Synechococcus , a key genus of marine cyanobacteria, plays a crucial role in global carbon fixation; however, its potential for carbon fixation under future climate change remains underexplored. Here, we utilize machine learning to analyze 689 Synechococcus reference genomes and 953 marine metagenomic samples, uncovering the global distribution of Synechococcus species and their carbon fixation genes. The abundance and carbon...