Disentangling source of moisture driving glacier dynamics and identification of 8.2 ka event: evidence from pore water isotopes, Western Himalaya

Abstract

Two atmospheric circulation patterns, the Indian Summer Monsoon (ISM) and mid-latitude Westerlies control precipitation and thus glacier variability in the Himalaya. However, the role of the ISM and westerlies in controlling climate and thus past glacier variability in the Himalaya is poorly understood because of the paucity of the ice core records. In this article, we present a new Holocene paleorecord disentangling the presence of the ISM and mid-latitude westerlies and their effect on glacier fluctuations during the Holocene. Our new record is based on high-resolution multi-proxy analyses (δ18Oporewater, deuterium-excess, grain size analysis, permeability, and environmental magnetism) of lake sediments retrieved from Chandratal Lake, Western Himalaya. Our study provides new evidence that improves the current understanding of the forcing factor behind glacier advances and retreat in the Western Himalaya and identifies the 8.2 ka cold event using the aforementioned proxies. The results indicate that the ISM dominated precipitation ~ 21% of the time, whereas the mid-latitude westerlies dominated precipitation ~ 79% of the time during the last 11 ka cal BP. This is the first study that portrays the moisture sources by using the above proxies from the Himalayan region as an alternative of ice core records.

Revisiting Glacier Dynamics for Stationary Approximation of Plane-Parallel Creeping Flow

“…Thus, we have pointed out two additional classes of exact solutions ( 12)-( 13) of Eqns. ( 1)-( 2) in their approximation (11) for creeping flow of glacial ice, which differ from solutions (10) for stationary approximation creeping flow of glacial ice with constant pressure field along the path of the plane-parallel flow of glacial ice. Videlicet, 1st class is also associated with stationary flow (but variable pressure field), the 2nd stems from assumption of constant pressure field along the path of the plane-parallel flow, but we have considered nonstationary case of glacial ice in this case.…”

“…But since at this stage algorithm for further obtaining of exact solution has no chance to be presented in analytical or semi-analytical way, we should apply additional simplifications to equations of system (11)…”

“…Illuminating the basic mechanisms, which govern by the dynamics of glaciers, plays a significant role at predicting of tracing of the prescribed trajectory for the entire glacier, moving under the action of non-Newtonian hydrodynamical forces, gradient of pressure and gravity; this is extremely nonlinear problem even in the case of glacier's slow spatial movement in 2D case (in two dimensions) on absolutely flat surface without any inclination. It is worth to note that only a few cases of analytical or semi-analytical solution are known in the field of glacier dynamics [7]; the problem of stability of motion of glacier dynamics or dynamical response to external influence as well as dynamical behavior have been studied in the past under various versions and there is a rich and extended international bibliography [8], especially in recent researches [9][10][11]. In the current research, we will restrict ourselves in presenting a new analytical technique for revisiting of Glacier dynamics for 2D plane-parallel stationary approximation, by providing the analytical solution for the case of creeping flow [12].…”

Sedimentary Black Carbon Isotope Record of Holocene Climate Changes on the Northeastern Tibetan Plateau

“…Rapid centennial climate changes, mainly occurred at 10.7‐9.5, 8.7‐8.5, 7.7‐7.4, 6.4‐6, 5.5‐5.2, 4.8‐4.5, 4‐3.6, 3.1‐2.7, 1.4‐1.2, and 0.8‐0.6 cal kyr BP, had also been recorded by rapid retreat of coniferous forest in peat deposits from Zoige Basin (Sun et al., 2017). Several other sediment archives including the δ 18 O values from Guliya ice core (Thompson et al., 1997), δ 18 O ost results from Lake Koucha (Mischke et al., 2008), δ 13 C values of cellulose remains from Hongyuan peat (Hong et al., 2003), pollen records from Lake Qinghai (Shen et al., 2005) as well as porewater δ 18 O values from Lake Chandratal (Kumar et al., 2020) have also suggested similar centennial climate fluctuations. A synthesis of all those records reveals that the climatic conditions on the TP might have been highly unstable throughout the Holocene.…”

“…Note the close correlation between those climate events and the Ice-rafted events in the North Atlantic. Lake Koucha (Mischke et al, 2008), δ 13 C values of cellulose remains from Hongyuan peat (Hong et al, 2003), pollen records from Lake Qinghai (Shen et al, 2005) as well as porewater δ 18 O values from Lake Chandratal (Kumar et al, 2020) have also suggested similar centennial climate fluctuations. A synthesis of all those records reveals that the climatic conditions on the TP might have been highly unstable throughout the Holocene.…”