Global warming, caused by increasing concentrations of greenhouse gases, has a significant impact on marine ecosystems. One of the most striking changes is rising sea water temperatures. As sea surface temperatures rise, many species of fish and other marine organisms, such as coral and plankton, begin to experience stress and put their health at risk. Higher temperatures also contribute to coral bleaching, a phenomenon in which coral loses the symbiotic algae that give it color and nutrients. Changes in temperature also affect the flow of ocean currents. Warmer currents can cause shifts in natural habitats for many species. For example, species that normally live in cold zones may migrate to colder areas, causing disruptions in food chains and ecosystems. This not only impacts the species themselves but also their predators, who may not be able to reach new prey. Increasing sea water temperatures are also associated with increasing frequency and intensity of tropical storms. These conditions can cause physical damage to coral reefs and other habitats, which are important for the survival of many marine species. Additionally, stronger storms can result in greater pollution, with pollutants carried by rainwater into the sea. Rising sea levels due to global warming trigger faster coastal erosion and threaten mangrove and seagrass ecosystems. This ecosystem functions as an environmental buffer and habitat for various species. Losing these areas could reduce biodiversity and violate the ecological balance. Ocean acidification due to increased carbon dioxide (CO2) in the atmosphere is also a worrying impact. When CO2 is absorbed by the ocean, the water’s pH decreases, creating more acidic conditions. This can significantly affect marine life, especially organisms that have shells, such as molluscs and crustaceans. These organisms have difficulty building their shells, affecting food production and availability for many marine animals. Climate change also affects the reproductive patterns of various species. Some fish species in the sea can have their reproductive cycles disrupted due to changes in temperature and current flow. This can result in serious population declines in the long term, and the decline in species numbers can cause a domino effect that affects the entire marine ecosystem. Increased human activities, such as overfishing and pollution, are further exacerbating the impacts of global warming. Uncontrolled fishing can disrupt the natural balance of ecosystems and threaten the survival of certain species. Plastic pollution, industrial waste and chemicals can also damage habitats and threaten marine life. Based on all these impacts, it is important to address global warming with effective mitigation measures. Reducing greenhouse gas emissions, protecting vulnerable ecosystems, and sustainable management of marine resources are crucial steps to ensure the future health of marine ecosystems. Global awareness and collaboration between countries is needed to address this issue comprehensively and effectively.