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The global carbon balance is a core issue in climate change research and a focus of international policy concern [[1]]. Through the close relationships between CO SB 2 sb flux and soil temperature, combined with historical soil temperature data in the study area at 0 and 10 cm every hour between 2004 and 2017, we estimated the total amount of CO SB 2 sb exchange per year in the TD shifting sand (Fig. An average of 6.71 × 10 SP 6 sp t of CO SB 2 sb per year was released to the atmosphere through the physical process of thermal expansion of soil air containing CO SB 2 sb in the TD shifting sand during 2004-2017. Besides, the combined action of the remaining components (salt/alkali + moisture + microbes) led the TD shifting sand to absorb atmospheric CO SB 2 sb , with an average absorption rate of 8.31 × 10 SP 6 sp t a SP -1 sp during 2004-2017. [Extracted from the article]

• Shifting sand in the Taklimakan Desert can sequester CO 2 at an uptake rate of 7.11 g m−2·a−1. • Soil respiration in the desert is dominated by soil air expansion/contraction and salt/alkali effects. • The carbon sink rate of shifting sand in Taklimakan Desert will decrease in the future. An understanding of the global terrestrial carbon cycle is crucial to predict future climate change. Deserts are an important part of the terrestrial ecosystem, but their role in the terrestrial carbon cycle has long been neglected. Recent studies have shown that deserts may sequester enormous volumes of CO 2 and play a pivotal role as a carbon sink. As the world's second-largest shifting desert, the Taklimakan Desert (TD) contributes substantially to the global desert carbon sink. However, the contributions of the internal processes of the TD to its carbon sink and the long-term trend of the carbon sink under climate change are still unclear. Based on an observational study, we determined that both the expansion/contraction of soil air containing CO 2 caused by heat fluctuation in shifting sand and the salt/alkali chemistry control the release/absorption processes of soil respiration in shifting sand. Besides, the mutual offset of these processes indicates that the shifting sand in the TD acts as a stable carbon sink at present, with an annual average CO 2 uptake rate of 7.11 g m−2. However, an increase in soil temperature difference will stimulate soil air expansion and release more CO 2 into the atmosphere under climate change, gradually lessening the carbon sink rate of shifting sand in TD in the future. These processes will be accelerated by a positive feedback loop, where this effect triggered by climate change will enhance regional warming. Our results highlight the status of deserts in the global carbon cycle and provide crucial information regarding the world's missing carbon sink. [ABSTRACT FROM AUTHOR]