Dataset construction of CO 2 flux over shifting sand in the Taklimakan Desert and assessment of carbon sequestration capacity

Desert ecosystems, which cover extensive global regions, play an essential yet often-overlooked role in sequestering atmospheric CO 2 at substantial yet gradual rates, primarily due to insufficient monitoring, data scarcity, and limited research attention. Current assessments of terrestrial carbon sinks often exclude desert areas, creating critical "data gaps" that undermine the completeness and accuracy of global carbon budget evaluations. Focusing on the Taklimakan Desert, we developed a highresolution CO 2 flux dataset for shifting sand areas, featuring hourly temporal resolution and 0.25°×0.25° spatial coverage, through an empirical estimation scheme incorporating internal carbon sequestration processes, ERA5 (the fifthgeneration ECMWF atmospheric reanalysis of the global climate) multi-layer soil temperature/moisture data, and extensive field-measured soil properties (soil organic carbon, SOC; pH). Our analysis reveals that spatiotemporal CO 2 flux patterns are jointly controlled by shifting sand temperature, moisture, and soil characteristics, with the shifting sand area of the entire desert sequestering approximately 1.05×10 6 t CO 2 annually. While two-thirds of the area functions as carbon sinks, the northwestern margins (one-third of the total area) exhibit carbon-source behaviour (peaking at 64.49 g m -2 a -1 ) due to higher precipitation and organic carbon content. The ongoing warm-wetting trend in northwestern China is reducing both the stability and rate of carbon sequestration in these shifting sands, processes that may accelerate through climate change feedbacks. These findings provide critical scientific evidence for assessing the role of the desert in climate mitigation and inform policy-making for carbon neutrality strategies.