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Mass Extinctions (Overall; In General)

The asteroid that wiped out most life on Earth was a hotbed for bacteria. They were the first organisms to bounce back

Source: CNN
Date: 4 February, 2020

(CNN)The asteroid that wiped out the dinosaurs some 66 million years ago almost took all of life on Earth along with it.

The impact of the Chicxulub asteroid devastated 76% of all species and nearly all of the planet's vegetation. Because dust clouded the atmosphere and blocked the sun, photosynthesis slowed and phytoplankton in oceans stopped producing oxygen.

It was dark, extremely hot in the crater left by the asteroid and extremely cold everywhere else -- conditions that made it impossible for most life to thrive.

Why did the dinosaurs go extinct? New study hopes to put debate to rest

But in the days, weeks and decades after the catastrophic event, microbacteria were swept back into the crater.

"We're talking about organisms recovering within days to decades,"said Timothy Bralower, professor of geosciences at Pennsylvania State University. "From a geological viewpoint, that discovery is pretty major."

Millions of years after the asteroid struck, geologists drilled into the asteroid's peak ring -- the center of the crater -- and based on the biomarkers left behind by microbacteria millions of years earlier, they knit together a timeline of how life returned after the asteroid hit.

The findings were published last month in the journal Geology.

https://amp-cnn-com.cdn.ampproject....w.google.com%26amp_tf%3DFrom%2520%25251%2524s
 
Newly published research implicates a major collapse in the earth's ozone layer as a key factor in the Late Devonian mass extinction event.
Study shows erosion of ozone layer responsible for mass extinction event

Researchers at the University of Southampton have shown that an extinction event 360 million years ago, that killed much of the Earth's plant and freshwater aquatic life, was caused by a brief breakdown of the ozone layer that shields the Earth from damaging ultraviolet (UV) radiation. This is a newly discovered extinction mechanism with profound implications for our warming world today.

There have been a number of mass extinction in the geological past. Only one was caused by an asteroid hitting the Earth, which was 66 million years ago when the dinosaurs became extinct. Three of the others, including the end Permian Great Dying, 252 million years ago, were caused by huge continental scale volcanic eruptions that destabilised the Earth's atmospheres and oceans.

Now, scientists have found evidence showing it was high levels of UV radiation which collapsed forest ecosystems and killed off many species of fish and tetrapods (our four limbed ancestors) at the end of the Devonian geological period, 359 million years ago. This damaging burst of UV radiation occurred as part of one of the Earth's climate cycles, rather than being caused by a huge volcanic eruption.

The ozone collapse occurred as the climate rapidly warmed following an intense ice age and the researchers suggest that the Earth today could reach comparable temperatures, possibly triggering a similar event. Their findings are published in the journal Science Advances. ...

The scientists concluded that, during a time of rapid global warming, the ozone layer collapsed for a short period, exposing life on Earth to harmful levels of UV radiation and triggering a mass extinction event on land and in shallow water at the Devonian-Carboniferous boundary.

Following melting of the ice sheets, the climate was very warm, with the increased heat above continents pushing more naturally generated ozone destroying chemicals into the upper atmosphere. This let in high levels of UV-B radiation for several thousand years.

Lead researcher Professor John Marshall, of the University of Southampton's School of Ocean and Earth Science, who is a National Geographic Explorer, comments: "Our ozone shield vanished for a short time in this ancient period, coinciding with a brief and quick warming of the Earth. Our ozone layer is naturally in a state of flux - constantly being created and lost - and we have shown this happened in the past too, without a catalyst such as a continental scale volcanic eruption." ....

Professor Marshall says his team's findings have startling implications for life on Earth today: "Current estimates suggest we will reach similar global temperatures to those of 360 million years ago, with the possibility that a similar collapse of the ozone layer could occur again, exposing surface and shallow sea life to deadly radiation. This would move us from the current state of climate change, to a climate emergency." ...
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FULL STORY:
https://www.eurekalert.org/pub_releases/2020-05/uos-sse052620.php

THE FULL RESEARCH ARTICLE:
https://advances.sciencemag.org/content/6/22/eaba0768
 
EnolaGaia said:
Newly published research implicates a major collapse in the earth's ozone layer as a key factor in the Late Devonian mass extinction event.
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Thankfully we beat that little ecological catastrophe.
 
Mythopoeika said:
Was that caused by CFCs? Or lots of sun activity?
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Significant warming led to massively increased production of chlorine monoxide (ClO) in the stratosphere. ClO is formed when chlorine reacts with ozone.

This ClO formation is same ozone-destroying chemical reaction fostered by CFCs, which decompose to release free chlorine in the upper atmosphere.
 
EnolaGaia said:
Significant warming led to massively increased production of chlorine monoxide (ClO) in the stratosphere. ClO is formed when chlorine reacts with ozone.

This ClO formation is same ozone-destroying chemical reaction fostered by CFCs, which decompose to release free chlorine in the upper atmosphere.
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So no need for human involvement (what with humans not being around).
 
Mythopoeika said:
So no need for human involvement (what with humans not being around).
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Right. In this case, the researchers hypothesize the chlorine was released by decomposition of organic material, which was massively accumulating during the period of increased temperatures. In combination, these factors set up a runaway positive feedback loop with increased atmospheric ClO production as a side-effect.
 
Mythopoeika said:
Was that caused by CFCs? Or lots of sun activity?
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Definitely CFCs. We know this because since we have stopped producing CFCs the hole has repaired itself consistently over the last few decades and is now almost gone entirely.
 
The Late Ordovician extinction event has always been difficult to explain. Newly published research results suggest the primary cause was extreme vulcanism and subsequent warming rather than (e.g.) a gamma ray burst or the glaciations known to have occurred around that time.
Familiar Culprit May Have Caused Mysterious Mass Extinction

A planet heated by giant volcanic eruptions drove the earliest known wipeout of life on Earth.

It has long been our planet’s greatest and oldest murder mystery. Roughly 445 million years ago, around 85 percent of all marine species disappeared in a geologic flash known as the Late Ordovician mass extinction. But scientists have long debated this whodunit, in contrast to clearer explanations for Earth’s other mass extinctions.

“The Ordovician one has always been a little bit of an oddball,” said Stephen Grasby of the Geological Survey of Canada.

Now he and David Bond of the University of Hull in England say they have cracked the case in a study published last month in the journal Geology. Widespread volcanic eruptions unleashed enough carbon dioxide to heat up the planet and trigger two pulses of extinction separated by 1 million years, they report. If true, it places the first grand wipeout of life on Earth in good company: Many of the other major mass extinctions are also thought to be victims of global warming.

Scientists have offered a range of culprits — including toxic metals and radiation released from a distant galaxy — but the favored explanation has long been global cooling.
Toward the end of the Ordovician, Earth underwent widespread glaciation. That could have caused the shallow seas to disappear, which provided optimal conditions for a variety of organisms.

But some scientists, including Keith Dewing, who is also at the Geological Survey of Canada but was not involved in this research, have struggled with this hypothesis. Geological evidence shows that both pulses of the extinction were quite abrupt, but glaciation often waxes and wanes over millions of years. ...

Dr. Bond and Dr. Grasby reached their volcanic hypothesis after collecting Ordovician rocks from a small stream in southern Scotland. They then shipped those rocks to Vancouver, British Columbia, where the specimens were heated in a lab until they released large amounts of mercury — a telltale sign that volcanoes had rocked the epoch.

The rocks also emitted molybdenum and uranium — geochemical proxies that suggest the oceans were deoxygenated at the time. Only warming so easily robs the oceans of oxygen, they say, asphyxiating the species that live there. ...
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FULL STORY: https://www.nytimes.com/2020/06/10/science/global-warming-ordovician-extinction.html
 
Here are the bibliographic particulars and abstract for the newly published paper about the Ordovician extinction event. The full article can be accessed (PDF) at the link below.

Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation
David P.G. Bond; Stephen E. Grasby
Geology (2020)

https://doi.org/10.1130/G47377.1

The Ordovician saw major diversification in marine life abruptly terminated by the Late Ordovician mass extinction (LOME). Around 85% of species were eliminated in two pulses 1 m.y. apart. The first pulse, in the basal Hirnantian, has been linked to cooling and Gondwanan glaciation. The second pulse, later in the Hirnantian, is attributed to warming and anoxia. Previously reported mercury (Hg) spikes in Nevada (USA), South China, and Poland implicate an unknown large igneous province (LIP) in the crisis, but the timing of Hg loading has led to different interpretations of the LIP-extinction scenario in which volcanism causes cooling, warming, or both. We report close correspondence between Hg, Mo, and U anomalies, declines in enrichment factors of productivity proxies, and the two LOME pulses at the Ordovician-Silurian boundary stratotype (Dob’s Linn, Scotland). These support an extinction scenario in which volcanogenic greenhouse gases caused warming around the Katian-Hirnantian boundary that led to expansion of a preexisting deepwater oxygen minimum zone, productivity collapse, and the first LOME pulse. Renewed volcanism in the Hirnantian stimulated further warming and anoxia and the second LOME pulse. Rather than being the odd-one-out of the “Big Five” extinctions with origins in cooling, the LOME is similar to the others in being caused by volcanism, warming, and anoxia.
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SOURCE: https://pubs.geoscienceworld.org/gs...486/Late-Ordovician-mass-extinction-caused-by
 
EnolaGaia said:
Newly published research implicates a major collapse in the earth's ozone layer as a key factor in the Late Devonian mass extinction event.
Click to expand...

This subsequent research article on the Late Devonian mass extinction event suggests one or more supernova explosions could explain the ozone depletion and describes the evidence that would support this hypothesis.
New Research Shows Exploding Stars May Have Caused Mass Extinction on Earth

... Killer cosmic rays from nearby supernovae could be the culprit behind at least one mass extinction event, researchers said, and finding certain radioactive isotopes in Earth’s rock record could confirm this scenario.

A new study led by University of Illinois, Urbana-Champaign astronomy and physics professor Brian Fields explores the possibility of astronomical events being responsible for an extinction event that occurred 359 million years ago, at the boundary between the Devonian and Carboniferous periods.

The paper is published in the Proceedings of the National Academy of Sciences.

The team concentrated on Devonian-Carboniferous boundary because those rocks contain hundreds of thousands of generations of plant spores that appear to be sunburnt by ultraviolet light – evidence of a long-lasting ozone-depletion event.

“Earth-based catastrophes such as large-scale volcanism and global warming can destroy the ozone layer, too, but evidence for those is inconclusive for the time interval in question,” Fields said. “Instead, we propose that one or more supernova explosions, about 65 light-years away from Earth, could have been responsible for the protracted loss of ozone.” ...

The team explored other astrophysical causes for ozone depletion, such as meteorite impacts, solar eruptions and gamma-ray bursts. “But these events end quickly and are unlikely to cause the long-lasting ozone depletion that happened at the end of the Devonian period,” said graduate student and study co-author Jesse Miller.

A supernova, on the other hand, delivers a one-two punch, the researchers said. The explosion immediately bathes Earth with damaging UV, X-rays and gamma rays. Later, the blast of supernova debris slams into the solar system, subjecting the planet to long-lived irradiation from cosmic rays accelerated by the supernova. The damage to Earth and its ozone layer can last for up to 100,000 years.

However, fossil evidence indicates a 300,000-year decline in biodiversity leading up to the Devonian-Carboniferous mass extinction, suggesting the possibility of multiple catastrophes, maybe even multiple supernovae explosions. “This is entirely possible,” Miller said. “Massive stars usually occur in clusters with other massive stars, and other supernovae are likely to occur soon after the first explosion.” ...

The team said the key to proving that a supernova occurred would be to find the radioactive isotopes plutonium-244 and samarium-146 in the rocks and fossils deposited at the time of extinction. “Neither of these isotopes occurs naturally on Earth today, and the only way they can get here is via cosmic explosions,” said undergraduate student and co-author Zhenghai Liu. ...
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FULL STORY: https://scitechdaily.com/green-bana...ars-may-have-caused-mass-extinction-on-earth/

An updated April 2021 version of this article appears in ScienceAlert :
https://www.sciencealert.com/an-exp...om-earth-may-have-triggered-a-mass-extinction
 
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Here are the bibliographic details and abstract for the Late Devonian supernova hypothesis research. The published research report can be reviewed at the link below.

Supernova triggers for end-Devonian extinctions
Brian D. Fields, Adrian L. Melott, John Ellis, Adrienne F. Ertel, Brian J. Fry, Bruce S. Lieberman, Zhenghai Liu, Jesse A. Miller, and Brian C. Thomas
PNAS first published August 18, 2020
https://doi.org/10.1073/pnas.2013774117

Abstract
The Late Devonian was a protracted period of low speciation resulting in biodiversity decline, culminating in extinction events near the Devonian–Carboniferous boundary. Recent evidence indicates that the final extinction event may have coincided with a dramatic drop in stratospheric ozone, possibly due to a global temperature rise. Here we study an alternative possible cause for the postulated ozone drop: a nearby supernova explosion that could inflict damage by accelerating cosmic rays that can deliver ionizing radiation for up to ∼100 ky. We therefore propose that the end-Devonian extinctions were triggered by supernova explosions at ∼20pc, somewhat beyond the “kill distance” that would have precipitated a full mass extinction. Such nearby supernovae are likely due to core collapses of massive stars; these are concentrated in the thin Galactic disk where the Sun resides. Detecting either of the long-lived radioisotopes Sm146 or Pu244 in one or more end-Devonian extinction strata would confirm a supernova origin, point to the core-collapse explosion of a massive star, and probe supernova nucleosynthesis. Other possible tests of the supernova hypothesis are discussed.

FULL ARTICLE: https://www.pnas.org/content/early/2020/08/17/2013774117
 
A new mass extinction event occurring during the Carnian period - the Carnian Pluvial Episode, circa 233 MYA - has been identified.
Discovery of a New Mass Extinction – Carnian Pluvial Episode – 233 Million Years Ago

t’s not often a new mass extinction is identified; after all, such events were so devastating they really stand out in the fossil record. In a new paper, published today in Science Advances, an international team has identified a major extinction of life 233 million years ago that triggered the dinosaur takeover of the world. The crisis has been called the Carnian Pluvial Episode.

The team of 17 researchers, led by Jacopo Dal Corso of the China University of Geosciences at Wuhan and Mike Benton of the University of Bristol’s School of Earth Sciences, reviewed all the geological and palaeontological evidence and determined what had happened.

The cause was most likely massive volcanic eruptions in the Wrangellia Province of western Canada, where huge volumes of volcanic basalt was poured out and forms much of the western coast of North America.

“The eruptions peaked in the Carnian,” says Jacopo Dal Corso. “I was studying the geochemical signature of the eruptions a few years ago and identified some massive effects on the atmosphere worldwide. The eruptions were so huge, they pumped vast amounts of greenhouse gases like carbon dioxide, and there were spikes of global warming.” The warming was associated with increased rainfall, and this had been detected back in the 1980s by geologists Mike Simms and Alastair Ruffell as a humid episode lasting about 1 million years in all. The climate change caused major biodiversity loss in the ocean and on land, but just after the extinction event new groups took over, forming more modern-like ecosystems. The shifts in climate encouraged growth of plant life, and the expansion of modern conifer forests.

“The new floras probably provided slim pickings for the surviving herbivorous reptiles,” said Professor Mike Benton. “I had noted a floral switch and ecological catastrophe among the herbivores back in 1983 when I completed my PhD. We now know that dinosaurs originated some 20 million years before this event, but they remained quite rare and unimportant until the Carnian Pluvial Episode hit. It was the sudden arid conditions after the humid episode that gave dinosaurs their chance.”

It wasn’t just dinosaurs, but also many modern groups of plants and animals also appeared at this time, including some of the first turtles, crocodiles, lizards, and the first mammals.

The Carnian Pluvial Episode also had an impact on ocean life. It marks the start of modern-style coral reefs, as well as many of the modern groups of plankton, suggesting profound changes in the ocean chemistry and carbonate cycle. ...
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FULL STORY: https://scitechdaily.com/discovery-...arnian-pluvial-episode-233-million-years-ago/
 
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Here are the bibliographic details and abstract for the Carnian mass extinction research publication. The full article can be accessed at the link below.

Extinction and dawn of the modern world in the Carnian (Late Triassic)
Jacopo Dal Corso Massimo Bernardi Yadong Sun Haijun Song, Leyla J. Seyfullah, Nereo Preto, Piero Gianolla, Alastair Ruffell, Evelyn Kustatscher, Guido Roghi, Agostino Merico, Sönke Hohn, Alexander R. Schmidt, Andrea Marzoli, Robert J. Newton, Paul B. Wignall and Michael J. Benton
Science Advances 16 Sep 2020: Vol. 6, no. 38, eaba0099
DOI: 10.1126/sciadv.aba0099

Abstract
The Carnian Pluvial Episode (Late Triassic) was a time of global environmental changes and possibly substantial coeval volcanism. The extent of the biological turnover in marine and terrestrial ecosystems is not well understood. Here, we present a meta-analysis of fossil data that suggests a substantial reduction in generic and species richness and the disappearance of 33% of marine genera. This crisis triggered major radiations. In the sea, the rise of the first scleractinian reefs and rock-forming calcareous nannofossils points to substantial changes in ocean chemistry. On land, there were major diversifications and originations of conifers, insects, dinosaurs, crocodiles, lizards, turtles, and mammals. Although there is uncertainty on the precise age of some of the recorded biological changes, these observations indicate that the Carnian Pluvial Episode was linked to a major extinction event and might have been the trigger of the spectacular radiation of many key groups that dominate modern ecosystems.

SOURCE / FULL ARTICLE:
https://advances.sciencemag.org/content/6/38/eaba0099
 
Seems odd that dinosaurs had been around for 20 million years and survived this but numerous other species apparently didn't..
 
EnolaGaia said:
A new mass extinction event occurring during the Carnian period - the Carnian Pluvial Episode, circa 233 MYA - has been identified. ...
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Here are two newer articles about the Carnian Pluvial Episode.

A Little-Known Mass Extinction and the “Dawn of the Modern World”
https://eos.org/articles/a-little-known-mass-extinction-and-the-dawn-of-the-modern-world

Triassic period ended with 'lost' mass extinction and a million-year rain storm, study claims
https://www.livescience.com/carnian-pluvial-episode-mass-extinction.html
 
After the Carnian Pluvial Episode (aka Carnian Pluvial Event) came the even more dramatic Triassic-Jurassic extinction event circa 200 million years ago. New research suggests this end-Triassic extinction event occurred later than previously believed.
The Mass Extinction That Ended The Triassic May Have Happened Later Than We Thought

The Triassic-Jurassic extinction event that ended the Triassic period and brought in the Jurassic around 200 million years ago was one of the biggest mass extinctions in the history of our planet.

In total, around 25-34 percent of marine genera are thought to have been lost during the event, and many land groups wiped out, clearing the way for dinosaurs and pterosaurs to dominate on Earth for the next 135 million years or so.

But new research suggests this extinction event occurred later than initially thought, and sheds new light on the contributing factors. ...
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FULL STORY: https://www.sciencealert.com/the-triassic-extinction-seems-to-have-taken-place-later-than-we-thought
 
Newly published research suggests that mass extinctions of land animals not only coincide with mass extinctions of marine life, but exhibit a pace or tempo with a periodicity of circa 27.5 million years.
Mass extinctions of land-dwelling animals occur in 27-million-year cycle

Researchers find that timing of mass extinctions lines up with asteroid impacts and massive volcanic eruptions

Mass extinctions of land-dwelling animals--including amphibians, reptiles, mammals, and birds--follow a cycle of about 27 million years, coinciding with previously reported mass extinctions of ocean life, according to a new analysis published in the journal Historical Biology.

The study also finds that these mass extinctions align with major asteroid impacts and devastating volcanic outpourings of lava called flood-basalt eruptions--providing potential causes for why the extinctions occurred.

"It seems that large-body impacts and the pulses of internal Earth activity that create flood-basalt volcanism may be marching to the same 27-million-year drumbeat as the extinctions, perhaps paced by our orbit in the Galaxy," said Michael Rampino, ... the study's lead author.

Sixty-six million years ago, 70 percent of all species on land and in the seas, including the dinosaurs, suddenly went extinct, in the disastrous aftermath of the collision of a large asteroid or comet with the Earth. Subsequently, paleontologists discovered that such mass extinctions of marine life, in which up to 90 percent of species disappeared, were not random events, but seemed to come in a 26-million-year cycle.

In their Historical Biology study, Rampino and co-authors Ken Caldeira ... and Yuhong Zhu ... , examined the record of mass extinctions of land-dwelling animals and concluded that they coincided with the extinctions of ocean life. They also performed new statistical analyses of the extinctions of land species and demonstrated that those events followed a similar cycle of about 27.5 million years.

What could be causing the periodic mass extinctions on land and in the seas? Mass extinctions are not the only events occurring in cycles: the ages of impact craters--created by asteroids and comets crashing to the Earth's surface--also follow a cycle aligning with the extinction cycle.

Astrophysicists hypothesize that periodic comet showers occur in the Solar System every 26 to 30 million years, producing cyclical impacts and resulting in periodic mass extinctions. The Sun and planets cycle through the crowded mid-plane of the Milky Way Galaxy about every 30 million years. During those times, comet showers are possible, leading to large impacts on the Earth. The impacts can create conditions that would stress and potentially kill off land and marine life, including widespread dark and cold, wildfires, acid rain, and ozone depletion. ...
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FULL STORY: https://www.eurekalert.org/pub_releases/2020-12/nyu-meo120720.php
 
Here are the bibliographic details and abstract for the published report on periodicity in mass extinction events.

Michael R. Rampino, Ken Caldeira & Yuhong Zhu (2020)
A 27.5-My underlying periodicity detected in extinction episodes of non-marine tetrapods
Historical Biology
DOI: 10.1080/08912963.2020.1849178

ABSTRACT
Non-marine tetrapods (amphibians, reptiles, birds and mammals) have apparently experienced at least 10 distinct episodes of intensified extinctions over the past 300 My. Eight of these ten non-marine extinction events are concurrent with known marine-extinction episodes, which previously yielded evidence for an underlying period of ~26.4 to 27.3 My. We performed circular spectral analysis and Fourier transform analysis of the ages of the ten recognised tetrapod-extinction events, and detected a statistically significant (99% confidence) underlying periodicity of ~27.5 My. We also find that the eight coeval non-marine/marine-extinction pulses all occurred at the times of eruptions of Large Igneous Provinces (LIPs) (continental flood-basalts and oceanic plateaus), with potentially severe environmental effects. Three of these co-extinction episodes are further correlated with the ages of the three largest (≥100-km diameter) impact craters of the last 260 My, which are also apparently capable of causing extinction events. These findings suggest that global cataclysmal events with an underlying periodicity of ~27.5 My were the cause of the coordinated periodic extinction episodes of non-marine tetrapods and marine organisms.

SOURCE: https://www.tandfonline.com/doi/full/10.1080/08912963.2020.1849178
 
A Japanese climate researcher has completed a survey of temperature changes versus global biodiversity for the five known great mass extinction events. Based on his calculations, any pending sixth extinction event won't be as (biologically) catastrophic as the earlier five, and it may still be a few hundred years in the future.
New Study Offers a Surprising Timeline For Earth's Sixth Mass Extinction

A climate scientist at Tohoku University in Japan has run the numbers and does not think today's mass extinction event will equal that of the previous five. At least not for many more centuries to come. ...

When Kunio Kaiho tried to quantify the stability of Earth's average surface temperature and the planet's biodiversity, he found a largely linear effect. The greater the temperature change, the greater the extent of extinction.

For global cooling events, the greatest mass extinctions occurred when temperatures fell by about 7°C. But for global warming events, Kaiho found the greatest mass extinctions occurred at roughly 9°C warming.

That's much higher than previous estimates, which suggest a temperature of 5.2°C would result in a major marine mass extinction, on par with the previous 'big five'.

To put that in perspective, by the end of the century, modern global warming is on track to increase surface temperatures by as much as 4.4°C.

"The 9°C global warming will not appear in the Anthropocene at least till 2500 under the worst scenario," Kaiho predicts.

Kaiho is not denying that many extinctions on land and in the sea are already occurring because of climate change; he just does not expect the same proportion of losses as before. ...
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FULL STORY: https://www.sciencealert.com/study-links-bigger-temperature-changes-with-larger-extinction-events
 
Here are the bibliographic details and abstract from the published study. The full report is accessible at the link below.

Relationship between extinction magnitude and climate change during major marine and terrestrial animal crises
Kunio Kaiho
Biogeosciences, 19, 3369–3380, 2022
https://doi.org/10.5194/bg-19-3369-2022

Abstract
Major mass extinctions in the Phanerozoic Eon occurred during abrupt global climate changes accompanied by environmental destruction driven by large volcanic eruptions and projectile impacts. Relationships between land temperature anomalies and terrestrial animal extinctions, as well as the difference in response between marine and terrestrial animals to abrupt climate changes in the Phanerozoic, have not been quantitatively evaluated. My analyses show that the magnitude of major extinctions in marine invertebrates and that of terrestrial tetrapods correlate well with the coincidental anomaly of global and habitat surface temperatures during biotic crises, respectively, regardless of the difference between warming and cooling (correlation coefficient R=0.92–0.95). The loss of more than 35 % of marine genera and 60 % of marine species corresponding to the so-called “big five” major mass extinctions correlates with a >7 ∘C global cooling and a 7–9 ∘C global warming for marine animals and a >7 ∘C global cooling and a  ∘C global warming for terrestrial tetrapods, accompanied by ±1 ∘C error in the temperature anomalies as the global average, although the amount of terrestrial data is small. These relationships indicate that (i) abrupt changes in climate and environment associated with high-energy input by volcanism and impact relate to the magnitude of mass extinctions and (ii) the future anthropogenic extinction magnitude will not reach the major mass extinction magnitude when the extinction magnitude parallelly changes with the global surface temperature anomaly. In the linear relationship, I found lower tolerance in terrestrial tetrapods than in marine animals for the same global warming events and a higher sensitivity of marine animals to the same habitat temperature change than terrestrial animals. These phenomena fit with the ongoing extinctions.

SOURCE / FULL REPORT: https://bg.copernicus.org/articles/19/3369/2022/
 
Newly published research findings indicate a previously unrecognized mass extinction occurred during the Ediacaran period.
Scientists Uncover Evidence of What May Be Earth's First Mass Animal Extinction

Since the Cambrian explosion 538.8 million years ago – a time when many of the animal phyla we're familiar with today were established – five major mass extinction events have whittled down the biodiversity of all creatures great and small.

Researchers from the US have uncovered evidence of one occurring earlier, around 550 million years ago during a period known as the Ediacaran.

Though the oceans teemed with a few familiar animals like sponges and jellyfish, most life during this early period of biological history would seem alien to us now. Many of the animals were soft-bodied. Some looked more like plant fronds stuck in place. Others had some form of shell.

Virginia Tech paleobiologist Scott Evans and colleagues compiled data on rare fossils of the squishier kinds of animals from around the world dated to the Ediacaran. They found sudden shifts in biodiversity that had previously been detected weren't mere sampling biases. ...

The team found that there was an overall increase in biodiversity between the earlier and middle stages of the Ediacaran, known as the Avalon (575 to 560 million years ago) and White Sea stages (560 to 550 million years ago).

"We find significant differences in the feeding mode, life habit, ecological tier, and maximum body size between the Avalon and White Sea assemblages," the team writes in their paper.

Between these two time periods, more smaller mobile animals appeared that fed on the microbial mats that dominated the seafloors. Previously many of the animals were stuck-in-place (sessile) filter feeders.

Feeding modes did not change in this way between the White Sea and the last stage, known as the Nama (550 to 539 million years ago). Rather, a staggering 80 percent of species seemed to vanish between these two stages of the Ediacaran. ...
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SOURCE: https://www.sciencealert.com/scient...at-may-be-earths-first-mass-animal-extinction
 
Here are the bibliographic details and abstract for the published stody.

Scott D. Evans, Chenyi Tu, Adriana Rizzo, and Mary L. Droser
Environmental drivers of the first major animal extinction across the Ediacaran White Sea-Nama transition
PNAS, November 7, 2022, 119 (46) e2207475119
https://doi.org/10.1073/pnas.2207475119

Abstract
The Ediacara Biota—the oldest communities of complex, macroscopic fossils—consists of three temporally distinct assemblages: the Avalon (ca. 575–560 Ma), White Sea (ca. 560–550 Ma), and Nama (ca. 550–539 Ma). Generic diversity varies among assemblages, with a notable decline at the transition from White Sea to Nama. Preservation and sampling biases, biotic replacement, and environmental perturbation have been proposed as potential mechanisms for this drop in diversity. Here, we compile a global database of the Ediacara Biota, specifically targeting taphonomic and paleoecological characters, to test these hypotheses. Major ecological shifts in feeding mode, life habit, and tiering level accompany an increase in generic richness between the Avalon and White Sea assemblages. We find that ∼80% of White Sea taxa are absent from the Nama interval, comparable to loss during Phanerozoic mass extinctions. The paleolatitudes, depositional environments, and preservational modes that characterize the White Sea assemblage are well represented in the Nama, indicating that this decline is not the result of sampling bias. Counter to expectations of the biotic replacement model, there are minimal ecological differences between these two assemblages. However, taxa that disappear exhibit a variety of morphological and behavioral characters consistent with an environmentally driven extinction event. The preferential survival of taxa with high surface area relative to volume may suggest that this was related to reduced global oceanic oxygen availability. Thus, our data support a link between Ediacaran biotic turnover and environmental change, similar to other major mass extinctions in the geologic record.

SOURCE: https://www.pnas.org/doi/pdf/10.1073/pnas.2207475119?download=true
 
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