Large igneous provinces erupt highly reactive, predominantly basaltic lavas onto Earth’s surface, which should boost the weathering flux leading to long-term CO₂ drawdown and cooling following cessation of volcanism. However, throughout Earth’s geological history, the aftermaths of multiple Phanerozoic large igneous provinces are marked by unexpectedly protracted climatic warming and delayed biotic recovery lasting millions of years beyond the most voluminous phases of extrusive volcanism. Here we conduct geodynamic modelling of mantle melting and thermomechanical modelling of magma transport to show that rheologic feedbacks in the crust can throttle eruption rates despite continued melt generation and CO₂ supply. Our results demonstrate how the mantle-derived flux of CO₂ to the atmosphere during large igneous provinces can decouple from rates of surface volcanism, representing an important flux driving long-term climate. Climate–biogeochemical modelling spanning intervals with temporally calibrated palaeoclimate data further shows how accounting for this non-eruptive cryptic CO₂ can help reconcile the life cycle of large igneous provinces with climate disruption and recovery during the Permian–Triassic, Mid-Miocene and other critical moments in Earth’s climate history. These findings underscore the key role that outgassing from intrusive magmas plays in modulating our planet’s surface environment.

大型火成岩省份在地球表面喷发，主要是玄武岩熔岩，这应该会增加风化通量，从而导致火山活动停止后 CO₂ 的长期吸收和冷却。然而，纵观地球的地质历史，多个显生代大型火成岩省份的后果以出乎意料的持久气候变暖和生物恢复延迟为标志，持续了数百万年，超过了喷发性火山活动最大量的阶段。在这里，我们对地幔熔化进行了地球动力学建模，并对岩浆输送进行了热力学建模，以表明尽管熔体持续产生和 CO₂ 供应，但地壳中的流变反馈会抑制喷发速度。我们的结果表明，在大型火成岩省份期间，地幔衍生的 CO₂ 通量如何与地表火山活动的速率脱钩，这是驱动长期气候的重要通量。跨越时间间隔的气候-生物地球化学模型与时间校准的古气候数据进一步表明，解释这种非喷发的神秘 CO₂ 如何帮助调和大型火成岩省份的生命周期与二叠纪-三叠纪、中新世中期和地球气候历史中其他关键时刻的气候破坏和恢复。这些发现强调了侵入性岩浆的脱气在调节地球表面环境方面的关键作用。