Mercury Isotopes Track the Causes of Carbon Perturbations in the Early Permian Ocean and Continent

Abstract The Early Permian witnessed the first icehouse‐to‐greenhouse turnover of the vegetated Earth, yet its climate dynamics remain enigmatic. Here, we used mercury (Hg) isotopes from pelagic and continental successions at low paleo‐latitudes to track the perturbations of the global carbon (C) cycle and the climatic impact. Our results indicate that small‐scale volcanism promoted marine organic C burial, and the concomitant extreme cooling triggered the waning of wetland ecosystems in North China block at ∼296.2 Ma. Subsequently, the mass‐independent fractionation of odd Hg isotopes (Δ199Hg) and C isotopes synchronously decline in the deep‐marine succession, likely supporting progressive oxidation of terrestrial biomass and airborne release of Hg and C. Lowered C sequestration (as coal swamps) on land and dampened continental weathering limited the drawdown of CO2 emissions from wildfires, initiating deglaciation. Our findings highlight that the climate forcing on terrestrial ecosystems could activate additional C reservoirs, driving Earth into a warmer state.