Abstract
AbstractA multiple parameter dating technique was used to establish a depth/age scale for a 171.3 m (145.87 m w.e.) surface to bedrock ice core (Bl2003) recovered from the cold recrystallization accumulation zone of the Western Belukha Plateau (4115 m a.s.l.) in the Siberian Altai Mountains. The ice-core record presented visible layering of annual accumulation and of δ18O/δD stable isotopes, and a clear tritium reference horizon. A steady-state glacier flow model for layer thinning was calibrated and applied to establish a depth/age scale. Four radiocarbon (14C) measurements of particulate organic carbon contained in ice-core samples revealed dates for the bottom part of Bl2003 from 9075 ± 1221 cal a BC at 145.2 ± 0.1 m w.e. (0.665 m w.e. from the bedrock) to 790 ± 93 AD at 121.1 m w.e. depth. Sulfate peaks coincident with volcanic eruptions, the Tunguska meteorite event, and the 1842 dust storm were used to verify dating. Analysis of the Bl2003 ice core reveals that the modern Altai glaciers were formed during the Younger Dryas (YD) (~10 950 to ~7500 cal a BC), and that they survived the Holocene Climate Optimum (HCO) (~6500 to ~3600 cal a BC) and the Medieval Warm Period (MWP) (~640 to ~1100 AD). A decrease in air temperature at the beginning and an abrupt increase at the end of the YD were identified. Intensification of winds and dust loading related to Asian desert expansion also characterized the YD. During the YD major ion concentrations increased significantly, up to 50 times for Na+ (background), up to 45 times for Ca2+ and Mg2+, and up to 20 times for SO42− relative to the recent warm period from 1993 to 2003. A warm period lasted for about three centuries following the YD signaling onset of the HCO. A significant and prolonged decrease in air temperature from ~2000 to ~600 cal a BC was associated with a severe centennial drought (SCD). A sharp increase in air temperatures after the SCD was coincident with the MWP. After the MWP a cooling was followed gradually with further onset of the Little Ice Age. During the modern warm period (1973–2003) an increase in air temperature is noted, which nearly reaches the average of HCO and MWP air temperature values.
Highlights
The climatic system exhibits moderate, abrupt and threshold state changes over a wide range of time
We considered significant volcanic eruptions with a volcanic explosivity index (VEI) ≥ 5 and focused on eruptions that are most likely recorded in Siberian Altai ice-core records, e.g. from Kamchatka, Japan (Table 1)
We suggest that during the Holocene Climate Optimum (HCO), high moisture availability in the Altai was associated with intrusions of Atlantic air masses as well as with moisture originating from the Pacific, evidenced by δ18O and d-ex (Aizen and others, 2005, 2006) that maybe associated with the Eastern Asian Pacific summer monsoon
Summary
The climatic system exhibits moderate, abrupt and threshold state changes over a wide range of time. This range in variability is explored through the analysis of past climate in order to predict future climate. The retreat or advance of alpine glaciers at low-, mid- and high latitudes of Asia is one of the most obvious and significant consequences of climate variability (Haeberli and Holzhauser, 2003; Li and others, 2006; Narama and others, 2006). Existing ensembles of climate models predict further largescale warming in central Asia (IPCC, 2014), details of regional climate predictions for high mountain regions and Downloaded from https://www.cambridge.org/core. Over the past 150 years, since the end of the Little Ice Age (LIA), alpine glaciers all over the world have tended to retreat (Mayewski and Jeschke, 1979; Kadota and others, 1997; Paul and others, 2004; Liu and others, 2006; Aizen, 2011) in response to rapid increase of air temperature coupled with changes in precipitation patterns in mountain regions.
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