The frequency and the intensity of extreme temperature events have both increased globally because of the effects of climate warming. Such extreme events should be distinct in high-elevation areas owing to the phenomenon of elevation-dependent warming; however, corroborating evidence remains limited because of scarce observations. This study used the percentile method to identify annual extreme temperature events recorded in the delta O-18 of the Laohugou ice core (1960-2006) retrieved from the high-elevation area of the northeastern Tibetan Plateau (NETP). Comparison of these events with synchronous observations obtained at surrounding meteorological stations indicated that extreme temperature events identified from the ice core corresponded well with most temperature observations from the meteorological stations, suggesting that the delta O-18 record could be considered a reasonable proxy for regional temperature. However, occasional discord between the ice core and station records might reflect specific climatic shifts. Using circulation synthesis, the influencing circulation mechanism of each event was determined on the basis of differences in atmospheric parameters between each event and the average climatic state during 1970-2000. A double blocking high with warming over the Ural Mountains and east of Kuril-Kamchatka resulted in Eurasian warming, which transported warm air to the NETP and triggered the extreme high-temperature events. Conversely, a polar vortex in the Arctic led to a cold low over Eurasia, which transported cold air to the NETP causing extreme low-temperature events. The finding that variation of the Arctic air mass triggers extreme temperature events at high elevations in the NETP provides crucial insight for improved comprehension and forecasting of regional extreme temperature events.

Permafrost serves as a natural cold reservoir for viral communities. However, little is known about the viromes in deep permafrost soil, as most studies of permafrost were restricted to shallow areas. Here, permafrost soil samples of up to 100 m in depth were collected from two sites in the Tuotuo River permafrost area on the Tibetan Plateau. We investigated the viral composition in these permafrost soil samples and analyzed the relationship of viral composition and diversity along with depths. Our study revealed that greater permafrost thickness corresponds to higher diversity within the viral community. Bacteriophages were found to be the dominant viral communities, with kill the winner dynamics observed within the Siphoviridae and Myoviridae. The abundance and diversity of viral communities may follow a potential pattern along soil layers and depths, influenced by pH, trace elements, and permafrost thickness. Notably, strong correlations were discovered between the content of inorganic elements, including B, Mg, Cr, Bi, Ti, Na, Ni, and Cu, and the viral composition. Moreover, we discovered highly conserved sequences of giant viruses at depth of 10, 20, and 50 m in permafrost, which play a crucial role in evolutionary processes. These findings provide valuable insights into the viral community patterns from shallow to 100 -m -depth in high -elevation permafrost, offering crucial data support for the formulation of strategies for permafrost thaw caused by climate change and anthropogenic activities.