The research team, led by Professors Ganlin Zhang from the Institute of Soil Science, Chinese Academy of Sciences, has made significant progress in understanding how SIC responds to climate change.
SIC—primarily in the form of carbonate minerals such as CaCO 3 —is the dominant carbon (C) pool in more than half of the world’s soils, storing an estimated 2,305 petagrams (Pg) of C within the top 2 m. For decades, this vast reservoir has been regarded as geochemically stable, with residence times at the scale of millennia under natural conditions. However, emerging evidence now challenges this long-standing paradigm, revealing the unprecedented sensitivity of SIC pools to contemporary environmental perturbations.
The team has developed a novel process-based Soil Inorganic Carbon Turnover Model (SINOCOM) with a vertical resolution of 10 cm to quantify the effects of climate change on SIC dynamics across China from 2015 to 2100. The model integrates a physically based soil water balance module with carbonate geochemical equilibrium, excluding acidification processes, to isolate climate-driven effects on SIC. The water balance module regulates SIC leaching and accumulation through precipitation and evapotranspiration. The carbonate equilibrium module exerts its influence through temperature, net primary productivity and CO 2 -driven carbonate dissolution and precipitation reactions.
A substantial decline in the total SIC stock of 209–225 Tg in 2 m soils in China is projected from 2015 to 2100 under the four SSPs. A total SIC loss of 307–321 Tg will occur in the topsoil (0–10 cm). Semi-arid regions experience more severe total topsoil SIC loss (124 Tg C, 10.5%) than those in humid (107 Tg C, 51.7%), dry sub-humid (63 Tg C, 40.0%), arid (16 Tg C, 1.1%), and hyper arid (1 Tg C, 0.2%) regions. Approximately 1% of topsoil SIC is lost through groundwater into aquatic systems (lateral export), whereas 29% to 31% of SIC is leached and accumulated in 10–200 cm soil layers, and the remaining 68% to 70% is leached out of the 200 cm soil layer (vertical translocation).
The study also highlights notable seasonality of the temporal SIC fluxes. Warm-season precipitation (March to August) in arid climates accounts for 68% of the mean annual input and results in 85% of the mean annual SIC loss. Similarly, intense seasonal precipitation accounts for 76–81% of the mean annual SIC loss under humid conditions. These findings challeng previous empirical models that emphasized mean annual precipitation as the sole predictor.
Overall, this work challenges the traditional view of SIC stability in terrestrial carbon cycles. By integrating climate change, hydrological processes, and carbonate chemical equilibrium modules, SINOCOM clarifies the climatic controls on SIC redistribution, reveals the relative contributions of SIC vertical translocation and hydrological export, and may provide a mechanistic foundation for improving predictions of SIC dynamics under climate change.
National Science Review
Experimental study