The Permian- Triassic mass extinction (the “Great Dying”), ~251.9- 252 million years ago, was Earth’s most severe extinction event.

It eliminated roughly 81- 96% of marine species and about 70% of terrestrial vertebrate species, with major losses among insects, plants, and other groups as well. Recovery of ecosystems took millions of years.

The dominant driver was prolonged, massive eruptions of the Siberian Traps large igneous province in what is now Siberia. These flood- basalt eruptions released enormous volumes of CO₂, sulfur gases, halocarbons, and other volatiles over a geologically short interval (hundreds of thousands of years, with intense pulses). Contact metamorphism of coal- bearing and organic- rich sediments by the intruding magmas amplified greenhouse- gas and toxic- gas release.

The sudden rise in atmospheric greenhouse gases produced rapid global warming (estimates often cite several degrees Celsius on average, with larger extremes in some regions), intensified the hydrological cycle, and drove ocean warming.

Key secondary impacts included:

• Ocean acidification from elevated CO₂.
• Widespread marine anoxia (oxygen- depleted “dead zones”) and euxinia (hydrogen- sulfide- rich conditions).
• Disruption of the carbon cycle, with evidence from large negative carbon- isotope excursions.
• Terrestrial effects such as wildfires, soil erosion, and changes in vegetation and weathering patterns.

These stresses acted synergistically, collapsing food webs in the oceans and on land.

The extinction was not a single instantaneous catastrophe but a prolonged crisis with one or more intense pulses coinciding with the main volcanic activity.

The Siberian Traps eruptions acted as a powerful natural catalyst for extreme climate change.

The resulting greenhouse- driven warming, ocean chemistry shifts, and ecosystem collapse is the clearest deep- time analogue for the environmental consequences of a rapid, large- scale injection of greenhouse gases.

Modern anthropogenic CO₂ release is occurring far faster than the volcanic pulses of the end- Permian, but the end-Permian record shows how high greenhouse- gas levels and associated feedback can push the Earth system past tipping points that produce mass extinction.

Other contributing factors sometimes discussed (possible asteroid impact, methane hydrate release, or earlier climatic shifts) are secondary or poorly supported compared with the volcanic– climate cascade.

The event marks the boundary between the Paleozoic and Mesozoic eras and permanently altered the trajectory of life on Earth.

The Siberian Traps form one of Earth’s largest continental Large Igneous Provinces (LIPs), with estimated original volumes commonly in the range of ~2- 5 × 10⁶ km³ (some estimates higher, up to ~7- 15 × 10⁶ km³ including intrusive and eroded material).

Magmatism spanned the Permian- Triassic boundary (~252 Ma) over roughly 1 million years (or less for the main pulse), with intense phases lasting hundreds of thousands of years.

The prevailing model involves a thermochemical mantle plume (hotter by ~100- 300°C and chemically distinct) rising from the core- mantle boundary, possibly combined with lithospheric delamination.

Plume impingement on the base of the thick Siberian Craton lithosphere triggered extensive melting. Early melts often show deeper (garnet -field) origins with stronger pyroxenite contributions; later melts reflect shallower, more extensive melting of predominantly peridotitic mantle (with recycled components).

Alternative or complementary ideas include:

• Subduction- related hydration of the mantle transition zone (releasing water that lowers the solidus), consistent with the back- arc tectonic setting and some arc-like geochemical signatures (low Nb, high Pb/Sr/Ba) in low-Ti basalts.
• Lithospheric delamination or edge-driven convection (less favored for explaining the full volume and extent).
• Extraterrestrial impact (poorly supported).

Seismic data and geochemical progression (high-Ti early suites to low-Ti tholeiitic main phase, with late alkaline activity) support plume- related melting under thinned or eroded lithosphere, especially beneath the West Siberian Basin and Tunguska region.

Magma ascended through the crust and created a complex sub- volcanic plumbing system of dikes and especially extensive sills.

Sills comprise a large fraction of the total volume (estimates ~37- 50%). They preferentially intruded the thick (several km) sedimentary fill of the Tunguska Basin, which includes Cambrian evaporites (halite, anhydrite), carbonates, marls, siliciclastics, and Permian coal- bearing rocks.

Borehole data show abundant thick sills (>100 m common; averages 115- 130 m in evaporites; maximum recorded ~428 m). Evaporites acted as preferred horizons for melt accumulation due to their thermal and mechanical properties. Some individual sills may have exceeded thousands of km³.

Eruptive styles evolved in stages (based on high- precision U- Pb geochronology):

Early phase (pre- extinction): Widespread explosive pyroclastic and phreatomagmatic activity (interaction with groundwater or surface water), producing thick volcaniclastic breccias (up to ~1 km in places), followed by and interspersed with flood- basalt lava effusion. About two-thirds of the lava/pyroclastic volume erupted over ~300 kyr before and during the extinction onset.

Critical intrusive phase (coinciding with extinction ~251.9 Ma): Shift to dominant sill emplacement into volatile- rich sediments. This initial widespread sill pulse is widely regarded as the “deadly” interval because it maximized contact metamorphism of previously untapped sediments.

Later phases: Continued sill intrusion and renewed extrusive activity (including alkaline rocks) for hundreds of kyr after the main extinction.

Phreatomagmatism was important early on, with distributed vents. Flood basalts formed thick, stepwise (“trap”) plateaus of relatively volatile- poor tholeiitic lavas.

Direct magmatic degassing released CO₂, SO₂, H₂O, and halogens from the melts themselves. However, the dominant environmental driver was interaction with sedimentary host rocks:

Contact metamorphism around sills heated organic- rich sediments (coal, shale), carbonates, and evaporites, generating large volumes of thermogenic gases (CO₂, CH₄, SO₂, and halogenated compounds such as CH₃Cl and CH₃Br). Thermal modeling of sill cooling indicates contact aureoles can produce ~52- 80 tonnes of CO₂ per m² (from both marine and terrestrial carbon sources). Scaling suggests that only a small fraction (~0.7- 1.2%) of the sill- affected area in the Tunguska Basin could generate 1,000 Gt CO₂; basin- scale estimates reach on the order of 100,000 Gt CO₂.

Overpressure from gas generation fractured the rocks, forming degassing structures: hydrothermal vents, diatreme pipes, and magnetite- rich pipes (especially rooted in evaporites). These acted as conduits linking deep aureoles to the atmosphere, enabling rapid, explosive gas release. Crater- lake deposits and pipe structures are documented, particularly in southern parts of the basin.

The combination of high magma flux, sill- dominated intrusion into a volatile- fertile sedimentary basin, and efficient venting produced rapid greenhouse- gas loading, sulfur aerosols (short- term cooling pulses), ocean acidification, and other stresses that drove the end- Permian crisis. Mantle- derived and thermogenic carbon both contributed, with the intrusive- metamorphic component especially critical at the extinction onset.

In summary, the Siberian Traps mechanisms center on plume-driven melting, a shift from early explosive/effusive surface volcanism to extensive shallow sill intrusion into carbon- and sulfur- rich sediments, and efficient release of both magmatic and thermogenic volatiles through a network of pipes and vents.

This architecture distinguishes it from purely extrusive flood- basalt provinces and explains its outsized climatic and biotic impact.

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Early Triassic super- greenhouse climate driven by vegetation collapse

For a long time, the prolonged Early Triassic “super- greenhouse” (roughly 5 million years of extreme warmth after the Permian-Triassic mass extinction) was attributed mainly to the lingering effects of Siberian Traps volcanism and associated greenhouse-gas release. Once the main volcanic pulses ended, silicate weathering and organic- carbon burial were expected to draw CO₂ down relatively quickly (on the order of ~100,000 years). The fact that extreme temperatures persisted far longer remained a puzzle.

New fossil evidence (macrofossils, palynology, and related indicators), combined with climate- biogeochemical modeling, points to a different primary driver for the persistence: the collapse of terrestrial vegetation, especially tropical forests and peat-bforming ecosystems.

Nature Communications volume 16, Article number: 5400 (2025). Published 2 July 2025 (with a later author correction).

The Permian- Triassic Mass Extinction (PTME, ~252 Ma) was triggered by intense greenhouse warming from Siberian Traps volcanism (and associated thermogenic gas release). However, extreme “super-greenhouse” conditions persisted for roughly 5 million years into the Early Triassic, long after the main volcanic pulses should have been offset by silicate weathering and organic- carbon burial.

The authors argue that the key reason was the dramatic and prolonged collapse of terrestrial vegetation, especially in the tropics. Loss of plant biomass reduced organic- carbon sequestration and limited chemical weathering, locking the climate- carbon system into a higher- temperature steady state.

Methods and evidence

• Compiled a large plant fossil database (macrofossils and palynology) spanning the latest Permian to Middle Triassic.
• Produced stage-level spatio- temporal maps of plant productivity and diversity, normalized for fragmentation and sampling bias.
• Combined these with lithological climate indicators.
• Fed the reconstructed vegetation changes into a linked climate- biogeochemical model.

Results show major loss of low- latitude (tropical) plant productivity at the PTME, coinciding with the well-known multimillion- year “coal gap” (near- absence of peat/coal formation). Tropical peat- forming ecosystems, normally important CO₂ sinks, largely disappeared and recovered only slowly.

Implications

Vegetation collapse created positive feedback:

• Reduced organic- carbon burial.
• Restricted chemical (silicate) weathering.
• Sustained high atmospheric CO₂ and global temperatures for ~5 Myr.

The work supports the existence of thresholds in the climate- carbon system: once warming and vegetation loss cross a critical point, the Earth system can stabilize at a much hotter state until plants gradually recover (which began more substantially in the Middle Triassic).

This mechanism helps explain why temperatures did not return to pre- extinction levels within the expected ~100 kyr window after volcanic degassing ended. It complements earlier ideas about changes in weathering rates or reverse weathering but ties the prolonged hothouse more directly to the timing of terrestrial biotic recovery.

As a result, atmospheric CO₂ stayed elevated and the climate locked into a hotter steady state until vegetation gradually recovered in the Middle Triassic. The study frames this as evidence of a threshold in the climate- carbon system: once warming and vegetation collapse cross a critical point, positive feedback can amplify and prolong the greenhouse conditions far beyond the original volcanic trigger.

In short, the Siberian Traps ignited the crisis, but the near- destruction of tropical forests is what kept the planet in a super- greenhouse state for millions of years afterward. This highlights how tightly the biosphere regulates long- term climate and how its collapse can turn a severe but temporary warming event into a prolonged one.

The study reinforces the tight coupling between the biosphere and long- term climate regulation and illustrates how a mass extinction of plants can amplify and extend the climatic effects of large igneous province eruptions.

Published: Nature Communications volume 16, Article number: 5400 (2025)

DOI: 10.1038/s41467-025-60396-y

Authors: Zhen Xu, 
Jianxin Yu, 
Hongfu Yin, 
Andrew S. Merdith, 
Jason Hilton, 
Bethany J. Allen, 
Khushboo Gurung, 
Paul B. Wignall, 
Alexander M. Dunhill, 
Jun Shen, 
David Schwartzman, 
Yves Goddéris, 
Yannick Donnadieu, 
Yuxuan Wang, 
Yinggang Zhang, 
Simon W. Poulton & 
Benjamin J. W. Mills

Abstract

The Permian–Triassic Mass Extinction (PTME), the most severe crisis of the Phanerozoic, has been attributed to intense global warming triggered by Siberian Traps volcanism. However, it remains unclear why super-greenhouse conditions persisted for around five million years after the volcanic episode, with one possibility being that the slow recovery of plants limited carbon sequestration. Here we use fossil occurrences and lithological indicators of climate to reconstruct spatio-temporal maps of plant productivity changes through the PTME and employ climate-biogeochemical modelling to investigate the Early Triassic super-greenhouse. Our reconstructions show that terrestrial vegetation loss during the PTME, especially in tropical regions, resulted in an Earth system with low levels of organic carbon sequestration and restricted chemical weathering, resulting in prolonged high CO₂ levels. These results support the idea that thresholds exist in the climate-carbon system whereby warming can be amplified by vegetation collapse.