Isotopic analyses of Ordovician-Silurian siliceous skeletons indicate silica-depleted Paleozoic oceans

Marine siliceous ecosystem decline led to sustained anomalous Early Triassic warmth

In the wake of rapid CO₂ release tied to the emplacement of the Siberian Traps, elevated temperatures were maintained for over five million years during the end-Permian biotic crisis. This protracted recovery defies our current understanding of climate regulation via the silicate weathering feedback, and hints at a fundamentally altered carbon and silica cycle. Here, we propose that the development of widespread marine anoxia and Si-rich conditions, linked to the collapse of the biological silica factory, warming, and increased weathering, was capable of trapping Earth’s system within a hyperthermal by enhancing ocean-atmosphere CO₂ recycling via authigenic clay formation. While solid-Earth degassing may have acted as a trigger, subsequent biotic feedbacks likely exacerbated and prolonged the environmental crisis. This refined view of the carbon-silica cycle highlights that the ecological success of siliceous organisms exerts a potentially significant influence on Earth’s climate regime.

The widespread disappearance of siliceous life sustained extreme temperatures in the wake of Earth’s most severe mass extinction event.