A 400-year reconstruction of wintertime Arctic sea-ice extent using a high-elevation, mid-latitude tree-ring record.

Abstract

We examined relationships between wintertime Arctic sea-ice extent (ASIE) and radial growth rates of alpine larch trees (LALY) in the northern Rockies, USA, during 1979-2015 (r= - 0.71, p< 0.01) and reconstructed ASIE fluctuations from 1613 to 2015. Wintertime ASIE corresponds with summertime mid-latitude upper-level atmospheric flow patterns with ridging (troughing) and warmer (cooler) conditions prevailing in the Rockies when ASIE are below (above) average. In turn, warmer (cooler) summertime conditions favor (disfavor) growth of LALY, thus "recording" interannual variations in ASIE. Both 1000hPa temperatures and 500hPa geopotential heights during years of anomalously high or low radial growth negatively correspond with ASIE, suggesting that a disjunct spatial influence on atmospheric conditions may be associated with interannual variability of ASIE. Reconstructed ASIE values show that 1996-2015 was the lowest 20-year period on record, but the mean value is not significantly different from six other distinct periods of below-average ASIE.