NOAA/WDS Paleoclimatology - Mt. Hunter, Alaska 230 Year Ice Core Melt Layer Data

STUDY NOTES: Melt layer stratigraphic data from the Mt. Hunter ice core
ABSTRACT SUPPLIED BY ORIGINATOR: Warming in high-elevation regions has societally important impacts on glacier mass balance, water resources, and sensitive alpine ecosystems, yet very few high-elevation temperature records exist from the middle or high latitudes. While a variety of paleoproxy records provide critical temperature records from low elevations over recent centuries, melt layers preserved in alpine glaciers present an opportunity to develop calibrated, annually-resolved temperature records from high elevations. Here we present a 400-year temperature proxy record based on the melt-layer stratigraphy of two ice cores collected from Mt. Hunter in Denali National Park in the Central Alaska Range. The ice core record shows a 60-fold increase in water equivalent total annual melt between the pre-industrial period (before 1850 CE) and present day. We calibrate the melt record to summer temperatures based on weather station data from the ice core drill site, and find that the increase in melt production represents a summer warming rate of at least 1.92 +/- 0.31C/century during the last 100 years, exceeding rates of temperature increase at most low elevation sites in Alaska. The Mt. Hunter melt layer record is significantly (p < 0.05) correlated with surface temperatures in the central tropical Pacific through a Rossby-wave like pattern that enhances high temperatures over Alaska. Our results show that rapid alpine warming has taken place in the Alaska Range for at least a century and that conditions in the tropical oceans contribute to this warming.