Reconstruction of recent climate change in Alaska from the Aurora Peak ice core, central Alaska

Abstract

Abstract. A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m depth temperature in the borehole was −2.2 • C, which corresponded to the annual mean air temperature at the drilling site. In this ice core, there were many melt-refreeze layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD) and chemical species in the ice core. The ice core age was determined by annual counts of δD and seasonal cycles of Na + , and we used reference horizons of tritium peaks in 1963 and 1964, major volcanic eruptions of Mount Spurr in 1992 and Mount Katmai in 1912, and a large forest fire in 2004 as age controls. Here, we show that the chronology of the Aurora Peak ice core from 95.61 m to the top corresponds to the period from 1900 to the summer season of 2008, with a dating error of ±3 years. We estimated that the mean accumulation rate from 1997 to 2007 (except for 2004) was 2.04 m w.eq.yr −1 . Our results suggest that temporal variations in δD and annual accumulation rates are strongly related to shifts in the Pacific Decadal Oscillation index (PDOI). The remarkable increase in annual precipitation since the 1970s has likely been the result of enhanced storm activity associated with shifts in the PDOI during winter in the Gulf of Alaska.

The 1200 year composite ice core record of Aleutian Low intensification

“…changepoint. The ice core record from Aurora Peak in the eastern Alaska Range (225 km east of Denali; Figure S1), although only spanning the twentieth century, likewise shows a doubling of snow accumulation since 1900 and an increase in sea-salt Na since the 1970s due to the strengthening ALow [Tsushima et al, 2015]. A recent SST reconstruction from Aleutian coralline algal skeletons similarly shows a shift to warming North Pacific SSTs circa 1740 C.E., and a second inflection point toward higher SSTs at circa 1840 C.E., both indicative of a strengthening ALow [Williams et al, 2017].…”

Isoscapes of δ18O and δ2H reveal climatic forcings on Alaska and Yukon precipitation

“…Stable isotope values of precipitation are widely used as climate tracers that vary spatially over oceanic and terrestrial regions [ Rozanski et al ., ]. Stable isotope data form a critical baseline for interpreting paleoclimate variations preserved in ice cores [ Osterberg et al ., ; Tsushima et al ., ; Wake et al ., ], lake sediment [ Anderson et al ., ], and permafrost ice [ Lachniet et al ., ; Meyer et al ., ], and constraining landscape evolution [ Mulch , ]. There is extremely poor understanding on δ 18 O and δ 2 H variability across Alaska and the western Yukon because of the sparse isotope observation network in this Arctic region [ IAEA/WMO , ], which are mostly concentrated in coastal locations in Alaska.…”

Isotopic composition of the ice cores obtained on the Western Plateau of the Mt Elbrus

“…К одному из основных и наиболее ценных источников палеоклиматической ин формации относится ледяной керн . По данным его изучения уже сделаны многочисленные ре конструкции климатических изменений в по лярных и горных регионах в разных временных масштабах [7,21,29,35,36,43,44] .…”