Volcanically driven Hg–C–S cycling and climatic change during the Late Paleozoic Ice Age

The driving mechanisms of climate change during the LPIA remain highly controversial, and cannot be entirely attributed to changes in atmospheric <i>p</i>CO₂ solely as commonly thought. Here we propose a new mechanism, volcanic C–S radiative forcing, by conducting a comprehensive study of the Lower Permian Lucaogou Formation in the Junggar Basin, northern Pangea. High-precision geochemical analyses and modeling reveal that volcanism drove synchronous changes in the Hg–C–S cycles, triggered fluctuations in the Early Permian carbon cycle and led to climate warming, while significantly altered the sulfur cycle, increasing sulfate aerosol concentrations and forcing rapid climate cooling. This implies that the dual radiative forcing effect of the volcanic C–S needs to be fully considered when explaining the short- and long-term climatic changes and glacial–interglacial cycles. Including the negative volcanic sulphate radiative forcing (VSRF) effects in an atmospheric <i>p</i>CO₂ model will result in better results coupled with the glacial evolution of the LPIA. The VSRF effects likely represent a long-overlooked yet crucial mechanism for initiating and sustaining low atmospheric <i>p</i>CO₂ levels and evolution of the LPIA.