Chemical reactions can occur when seawater absorbs carbon dioxide (CO2). It can reduce seawater pH level, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals.

These chemical reactions are called "ocean acidification" or also known as OA. For many marine organisms, calcium carbonate minerals are the building blocks for their skeletons. The seawater is supersaturated with calcium carbonate in areas where most marine life congregates.

However, ocean acidification causes many parts of the ocean to become unsaturated which would likely affect the stability of some calcifying organisms such as mussels and "sea butterflies" to produce and maintain their shells and could have severe implications for the food chain.

Such phenomenon is happening to the Arctic Ocean right now, and climate models predict that it will take up more carbon dioxide over the 21st century. The Arctic Ocean is where ocean acidification is greatly expected to happen, according to a report from

Arctic Ocean will take up 20% more CO2 over the 21st century

A recent study by Jens Terhaar from Bern and Lester Kwiatkowski and Laurent Bopp from the école normale supérieure in Paris, published in the scientific journal Nature, shows that ocean acidification in the Arctic Ocean is likely to be even worse than previously thought.

Under the assumption that the atmospheric carbon dioxide concentrations continue to increase, the results of their study showed that the smallest of the seven seas would most likely take up 20% more carbon dioxide over the 21st century.

Jens Terhaar, research author and a member at the Oeschger-Center for Climate Change Research at the University of Bern, explained that the increase in carbon dioxide absorption could enhance ocean acidification, particularly between 200 and 1000 meters deep- an important refuge for many marine animals.

In sufficiently acidic waters, shells of organisms that build calcium carbonate skeletons and shells become unstable and begin to dissolve, a sign of the negative impact of ocean acidification.

"Our results suggest that it will be more difficult for Arctic organisms to adapt to ocean acidification than previously expected," co-author Lester Kwiatkowski said. More so, the loss of these organisms can severely impact the entire Arctic food chain up to fish and marine mammals.

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Climate models used in predicting Arctic Ocean acidification

Using the current climate models, the international research team were able to exploit the large divergence in simulated Arctic Ocean carbon uptake.

They found a physical relationship across the models of the simulation of the present-day Arctic sea surface densities and associated deep-water formation, which causes the enhanced transport of carbon dioxide into the deeper part of the ocean, therefore, increasing its acidification level.

The team was able to right the incorrect previously held beliefs in the climate models using the measurements of Arctic sea surface density. They were able to use it to reduce the uncertainty associated with the projections of future Arctic Ocean acidification.

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