% land based. Waves and the sun break the waste up into fine particles, causing a sort of “plastic soup” to form. This phenomenon can be seen in five large ocean basins – the North and South Pacific, North and South Atlantic and Indian oceans – within ocean gyres (huge whirlpools brought about by ocean currents and forces created by the Earth’s rotation).

This plastic pollution is a big threat to marine ecosystems. It has an impact on the entire food chain, linked not only to plastic being ingested by marine fauna, but also to toxic substances being given off as it decomposes. In the face of these findings, it is urgent that we act to stop plastic waste being dispersed in our oceans.


In 2030, 47% of the world’s population will be living in areas of high water stress. While today 40% of the population lives near the coast, desalination of sea water may be a way to produce new water resources to meet the needs of inhabitants, industry and agriculture.

Representing 2% of water consumed worldwide in 2015, desalinated sea water is already a viable solution for some countries, such as Spain, USA, Australia and countries of the Persian Gulf.


Preservation, protection and management of ocean resources are, of course, environmental issues, but they also have an economic impact.
A 2015 report by WWF, produced in association with the Global Change Institute at the University of Queensland and the Boston Consulting Group, estimated that “calculated in the same way as national GDP, the annual Gross Marine Product would rank oceans as the seventh world economy thanks to its annual production of goods and services valued at $2.5 trillion.” WWF went as far as estimating that total ocean assets were worth $24 trillion.

In the Mediterranean region, for example, coastal and maritime tourism represents over one third of the total maritime economy, employing 1.7 million people according to WWF.


a. Climate change and rising sea levels

The earth’s oceans constitute a resource that is significantly affected by global warming, particularly due to rising sea levels.
In 2015, the latest report by the IPCC predicted a worst-case scenario of a rise in sea levels of almost one metre by 2100. This compares with an increase of just 19 cm since the end of the 19th century.

This rise in sea levels is directly linked to an increase in water temperatures, which brings about a phenomenon of thermal expansion (water volume increasing as it warms), and to the melting of land ice and polar ice caps. The Met Office, the United Kingdom’s national weather service, recorded an increase of 0.72 degrees Celsius at the surface of oceans last September, the highest ever recorded.

b. The role of oceans in the fight against global warming

Paradoxically, oceans are themselves a barrier against global warming. Phytoplankton living at the ocean surface use the process of photosynthesis to grow, absorbing CO2 and releasing oxygen. Producing over 50% of the oxygen we breathe, oceans are both an essential source of oxygen and one of the main climate regulators – they absorb 30% of CO2 emissions caused by human activity.
Global warming has a direct impact on these functions – excessive absorption of carbon by oceans increases their acidity and threatens marine biodiversity, while rising sea water temperatures are one of the causes of lower oxygen content in oceans.