Comparative assessment of two neighbouring glaciers (Raj Bank and Kosa), Dhauliganga Basin, central Himalaya, India, since 1962 to 2019

We examined the two neighbouring Raj Bank and Kosa glaciers of the upper Dhauliganga catchment of Uttarakhand, central Himalaya, India, to assess their variability towards climate change. We performed the analysis of multiple satellite images for the period of 1962–2019 and field-based GNSS data obtained during 2018–2019. Length change, area change, debris cover area, and snowline altitude (SLA) were obtained using that. During the last 57 years (1962–2019), the Raj Bank and Kosa glaciers lost 2.43% (0.32 km 2 or 0.006 km 2 a −1 ) and 4.54% (0.45 km 2 or 0.008 km 2 a −1 ) area; and for the same time span, their frontal retreat was estimated 639.39 m (11.22 m a −1 ) and 206.71 m (3.69 m a −1 ), respectively. The study also depicts that from 1968 to 2019, the Raj Bank glacier shows a significant increase in the debris cover area of 4.41%, while in the Kosa glacier, it was 4.08% only. Between 1968 and 2017, the SLA of the Raj Bank and Kosa glaciers shifted on an average by 82 and 71 m upwards, respectively. Loss in glacial area, enhanced debris cover area, and shift in SLA are the indicators of ice volume loss under the present climatic scenario. Research highlights Our findings show that both the neighbouring glaciers (Raj Bank and Kosa) not only losing their area and length, but also show an upshifts of the SLAs during the last 57 years (1962-2019). The debris cover areas of the glaciers are also increased during the study period. The retreat rate of the Raj Bank glacier was found higher compared to the Kosa glacier. During the above-mentioned study period, length wise a reduction of 6.2% and 1.8% was observed in the Raj bank and Kosa glaciers, while both the glaciers lost about 2.43% and 4.54% area respectively from 1962 to 2019. Besides global warming, we observed that the role of local topographical factors (i.e. altitude, size, slope, aspect and debris cover) have significant impact on glacial dynamics. The frontal retreat and area loss of both the glaciers suggest negative mass balance in response to the ongoing temperature rise. The observed heterogeneity in various glacier parameters of these two neighbouring glaciers is probably topographically induced.