Ocean acidification, driven by increased carbon dioxide absorption, is rapidly lowering the ocean’s pH, posing a significant threat to marine life and global food security. Calcifying organisms—such as corals, mollusks, and certain plankton—struggle to build and maintain shells or skeletons in more acidic conditions, leading to weakened reefs and disrupted food webs. Even non-calcifying species, including fish and squid, suffer from impaired respiration, altered behavior, and reduced reproductive success. These effects are compounded by other stressors like warming waters and pollution. Particularly vulnerable regions, such as polar waters and upwelling zones, face accelerated acidification. Ultimately, addressing ocean acidification requires cutting CO₂ emissions, protecting natural carbon sinks, and increasing public awareness.