The ocean and its reliant ecosystems are major carbon sinks. They absorb CO2 from the atmosphere, representing about a quarter of human’s emissions each day. Some of this CO2 is incorporated by organisms and stored in the deep sediments. However, the ocean itself also physically absorbs much of the emissions we produce.
Once absorbed, CO2 reduces ocean’s pH, hence transforming it and changing the water’s acidity conditions. Acidification can only be solved by reducing carbon emissions. While the Paris Agreement has set the path, solutions must be developed to increase the resilience of human activities, ecosystems and communities impacted by ocean acidification.
The ocean has absorbed a third of the CO2 emitted since the Industrial Revolution, resulting in a 26% increase in its acidity, and it is expected to further increase by 150% by 2100.
In 2007 and 2008 a wide loss of oysters occurred in Northern America Pacific states, and as the Ocean Acidification described it, it was “some of the earliest and clearest impacts of increased acidification in West coast marine waters”.
The consequences of ocean acidification, already visible, might be tremendous in the years to come. Ecosystems with great cultural and economic values, such as coral reefs, might disappear as more acidic conditions make it harder for corals to form their calcareous structures. Moreover, rises in the temperature cause stress and result in coral bleaching – when corals expel the algae (zooxanthellae) with which they are in symbiosis, potentially causing their death. Other organisms that live within shells also suffer from ocean acidification: mussels, oysters, and many more. It is essential to understand and fully consider the intricate relationships within and between marine ecosystems. Threats to these organisms and corals will eventually impede on the functioning of the whole marine ecosystem. From small-scale fisheries to industrial productions, millions depend on the well-being of these ecosystems to support their livelihoods.
Ocean acidification requires global efforts and cooperation to be strengthened to provide a better understanding of the issue and its consequences. Since many impacts of ocean acidification remain partly unknown and difficult to monitor, a global response should be made in terms of research efforts and in finding innovative solutions and techniques to increase ecosystem resilience. The source of acidification, anthropogenic CO2 emissions, must be controlled. International negotiations and regional, national and local actions must grow momentum and persevere to reduce ocean acidification and combat climate change.