The Arctic Ocean, though covering only 4% of ocean surface, contributes disproportionately to global carbon uptake and fisheries. Productivity in this region depends on light and nitrogen. While traditional views emphasise nitrogen supply from rivers, glaciers, erosion, and adjacent oceans, recent findings reveal an overlooked source: marine nitrogen fixation by diazotrophs. Our team discovered active diazotrophs in glacier-influenced Arctic fjords, suggesting that melting glaciers create favorable niches for these microbes. Unlike low-latitude oceans, where diazotrophy is well-studied, knowledge of its role in the rapidly changing Arctic is limited.