Abstract Arctic warming accelerates permafrost thaw and coastal erosion, increasing terrestrial material transport to the ocean. Using Moderate Resolution Imaging Spectroradiometer (MODIS) data (2002–2023), we report a widespread increase in the diffuse attenuation coefficient Kd(490) across Arctic shelves since 2018, notably in the Laptev and Kara Seas, which are subject to high runoff and coastal erosion. These regions exhibited Kd(490) increases of 25% and 22%, respectively, relative to the 2002–2017 baseline period. Spatiotemporal correlation analysis attributes these optical changes primarily to warming in coastal areas and major river basins, rather than local atmosphere‐ice‐ocean influences. These results indicate that rising temperatures are increasing material transport from Arctic land to ocean, which has affected Arctic optical properties. This process compresses the euphotic zone and enhances radiant heating in the surface layer, potentially contributing to a terrestrial input–radiant heating positive feedback that may further accelerate Arctic shelf warming and terrestrial material inputs.