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The Mass Extinction Event of about 252 million years ago has been described as The Great Dying. This end-Permian event caused the extinction of about 90% of species on Earth. For many years, paleoecologists and climate scientists have believed this event would not be eclipsed. It would go down in history as the worst of the Mass Extinction Events, never to be outdone.
Along comes the Intergovernmental Panel on Climate Change, the IPCC. Designed-to-fail when it was created during the Ronald Reagan administration, the IPCC has concluded that the end-Permian Mass Extinction Event is minor compared to the current one. It’s not even close. No previous Mass Extinction Event comes close to the ongoing event. Consider the language used in the IPCC’s Global Warming of 1.5°, a report published 8 October 2018: “These global-level rates of human-driven change far exceed the rates of change that have altered the Earth System trajectory in the past …; even abrupt geophysical events do not approach currents rates of human-driven change.” As with all reports published by the IPCC, Global Warming of 1.5° relies on peer-reviewed publications to reach this conclusion.
As I have mentioned previously in this space, the IPCC is scientifically conservative, as pointed out by the scientifically conservative peer-reviewed literature. Consider this title, which refers to the IPCC, for the March 2019 issue of BioScience: “Statistical Language Backs Conservatism in Climate-Change Assessments.” This peer-reviewed paper includes this language in the Abstract: “We found that the tone of the IPCC's probabilistic language is remarkably conservative …, and emanates from the IPCC recommendations themselves, complexity of climate research, and exposure to politically motivated debates.”
Politically motivated debates? I suspect those are just getting started as Round Two of the Trump administration pushes its anti-science agenda into the public sphere.
President Trump has distanced himself from science and scientists by claiming anthropogenic climate change is a hoax. Coupled with many other equally bizarre statements, the idea that anthropogenic climate change is a hoax borders on insanity. It is rooted in belief, not science. Rational thought seems stunningly absent from the Trump administration. The rabid pursuit of personal wealth is among the defining characteristics of Trump and his ilk. Justifying this behavior and the underlying belief system is characteristic of cults, not rationalists. Rationalists appear to be absent from Trump’s cabinet and his advisers.
A peer-reviewed, open-access paper published in the renowned Nature series of publications addresses the end-Permian Mass Extinction Event. Published on 2 July 2025, the paper was penned by 17 scholars and titled Early Triassic super-greenhouse climate driven by vegetation collapse. Referring to the end-Permian Mass Extinction Event as the Permian-Triassic Mass Extinction, the Abstract includes this information: “The Permian–Triassic Mass Extinction …, 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 … [Permian-Triassic Mass Extinction] and employ climate-biogeochemical modelling to investigate the Early Triassic super-greenhouse. Our reconstructions show that terrestrial vegetation loss during the … [Permian-Triassic Mass Extinction], 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.”
“[T]he idea that thresholds exist in the climate-carbon system” has long been understood. The notion that “warming can be amplified by vegetation collapse” is not surprising.
Beneath a section titled Discussions, we find this information: “[T]he reduction in continental silicate weathering intensity caused by decreased plant productivity had a greater impact on increasing atmospheric CO2 than the direct effect of a decline in organic carbon burial ... This is because while the large reduction in terrestrially derived organic carbon burial acts to increase CO2 levels, it also decreases atmospheric oxygen levels and redistributes nutrients to the ocean, meaning that more marine organic carbon is produced and preserved, and less fossil organic carbon is weathered.”
Surprisingly, the paper then describes under-predictions of the magnitude of temperature rise: “The negative feedback on the organic carbon cycle may be too strong, which may be why SCION fails to replicate more rapid variation in Phanerozoic atmospheric O2.”
SCION is a widely used global climate-biogeochemical model that links steady-state 3D climate and surface processes to a biogeochemical box model. As explained in the peer-reviewed paper, which relies upon many other peer-reviewed papers, “the weathering of sedimentary organic carbon likely increases with temperature, which is not accounted for in the model, and may nullify these negative feedbacks further. A further uncertainty in our modeling is the degree to which plants amplify continental weathering … with the ‘best guess’ values from Phanerozoic-scale models of plant weathering strength … producing different magnitudes of warming. Previously suggested mechanisms for Early Triassic warmth, such as limited erosion rates or amplified reverse weathering, also potentially played a part in the extreme warmth. They are not included in our model due to the difficulty in quantifying their magnitudes and their timeframes of operation, but they could feasibly raise CO2 and surface temperature further.”
In other words, this peer-reviewed paper relies on additional evidence and the current findings to conclude that, as with many other peer-reviewed papers, the results are probably scientifically conservative. The conservative language continues: “we show that the large and prolonged decrease in tropical plant productivity in the Early Triassic likely resulted in a world that was lethally hot by Phanerozoic standards, a consequence of substantially weakened terrestrial carbon sequestration rates. These conditions persisted for nearly five million years and cooling was only achieved as plant productivity began to increase in the Middle Triassic. We believe this case study indicates that beyond a certain global temperature, vegetation die-back will occur, and can result in further warming through removal of vegetation carbon sinks. Our study demonstrates that thresholds exist in the Earth system that can accelerate climate change and have the potential to maintain adverse climate states for millions of years, with dramatic implications for global ecosystem behavior.”
The idea that “thresholds exist in the Earth system that can accelerate climate change and have the potential to maintain adverse climate states for millions of years” is an understatement. As demonstrated by earlier peer-reviewed research, the “adverse climate states” may well carry over to the extinction of all life on Earth.
I understand the propensity for understatement in peer-reviewed papers. In addition to the process of peer-review leading to scientific conservatism, I doubt any ecologist desires the extinction of all life on Earth. These are people who chose careers based on their interest in, and love for, life. I cannot imagine other ecologists desiring the loss of complex life. It’s what I live for, and I doubt I’m alone in that thought.
Hi Guy, hope you're well and always appreciate your work, however this piece is way too erudite for my medically/psychiatrically trained and now COVID-19 and prostate cancer/chemical castration befuddled mind. I know Trump's madness to a "t" and trying to rationalize the ravings of a mind functioning at the level of a 2yo is a fool's errand. A Swiss psychoanalyst, Alice Miller, wrote and published in 1983 an analysis of the childhood trauma, development, and well known outcome of Adolf Hitler, which I find on a parallel trajectory to DJT. It will blow your fine mind and I'd love to hear your response. Simply put, we have a bone fide madman at the helm of the ship of state with deep self-destructive intent. What could go wrong? Everything.
This paper got some media coverage when it was released. Both CNN and the Conversation did articles on it and talked to the authors.
The Conversation article was exceptionally good.
The trigger for the Permian–Triassic mass extinction event was the eruption of massive amounts of molten rock in modern day Siberia, named the Siberian Traps.
On land it is thought surface temperatures increased by as much as +10°C to +14°C (from 18°C (64°F) to around 30°C (86°F)) too rapidly for many life forms to evolve and adapt.
In other similar eruptions, the climate system usually returns to its previous state within 100,000 to a million years. But these “super greenhouse” conditions, which resulted in equatorial average surface temperatures upwards of 34°C (93°F) persisted for roughly five million years. In our study we sought to answer why.
We analysed how the biomes changed from just before the mass extinction event, until about eight million years after.
We hypothesized that Earth warmed too rapidly, leading to the dying out of low- to mid-latitude vegetation, especially the rainforests. As a result the efficiency of the organic carbon cycle was greatly reduced immediately after the volcanic eruptions.
Plants, because they are unable to simply get up and move, were very strongly affected by the changing conditions.
Before the event, many peat bogs and tropical and subtropical forests existed around the equator and soaked up carbon. However, when we reconstructed plant fossils from fieldwork, records and databases around the event we saw that these biomes were completely wiped out from the tropical continents. This led to a multimillion year “coal gap” in the geological record.
The tropical forests were replaced by tiny lycopods, only two to 20 centimetres in height. Nothing would have been growing higher than your knees by the end of the Permian and Early Triassic.
Enclaves of larger plants remained towards the poles, in coastal and in slightly mountainous regions where the temperature was slightly cooler. After about five million years they had mostly recolonized Earth. However these types of plants were also less efficient at fixing carbon in the organic carbon cycle.
We found that the initial increase in temperature from the Siberian Traps was preserved for five to six million years after the event because of the reduction in net primary productivity.
"Nothing would have been growing higher than your knees by the end of the Permian and Early Triassic."
Analysis indicates that global "forest death" starts if temperatures increase rapidly by +8°C. It's simply too much for trees to adapt to if they don't have enough time.
I'm afraid that's where we are headed.
The paleoclimate record indicates that each iteration of 2XCO2 is +8°C of warming.
180ppm to 360ppm = +8°C
360ppm to 720ppm = another +8°C
We are at 425ppmCO2 with a CH4 level 1900ppb and an albedo decline of -0.5% since 2014.
425ppmCO2 + 100ppmCO2e (for the CH4) +138ppmCO2e (for the forcing caused by albedo dimming)
Puts us at about a level of 660ppmCO2e as of right now.
With yearly increases of +3ppm/year in the CO2 levels.
We could hit 720ppmCO2e in about 20 years.