A study published on October 17, 2025, in Science Advances highlights a concerning decline in ocean greenness, measured by chlorophyll concentration, which serves as a proxy for phytoplankton biomass. Over the past two decades, chlorophyll levels have decreased, especially in coastal regions, threatening marine food webs and fisheries. Phytoplankton are crucial for marine ecosystems and play a significant role in carbon sequestration. The study's authors, primarily from Tsinghua University, warn that this trend could severely impact coastal communities dependent on the ocean's productivity. The research utilized satellite observations and AI-based models to analyze chlorophyll data, revealing an average decline of 0.00035 mg/m³ per year in low- to mid-latitude waters. The findings suggest that the ocean's capacity to act as a carbon sink is diminishing, necessitating urgent attention from researchers and policymakers to address the implications of global warming on marine ecosystems.