Global warming has a significant impact on marine ecosystems, which are an important part of environmental balance. Rising sea surface temperatures due to increases in greenhouse gases cause drastic changes in aquatic habitats, species, and biogeochemical processes. One of the main impacts of global warming is increasing sea temperatures, which triggers coral reef bleaching. Healthy corals collaborate with symbiotic algae, zooxanthellae, which provide color and nutrition. When temperatures rise, these algae are stressed and leave the coral, leaving it white and susceptible to death. Approximately 30% of coral reefs worldwide have been damaged, affecting marine biodiversity. Changes in temperature also affect the distribution of fish species. Many fish species are moving towards cooler waters, posing challenges for fishermen and communities that depend on fish catches. For example, fish such as tuna and sardines have been found in unusual new locations. These changes in migration patterns can affect entire ecosystems and disrupt food webs. Increased levels of carbon dioxide in the atmosphere cause ocean acidification, which negatively affects organisms with shells such as clams, limpets, and some types of plankton. This process disrupts the organisms’ ability to form shells, which can reduce populations and affect predators that rely on them for food. With more CO2 absorbed into the ocean, the new acidic conditions could make marine ecosystems more vulnerable. Following the increase in temperature, the nutrient cycle in marine ecosystems is also affected. The mixed layer at the ocean surface becomes warmer, which has the potential to reduce the efficiency of upwelling – the process of lifting nutrients from the depths of the ocean to the surface. This reduction in nutrients impacts primary productivity, which is the basis of the marine food chain. Climate change is also increasing the frequency and intensity of tropical storms, which have devastating impacts on coastal habitats such as mangroves and seagrasses. This damage results in the loss of nesting sites and protection for many species. Additionally, pollution from storms, including waste and chemicals, worsens ocean health. The impact of global warming on marine ecosystems has serious long-term consequences. The sustainability of the fishing industry is disrupted, biodiversity loss increases, and ecosystem quality is reduced. Understanding and taking appropriate action on this issue is critical to maintaining ocean health for future generations. Protection and mitigation initiatives must be prioritized to increase the resilience of marine ecosystems in the face of global climate change.