Tag: mass extinctions

The Day the Dinosaurs Died: Asteroid Impact and Deccan Volcanoes at the End of the Cretaceous

Paleontologists recognize five major mass extinctions (the “Big Five”) over the past ~540 million years (the Phanerozoic Eon).

The End- Cretaceous (K- Pg or Cretaceous- Paleogene) mass extinction occurred approximately 66 million years ago. It is the most recent of the “Big Five” mass extinctions and the event that ended the reign of the non- avian dinosaurs.

An artistic depiction of the Chicxulub asteroid impact on the Yucatan coast, featuring dinosaurs reacting to the catastrophic event with a massive explosion and tsunami in the background.
AI generated by Grok

Mass extinctions are periods in Earth’s history when a large percentage of species die out in a relatively short geological time (typically thousands to a few hundred thousand years), far above the normal “background” extinction rate.

Paleontologists recognize five major mass extinctions (the “Big Five”) over the past ~540 million years (the Phanerozoic Eon). These events reshaped life on Earth and opened ecological opportunities for surviving groups.

The Big Five Mass Extinctions

EventTime (approx.)Species Lost (est.)Main CausesKey Victims
End- Ordovician444 million years ago~85%Rapid glaciation & sea- level fall, then warmingMarine invertebrates (graptolites, trilobites, brachiopods)
Late Devonian372- 359 million years ago~70- 75%Climate cooling, ocean anoxia, possible volcanism or impactsReef-building organisms, many marine groups, early fish
End- Permian (“The Great Dying”)252 million years ago~90- 96% (marine), ~70% (terrestrial)Massive Siberian Traps volcanism → global warming, ocean acidification, anoxiaMost marine life, many land vertebrates, insects, plants
End-Triassic201 million years ago~70- 80%Central Atlantic Magmatic Province volcanism → climate change & ocean chemistry shiftsMany marine groups, early reptiles, some amphibians
End- Cretaceous (K- Pg)66 million years ago~75%Asteroid impact (Chicxulub) and Deccan Traps volcanismNon- avian dinosaurs, pterosaurs, ammonites, many marine reptiles

Notes on severity:

  • The End- Permian was by far the most severe, the closest life has come to total annihilation.
  • The End- Cretaceous is the best- known because it ended the age of dinosaurs and allowed mammals (and eventually humans) to diversify.

Most mass extinctions involved rapid environmental upheaval, often triggered by:

  • Large Igneous Province (LIP) volcanic eruptions (releasing CO₂, SO₂, and other gases)
  • Asteroid/comet impacts (confirmed mainly for the K- Pg event)
  • Climate shifts (cooling or extreme warming)
  • Ocean anoxia, acidification, or sea- level changes

These ultimate triggers created proximate “kill mechanisms” such as temperature extremes, loss of oxygen in the oceans, acid rain, and disruption of food webs.

Many scientists argue that we are currently in the early stages of a sixth mass extinction, driven by human activities (habitat destruction, climate change, pollution, overexploitation, and invasive species).

Current extinction rates for vertebrates and other groups are estimated to be tens to hundreds of times higher than background rates. While we have not yet reached the classic threshold of ~75% species loss, the trajectory is accelerating and is considered by many researchers to meet the definition of a mass extinction in progress (often called the Holocene or Anthropocene extinction).

Mass extinctions are rare but transformative events. Each one permanently altered the course of evolution, eliminating dominant groups and allowing survivors to radiate into vacant ecological niches.

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Large Igneous Provinces (LIPs) are among the most extreme volcanic events in Earth’s history. They involve the rapid emplacement of enormous volumes of mostly mafic (basalt- rich) magma, far larger than ordinary volcanoes or even flood- basalt fields produced by typical hotspot activity.

A standard modern definition describes LIPs as magmatic provinces with:

  • Areal extent greater than ~100,000 km²
  • Igneous volume greater than ~100,000 km³ (often millions of km³)
  • Emplacement mainly in short pulses lasting 1- 5 million years (sometimes with longer overall duration up to ~50 million years)
  • Predominantly intraplate tectonic setting (not normal mid- ocean ridge or subduction- zone volcanism)

They produce thick stacks of flood basalts (“traps”), extensive dike and sill complexes, and sometimes oceanic plateaus. Some LIPs also include significant silicic (rhyolitic) components.

Famous Examples

LIPAge (approx.)LocationNotes / Associated Events
Siberian Traps252 MaSiberia, RussiaLinked to the end-Permian mass extinction (“Great Dying”)
Central Atlantic Magmatic Province (CAMP)201 MaEastern North America, parts of Europe, Africa, South AmericaLinked to the end-Triassic mass extinction; associated with the breakup of Pangaea
Deccan Traps66 MaWestern IndiaContemporaneous with the end- Cretaceous (K-Pg) extinction; combined effects with the Chicxulub impact
Paraná -Etendeka~132 MaSouth America & southern AfricaRelated to the opening of the South Atlantic
Columbia River Basalts17- 6 MaNorthwestern USAYoungest major continental flood basalt province
Ontong Java Plateau~120 MaPacific OceanOne of the largest oceanic LIPs

Other notable LIPs include the Emeishan Traps (China, ~260 Ma) and the North Atlantic Igneous Province.

The leading hypothesis involves mantle plumes, large upwellings of hot material from deep in the mantle (possibly the core- mantle boundary). When a plume head reaches the base of the lithosphere, it causes widespread melting and massive magma production.

Alternative or complementary ideas include lithospheric extension, edge- driven convection, or interactions with subducted material. Many LIPs are associated with continental breakup.

LIPs can release vast quantities of volcanic gases (especially CO₂, SO₂, and halogens) plus additional gases from heating surrounding sedimentary rocks (thermogenic gases). These emissions can drive:

  • Rapid global warming (from CO₂)
  • Short- term cooling (from sulfate aerosols)
  • Ocean acidification and anoxia
  • Acid rain
  • Possible ozone depletion

Because of these effects, LIPs are strongly linked to several of the “Big Five” mass extinctions and many lesser biotic crises. The Siberian Traps, CAMP, and Deccan Traps are the clearest examples of this connection.

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The End- Cretaceous (K- Pg or Cretaceous- Paleogene) mass extinction occurred approximately 66 million years ago. It is the most recent of the “Big Five” mass extinctions and the event that ended the reign of the non- avian dinosaurs.

Scale of the Extinction

  • Roughly 75% of species went extinct.
  • Major losses included:
    • All non- avian dinosaurs
    • Pterosaurs
    • Marine reptiles (mosasaurs, plesiosaurs)
    • Ammonites and many other marine invertebrates
    • Significant losses among plants, plankton, and other groups
  • Survivors included birds (the only remaining dinosaur lineage), mammals, crocodilians, turtles, lizards, snakes, amphibians, and many plant groups. These survivors later diversified dramatically in the Paleogene.

The Two Major Events

Two large-scale perturbations occurred around the same time:

1. Chicxulub Asteroid Impact

  • A ~10- 15 km asteroid struck the Yucatán Peninsula (Mexico), creating the ~180- 200 km Chicxulub crater.
  • Immediate effects: massive earthquakes, tsunamis, wildfires, and a global “impact winter” caused by dust, soot, and sulfate aerosols blocking sunlight for months to years.
  • This led to the collapse of photosynthesis, rapid cooling, and the breakdown of food webs on land and in the oceans.
  • The impact is widely accepted as the primary trigger for the abrupt, global extinction.

2. Deccan Traps Volcanism (a Large Igneous Province)

  • Massive flood- basalt eruptions in what is now western India produced ~1 million km³ of lava over roughly 700,000- 800,000 years, spanning the K- Pg boundary.
  • These eruptions released large volumes of CO₂ (causing warming) and SO₂ (causing short- term cooling and acid rain).
  • Activity began before the impact and continued afterward. Some evidence suggests the impact itself may have intensified later eruptive phases through seismic triggering.

Most researchers agree that the Chicxulub impact was the decisive kill mechanism that produced the sudden, global extinction pattern seen in the fossil record.

The Deccan Traps likely stressed ecosystems beforehand (through climate fluctuations) and may have contributed to the overall severity, but modeling studies indicate that Deccan volcanism alone would not have caused the extinction of the non- avian dinosaurs. In some scenarios, the long- term CO₂ warming from the Deccan Traps may even have partially buffered the extreme cold of the impact winter.

The combination is sometimes described as a “press- pulse” scenario: prolonged volcanic stress (the press) followed by the catastrophic impact (the pulse).

Ecosystems began recovering relatively quickly in some regions (within tens of thousands of years for primary productivity), though full recovery of diversity took much longer. Mammals, in particular, underwent a major adaptive radiation in the ecological space left vacant by the dinosaurs, eventually leading to the rise of larger forms and, much later, primates and humans.

This event marks the boundary between the Mesozoic and Cenozoic Eras and remains one of the best-studied mass extinctions due to the clear geological markers (the iridium- rich boundary layer, shocked quartz, and the Chicxulub crater itself).

By the way, the Chicxulub asteroid impact did not start (activate from nothing) the Deccan Traps volcanism.

The Deccan Traps eruptions were already underway for hundreds of thousands of years before the impact. High- precision dating shows that Deccan volcanism began well before the Cretaceous- Paleogene (K- Pg) boundary.

However, there is a credible scientific hypothesis that the Chicxulub impact intensified or triggered the largest and most voluminous phase of the Deccan eruptions.

Key points supporting this idea:

  • Around the time of the impact (~66 million years ago), the Deccan Traps experienced a major “state shift.” The eruptions became larger, more episodic, and much more voluminous.
  • The most massive lava flows (the Wai Subgroup: Poladpur, Ambenali, and Mahabaleshwar formations) account for roughly 70% of the main- stage volume of the Deccan Traps. High- precision dating places the start of this major pulse within about 50,000 years of the Chicxulub impact (essentially simultaneous within dating precision).
  • The impact would have generated enormous seismic energy, equivalent to a magnitude ~10-11 earthquake. Modeling shows this seismic energy could have traveled through the mantle and increased the permeability of the existing magmatic system beneath India, allowing a large volume of already-generated magma to erupt more rapidly.

This idea was formally proposed in papers by Richards et al. (2015) and Renne et al. (2015) and remains an active area of research. It is supported by the close timing, changes in eruption style and geochemistry, and analogies with historical earthquakes that have triggered volcanic eruptions.

The Deccan Traps were already active independently (linked to the Réunion mantle plume).

The Chicxulub impact is the primary cause of the mass extinction.

It is plausible (but not universally accepted as proven) that the impact’s seismic waves amplified the ongoing Deccan volcanism, leading to the most intense eruptive phase right around the extinction boundary.

In short: The impact did not create the Deccan Traps, but it may have “shaken the can” and caused the biggest eruptions to happen at the worst possible time.

Climate Change is Not Causing Mass Extinctions, Says Bombshell Royal Society Paper

When the history of the great Net Zero climate hoax comes to be written, pride of place will be given to the terrifying sixth mass extinction scare. Mainstream media barely question the idea that human-controlled climate is wreaking havoc with the life chances of millions of animal and plant species around the world. In November 2024, the Guardian reported that “as the planet warms up, scientists predict a series of ‘extinction cliffs’”. We are in danger of forgetting what the climate crisis means: extinction, was the cheerful article headline.

Collage of news headlines about the sixth mass extinction, with a fiery background.

The Daily Sceptic

By Chris Morrison

A vibrant green tree frog with red eyes perched on a large green leaf.

When the history of the great Net Zero climate hoax comes to be written, pride of place will be given to the terrifying sixth mass extinction scare. Mainstream media barely question the idea that human-controlled climate is wreaking havoc with the life chances of millions of animal and plant species around the world. In November 2024, the Guardian reported that “as the planet warms up, scientists predict a series of ‘extinction cliffs’”. We are in danger of forgetting what the climate crisis means: extinction, was the cheerful article headline. But a recent bombshell report from the UK Royal Society has knocked seven bells out of all this nonsense by showing that species-level extinctions related to climate change “have not significantly increased over the last approximately 200 years”.

It was further found that decadal extinction rates over the last 100 years had “significantly declined” for arthropods and plants, the two groups of organisms encompassing most known global biodiversity. Overall, it was found that extinction rates have increased over the last 500 years, “but generally declined in the last 100 years”. Past extinctions are said to “strongly suggest” that climate change is not an important threat to biodiversity. Such a finding is hardly the smoking gun that shows humans burning hydrocarbons of late have or are causing a sixth mass extinction.

How future generations will chuckle over the extinction sandwich boards paraded on a regular basis in the public spaces. The Swedish Doom Goblin screeching in front of the UN cameras, of course, but also David Attenborough stating that humanity was halfway through a new extinction. Current extinction rates, he has claimed, far exceed natural levels. Another BBC doomster was Chris Packham who said that it was not a sixth mass extinction event, rather it was a “mass extermination event”.

To try to understand the motives of some activists, the unfalsifiable computer model-driven claims that small rises in temperature could collapse the ecological system are a useful bandwagon to ride. While doing so, attention can be drawn to the real problems of habitat loss and the introduction of invasive species. It is these last two issues that the Royal Society authors draw attention to, noting that recent extinctions were predominately on islands, and were caused by the introduction of invasive species. The most common current threat is said to be habitat loss. Both these issues can, and are, being tackled away from any discussion about the role of trace gases in the atmosphere. The authors note that “some studies” conclude that 20-30% of all plant and animal species may be lost to climate change in future decades under “pessimistic climate scenarios”. Pessimistic is one way to describe the scenarios that appear on the media sandwich boards – invented, unscientific, politicised computer garbage is another.

Consulting the IUCN Red List of over 163,022 assessed species, it was found that the highest extinction frequencies were among turtles and molluscs. Neither have fared well on islands due to a number of factors such as small population size, predation and limited ranges. It was also found that freshwater fish were more vulnerable than marine species. Extinctions among these were said to be common and rare respectively, which was put down to differences in potential range size and distribution. Furthermore, many freshwater extinctions have been caused by dams. Many narrowly endemic molluscs were said to have been driven to extinction by the damming of Alabama’s Coosa River in the 1900s.

There are of course many difficulties in assessing the huge field of animal and plant extinction, which the authors readily acknowledge. But many statements based on rigorous analysis of data can be made. For instance, it is noted that a larger list of generally assumed plant extinctions suggests that extinctions peaked in the 1920s. This is said to agree with the authors’ own analysis.

One of the tragedies of modern environmentalism is that it has been captured for political purposes by those seeking to centralise power through the hard-Left Net Zero political agenda. Taking control of energy, and by extension the rest of industry and agriculture, by peddling unproven opinions that humans control the climate by burning hydrocarbons requires constant made-up scares of climate collapse and ecological disaster. But taking care of the planet, reducing habitat loss and protecting the natural world is a separate issue. Often it involves proper waste management as in the disposal of plastic. It is often noted that societies that have prospered by using natural resources such as hydrocarbons are those best able to clean up and protect nature.

There are few sadder sights than environmentalists turning blind eyes to the bat, avian and insect carnage of wind turbines, the digging up of Indonesian rainforests for EV battery enhancing nickel and the rape of the Amazon to provide balsa wood cores for the proliferating but highly unreliable windmills. Quite how 50,000 green activists justified ripping down 100,000 mature rainforest trees to help them run a recent COP conference in Brazil dedicated to preserving the rainforest must, alas, remain a complete mystery.

All these political acts are committed under a ‘settled’ climate science directive that allows scares to be invented seemingly to unquestioning order. When English Test cricket used to regularly shut up shop in mid-afternoon due to fading light and despite the floodlights being on to ‘protect’ the players, the legendary fast bowler Bob Willis used to ask, ‘Where are the bodies?’ When ‘national treasure’ David Attenborough next reads from his sandwich board script about a new mass extinction, a similar reply should come to mind.

Chris Morrison is the Daily Sceptic’s Environment Editor. Follow him on X.

The Last Gasp of the Anthropocene?

The Anthropocene Working Group (AWG) was established in 2009 to see if there was a way to geologically differentiate an Anthropocene Epoch from the Holocene Epoch.

From Watts Up With That?

Guest “geologizing” by David Middleton

The Anthropocene Working Group (AWG) was established in 2009 to see if there was a way to geologically differentiate an Anthropocene Epoch from the Holocene Epoch. The notion has always been preposterous because the only true difference between the Holocene and the preceding Pleistocene Epoch is the impact of humans on the planet. Otherwise, the Holocene has just been a run of the mill interglacial stage, geologically indistinct from the prior Pleistocene interglacial stages. After thirteen years, the AWG is finally prepared to present a recommendation for an official Global Boundary Stratotype Section and Point (GSSP), also known as a “golden spike.” GSSP’s are stratigraphic markers that define the beginning and/or end of a geologic time period.

Scientists say they’ve found a site that marks a new chapter in Earth’s history

By Katie Hunt, CNN

Published 1:31 PM EDT, Tue July 11, 2023

CNN — 

Scientists have identified the geological site that they say best reflects a proposed new epoch called the Anthropocene — a major step toward changing the official timeline of Earth’s history.

The term Anthropocene, first proposed in 2000 to reflect how profoundly human activity has altered the world, has become a commonly used academic buzzword uniting different fields of study.

“When it’s 8 billion people all having an impact on the planet, there’s bound to be a repercussion,” said Colin Waters, an honorary professor…

[…]

The AWG, a group currently comprised of 35 geologists, has been working since 2009 to make the Anthropocene part of Earth’s official timeline. The group determined in 2016 that the Anthropocene epoch began around 1950 — the start of the era of nuclear weapons tests, the geochemical traces of which can be found around the world.

[…]

Birthplace of the Anthropocene

For the Anthropocene, the proposed golden spike location is sediment cored from the bed of Crawford Lake that reveals the geochemical traces of nuclear bomb tests, specifically plutonium — a radioactive element widely detected across the world in coral reefs, ice cores and peat bogs.

[…]

The AWG will present a proposal to make the Anthropocene official to the Subcommission on Quaternary Stratigraphy later this summer. If the subcommission’s members agree with a 60% majority, the proposal will then pass on to the International Commission on Stratigraphy, which will also have to vote and agree with a 60% majority for the proposal to move onward for ratification. Both bodies are part of the International Union of Geological Sciences, which represents more than 1 million geoscientists around the world.

A final decision is expected at the 37th International Geological Congress in Busan, South Korea, in August 2024.

[…]

CNN

The odds of the Anthropocene being ratified as a geologic epoch are slightly lower than…

Stan Finney, an actual professor of geology, and Secretary General of the International Union of Geological Sciences summed it up best…

He also feels that the push to officially recognize the Anthropocene may, in fact, be more political than driven by on-the-ground geology. The term was coined in 2000 not by a geologist but by the late atmospheric chemist and Nobel laureate Paul Crutzen — apparently in off the cuff remarks at a conference.

Finney said it’s more accurate to describe humanity’s profound impact on Earth as an ongoing geological event rather than a formal epoch with a precise global start date. It’s also possible, he said, that stratigraphers may decide that the Anthropocene doesn’t rise to the level of epoch, but it could be the fourth age of the Holocene — the much less catchy Crawfordian Age.

CNN

Finney and Edwards outlined many of the misleading, if not outright false, statements that Anthropocene proponents have made in this GSA article, particularly noting the political nature of their advocacy.

Political Statement

When we explain the fundamental difference of the Anthropocene from the chronostratigraphic units established by the International Commission on Stratigraphy to proponents for its recognition, they often reply that the human impact on the Earth system must be officially recognized, if for no other reason than to make the public and governmental agencies aware of that impact. Or, as the editorial in Nature (2011) argued, official recognition would encourage cross-disciplinary science and a “mindset” to understand and to take control of the current transformation. However, it is political action that is required to meet the ultimate goals of ameliorating human impact, which raises the question of the ICS making a political statement. Pope Francis has spoken out about the human-induced impact on the Earth system—so too have leaders of many nations, the United Nations, and numerous non-governmental organizations. In California, Governor Jerry Brown has initiated and promoted many legislative actions with the goal of ameliorating human-induced impact. Is the role of the ICS to make such a political statement? Would official recognition of the term Anthropocene as a unit of the ICS Chart realistically have any effect on promoting cross-disciplinary science or recognizing that we are in the driver’s seat as Nature editorialized? Or, is that not already the case?

The evolution of vascular land plants and their spread across the continents from late in the Devonian to early in the Permian completely altered Earth’s surface, left a significant stratigraphic record, and dramatically altered CO2 and O2 concentrations in the atmosphere and oceans far greater than humans are projected to do (Berner and Canfield, 1989; Berner, 1998). Yet there is no drive to name a unit in the ICS Chart that formally recognizes that profound and irreversible change to the Earth system. Perhaps promotion of the Anthropocene is anthropocentric as well as political?

The “Atomic Age,” a term coined by The New York Times journalist William L. Lawrence in September 1946, has an identical boundary and content to the Anthropocene proposal of Zalasiewicz et al. (2015). By rights, the Atomic Age has nomenclatural priority. If the Anthropocene is not a political statement, those who value priority should prefer the Atomic Age.

Finney and Edwards

This bears repeating:

If the Anthropocene is not a political statement, those who value priority should prefer the Atomic Age.

Finney and Edwards

The CNN article goes on to note that folks farther to the left than the AWG don’t like the term Anthropocene because only capitalism is to blame for everything bad that has ever happened in human history.

Others object to the term Anthropocene because it implicates all of humanity in the activity that has irrevocably altered the planet. Some researchers say the changes are the doing of a powerful and elite minority and that the epoch would be better named the Capitalocene.

CNN

If you want a fast track to a migraine headache, open up the Capitalocene link and try reading the gobbledygook.

These people a certifiably bat schist crazy…

Previous studies of the lake’s sediments revealed two major periods of change: one lasting from the thirteenth to fifteenth century, when Indigenous peoples speaking the Iroquois language lived in the area, and another beginning in the nineteenth century, marking the arrival of European colonists. The biggest number of changes appear in layers from the middle of the twentieth century, a period dubbed the great acceleration3 of human impacts.

Those layers document the rise of radioactive plutonium fallout from nuclear bomb testing; the working group chose that rise as the marker for the Anthropocene’s start. Cores taken at Crawford in 2019 and 2022 showed that plutonium traces increased in the early 1950s, but McCarthy and colleagues have collected an extra core this year to perform a more detailed analysis. Depending on their findings, the year proposed for the golden spike could be 1950 — when several environmental changes accelerated — or 1952, when plutonium levels rose sharply. “The difference is 2 millimetres, but philosophically it matters,” McCarthy says. If 1950 is chosen, the golden-spike core will be the one gathered in 2019, which resides at the Canadian Museum of Nature in Ottawa. If 1952 is chosen, it will be this year’s core.

No more cores

McCarthy does not plan to collect cores at Crawford Lake again. The lake is sentient according to Indigenous groups who live or have lived in the area, and taking samples from the lake violates that personhood.

In the coming months, the working group will submit three ideas to the Subcommission on Quaternary Stratigraphy. First, Crawford Lake should serve as the golden spike for the Anthropocene’s start, with the year to be determined. Second, the Anthropocene should become a geological epoch ending the Holocene; the name of its first age could be the Crawfordian age. And finally, some of the eight sites that didn’t win the golden-spike designation could serve as supplementary sites to help define the Anthropocene across geological environments.

Nature

I don’t know which of the following is more laughable:

  1. Debating whether or not a geologic time period started in 1950 or 1952.
  2. An Epoch that’s only 6-8 years longer than I’ve been alive.
  3. Having a “golden spike” that won’t be there in a few million years.
  4. Declaring the “golden spike” off limits to future evaluation because it would violate the lake’s “personhood.”
  5. Spending nearly 20% of a geologic time period, looking for evidence that it exists… This is like taking 3.2 million years to find evidence that the Miocene Epoch deserved to be differentiated from the preceding Oligocene Epoch. Geologic time refers to periods of hundreds of thousands to hundreds of million years, not hundreds of years… Much less seven decades.

Plutonium is not forever

The primary basis for starting the proposed Anthropocene Epoch around 1950 is the presence of plutonium in sediments, coral reefs and ice sheets.

Plutonium is a radioactive metallic element with the atomic number 94. It was discovered in 1940 by scientists studying how to split atoms to make atomic bombs. Plutonium is created in a reactor when uranium atoms absorb neutrons. Nearly all plutonium is man-made.

Plutonium predominantly emits alpha particles – a type of radiation that is easily stopped and has a short range. It also emits neutrons, beta particles and gamma rays. It is considered toxic, in part, because if it were to be inhaled it could deposit in the lungs and eventually cause damage.

There are five “common” isotopes of plutonium, Pu-238, Pu-239, Pu-240, Pu-241, and Pu-242. These are all “fissionable” – the atom’s nucleus can easily split apart if it is struck by a neutron.

The different isotopes have different “half-lives” – the time it takes to lose half of its radioactivity. Pu-239 has a half-life of 24,100 years and Pu-241’s half-life is 14.4 years. Substances with shorter half-lives decay more quickly than those with longer half-lives, so they emit more energetic radioactivity.

Like any radioactive isotopes, plutonium isotopes transform when they decay. They might become different plutonium isotopes or different elements, such as uranium or neptunium. Many of these “daughter products” are themselves radioactive.

US NRC

239Pu has a very long half-life of 24,100 years. If you start out with 1 gram of 239Pu, in just over 1 million years, you would have a sample that is 99.99999999998% composed of 235U. While naturally occurring uranium-235 is uncommon, it does exist. Over a geologically meaningful time-span, the anthropogenic “fingerprint” would no longer definitively be of anthropogenic origin, assuming the sediment core was lithified and preserved in the rock record. At best, the dawn of the Anthropocene would be represented by an anomalous uranium isotope ratio.

A likely compromise

While the IUGS is unlikely to ratify an Anthropocene Epoch, they do seem to be open to recognizing it as “geological event” rather than a formal geologic time period.

In contrast to the definition of a new Series/Epoch of the GTS, the designation of a geological event has no such formalization procedures nor GSSP requirements. Yet, to designate the Anthropocene as a geological event would not decrease its significance in Earth’s history. In fact, it would place the Anthropocene with other great transformations of the Earth system. Consider the example of the Great Oxidation Event, which occurred roughly 2.4-2.1 billion years ago and demonstrates that humans are not the first organisms to contribute to a global transformation of Earth (Sagan, 2020). Before the Great Oxidation Event, Earth had a weakly reducing atmosphere in which oxidation was prevented. After cyanobacteria began to produce oxygen as the waste product of photosynthesis, atmospheric oxygen levels rose and radically changed the course of planetary development, including the evolution of multicellular life and the colonization of land following the development of an ozone layer (Schirrmeister et al., 2013). Despite its firm basis in stratigraphy (Buick, 2008; Eriksson and Cheney, 1992), the Great Oxidation Event is not used as part of the GTS but is recognized as a major transformative phase of the Earth system. The same is true for the Great Ordovician Biodiversification Event (GOBE), and for the continental invasion by land plants that transformed the Earth system and stratigraphic records during the Devonian Period (Le Hir et al., 2011; Dahl and Arens, 2020). These examples emphasize that geologic events are not points in time: they are significant happenings or occurrences that are heterogeneous over time and across the Earth.

Gibbard et al., 2021

I discussed thieir paper in more detail in this 2021 post.

We already have an Anthropocene. It’s called the Holocene and really doesn’t deserve its status as an Epoch. Apart from the phrase “mass extinctions,” this is a fairly reasonable characterization of the human-related geological event.

Gibbard et al., 2021

The entire discussion is kind of pointless. Even if humans do leave definitive proof in the rock record that we significantly altered the “Earth system”… Proof that outlives us as a species and is preserved in the rock record, long after we’re gone… Who’s going to see it? Space aliens? Whatever lifeforms evolve to replace humans?

But, it’s always enjoyable to ridicule these folks…

AWG

There’s also a problem with using the word element, “-cene.” The current naming convention applies “-cene” to Cenozoic Era epochs. Instead of the Anthropocene Event, I would call it, the Anthropolitan Event… Better yet… The Fabulous Anthropolitan Event!

‘Habitus’ (2013 – ongoing) is an art installation by Robyn Woolston (robynwoolston.com), commissioned by Edge Hill University, which announces the Anthropocene epoch, Vegas-style. AAPG Explorer

References

Finney, Stanley C. & Lucy E. Edwards. “The “Anthropocene” epoch: Scientific decision or political statement?”GSA Today, 2016; 26 (3): 4 DOI: 10.1130/GSATG270A.1

Gibbard PL, Bauer AM, Edgeworth M, Ruddiman WF, Gill JL, Merritts DJ, Finney SC, Edwards LE, Walker MJC, Maslin M, Ellis EC.  A practical solution: the Anthropocene is a geological event, not a formal epoch.  Episodes 2022;45:349-357.  https://doi.org/10.18814/epiiugs/2021/021029

New Study: Neither Global Warming Or CO2 Radiative Forcing Were A Cause Of Past Mass Extinctions

Over the last 210 million years [Myr], (a) CO2 falls as temperatures rise (negative correlation, r = -0.76), (b) mass extinctions occur 4.08 Myr after CO2 peaks, and (c) global warming/CO2 radiative forcing “did not cause extinction of biodiversity.”

From NoTricksZone

By Kenneth Richard on 10. July 2023

Over the last 210 million years [Myr], (a) CO2 falls as temperatures rise (negative correlation, r = -0.76), (b) mass extinctions occur 4.08 Myr after CO2 peaks, and (c) global warming/CO2 radiative forcing “did not cause extinction of biodiversity.”

A new study has been published in Earth’s Future journal that supplements a 2017 analysis of hundreds of millions of years of CO2 and temperature variations.

Davis (2017) argued that for 97.44% of the last 425 Myr there was either a negative correlation (CO2 falls, temperatures rise or CO2 rises as temperatures fall) or no correlation at all between variations in global temperatures and radiative forcing by atmospheric CO2. In other words, the IPCC-proposed link between the rise in atmospheric CO2 as the causal mechanism and global warming could only explain 2.56% of the variance in the long-term paleoclimate record.

Image Source: Davis, 2017

A positive correlation between high CO2 and extinctions

But now a new study by the same author looks at the timing of mass extinctions and their correspondence with atmospheric CO2 concentrations over the last 210 Mya. There were reportedly 12 mass extinction events that occurred when CO2 was rising to peak levels (~1,000 ppm) during this period, whereas 6 occurred as CO2 was falling. This is considered a weakly positive correlation.

Interestingly, though, the timing for the mass extinctions was, on average, 4.08 Myr after the CO2 levels had reached their apex. This leads one to question why it would be thought the effect (mass extinctions) should lag the triggering cause (peak CO2) by millions of years. Especially since species extinctions can occur in time spans of decades to centuries.

A negative correlation between global warming and atmospheric CO2

As he did in his previous paper, Davis (2023) documents an overall negative correlation between global temperatures and atmospheric CO2 concentrations over the last 210 Mya. Specifically, multiple degrees of increases in global temperatures occurred as CO2 levels fell (for example, from 772 ppmv to 291 ppmv).

“The correlation between atmospheric CO2 concentration and interpolated global temperature proxies is discernible and negative (r = −0.76, n = 8, p = 0.01).”

Since the correlation between CO2 and global temperature is more often negative than positive, the positive link between high CO2 levels and extinctions Davis addresses in his study could be explained as a better correlation with high CO2 and global cooling than with high CO2 and global warming.

Image Source: Davis, 2023

Earth-s-Future-2023-Davis-Mass-Extinctions-and-Their-Relationship-With-Atmospheric-Carbon-Dioxide-ConcentrationHerunterladen

Neither global warming or CO2 radiative forcing caused past mass extinctions

Over the last 210 Myr, the correlation between global warming periods and mass extinctions is “not discernibly different from zero” (r = 0.03), and the correlation between atmospheric CO2 radiative forcing (RF) is also “not discernibly different from zero” (r = -0.001). Without correlation, there can be no causal relationship between either global warming or CO2 radiative forcing and the record of mass extinctions.

“These results collectively require rejection of the hypothesis that long-term (Myr timescale) global temperature change caused extinction of biodiversity across the most highly resolved portion of the fossil record, the last 210 Myr.”

“This study therefore excludes long-term temperature (climate) change as a possible cause of past mass extinctions.”

“If long-term global warming was the cause of past extinctions, then long-term temperature and marginal RF by atmospheric CO2 should both be correlated positively with biodiversity loss. As shown here, however, biodiversity loss is not correlated discernibly with marginal RF by atmospheric CO2…that is, changes in RF by atmospheric CO2 did not cause past collapses in biodiversity and are not a plausible kill mechanism of mass extinctions.”