Warm winds from the Pacific caused extensive Arctic sea-ice melt in summer 2007

During summer 2007 the Arctic sea-ice shrank to the lowest extent ever observed. The role of the atmospheric energy transport in this extreme melt event is
explored using the state-of-the-art ERA-Interim reanalysis
data. We find that in summer 2007 there was an anomalous
atmospheric flow of warm and humid air into the region that suffered severe
melt. This anomaly was larger than during any other year in the data (1989-2006). Convergence of the atmospheric energy transport over this area
led to positive anomalies of the downward longwave radiation and turbulent
fluxes. In the region that experienced unusual ice melt, the net anomaly of the
surface fluxes provided enough extra energy to melt roughly one meter of ice during the melting season. When the ocean
successively became ice-free, the surface-albedo decreased causing additional
absorption of shortwave radiation, despite the fact that the downwelling solar
radiation was smaller than average. We argue that the positive anomalies
of net downward longwave radiation and turbulent fluxes played a key role in initiating the
2007 extreme ice melt, whereas the shortwave-radiation changes acted as an
amplifying feedback mechanism in response to the melt.