Article Open access Özgür Gürses , Sinhué Torres-Valdés , Clara J. M. Hoppe , Björn Rost , Onur Karakuş , Christopher Danek , Boris P. Koch , Cara Nissen , Nikolay Koldunov , Qiang Wang , Christoph Völker , Morten Iversen , Bennet Juhls & Judith Hauck Nature Climate Change (2025) Cite this article Metrics Abstract The Arctic experiences climate changes that are among the fastest in the world and affect all Earth system components. Despite expected increase in terrigenous inputs to the Arctic Ocean, their impacts on biogeochemical cycles are currently largely neglected in IPCC-like models. Here we used a state-of-the-art high-resolution ocean biogeochemistry model that includes carbon and nutrient inputs from rivers and coastal erosion to produce twenty-first-century pan-Arctic projections. Surprisingly, even with an anticipated rise in primary production across a wide range of emission scenarios, our findings indicate that climate change will lead to a counterintuitive 40% reduction in the efficiency of the Arctic’s biological carbon pump by 2100, to which terrigenous inputs contribute 10%. Terrigenous inputs will also drive intense coastal CO 2 outgassing, reducing the Arctic Ocean’s carbon sink by at least 10% (33 TgC yr −1 ). These unexpected reinforced feedback, mostly due to accelerated remineralization rates, lower the Arctic Ocean’s capacity for sequestering carbon. Main In the Arctic, anthropogenic climate change is causing one of the most rapid and profound climate transformations on the planet 1 . Remote-sensing studies estimate that net primary production (NPP) in the Arctic Ocean (AO) has linearly increased by 56% during the past two decades due to enhanced light (caused by increased ice melt) and nutrient availability 2 . As a result of the ‘AO Amplification’ (that is, the warming of the AO at twice the global average rate 3 ), it is expected that the AO […]