Perennial sea ice is a primary indicator of Arctic climate change. Since 1980 it has decreased in extent by about 15%. Analysis of new satellite-derived fields of winds, radiative forcing, and advected heat reveals distinct regional differences in the relative roles of these parameters in explaining variability in the northernmost ice edge position. In all six peripheral seas studied, downwelling longwave flux anomalies explain the most variability -- approximately 40% -- while northward wind anomalies are important in areas north of Siberia, particularly earlier in the melt season. Anomalies in insolation are negatively correlated with perennial ice retreat in all regions, suggesting that the effect of solar flux anomalies is overwhelmed by the longwave influence on ice edge position.