Climate change has emerged as one of the most pressing global challenges, and its influence on the ocean ecosystem is particularly profound. Oceans cover more than 70 percent of the Earth’s surface and act as the largest carbon sink, absorbing about a quarter of global carbon dioxide emissions and over 90 percent of the excess heat produced by human activities. This role places oceans at the center of climate regulation, but also makes them highly vulnerable to the adverse impacts of global warming. Rising atmospheric carbon dioxide, increasing temperatures, melting ice sheets, and changing weather patterns are altering the chemistry, temperature, and circulation of the oceans, leading to cascading effects on marine life, food security, and human livelihoods. The impacts of climate change on the ocean ecosystem are complex and interlinked, influencing physical, chemical, and biological dimensions of marine systems. One of the most significant impacts of climate change on oceans is the phenomenon of ocean warming. Since the mid-20th century, global sea surface temperatures have increased, altering the distribution and behavior of marine organisms. Warm-water species are expanding their ranges towards the poles, while cold-water species are losing their habitats. For example, cod populations in the North Atlantic and certain plankton communities are declining due to unsuitable temperature conditions. Coral reefs, often called the “rainforests of the sea,” are highly sensitive to thermal stress. Rising sea temperatures cause corals to expel the symbiotic algae living in their tissues, leading to coral bleaching. When bleaching events become prolonged or severe, coral mortality occurs, disrupting biodiversity and depriving fish species of critical habitats. The loss of coral reefs also weakens natural coastal defenses, leaving shorelines more exposed to storm surges and erosion. Another major impact is ocean acidification, which results from the absorption of atmospheric carbon dioxide by seawater. When carbon dioxide dissolves in seawater, it forms carbonic acid, which lowers the pH of the ocean. Since the industrial revolution, ocean acidity has increased by approximately 30 percent. Acidification impairs the ability of marine organisms such as corals, mollusks, and certain plankton species to build their calcium carbonate shells and skeletons. This weakening of shell formation affects food webs because plankton and shellfish are primary sources of nutrition for larger species, including fish and whales. Declining shellfish populations threaten not only marine biodiversity but also coastal economies that depend on aquaculture and fisheries. Furthermore, coral reef degradation from acidification and warming creates a dual stress that accelerates the decline of one of the ocean’s most vital ecosystems. Sea-level rise is another consequence of climate change