Eutrophication, caused by too many nutrients in the water, is a growing problem worldwide. Scientists created a tool using satellite data to map areas at risk of eutrophication. They found that about 1.15 million square kilometers of coastal waters could be affected. Areas with increasing chlorophyll levels, a sign of eutrophication, were twice as common as those showing improvement. The tool can help identify regions with severe eutrophication issues and areas needing more monitoring. This tool could be crucial for tracking progress towards Sustainable Development Goals and using satellite data to support these goals.