Role of Polar Amplification in Long-Term Surface Air Temperature Variations and Modern Arctic Warming

Abstract

This study uses an extensive dataset of monthly surface air temperature (SAT) records (including previously unutilized) from high-latitude (>60°N) meteorological land stations. Most records have been updated by very recent observations (up to December 2008). Using these data, a high-latitude warming rate of 1.36°C century?1 is documented for 1875?2008?the trend is almost 2 times stronger than the Northern Hemisphere trend (0.79°C century?1), with an accelerated warming rate in the most recent decade (1.35°C decade?1). Stronger warming in high-latitude regions is a manifestation of polar amplification (PA). Changes in SAT suggest two spatial scales of PA?hemispheric and local. A new stable statistical measure of PA linking high-latitude and hemispheric temperature anomalies via a regression relationship is proposed. For 1875?2008, this measure yields PA of ?1.62. Local PA related to the ice?albedo feedback mechanisms is autumnal and coastal, extending several hundred kilometers inland. Heat budget estimates suggest that a recent reduction of arctic ice and anomalously high SATs cannot be explained by ice?albedo feedback mechanisms alone, and the role of large-scale mechanisms of PA of global warming should not be overlooked.