Permafrost changes in the northern Tien Shan during the Holocene

Abstract

The evolution of permafrost within the northern Tien Shan during the Holocene is described. It is based on the interpretation of a temperature curve obtained from a deep borehole in the Zhusalykezen mountain pass (3336 m ASL), located in the Zailiysky Alatau Range. This curve indicates a zone where the temperature falls as the depth increases. Such an anomaly reflects past thermal conditions in the high mountains. At present, permafrost is absent on the southern slope where the borehole was drilled. Analysis of the temperature curve indicates that warming and cooling took place during the Holocene. Maximum warming occurred about 7000–10,000 years ago when the ground temperature rose by approximately 0.5–1.5 °C. Maximum cooling was recorded in the last millennium, the ground temperature being lower than today by 1.0–1.5 °C. These fluctuations are corroborated by relict permafrost and palaeocryogenic structures © 1997 John Wiley & Sons, Ltd.

Rock‐glacier dams in High Asia

“…Our data support the idea that lower-lying and riverdisrupting rock glaciers are likely closer to non-equilibrated permafrost conditions. Local effects also come into play, as the temperature regime below large blocks can be several degrees lower compared with surrounding soils (Harris et al, 1998), thus stabilising rock glaciers or permafrost patches below the 0°C isotherm (Marchenko and Gorbunov, 1997;Bolch and Gorbunov, 2014). They argued that these rock glaciers were not equilibrated with the current climate, and suggested topography, weathering, and seismic activity as additional drivers.…”

Proceedings of the 12th International Conference on Permafrost: Volume 2 (Conference Papers)

“…The method of obtaining these properties is based on numerical solution for a coefficient inverse problem and on minimization locally the misfit between measured and modeled temperatures by changing thermal properties along the direction of the steepest descent. The method used and its limitations are described in more detail elsewhere (Alifanov 1994;Alifanov et al 1996;Tikhonov et al 1996;Marchenko and Gorbunov 1997;Nicolsky, 2009).…”

“…The developed approach attempts to addresses the problem of computing the ground temperature projections at the regional scale that is sufficient to gain some understanding how potential changes in the permafrost might affect ecosystems and impact the infrastructure under various climate scenarios. The developed parametrization of the ground thermal properties is obtained using a data assimilation technique (e.g., Marchenko and Gorbunov 1997;Nicolsky et al 2009). The mean values for ALT are computed over the 1996-2022 period, while the MAGT values are computed over the period when the observations are available.…”

“…This research explores data on the ground thermal properties and surface conditions for the major ecotypes and deposits across Alaska, which were obtained using the ecosystem and vegetation maps, map of deposit types and ground ice as a source of a priory information (Figure 2) and the solution of the inverse problem as well (Alifanov 1994;Alifanov et al 1996;Tikhonov et al 1996;Marchenko and Gorbunov 1997;Nicolsky et al 2009). For each ecosystem type the soil texture and thickness of the organic layer were parameterized according to field measurements and maps.…”

Estimation rates of permafrost degradation and their impact on ecosystems across Alaska

“…The method of obtaining these properties is based on numerical solution for a coefficient inverse problem and on minimization locally the misfit between measured and modeled temperatures by changing thermal properties along the direction of the steepest descent. The method used and its limitations are described in more detail elsewhere (Alifanov 1994;Alifanov et al 1996;Tikhonov et al 1996;Marchenko and Gorbunov 1997;Nicolsky, 2009).…”