The only thing that has been constant in the Arctic during recent decades is sweeping change. Observations of almost every aspect of the climate system suggest a cohesive shift toward an Arctic with warmer temperatures and less permanent ice, the most conspicuous indicator being the loss of perennial sea ice. Our recent analyses of satellite-derived dynamic and thermodynamic forcing parameters suggest that anomalies in downwelling longwave (infrared) radiation fluxes (DLF) explain the most variance in summer sea ice extent in six peripheral seas around the Arctic Ocean [Francis et al., 2005; Francis and Hunter, submitted]. We also observe significant increases in DLF in spring through autumn over most of the region, pointing to DLF as an important driver of sea ice loss. What is unclear, however, is which of the many possible atmospheric variables are causing DLF variability and change? In this presentation we examine the contributions of varying temperature, cloud properties, and precipitable water to DLF changes using measurements from the ARM site at Barrow, AK, and extend this analysis to the pan-Arctic using retrievals from satellite sounders.