Arctic Amplification, the accelerated warming of the Arctic compared to lower latitude, remains incompletely understood, particularly regarding the role of clouds. In this study, we analyze 26 years of Downwelling Longwave Radiation (DLR) measurements from an Extended-range Atmospheric Emitted Radiance Interferometer (E-AERI) at the U.S. Department of Energy’s North Slope Alaska site. Our analysis reveals a pan-spectral increase in DLR under all sky conditions, primarily driven by an enhanced greenhouse effect from thick/low clouds and greenhouse gases. Changes in radiance, rather than cloud fraction, dominate these trends, suggesting fundamental shifts in atmospheric emissivity and/or temperature. Comparative analysis between mid- and high-latitudes demonstrates that cloud impacts the longwave surface energy balance differently between the two locations. In the Arctic, the pan-spectral increase in DLR trend dampens out the radiative cooling of the warming surface, contributing significantly to Arctic Amplification. Consistent positive trends are found in the far-infrared, a spectral region particularly sensitive to the dry and cold Arctic’s atmosphere and of significant interest in the current warming context. Additionally, we observe a relatively weaker DLR trend in the ozone absorption band under every sky condition, indicating a tropospheric ozone radiative forcing in the Arctic climate.