The status and role of the alpine cryosphere in Central Asia

Abstract

• The alpine cryosphere, including snow, glaciers and permafrost, is critical to water management in the Aral Sea Basin (ASB) and larger Central Asia (CA) under the changing climate, as it stores large amounts of water in its solid forms. Most cryospheric components in the Aral Sea Basin are close to melting point, and hence very vulnerable to a slight increase in air temperature with significant consequences to long-term water availability and to water resources variability and extremes. The alpine cryosphere 101 • Current knowledge about different components of the cryosphere and their connection to climate in the Basin and in the entire Central Asia region varies. While it is advanced in the topics of snow and glaciers, knowledge on permafrost is rather limited. • Observed trends in runoff point in the direction of increasing water availability in July and August at least until mid-century and increasing possibility for water storage in reservoirs and aquifers. However, eventually this will change as glaciers waste away. Future runoff may change considerably after mid-century and start to decline if not compensated by increasing precipitation. • Cryosphere monitoring systems are the basis for sound estimates of water availability and water-related hazards associated with snow, glaciers and permafrost. They require a well-distributed observational network for all cryospheric variables. Such systems need to be re-established in the Basin after the breakup of the Soviet Union in the early 1990s. This process is slowly emerging in the region. Collaboration between local operational hydro-meteorological services and the academic sector, and with international research networks, may improve the observational capabilities in high-mountain regions of CA in general and in the ASB in particular.

Trends in Snow Cover Duration Across River Basins in High Mountain Asia From Daily Gap-Filled MODIS Fractional Snow Covered Area

“…Indeed, the decrease in snow cover duration across High Mountain Asia is a broad scale assessment that could be further refined in future work by considering trends at smaller spatial scales across each basin in the study area. For instance, glaciers have been shrinking at a slower rate at higher elevations in the Pamir and the Tien Shan mountain ranges compared to glaciers found in the lower elevations of the outer Pamir (Unger- Shayesteh et al, 2013;Hoelzle et al, 2019). Generalizing trends across the Syr Darya and Amu Darya, therefore, does not capture the full variability across varying aspects and other topographic controls.…”

“…The relatively few snow data collection sites and in situ measurement stations cannot adequately represent the entire region (Tang et al, 2013). Many ground stations were also abandoned in the Syr Darya and Amu Darya after the disintegration of the Soviet Union in the early 1990s, leaving the number of snow surveys (either in situ or aerial) to decrease substantially since that time (Unger-Shayesteh et al, 2013;Hoelzle et al, 2019). The use of remote sensing data, therefore, is the preferred method for monitoring snow cover (Tahir et al, 2011).…”

Geodetic mass balance of Abramov Glacier from 1975 to 2015

“…The break-up of the former Soviet Union led to a lack of funding and the monitoring programme was interrupted in 1999 when the research station was attacked and destroyed (WGMS, 2001). In 2010/11, the monitoring of several glaciers in Central Asia, including Abramov Glacier, was re-initiated (Hoelzle and others, 2017, 2019).…”

Towards accurate quantification of ice content in permafrost of the Central Andes – Part II: an upscaling strategy of geophysical measurements to the catchment scale at two study sites

“…CC BY 4.0 License. power generation, mining and drinking water during the summer (Urrutia and Vuille, 2009;Salzmann et al, 2013;Rangecroft et al, 2015;García et al, 2017;Hoelzle et al, 2019). With continued climate change further enhancing the recession of glaciers globally, their contribution to the summer runoff will eventually decline, whereby the timing of this decline differs globally based on the region (IPCC, 2019).…”