Global seagrass loss is accelerating, threatening coastal ecosystems. Seagrass meadows, found in shallow coastal waters, provide critical ecosystem services such as nutrient cycling, habitat for marine life, and carbon sequestration. A global assessment of 215 studies found that seagrass areas have declined by 110 km² per year since 1980, with 29% of the known area lost since 1879. The rate of decline has accelerated from 0.9% per year before 1940 to 7% per year since 1990, placing seagrass meadows among the most threatened ecosystems. Seagrass loss is comparable to that of mangroves, coral reefs, and tropical rainforests. Seagrass loss is attributed to coastal development, degraded water quality, and climate change. The decline has significant ecological and economic consequences, including reduced energy subsidies for other ecosystems, threats to endangered species, and loss of carbon sequestration. Despite some local increases in seagrass area, the overall trend remains negative, with more than 51,000 km² lost in 127 years. The study highlights the need for integrated management approaches to protect seagrass meadows, including reducing nutrient and sediment inputs, preventing mechanical damage, and addressing climate change impacts. Successful management examples include the recovery of seagrass in Tampa Bay and Mondego Bay through improved water quality and habitat protection. However, transplant projects have had limited success in reversing large-scale losses. Seagrass meadows are global in extent, except for the highest polar regions, and are vital for coastal ecosystems. Their decline signals a major environmental crisis, with severe impacts on marine and terrestrial biodiversity. The study underscores the urgency of protecting seagrass ecosystems to maintain the ecological services they provide.Global seagrass loss is accelerating, threatening coastal ecosystems. Seagrass meadows, found in shallow coastal waters, provide critical ecosystem services such as nutrient cycling, habitat for marine life, and carbon sequestration. A global assessment of 215 studies found that seagrass areas have declined by 110 km² per year since 1980, with 29% of the known area lost since 1879. The rate of decline has accelerated from 0.9% per year before 1940 to 7% per year since 1990, placing seagrass meadows among the most threatened ecosystems. Seagrass loss is comparable to that of mangroves, coral reefs, and tropical rainforests. Seagrass loss is attributed to coastal development, degraded water quality, and climate change. The decline has significant ecological and economic consequences, including reduced energy subsidies for other ecosystems, threats to endangered species, and loss of carbon sequestration. Despite some local increases in seagrass area, the overall trend remains negative, with more than 51,000 km² lost in 127 years. The study highlights the need for integrated management approaches to protect seagrass meadows, including reducing nutrient and sediment inputs, preventing mechanical damage, and addressing climate change impacts. Successful management examples include the recovery of seagrass in Tampa Bay and Mondego Bay through improved water quality and habitat protection. However, transplant projects have had limited success in reversing large-scale losses. Seagrass meadows are global in extent, except for the highest polar regions, and are vital for coastal ecosystems. Their decline signals a major environmental crisis, with severe impacts on marine and terrestrial biodiversity. The study underscores the urgency of protecting seagrass ecosystems to maintain the ecological services they provide.