Global climate change is having a significant impact on marine ecosystems throughout the world. A rise in sea surface temperatures, acidification of sea water, and changes in ocean current patterns are some of the main factors affecting life in the ocean. When sea temperatures rise, many species of fish and marine organisms are forced to move to areas with cooler conditions. This can disrupt food chains and increase competition between species. One of the most striking impacts is on coral reefs. Coral reefs are very sensitive to temperature. Rising temperatures cause coral bleaching, which threatens the lives of thousands of species that depend on them. When coral reefs die, the complex ecosystems they support also begin to collapse, which can lead to a decline in biodiversity. Ocean acidification is also a serious problem due to the absorption of carbon dioxide. As CO2 increases, seawater absorbs most of this gas, causing a decrease in pH. This change in pH is very dangerous for organisms that have calcium carbonate shells or skeletons, such as molluscs, crustaceans and some types of plankton. The decline in populations of these organisms has a detrimental domino effect on the entire marine ecosystem. Changes in ocean current patterns caused by climate change also affect the distribution of nutrients and marine organisms. Changing currents can change the location of fertilizing areas, which are critical for the growth of plankton at the base of the food chain. This uncertainty can cause a decrease in fish catches and have economic impacts on communities that depend on fisheries. Lack of oxygen is an additional problem in the ocean. As temperature increases, most seawater becomes less dissolved oxygen. The rise of warmer water layers over cooler layers causes stratification, limiting exchange between water layers. This adds pressure to marine species, which need oxygen to survive. Meanwhile, invasive species are also increasingly appearing in marine ecosystems disrupted by climate change. Moving species to new, warmer areas can have negative impacts, as alien species often have no natural predators, increasing competition for limited resources. The sustainability of marine ecosystems relies heavily on collective action to address climate change. Mitigation measures, including reducing carbon emissions, protecting coral reefs, and sustainable management of fisheries, are critical to protecting marine ecosystems. Research and public education also need to be carried out to increase awareness of the importance of maintaining healthy marine ecosystems. The resilience of marine ecosystems to climate change can be increased through strengthening and restoring natural habitats. By creating marine protection zones and restoring mangroves and seagrass beds, we can help stabilize ecosystems and support biodiversity. International collaboration is also key in efforts to address the impact of global climate change on the oceans.