Global climate change has a significant impact on ocean ecosystems. Rising sea temperatures, water acidification, and changes in ocean current patterns have drastically changed marine habitats. One of the main impacts is warming sea temperatures which causes coral bleaching. When water temperatures increase, coral reefs, which are habitat for many marine species, will lose color and essential nutrients. As a result, thousands of species that depend on coral reefs are threatened with extinction. Ocean acidity is also increasing along with greater absorption of CO2 by the ocean, which can interfere with calcium carbonate synthesis. Many organisms such as mollusks, clams, and other marine organisms depend on this process to form shells and skeletal structures. If acidity continues to rise, the survival of these species is under threat. This not only impacts the populations of these organisms but also the predatory organisms that utilize them as a food source. Changes in ocean current patterns due to global warming affect the distribution of nutrients in marine ecosystems. Nutrients necessary for the growth of plankton—the basis of the marine food chain—can be distributed unevenly. When plankton are affected, all the species that depend on them, including small fish and marine mammals, feel the impact. These changes could also affect fishing activities globally, resulting in reduced catches in some regions. Meanwhile, species migration is also a big issue. Some fish and marine mammals are starting to move to cooler waters due to rising temperatures. This could cause an imbalance in their new ecosystem. Fish known as target species for the fishing industry become inaccessible for fishermen who depend on their traditional locations. Disease outbreaks affecting marine species also increase with changes in temperature. As temperatures rise, pathogens and parasites can reproduce more quickly, causing disease outbreaks that can devastate fish and marine mammal communities. Human activities such as overfishing and waste pollution also contribute to this problem. As the focus of marine ecosystems shifts due to climate change, the cumulative effects of human pressures could exacerbate impacts already considered critical. Protecting marine ecosystems from climate change requires collective action at the international level. Greater awareness of the negative impacts of climate change on the oceans must be a priority. Preserving marine areas and reducing carbon emissions are important steps to face this challenge. Initiatives that integrate research, policy and local action will help ensure that ocean ecosystems not only survive but also function ecologically into the future.