Local changes in snow depth dominate the evolving pattern of elevation-dependent warming on the Tibetan Plateau

Elevation-dependent warming (EDW), whereby warming rates are stratified by elevation, may increase the threat to the life-supporting solid water reservoir on the Tibetan Plateau. Previous studies have debated whether EDW exists and how it is driven. Using temperatures at 133 weather stations on the Tibetan Plateau during 17 different periods generated using a 30-year sliding window over 1973-2018, this study finds that the existence of EDW varies as the period moves forward, and critically it has become more severe over time. During the early part of the record with weaker regional warming, there were limited changes in snow depth and no EDW, but as time advances and regional warming intensifies, snow depth declines significantly at higher elevations, causing development of EDW. We conclude that enhanced regional warming has caused decreases in snow depth, largely controlling the pattern of EDW on the Tibetan Plateau. This may explain contrasting conclusions on EDW from previous studies which have used data for different periods, and our findings support enhanced EDW and more severe depletion of the Tibetan Plateau solid water reserves in a warmer future.

Status of glaciers and climate change of East Karakoram in early twenty-first century

This study aims to assess the glaciers change status in Shyok basin, East Karakoram in terms of area and mass balance, and to ascertain if glaciers in this part of Karakoram also display similar anomaly like central or western counterparts. The spatio-temporal monitoring of glaciers during the time frame of 24 years (1990/2000/2014) suggests major percentage of stable glaciers and insignificant retreat in the total glaciated area. The percentage of retreating glaciers has increased after year 2000. Area change analysis of glaciers having size >1 km² (569 glaciers) suggests the number of fluctuated glaciers have substantially increased i.e. overall 56% glaciers remained stable, 35% retreated and 9% advanced during 1990-2014. The geodetic based findings using SRTM-C (2000) and Cartosat-1 (2010/2011/2014) stereo-imageries for 201 glaciers suggest the mass loss at the rate of -0.10 ± 0.07 m w.e. a^-1. To better apprehend the status of glaciers changes in the region, climatic studies using in-situ observations as well as reanalysis dataset (ERA-I) were also undertaken of past 30 years. Therefore, this study is also a maiden attempt to ascertain if along with Karakoram anomaly, a climatic anomaly exists in the Eastern parts of Karakoram or not. A long term field collected snow-meteorological data of East Karakoram region suggests overall warming trend in annual temperature and no trend for snowfall during 1985-2015. The statistically significant increased rates of warming and decreased snowfall after year 2000 support the spatial variations in glaciers of East Karakoram and marginal mass loss. The observations of the marginal mass loss along with warming temperatures indicate that no Karakoram or climatic anomaly is existent over the East Karakoram region. Our study further refutes the prevalence of the elevation-dependent warming (EDW) over East Karakoram region vis-à-vis North-West Himalayan ranges. The impact of hiatus in global warming was also not observed over studied region.