Why are the ocean’s pH levels significant?

The ocean's pH levels are significant primarily because they directly affect marine life, particularly calcifying organisms like corals, mollusks, and some types of plankton. These organisms utilize calcium carbonate to build their shells and structures. When the pH of ocean water decreases—as is occurring due to increased carbon dioxide absorption—it leads to ocean acidification, which reduces the availability of carbonate ions necessary for calcification. This process can have devastating effects on marine ecosystems, impacting food webs, biodiversity, and the overall health of ocean habitats.

The correct answer highlights the crucial relationship between pH levels and the biological processes that sustain marine life, emphasizing the importance of maintaining stable pH levels in the ocean to support these sensitive organisms.