Glacial Flooding & Disaster Risk Management Knowledge Exchange and Field Training July 11-24, 2013 in Huaraz, Peru HighMountains.org/workshop/peru-2013
Modern and past climate and environmental change impact on cryosphere/water resources in Central Asia Vladimir B. Aizen and Elena M. Aizen University of Idaho, USA E-‐mail: aizen@uidaho.edu Abstract The central Asian cryosphere is a part of planet's climate and hydrological system, one that is particularly at risk from accelerated climate changes. Despite the very arid climate, the central Asian glaciers comprise approximately 10,000 km3 fresh water that is a vital source of life for more than 100 million people. The history of climate revealed from the ice-‐core isotope-‐ chemistry records large variability in the past 12,600 years in central Asia. Glaciers in Altai and inner Tien Shan did not exist at the end of Pleistocene, and were regenerated during and the Younger Dryas, when air temperature was 6.1 ± 0.3◦C lower than the modern mean air temperature (Aizen et al, 2013d). An abrupt increase in air temperature of more than 6.7°C at the end of the Younger Dryas occurred for less than one century did not destroyed glaciers in Altai. During the last 30 years of modern time, annual air temperature increased 0.65°C, mainly in summer, and up to 1.6°C over the prairies and deserts. In high mountains of central Tien Shan air temperature increased on 0.21°C but, even a small increase of summer air temperatures intensifies seasonal snow and glacier melt, decreasing snow cover duration for one month. The glaciers lost on average 14% of area and 27% of volume in Altai from 1960s to 2009, 8.5% of area in Tien Shan and 5% in Pamir from 1970th to 2009. Keywords: Central Asia; cryosphere, climate, snow cover; glaciers; paleoclimate Introduction Shrinking of alpine glaciers and the acceleration of the glacier’s recession appears from the middle of 1970 in the majority of mountain regions of the World (Heiberly, 1990; Kadota et al., 1997; Liu et al., 2002; Zemp et al., 2006; Aizen et al., 2006; Niederer et al., 2008; Paul and Andreassen, 2009; Shahgedanova et al., 2010). An accurate evaluation of cryospheric changes becomes a crucial issue for water resource, water supply and hydropower assessments in central Asia. Central Asia has extremely fragile arid lowlands and water-‐rich highlands, where melt of glacier and seasonal snow cover supplies over 80% of river runoff (Dikih, 1993; Aizen, et al., 1998; Shi, et al., 2007). During droughts, glacial runoff can reach 45% (Schultc, 1965, Aizen, 1997). There is a lack of generalized knowledge on cryospheric changes over high central Asia. Existent investigations used data from a few stations (Table 1a), accounting for a relatively limited number of glaciers (Table 1b), which results often do not account for the extended terrain in central Asia and are valid only for local purposes. Central Asia (Fig. 1) with area of about 6.2 million km2 consists primarily of planes, with high mountains, reaching 7,000 m in the south and southeast. The highest point is Kongur in the eastern Pamir, of 7719 m, and the lowest point is the Turphan depression in eastern Tien 1