| Summary: | During the last three decades, the glacierised areas of the Himalaya have shown cooling and drying conditions, caused by higher ablation rates of glaciers in response to global warming (Salerno et al., 2023. Glacier feedback on Himalayan climate under global warming - this conference). While this local negative feedback does not preserve glaciers from melting, it could protect the periglacial environment, extending between the mean elevation of glaciers (~5400 m a.s.l.) and downslope areas (even below 4500 m a.s.l.). Across this elevation band, areas of permafrost are likely to exist. Here, we analyse the world’s longest time-series of soil temperature data (from 2003 to 2022) measured at a high-elevation station located close to the glacier masses (Pyramid, Mt Everest, 5035 m a.s.l.), together with climate observations, reanalysis (ERA5-Land), and remote sensing data (MODIS). We show that a diurnal cooling of soil temperature at 5-cm depth occurred in the last twenty years during summer in response to the air temperature decrease. Therefore, the glacier negative feedback has potentially slowed down or even preserved permafrost from thawing, thus potentially depicting a different picture from what is generally postulated for these Himalayan areas. However, in the region, there is a lack of long-term observations to confirm this hypothesis, thus the real implications of this process are currently unknown. Our analysis goes further in evaluating the potential impacts on snow cover and vegetation greening and more generally on how the glacier negative feedback has been able to protect the Himalayan periglacial environment.
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