Carbon emissions contribute to ocean acidification by increasing the concentration of carbon dioxide dissolved in seawater, which leads to the formation of carbonic acid.

When carbon dioxide ($\text{CO}_2$) is released into the atmosphere, a considerable portion is absorbed by the world’s oceans. This phenomenon is part of the natural carbon cycle, wherein the oceans function as a significant carbon sink, absorbing approximately one-third of the $\text{CO}_2$ emissions generated by human activities. However, the rising levels of atmospheric $\text{CO}_2$—primarily due to human actions such as the combustion of fossil fuels and deforestation—have resulted in a greater amount of $\text{CO}_2$ being taken up by the oceans.

Once dissolved in the ocean, $\text{CO}_2$ reacts with seawater to form carbonic acid ($\text{H}_2\text{CO}_3$), which is a weak acid. This reaction is reversible, and carbonic acid can dissociate into bicarbonate ions ($\text{HCO}_3^-$) and hydrogen ions ($\text{H}^+$). The increase in hydrogen ions causes a decrease in the ocean’s pH, leading to a more acidic environment. This phenomenon is termed ocean acidification.

Ocean acidification poses significant threats to marine life, particularly for organisms that construct shells or skeletons from calcium carbonate, such as corals and shellfish. The heightened acidity can erode the calcium carbonate structures of these organisms, jeopardizing their survival. Furthermore, the increased concentration of $\text{H}^+$ ions can diminish the availability of carbonate ions ($\text{CO}_3^{2-}$), which are essential for shell formation.

Beyond its direct effects on marine organisms, ocean acidification can disrupt the balance of marine ecosystems. Changes in the abundance or distribution of specific species can trigger cascading effects throughout the food web, potentially impacting commercial fisheries and various aspects of human society.

In summary, carbon emissions from human activities are substantially increasing the acidity of the oceans. This process, known as ocean acidification, has profound implications for marine life and ecosystems. Therefore, it is imperative to reduce carbon emissions to mitigate the adverse effects of ocean acidification.