Global warming has a significant impact on marine ecosystems, which are one of the most vulnerable parts of the earth. One of the most direct effects of global warming is rising sea surface temperatures. Rising temperatures cause bleaching of corals. Degraded corals not only reduce biodiversity but also threaten the lives of other species that depend on them. Temperature changes also affect fish migration patterns. Many fish species that are sensitive to temperature changes will shift to colder waters, which could disrupt local ecosystems and alter marine food webs. This diversion could lead to more intensive hunting in new areas, resulting in conflict between local fishermen and the large fishing industry. Sea level rise, resulting from melting polar ice caps and warming waters, is also impacting coastal ecosystems. Mangrove forests and coral reefs, which serve as natural protection from storms and erosion, could suffer serious damage. These ecosystems are spawning grounds for many fish species, and their loss will reduce the sustainability of fish stocks. Increased ocean acidity due to the absorption of carbon dioxide is also a major concern. More acidic seawater can disrupt the ability of marine organisms, such as shellfish and plankton, to form strong shells. The decline in the population of these organisms has a chain impact on the entire ecosystem, including species that depend on plankton as their main food. Increased sedimentation and pollution due to human activities are also exacerbated by global warming. This phenomenon results in eutrophication, where excess nutrients cause harmful algal blooms. These blooms, apart from reducing oxygen in the waters, also threaten fish and marine mammal species. Climate change also has the potential to increase the frequency and intensity of storms, which could result in major losses for marine ecosystems. Casualties include not only physical damage but also long-term impacts on the population and distribution of marine organisms. With the various impacts of global warming, it is important for us to maintain and protect marine ecosystems. Policy changes, sustainable practices, and public education are the keys to protecting marine resources, so that these ecosystems can survive future challenges. Stronger global research and collaboration is also needed to understand and effectively address the impacts of global warming on marine ecosystems.