ABRUPT SUMMER WARMING IN THE ALASKA RANGE FROM MELT LAYERS IN THE MT. HUNTER ICE CORE

The Arctic has experienced dramatic warming trends during the instrumental period. Alaska, in particular has undergone temperature increases of 1-2 °C since 1950, when widespread meteorological records have been available. Melt layers in ice cores provide a means of extending temperature records far into the past. We present an ice core melt layer record extracted from the Central Alaska Range from a plateau location on Mt. Hunter (63° N, 151° W, 4,000 meters above sea level). This melt layer record provides an estimate of summer temperatures at this site over the last 170 years. Our results show an increase in summer melting on Mt. Hunter during the period of record. Most of this increase occurred rapidly during the mid-twentieth century. Very infrequent melting occurred on Mt. Hunter prior to the mid-twentieth century (roughly 3 events/century). Since 1950, melt frequency and percentage has been increasing, in agreement with the instrumental records at lower elevations. Based on the temperature distributions at other weather stations in the Alaska Range, we estimate that a warming of 3-5 °C occurred during the mid-twentieth century.