Climate Change and Dynamics of Glaciers and Vegetation in the Himalaya: An Overview

Abstract

Mountains are globally signifi cant as 'water towers' of the Earth, as core areas of biodiversity and as source regions for important natural resources and ecosystem services. The ecological integrity of mountain environments is increasingly threatened by global environmental changes including climate change to which physical and ecological systems in mountains are highly vulnerable. Global warming rates have been higher in mountain regions compared to the global mean and have strongly affected the cryosphere, mountain biota and ecosystem processes.Temperature trends in most Himalayan regions substantially exceed the global mean trend of 0.85 °C between 1880 and 2012, with winter season temperature trends being generally higher than those of other seasons. Precipitation patterns are spatio-temporally differentiated, but show rather decreasing than increasing trends, in particular during summer. On average, glacier mass budgets have been negative for the past fi ve decades, with glaciers in the Himalaya and in the Hindu Kush showing distinct mass losses, while those in the Karakoram are close to balance. Shrinking rates are regionally variable, but often accelerating, corresponding approximately to a W-E gradient of increasing glacier retreat. Biotic responses to current climate change include elevational range shifts of species, intense recruitment of tree species in treeline ecotones and shifts in phenology, resulting in modifi ed structure, composition and functioning of Himalayan ecosystems.

Future Changes in Seasonal Temperature Over Pakistan in CMIP6

“…The EDW phenomenon is significantly increasing during winters and annual scale due to mechanisms involving snow-albedo positive feedback, nighttime cloud cover, higher midtroposphere water vapor, aerosols' concentration, and land-use changes at higher altitudes (Pepin et al, 2019;You et al, 2017You et al, , 2020. The future temperature surge under the aforementioned phenomenon of EDW will pose severe impacts on the hydrology (Hasnain, 2014), ecosystems (Schickhoff et al, 2016) and human development (Shrestha et al, 2015) of the HKH region. .…”

Species richness is a strong driver of forest biomass along broad bioclimatic gradients in the Himalayas

“…Thus, climate change can interact with diversity attributes affecting the large-scale production of biomass in the Himalayas. In addition, higher availability of water at our study sites may buffer against negative effects of climate change (principally climate warming) on biomass by reducing the susceptibility of trees to drought and by modulating the biotic interactions among tree species (Chhetri et al, 2020;Schickhoff et al, 2016;Sigdel et al, 2020).…”

“…A national inventory on biomass is documented based on the physiographical regions across Nepal (DFRS, 2015), while a limited research tried to detect factors governing biomass in tropical and temperate forests (Luintel et al, 2018; Måren & Sharma, 2021). The eastern Himalayan forests are anticipated to experience a severe loss in plant biodiversity as a result of climatic warming (Mittermeier et al, 2011) and increasing anthropogenic pressure (Chaudhary et al, 2015; Chettri et al, 2007; Schickhoff et al, 2016). Thus, an improved understanding of the current stock of forest biomass and its drivers is critical.…”