Climate variations over the southern Altai Mountains and Dzungarian Basin region, central Asia, since 1580 CE

Abstract

An improved knowledge of long-term climatic variations over the Altai-Dzungarian region will increase our understanding of the current climate and help to predict the effects of global warming on future water availability in this region. We sampled 77 Larix sibirica Ledeb. trees at upper and lower treelines in the southern Mongolian Altai mountains and reconstructed temperature and precipitation for longer periods than previous studies from this area. We reconstructed mean June-July air temperatures for the period 1402-2012 and June-December precipitation for the period 1569-2012 based on tree ring width chronologies. The temperature and precipitation reconstructions explain 39.7 and 41.3% of the respective station observation variance during the common periods. The precipitation reconstruction shows alternating wet and dry conditions during the Little Ice Age (1580-1874) followed by more stable conditions until a late 20th century wetting. The temperature reconstruction attributes the warmest period to the 20th century, which follows cooler periods related to volcanic and low solar activities during the Little Ice Age. Long-term climatic variation and change over the Altai-Dzungarian region is inferred from the analysis of the combined temperature and precipitation reconstructions for the common period 1580-2012. Accordingly, this region has become warmer since 1875 as the number of warm/moist and warm/dry years increased by 2 and 14%, respectively, while the number of cool/moist and cool/dry years both decreased by 8% compared to the Little Ice Age. Our findings also reveal a late 20th century cool and wet period, which has also been observed across other mountainous areas of China and Nepal. This period was most probably caused by volcanic-induced cooling and coincided positive phases of the Arctic Oscillation and North Atlantic Oscillation promoting an intensified subtropical westerly jet and a positive summer rainfall anomaly over the Altai-Dzungarian region.

Accelerated Recent Warming and Temperature Variability Over the Past Eight Centuries in the Central Asian Altai From Blue Intensity in Tree Rings

“…Strong positive correlations were found with mean June and July (JJ) monthly temperatures from the nearest station records over 1950-2004 (Figure S4), consistent with RW studies from this region (Davi et al, 2015;Oyunmunkh et al, 2019). June-July correlations ranged from 0.55-0.70 for the ADS-SF chronology with the five closest and most complete station records, which ranged from ~ 134km (strongest correlation), to 310kms away from the study site.…”

Feed Intake of Small Ruminants on Spring and Summer Pastures in the Mongolian Altai Mountains

“…We thereby understand primary productivity as the plant biomass produced per unit surface and unit time, and secondary productivity as the animal mass (weight) produced per unit surface (or unit plant biomass) and unit time. In view of (a) increasing climate variability and change [10], (b) increasing numbers of domestic herbivores and particularly goats [26], (c) decreasing herd mobility [25], and (d) very clustered grazing patterns [27] that were evidenced in companion studies for the southern Altai region of Mongolia, we aimed at evaluating (1) quantity and quality of herbaceous biomass offered along the daily grazing itineraries of sheep and goats and (2) grazing behaviour, feed and nutrient intake of small ruminants during spring and summer seasons in order to (3) determine if forage availability and quality sustain secondary pasture productivity in the southern Mongolian Altai despite ongoing agro-ecological change processes (a-d).…”

Unprecedented acceleration of winter discharge of Upper Yenisei River inferred from tree rings

“…Tree-ring reconstructions of summer temperature and precipitation across the Altai-Sayan Mountains suggest that the rate of precipitation and temperature change in the late 20th century is not unusual in the context of the last 300 years. The late 20th century was relatively cool and wet and the most recent decades warm and dry (Myglan et al 2012, Kostyakova et al 2018, Fedotov et al 2019, Oyunmunkh et al 2019. Strong correspondence of river discharge to seasonal snow cover changes does not fully explain the winter flow rate (Yang et al 2007, Troy et al 2012.…”