Inconsistent response patterns of snow cover duration and snow depth over the Tibetan Plateau to global warming

Snow cover possesses high albedo and thermal insulation properties, greatly influencing climate change and responding rapidly to climatic variation, particularly on the Tibetan Plateau. The region's combination of low latitude and intense solar radiation further amplifies the effects of climate change on snow cover. During the spring and summer seasons, changes to snow cover patterns driven by climate change initiate shifts in hydrological cycles, affecting freshwater availability and vegetation growth. However, previous studies investigating snow cover changes across the Tibetan Plateau have yielded inconsistent results due to the use of diverse datasets across varying periods. This study aims to analyze the response patterns of snow cover to climate change on the Tibetan Plateau by comparing trends in snow cover duration (SCD) and snow depth (SD) during spring and summer from 1990 to 2019. Based on the spatial distribution of changes in these two parameters, we categorized regions into four distinct types: areas where both snow cover duration and snow depth increase (SCD+SD+), areas where snow cover duration increase while snow depth decreases (SCD+SD−), areas where snow cover duration decrease while snow depth increases (SCD−SD+), and areas where both snow cover duration and snow depth decreases (SCD−SD−). Rising temperatures are driving a shift from snowfall to rainfall in lower-altitude regions, while high-altitude areas remain predominantly below freezing, limiting this conversion. By analyzing temperature and precipitation changes in the four areas, we observed that the response of snow cover duration to global warming is limited at altitudes above 4700 m during spring and summer, with an increases in spring snowfall dominating the overall rise of snow cover duration. In contrast, the declines in snow cover duration observed in lower-altitude areas are primarily attributed to warming effects, regardless of variations in snowfall. The snow depth variation is mainly influenced by winter snowfall trends during spring and summer. Furthermore, the negative trends (p < 0.05) in summer snowfall are mainly influenced by the increase (p < 0.05) summer temperatures. The study aids in understanding the complexity and inconsistencies of snow cover changes under the combined effects of climate change and altitudes.