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Despite several regional glacier and glacier lake inventories, the relationship between receding glacier, glacial lake evolution (glacial-lake interactions) and their sensitivity to different forcing factors have not been properly understood yet. To better understand these processes, we used satellite images collected in 1994, 2015 and 2017 to monitor the spatially-explicit evolution of glacial lakes and glacier changes. The results show a total of 1 353 glacial lakes covering an area of 7.96 km2 in the year 2015. Out of these, a total of 137 glacial lakes having an area of >0.01 km2 and located within 2 km periphery of mother glacier have been selected for the monitoring of spatial development between 1994 and 2017. We found an increase in the total lake area from ∼4.9 to ∼7.73 km2 between 1994 and 2017, corresponding to an overall expansion of ∼57%. The total area covered by the glaciers associated with these lakes reduced from ∼365 km2 in 1994 to ∼358 km2 in 2017, accounting for a glacier loss of ∼7 km2 and corresponding to ∼1.92% reduction. Our study results are in agreement with global glacier behavior, revealing a rapid glacier recession and accelerated glacial lake expansion under an unprecedented climate change scenario. In addition, the results suggest a significant reduction in the glacier area and a close relationship between the glacier melting and lake changes. [ABSTRACT FROM AUTHOR]

The Himalayan high mountain areas are more vulnerable to climate change and the awareness of its impacts among the natives is very crucial as well as beneficial to stakeholders and policymakers. The impacts of climate change via food security, water availability, natural hazards, agriculture, and livelihoods have a direct relation or threat to the lives of high mountain communities, as these areas are experiencing the immediate and greatest impacts of climate change. Although the tourism industry has become the backbone of the economy in these areas, a significant increase in tourist footfall has also impacted the environment, livelihoods, culture and food habits. To understand the local perceptions of climate change, a binary question-based survey (interview) was conducted in six main subdivisions of North Sikkim, which is a biodiversity and tourism hotspot. The data revealed that irrespective of the locality (urban/rural) people are aware of climate change. Significant coherence in the responses among gender and age groups, and between remote and developed areas exist. The transhumant herder populations are also well aware of climate change (80%). Peoples' perception about temperature change and the meteorological data are also consistent, however, a misperception is observed with the precipitation data. Decreasing snowfall patterns and increasing landslides in the higher altitudes are major concerns among the natives. The majority of people have denied any positive outcome of climate change and around 85% of the respondents are willing to participate at the community level in mitigation efforts to help curb climate change. [ABSTRACT FROM AUTHOR]

A 1.3-m-long sediment core from the Penzi-la pass, Zanskar Valley, provides a record of hydroclimatic conditions and abrupt climate changes over short time scales since the mid-Holocene. These climatic changes of centennial time scale are crucial to understanding the hydroclimatic variability in northwestern (NW) Himalaya. Relatively higher δ13C values complemented by total organic carbon, loss on ignition, grain size parameters, and lower Rubidium/Strontium ratios during the Late Northgrippian imply that the area had a dry climate during the period from ~6200–4500 cal yr BP. Subsequently, a relatively stable hydroclimatic environment was experienced between ~4500 and 3400 cal yr BP. After ~3400 cal yr BP the multiproxy data show gradual strengthening of hydroclimatic conditions, however, this trend is interrupted by high-amplitude abrupt reversals (dry events) with a stepwise decreasing intensity at ~3300, 2600, 1700, and 400 cal yr BP. The two most important climatic events of the last millennia (i.e., Medieval Climate Anomaly and the Little Ice Age) were also recorded from the sedimentary archive. Overall, our data show a progressive increase in the moisture availability in the Zanskar Valley and are in agreement with the late Holocene climatic trends of central and western Himalaya. [ABSTRACT FROM AUTHOR]

Glaciers in the Himalaya are generally showing a recessional pattern since the little ice age. In contrast to this, some glaciers in the Karakoram are either advancing or stagnant. Such behaviours of glaciers in the region have been termed as "Karakoram Anomaly" (Hewitt Kenneth, 2005; Raina, 2008; Kumar et al., 2015). In the present study, an attempt has been made to analyze the surging phenomena of four selected glaciers viz. Chong Kumdan, Kichik Kumdan, Aqtash and Rimo group of glaciers in the Shyok valley of Karakoram Himalaya; and also to analyze the inter-annual variations in their behaviour by using high temporal resolution remote sensing satellite images acquired from 1975 to 2013. These glaciers responded for surging phenomena differently in different time periods. The present study also fills the gaps of the earlier study of Bhambri et al. (2013) on the Rimo glacier, and demonstrates a different and unique pattern of snout movement. Findings of the present investigation depicts that the short-term variations in surging phenomena of the glaciers can be easily monitored using satellite images acquired from Indian Remote Sensing (IRS) Satellite and Landsat Satellite Sensor. Further, as it is well established that the surging phenomenon is a rapid process, we suggest that annual to biennial data should be used to monitor the movements and understanding the dynamics of surging process. [ABSTRACT FROM AUTHOR]

The late Quaternary glacier advances in the Himalayan orogen exhibit a complex interplay of insolation induced changes in summer monsoon and winter westerlies. However, the relative contributions of these moisture sources in driving the glacier advances in the Himalaya are still being debated. Additionally, uncertainties about the timing, and hence the processes, responsible for driving the penultimate Last Glacial Maximum (LGM) in the Central Himalaya, still persist. The present study attempts to address some of these issues by employing detailed moraine stratigraphy supplemented with luminescence dating of three moraine and two relict lake sequences in the Kunti-Banar valley of the Central Himalaya, India. The study revealed that the penultimate glacier advance was significantly more extensive compared to its LGM counterpart. Stratigraphically and chronologically correlated sequences indicate that the penultimate glacial advance corresponded to the cool and dry Marine Isotope Stage 4 (MIS 4) and pluvial early to middle MIS 3. The restricted LGM glacier advance is dated to ∼23 ± 4 ka; while the youngest glacial advance is dated to ∼16.6 ± 0.4 ka and corresponds to the oldest Dryas (OD). Geomorphologically, the oldest Kunti-Banar glacier advance (KBGA)-I moraine was responsible for the obstruction of the meltwater stream leading to the formation of a proglacial lake around 30 ± 3 ka. Similarly, the KBGA-II moraine is overlain by relict lake sediments, with an age range of ∼15 ± 1 ka to present, implying that deglaciation has occurred prior to it. Evidence from the Dhauliganga valley resonates reasonably well with the pattern of glacier advances from Central Himalaya implying the influence of mid-latitude, synoptic-scale climatic perturbations. Particularly, there seems to be a coupling between the enhanced mid-latitude westerlies and phases of glacier advance, whereas the deglaciation phases correspond to the insolation driven enhanced monsoon periods. • Kunti-Banar valley preserves evidence of Central Himalaya's oldest glacier advance. • Three prominent glacier advances extending back to MIS-4 have been identified. • KBGA-I dated between 81 and 41 ka represents the most extensive glacier advance. • KBGA-II dated between 26 and 21 ka broadly corresponds to LGM. • Glacier advances during MLW phases are coupled with Northern Hemisphere cooling. [ABSTRACT FROM AUTHOR]

The presence and extent of permafrost in the Himalaya, which is a vital component of the cryosphere, remains severely under-researched with its future climatic-driven trajectory only partly understood and the future consequences on high-altitude ecosystem tentatively sketched out. Previous studies and available permafrost maps for the Himalaya relied primarily upon the modelled meteorological inputs to further model the likelihood of permafrost. Here, as a maiden attempt, we have quantified the distribution of permafrost at 30 m grid-resolution in the Western Himalaya using observations from multisource satellite datasets for estimating input parameters, namely temperature, potential incoming solar radiation (PISR), slope, aspect and land use, and cover. The results have been compared to previous studies and have been validated through field investigations and geomorphological proxies associated with permafrost presence. A large part of the study area is barren land (~69%) due to its extremely resistive climate condition with ~62% of the total area having a mean annual air temperature of (MAAT) <1 °C. There is a high inter-annual variability indicated by varying standard deviation (1–3 °C) associated with MAAT with low standard deviation in southern part of the study area indicating low variations in areas with high temperatures and vice-versa. The majority of the study area is northerly (~36%) and southerly (~38%) oriented, receiving PISR between 1 and 2.5 MW/m2. The analysis of permafrost distribution using biennial mean air temperature (BMAT) for 2002-04 to 2018-20 suggests that the ~25% of the total study area has continuous permafrost, ~35% has discontinuous permafrost, ~1.5% has sporadic permafrost, and ~39% has no permafrost presence. The temporal analysis of permafrost distribution indicates a significant decrease in the permafrost cover in general and discontinuous permafrost in particular, from 2002-04 to 2018-20, with a loss of around 3% for the total area (~8340.48 km2). The present study will serve as an analogue for future permafrost studies to help understand the permafrost dynamics associated with the effects of the recent abrupt rise in temperature and change in precipitation pattern in the region. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pollen, δ13C and TOC data revealed vegetation and climatic changes of western Himalaya during the last 15 ka. • Expansion of arboreals between 12.7 and 9.2 ka suggests a warm and humid environment. • A warm and humid climate from 7.8 to 5.2 ka represents the Holocene Climate Optima. • Vegetation expansion (decline) with enhanced (weaker) monsoon periods implies vegetation sensitivity to insolation driven ISM. Multiproxy analyses of sediment samples from a 2.7 m trench from western Himalaya have helped in the reconstruction of vegetation and climatic changes during the last ∼ 15.2 ka. The data revealed that between 15.2 and 12.7 ka, the region supported alpine–scrubs and trees interspersed with meadows in a cool and moderately humid climate. The lowest d13C values and coarse-grained sediment texture indicate improved hydroclimatic conditions. The expansion of arboreals between 12.7 and 9.2 ka also suggests a warm and humid climate. Despite this, slightly higher d13C values reflect decreasing hydrological conditions. Reduced arboreals and increased d13C values imply a cold and dry climate between ca. 9.2 and 7.8 ka. The proliferation of arboreals supports a warm and humid climate from 7.8 to 5.2 ka, representing the Holocene Climate Optima. However, between 5.2 and 3.7 ka, a decrease in arboreals with associated d13C values suggest climate deterioration. Based on changes in arboreals and non–arboreals, the Late Holocene phases advocate for warm and wet (ca. 3.7–2.3 ka), cool and dry (ca. 2.3–1.7 ka), and warm and wet (1.5–0.75 ka) climatic conditions, respectively. Since 0.75 ka, a modest increase in arboreals, TOC, and a decrease in d13C values, implying that hydroclimatic conditions have improved. These findings are broadly consistent with previous Himalayan palaeoclimatic reconstructions; nevertheless, the absence of any major shift in vegetation during the younger Dryas is surprising. [ABSTRACT FROM AUTHOR]

Moraines, outwash gravel terraces, fluvial drapes and lacustrine sequences are used to infer the pattern of glacial fluctuations in the Saraswati valley (upper Ganga catchment). Located in transitional climatic zone between dry steppe of the Tibetan plateau in the north and sub-humid higher Himalaya in the south, the Saraswati valley has preserved evidence of four glacier advances. These are identified as the Saraswati Glacial Stage (SGS)-1 (oldest) to SGS-4 (youngest). Based on the relative dating and luminescence ages obtained on younger advances, the SGS-1 is ascribed to pre-Marine Isotopic Stage (MIS)-2. The SGS-2 is dated to the MIS-2 (24.5 ± 2.8–21.2 ± 2.0 ka); the SGS-3 is speculatively ascribed to the Younger Dryas (YD) and the SGS-4 is suggested to be of the mid-Holocene (~6 ka) age. The bifurcated moraine ridges of SGS-2 represent standstill conditions during the post-Last Glacial Maximum (LGM) period. The deglaciation is represented by outwash gravel terraces, impounded sedimentary (lacustrine) sequences and fluvial drapes overlying and abutting the moraines are dated to early-mid (11.9 ± 0.9–7.5 ± 0.6 ka) and late Holocene (3.3 ± 0.2–1.7 ± 0.3 ka) intensified/moderate Indian Summer Monsoon. Considering the timing of glacial advances and stand-still condition, it is proposed that across the orographic barrier (rain shadow valleys), glaciers responded sensitively to the intensified anticyclonic flow of the cooler Mid-latitude Westerlies; implying that in a monsoon dominated transient climatic zone, even the rain shadow valleys responded sensitively to temperature changes. • Transitional climate glaciers in central Himalaya responded to cool climate phases. • Advances were facilitated by enhanced winter snowfall due to orographic forcing. • The Mid-latitude Westerlies anticyclones played a critical role. • Retreat occurred during insolation driven strengthened/moderate monsoon. [ABSTRACT FROM AUTHOR]

Relying on the ability of pollen assemblages to differentiate among elevationally stratified vegetation zones, we assess the potential of a modern pollen-climate dataset from the Darjeeling area, eastern Himalaya, in past climate reconstructions. The dataset includes 73 surface samples from 25 sites collected from a c. 130–3600 m a.s.l. elevation gradient along a horizontal distance of c. 150 km and 124 terrestrial pollen taxa, which are analysed with respect to various climatic and environmental variables such as mean annual temperature (MAT), mean annual precipitation (MAP), mean temperature of coldest quarter (MTCQ), mean temperature of warmest quarter (MTWQ), mean precipitation of driest quarter (MPDQ), mean precipitation of wettest quarter (MPWQ), AET (actual evapotranspiration) and MI (moisture index). To check the reliability of the modern pollen-climate relationships different ordination methods are employed and subsequently tested with Huisman–Olff–Fresco (HOF) models. A series of pollen–climate parameter transfer functions using weighted-averaging regression and calibration partial least squares (WA-PLS) models are developed to reconstruct past climate changes from modern pollen data, and have been cross-validated. Results indicate that three of the environmental variables i.e., MTCQ, MPDQ and MI have strong potential for past climate reconstruction based on the available surface pollen dataset. The potential of the present modern pollen-climate relationship for regional quantitative paleoclimate reconstruction is further tested on a Late Quaternary fossil pollen profile from the Darjeeling foothill region with previously reconstructed and quantified climate. The good agreement with existing data allows for new insights in the hydroclimatic conditions during the Last glacial maxima (LGM) with (winter) temperature being the dominant controlling factor for glacial changes during the LGM in the eastern Himalaya. [ABSTRACT FROM AUTHOR]