The Acidification of the Mediterranean Sea: Secondary effects of the rise of CO2

OCEANA Acidification chemistry

Author: Helena Alvarez
Date: April 15, 2014



Oceans play a fundamental role in regulating Earth’s temperature and the natural greenhouse effect that maintains life as we know it. They are able to do so by acting as a “carbon sink” and absorbing carbon dioxide (CO2).  However, due to our rapidly growing greenhouse gas emissions, too much carbon gets into the oceans, lowering their pH and resulting in a phenomenon known as ‘ocean acidification’.

Acidification not only dissolves the carbonate structures (e.g. shells and skeletons) of species such as corals, sponges, crustaceans, but also prevents these creatures from creating new ones because of the chemical processes that occur with the rise of CO2 in the water. Some of these species form essential habitats that sustain the entire ecosystem by providing shelter, nurseries, and feeding grounds to many other important species (e.g. commercial species). Ocean acidification can also disrupt biological and psychological processes that affect species’ reproduction, respiration and behavior.

The Mediterranean, which is a semi-enclosed sea, is already suffering from signs of acidification and other stress factors, including rising temperatures, overfishing and pollution. It is a complex body of water that supports an estimated population of 400 million people and an additional 175 million visitors a year.

Scientific information is essential to determine the short and long term effects of acidification and how this phenomenon will affect important sectors like tourism and fisheries. This work has already started: the Mediterranean Sea Acidification in Changing Climate (MedSeA) is a project whose purpose is to understand how key biogeochemical and ecosystem processes will be affected by acidification increases. The project, which Oceana participates in through its advisory body (MRUG – Mediterranean Reference User Group), aims to:

  • Reduce other environmental stresses (e.g. pollution, overfishing, habitat destruction, etc.)
  • Create effective marine protected areas (MPAS) to increase resilience and help the ocean to cope with these global stressors
  • Use marine spatial planning to promote the conservation and sustainable management of coastal ecosystems as major carbon sinks (so called “Blue Carbon”)
  • Adopt stringent reductions in greenhouse gas emissions

Scientific information must therefore be coupled with adequate management at the national, regional and local levels. Mitigation measures, such as the establishment of a network of MPAs, strengthen the Mediterranean’s resilience, helping it to better assimilate and store the excess of carbon. However it is also crucial to focus on the source of the problem and limit carbon emissions by promoting low carbon fuels and shifting to alternative energy sources. This would be the most effective tool with which to solve the ocean acidification problem.

More info @:

Acid test: Can we save our oceans from C02? (Oceana, 2009)

MedSeA Project