Heterogeneity in glacier thinning and slowdown of ice movement in the Garhwal Himalaya, India.

Limited ground-based surveys and extensive remote sensing analyses have confirmed glacier thinning in the Garhwal Himalaya. More detailed studies on specific glaciers and the drivers of reported changes are essential to comprehend small-scale differences in the effects of climatic warming on Himalayan glaciers. We computed elevation changes and surface flow distribution for 205 (≥0.1 km2) glaciers in the Alaknanda, Bhagirathi, and Mandakini basins, all located in the Garhwal Himalaya, India. This study also investigates a detailed integrated analysis of elevation changes and surface flow velocities for 23 glaciers with varying characteristics to understand the impact of ice thickness loss on overall glacier dynamics. We observed significant heterogeneity in glacier thinning and surface flow velocity patterns using temporal DEMs and optical satellite images with ground-based verification. The average thinning rate was found to be 0.07 ± 0.09 m a-1 from 2000 to 2015, and it increased to 0.31 ± 0.19 m a-1 from 2015 to 2020, with pronounced differences between individual glaciers. Between 2000 and 2015, Gangotri Glacier thinned nearly twice as much as the neighbouring Chorabari and Companion glaciers, which have thicker supraglacial debris that protects the beneath ice from melting. The transitional zone between debris-covered and clean ice glaciers showed substantial flow during the observation period. However, the lower reaches of their debris-covered terminus areas are almost stagnant. These glaciers experienced a significant slowdown (~25 %) between 1993-1994 and 2020-2021, and only the Gangotri Glacier was active even in its terminus region during most observational periods. The decreasing surface gradient reduces the driving stress and causes slow-down surface flow velocities and an increase in stagnant ice. Surface lowering of these glaciers may have substantial long-term impacts on downstream communities and lowland populations, including more frequent cryospheric hazards, which may threaten future water and livelihood security.

Emission of greenhouse gases due to anthropogenic activities: an environmental assessment from paddy rice fields.

Paddy rice fields (PRFs) are a potent source of global atmospheric greenhouse gases (GHGs), particularly CH4 and CO2. Despite socio-environmental importance, the emission of GHGs has rarely been measured from Haryana agricultural fields. We have used new technology to track ambient concentration and soil flux of GHGs (CH4, CO2, and H2O) near Karnal's Kuchpura agricultural fields, India. The observations were conducted using a Trace Gas Analyzer (TGA) and Soil Flux Smart Chamber over various parts, i.e., disturbed and undisturbed zone of PRFs. The undisturbed zone usually accounts for a maximum ambient concentration of ~ 2434.95 ppb and 492.46 ppm of CH4 and CO2, respectively, higher than the average global concentration. Soil flux of CH4 and CO2 was highly varied, ranging from 0.18 to 11.73 nmol m-2 s-1 and 0.13-4.98 µmol m-2 s-1, respectively. An insignificant correlation was observed between ambient concentration and soil flux of GHGs from PRFs. Waterlogged (i.e., irrigated and rain-fed) soil contributed slightly lower CH4 flux to the atmosphere. Interestingly, such an agricultural field shows low CO2 and CH4 fluxes compared to the field affected by the backfilling of rice husk ash (RHA). This article suggests farmers not mix RHA to increase soil fertility because of their adverse environmental effects. Also, this study is relevant in understanding the GHGs' emissions from paddy rice fields to the atmosphere, their impacts, and mitigating measures for a healthy ecosystem.

Aquatic geochemistry of a major freshwater lake in the Kashmir Himalaya: solute acquisition and denudation process in the lacustrine system.

Lakes, the main entities of lacustrine environments, are a rich archive of environmental and geogenic changes in terms of compositional variation of water and sediment. Water and sediment samples (N = 173) were collected during 2013-2014 from the Wular Lake, one of the important fresh lakes within the Indian landmass. The study provides insights on the solutes acquisition mechanism and provenance of ionic constituents within the lake water and the sediments. Besides, the impact of catchment attributes on the lake system was in addition assessed. The hydrochemical results suggest that the chemical weathering of silicate and carbonates within the catchment shapes the lake water chemistry and characterizes the facies pattern into a hybrid type. The geochemical results of the lake sediments demonstrate that the improved abrasion rates and ensuant settling of detritus into the lake are closely linked with the prominent physical weathering over chemical weathering. The new finding of the present study is that sediments represent an unweathered basalt compositional trend, plausible provenance from mafic rocks, experiencing low to moderate degree of chemical weathering. The study found that increased encroachment within the lake catchment due to continued anthropogenic forcing is the primary source contributing the organic matter (OM) as well as the higher levels of Cl, NO3, SO4, and P to the lake. These findings corroborate with the land use-land cover changes (from the last 50 years) within the lake catchment in significantly deteriorating the lake system. The study recommends that the ongoing conversion of lake peripheral areas into urban settlement and agro-horticulture land by filling activities should be restricted.

High-altitude meteorology of Indian Himalayan Region: complexities, effects, and resolutions.

The Himalaya, by virtue of its location and stupendous height, acts as a great climatic divide and regulates meteorological conditions in the subcontinent regions of South Asia. However, the associated complexities and their effects are yet to be resolved to understand the meteorology of the Indian Himalayan Region (IHR). In this review volume, we synthesize the results and inferences of several studies carried out in the IHR using in situ data, remotely sensed data, and model-based meteorological observations. Results provide insights into climate change, scientific gaps, and their causes in deciphering meteorological observations from the last century to recent decades and envisage impacts of climate change on water reservoirs in the future. Warming trend of air temperature, in contrast to global temperature, has been projected in recent decades (after 1990) with a greater warming rate in the maximum temperature than the minimum temperature. This drifting of air temperature from the beginning of last century accelerates the diurnal temperature range of the Himalayas. An elevation-dependent warming trend is mostly perceived in the northwest Himalayan region, implicating an increased warming rate in the Greater Himalaya as compared to the lower and Karakoram Himalaya. No definite trends of precipitation have been observed over different regions of the IHR, suggesting heterogeneous cryosphere-climate interaction between western and central Himalaya. In this review, we have tried to emphasize to the scientific community and policy-makers for enhancing the knowledge of physical and dynamical processes associated with meteorological parameters in the Himalayan terrain.