4.4 Oceans

Healthy oceans are key to sustaining life on the planet. The oceans are essential for world trade transport routes, and connect peoples and markets. The oceans provide much of the world’s food, moderate climates, sequester carbon and provide for many of nature’s most important habitats and biodiversity. Oceans recycle nutrients, give countless jobs and are crucial for tourism.

Atlantic ocean – Los Gigantes. Photo: Å. Bjørke

Life began in the oceans. Without living oceans, civilisation may not continue. Nevertheless, human greed and reckless profit-seeking activities have put the oceans under risk of irreversible damage.

Coral reefs are the most diverse and beautiful of all marine habitats. Large wave resistant structures have accumulated from the slow growth of corals. The development of these structures is aided by algae that are symbiotic with reef-building corals. Coralline algae, sponges, and other organisms, combined with a number of cementation processes also contribute to reef growth. Photo: Glenn Edney

Over-fishing and ocean acidification from carbon emissions threaten the marine eco systems.

More than 90 percent of the excess heat from greenhouse gas emissions has been absorbed into the oceans, where that energy can fuel larger and more intense hurricanes and contributes to sea level rise as warming seawater expands.

Massive coral reef bleaching due to warmer climates, billions of tonnes of dumped plastic, micro-particles invading food chains, severe chemical pollution and  unsustainable dumping of sewage and other nutrients imperil not just marine life, but put the health of millions of people in jeopardy.

Unsustainable coastal area development, impacts from resource extraction, enormous  loss of biodiversity and damage to habitats and eco-systems are among the factors damaging the oceans and sustainable use of marine and coastal resources.

We treat the oceans as limitless garbage bins, but expect beaches and water to be clean and sparkling. We expect the oceans to provide unlimited amounts of free seafood.

A main ecological rule is that there is no free lunch. Do we now see the bills beginning to dump down on our table?

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Acidification and oxygen production


Plastic pollution

emma maldivene
Maldives Photo: J. Wellen

Coral reefs



Oceans and ecosystems


Chapter 33. Impacts
Chapter 44. Ecosystems
4.1 Ecosystems and energy flow
4.2 Forests
4.3 Agricultural land
 4.4 Oceans
Chapter 55. Green economy