Quantifying the contribution of climate change and human activities to surface drought in Qinghai, northeastern Qinghai-Tibetan Plateau

Quantifying the change of drought and their driving mechanisms is essential for monitoring land surface environmental changes and for understanding the land–atmosphere interaction in the arid region. Most researches are limited to average climate change, whereas the response analysis of extreme climate, the interaction of different climate factors and human activities to changes in drought are still lacking or not comprehensively considered. Firstly, we employed the temperature vegetation dryness index (TVDI), which associates land surface temperature with vegetation cover, to explore the spatiotemporal variation of drought across seasons in Qinghai province. Then, we specifically quantify the contribution of different climate factors and human activities to surface drought. Our findings revealed that drought exhibited upchange covering 73.71% in spring, 19.32% in summer, and 89.25% in winter, while autumn witnessed an decreasing trend in TVDI, with a rate of decrease exceeding 0.005 per year. Notably, drought in the meadow region was primarily influenced by average climate change. In the shrub-tussock region, extreme climate factors predominantly affected drought during spring and winter, whereas average climate change played a greater role during summer and autumn. The sensitivity of drought to temperature was greater than precipitation during spring and autumn, whereas the reverse was observed during summer and winter. In the steppe, swamp, and desert region, drought was mainly driven by average climate change during spring but by extreme climate events during summer, autumn, and winter. Furthermore, we discovered that the interaction between any two climate factors had a stronger explanatory power for the spatial distribution of drought in the steppe and desert region. The effect of the interaction between any two environmental factors on the TVDI was greater than that of a single climate factor. In summary, our study demonstrated significant spatiotemporal variations in the response of drought to different environmental factors across various grassland types and seasons, highlighting the importance of considering the interactions between environmental factors in understanding drought dynamics.