CO2 and the oceans

The importance of the oceans as a carbon reservoir is not to be underestimated. The CO² present in the atmosphere is partly transformed into O² (oxygen) and this is done mainly by two extremely important ecological systems: by forests (mainly tropical rainforest) and by the oceans. The phytoplankton present in the ocean takes care of more than half the CO² absorption and O² production!

The Greenhouse Effect

The greenhouse effect is originally a natural phenomenon. Greenhouse gases form a sort of blanket in the atmosphere, which reflects part of the earth’s warmth right back. On average this makes earth ± 30°C warmer (+ 15°C) than without the greenhouse effect (- 18°C). Greenhouse gases end up in the atmosphere through natural processes like breathing of animals and plants, decay of dead material, forest fires, volcano eruptions, etc… The problem is that mankind, since the beginning of the industrial (r)evolution, started emitting a huge amount of extra greenhouse gases (mostly CO₂ or carbon dioxide), mainly by burning fossil fuels. By now the temperature on earth rose by ± 0,6°C. This rise in temperature, together with the concentration of greenhouse gases, has an exponential course. To keep the consequences of climate change in check, the rise in temperature must not exceed the 2°C limit compared to the pre-industrial level.


If too much CO² ends up in the atmosphere – as is the case right now – this has two major consequences on the oceans. On the one hand the oceans become warmer, thus following the general trend of warming caused by the greenhouse effect. On the other hand the oceans become more acid. The excess CO₂ from the air binds with the ocean water (H₂O) forming an acid (H₂CO₃ or carbonic acid).

The warming and acidification of the oceans has consequences for fauna and flora in and around the oceans as well as for humans. Here are some examples:

  • The warming of the seawater forces many fish species an marine mammals to migrate to colder waters to look for food. Other animals depending on the ocean like the penguin and the weddell seal, find less and less food because the food chain gets disturbed (less plankton → less molluscs → less fish).
  • The melting of the pack ice makes polar bears swim further and further away to find food and the young of seals and walruses take to water too early.
  • The warming of the water and the melting of the icepack cause sea levels to rise. This causes certain species to lose their habitat (ex. the Bengal tiger) or they can find no more breeding areas (ex. the sea turtle).
  • The rising sea level also has disastrous consequences for people living on lower islands and coastal areas.
  • Through the acidification of sea water the calcium skeletons of molluscs are affected. Which endangers the food on offer for many fish, sea mammals and sea birds.
  • The acidification of sea water also affects the skeletons of corals. On top of that corals are very sensitive to rises in temperature of the sea water. This causes a very rapid decline in corals worldwide which in it’s turn has devastating consequences for the fish depending on them and the people who catch the fish.
  • Another consequence of global warming is an increase in heavy storms and cyclones which will plague coastal- and island inhabitants more and more often.


It goes without saying political leaders of every country have an important task at hand and should reach powerful and firm international agreements in order to reduce CO²-emissions. Nevertheless each and every one of us can do his part, because many little ones make a big one. We can work on limiting our own CO₂-emissions, or protect natural ecosystems which absorb CO₂, namely forests and oceans.

To limit our own CO₂-emission we can:

  • whenever possible choose to walk, use the bike or public transport for our transportation ;
  • travel by train rather than by airplane ;
  • eat less meat. Emissions of greenhouse gases are extremely high in intensive stock-breading ;
  • look for organic, local and seasonal produce when shopping ;
  • be sparing with energy and use green energy ;
  • develop an sensible and sustainable consumption pattern.

By protecting natural eco-systems that absorb CO² we think of, for example :

  • only buy wood with a sustainability label (ex. FSC);
  • eat less meat. These days enormous surfaces of tropical rainforests are cut to make room for soy plantations to be made into fodder;
  • eat less fish. Their excrements are very rich in calcium which has a neutralizing effect on the acidification of the seawater;
  • become a member of nature conservation organizations that take actions to protect the (tropical) rainforests and the oceans.


  • In de weer voor het klimaat. Educatief dossier voor leerkrachten. WWF ism. de Federale Overheidsdienst voor Volksgezondheid, Veiligheid van de voedselketen en Leefmilieu, 2008.
  • DVD: SOS Klimaat. Voor ons is het de hoogste tijd. WWF.
  • Dit is mijn planeet. Gids voor kinderen over het opwarmen van de aarde. Jan Thornhill, Biblion Uitgeverij, 2009.
  • Winkel, Dos (red). 2010. De Huilende Zee. Elmar Uitgeverij.

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