Global warming is now a major concern throughout the world, especially its impact on marine ecosystems. Oceans regulate climate, provide food sources, and support biodiversity. However, rising global temperatures and climate change are changing these conditions in detrimental ways. One of the direct impacts of global warming is an increase in sea surface temperatures. This increase in temperature results in ocean acidification due to increased concentrations of carbon dioxide (CO2) in the atmosphere. This acidification has a negative impact on marine organisms such as coral reefs and molluscs, which have difficulty forming shells. Coral reef loss not only threatens the habitat of various species, but also disrupts the balance of the entire ecosystem. In addition, changes in sea temperature affect fish migration patterns. Many fish species move to cooler areas, looking for suitable habitats to breed. This can cause negative impacts on fishing communities and food security in areas that depend on marine resources. Fish species that cannot adapt quickly are threatened with extinction, affecting the marine food chain. Sea level rise is also a serious problem due to melting ice in Antarctica and Greenland. As the volume of water increases, coastal areas become vulnerable to flooding and erosion. Mangrove and seagrass habitats that function as protection will be increasingly threatened, resulting in the loss of protection for various marine species and a reduction in the quality of habitat for fish and other species. Extreme weather changes, such as stronger storms and irregular rainfall frequency, also impact marine ecosystems. Human activities such as overfishing have the potential to worsen this condition. Overall changes in the ecosystem directly affect the health of the marine ecosystem, reducing biodiversity and disrupting ecosystem stability. The impact of global warming on marine ecosystems is not only focused on the survival of species, but also has the potential to disrupt the economic value system obtained from the ocean. Ecotourism, which depends on the beauty and diversity of marine life, is also under threat. As coral reef fields continue to disappear, the attraction for tourists is decreasing. In order to overcome these impacts, mitigation efforts such as reducing greenhouse gas emissions, protecting marine habitats, and sustainable management of marine resources are very important. Public awareness of the issue of global warming and its impact on marine ecosystems must also be increased. International cooperation is needed to encourage effective action to protect the oceans from global warming and maintain sustainability for future generations. With the various challenges facing us, the future of marine ecosystems depends greatly on our collective actions today. Global awareness regarding the impacts of global warming has increased, but real action is needed so that we can maintain the sustainability of the ocean for the sake of life on this planet. Through cooperation, innovation and commitment, marine ecosystems can be protected from the negative impacts of global warming.