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  • richardmitnick 10:50 am on April 16, 2016 Permalink | Reply
    Tags: Ancient volcanoes could be key to predicting impact of climate change, , , Mass extinctions,   

    From USC: “Ancient volcanoes could be key to predicting impact of climate change” 

    USC bloc

    University of Southern California

    April 13, 2016
    Andrew Good

    Researchers think emissions from volcanos, such as the one seen here, may have led to a dramatic rise in CO2 leading to a mass extinction 200 million years ago. (Photo/NASA Earth Observatory)

    Just over 200 million years ago, long before the demise of the dinosaurs, a cataclysm killed off a significant chunk of the planet’s animal life. The leading theory implicates massive volcanic eruptions, triggered when the supercontinent of Pangea was ripped apart into separate continents.

    A new study co-authored by USC researchers strengthens evidence for that theory and has wider implications for how rapid climate change can affect life on Earth. Along with lava flows, the volcanic eruptions released massive amounts of the greenhouse gas carbon dioxide, creating havoc in the ecosystem.

    The study*, published April 6 in Nature Communications, charts the sharp escalation of the element mercury in samples of rock preserved from the Triassic-Jurassic extinction event. It isn’t the ordinary mercury you’d find on the surface of the planet: Isotopic data suggests it can be traced to the eruptions.

    Frank Corsetti, a geobiologist at the USC Dornsife College of Letters, Arts & Sciences, was a co-author on the study along with USC professors David Bottjer, Josh West and William Berelson; current USC graduate student Joyce Yager; and a host of current and past graduate students, including Kathleen Ritterbush, now an assistant professor at the University of Utah, and Yadira Ibarra, now a postdoctoral research fellow at Stanford University.

    Mercury rising

    Corsetti said the rise in mercury seems to match changes in the planet’s biosphere during the era. As the mercury was found to rise in the rock samples, it matched a wave of animal extinctions on the planet’s surface and in its seas. The mass extinction peaks just as the level of mercury does; biodiversity begins to return once the mercury level recedes, about 700,000 years after the event began.

    The mercury, Corsetti said, serves as a kind of fingerprint for a massive volcanic eruption in what’s known as the Central Atlantic Magmatic Province (CAMP). Essentially, CAMP was the spot in Pangea where the Atlantic Ocean would later appear after the land mass split.

    CAMP’s appearance was a cataclysm on its own.

    “If that much material erupted today, it would cover the contiguous United States with about 400 meters of lava — it was an enormous series of eruptions,” Corsetti said.

    But the reason CAMP is suspected of being the culprit in the mass extinction has to do with carbon dioxide — the gas that climate change experts now worry is being released into the atmosphere in rapid and massive quantities.

    “By some estimates, it rose nearly as rapidly as we’re putting CO2 into the atmosphere today,” Corsetti said. “We wanted to see how the Earth system responded from a rapid rise of CO2. The spoiler alert is there was a mass extinction. What we’ve been able to do is use this mercury as a fingerprint to tie the event to the volcanos, and therefore the emissions.”

    The Triassic-Jurassic extinction is particularly pertinent because it was selective, Corsetti said. It preferentially affected coral reefs and animals most similar to the ones common in today’s oceans. An earlier and more severe event, the Permian extinction — sometimes called “the mother of all extinctions” — was even bigger, but the dominant organisms affected were different from the ones common today.

    That makes the T-J event perhaps the most relevant mass extinction to study when trying to predict what might happen with rising CO2 levels, Corsetti said.

    The study was sponsored by the National Science Foundation, the Roger E. Deane Postdoctoral Fellowship, the Geological Society of America, the Society for Sedimentary Geology, the American Philosophical Society, the Natural Sciences and Engineering Research Council of Canada and the Canadian Institute for Advanced Research.

    *Science paper:
    Mercury anomalies and the timing of biotic recovery following the end-Triassic mass extinction

    Science team and affiliations:

    Department of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada
    Alyson M. Thibodeau & Bridget A. Bergquist
    Department of Earth Sciences, Dickinson College, Carlisle, Pennsylvania 17013, USA
    Alyson M. Thibodeau
    Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84103, USA
    Kathleen Ritterbush
    Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA
    Joyce A. Yager, A. Joshua West, David J. Bottjer, William M. Berelson & Frank A. Corsetti
    Department of Earth System Science, Stanford University, Stanford, California 94305, USA
    Yadira Ibarra


    D.J.B., F.A.C. and A.J.W. conceived the study and designed it with A.M.T. and B.A.B. K.R., J.A.Y. and Y.I. collected the samples. A.M.T. and J.A.Y. collected, analysed and interpreted the mercury and carbon data, respectively, with B.A.B., A.J.W., W.M.B. and F.A.C. K.R. provided the stratigraphic and paleoenvironmental context as well as the paleoecological data. K.R., Y.I. and F.A.C. were responsible for paleoenvironmental interpretation. F.A.C., J.A.Y., A.J.W. and A.M.T. conceived and drafted the figures. F.A.C. and A.M.T. wrote the paper with contributions from all other co-authors.

    See the full article here .

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    The University of Southern California is one of the world’s leading private research universities. An anchor institution in Los Angeles, a global center for arts, technology and international business, USC’s diverse curricular offerings provide extensive opportunities for interdisciplinary study, and collaboration with leading researchers in highly advanced learning environments. With a strong tradition of integrating liberal and professional education, USC fosters a vibrant culture of public service and encourages students to cross academic as well as geographic boundaries in their pursuit of knowledge.

  • richardmitnick 7:46 pm on December 20, 2015 Permalink | Reply
    Tags: , Mass extinctions,   

    From The Atlantic: “The Chilling Regularity of Mass Extinctions” 

    Atlantic Magazine

    The Atlantic Magazine

    Nov 3, 2015
    Adrienne LaFrance

    An artist’s rendering of an asteroid or comet striking Earth. Andrea Danti / Shutterstock

    One thing we know for sure is that conditions on Earth were, shall we say, unpleasant for the dinosaurs at the moment of their demise. Alternate and overlapping theories suggest the great beasts were pelted with monster comets, drowned by mega-tsunamis, scorched with lava, starved by a landscape stripped of vegetation, blasted with the radiation of a dying supernova, cloaked in decades of darkness, and frozen in an ice age.

    Now, a pair of researchers have new evidence to support a link between cyclical comet showers and mass extinctions, including the one that they believe wiped out the dinosaurs 66 million years ago. Michael Rampino, a geologist at New York University, and Ken Caldeira, an atmospheric scientist at the Carnegie Institution for Science, traced 260 million years of mass extinctions and found a familiar pattern: Every 26 million years, there were huge impacts and major die-offs. Their work was accepted by the Monthly Notices of the Royal Astronomical Society in September.

    In recent decades, researchers using other methods have found evidence for a 26-million-year cycle of extinction on Earth, but the idea has remained controversial and unexplained. “I believe that our study, using revised dating of extinctions and craters, and a new method of spectral analysis, is strong evidence for the cycles,” Rampino told me.

    Other scientists who have researched mass extinctions are more measured about the latest findings. “I’m sort of agnostic [about the larger theory],” said Paul Renne, the director of Berkeley Geochronology Center. “But I was really disappointed to see they used an age-database for the craters which is full of outdated information.”

    Renne is the author of another new study that focuses on the Chicxulub crater, the massive divot beneath the Yucatán Peninsula that was created by the same impact blamed for the extinction of the dinosaurs.

    Chicxulub crater. NatGeo Illustration by Detlev van Ravenswaay, Science Source

    Renne and his colleagues believe that the comet or asteroid that blasted into Earth and made Chicxulub also set off a global chain-reaction of volcanic eruptions that accelerated the end of the dinosaurs. Volcanoes were, they believe, erupting continuously for millions of years. Long enough to make Hawaii’s Kilauea, which has been flowing since 1983, seem laughable. (“Kilauea is nothing,” Renne told me. “Kilauea is a flea.”)

    And while Renne is interested in the possibility that volcanism is tied to intervals of mass extinction, that possible connection doesn’t explain what kind of cycles might trigger the awakening of Earth’s most powerful magma systems on a global scale. That’s where theories about galactic periodicity come back into play.

    “One of the earliest proponents of a periodic record [of mass extinction] was by a guy named Rich Muller,” Renne said. “He proposed a kind of phenomenological periodicity in which they didn’t really have a mechanism.” In other words, Muller found the 26-million-year pattern of mass extinctions on Earth, but didn’t immediately know what drove the cycle.

    The latest findings from Rampino and Caldeira build on the idea that regular comet showers cause intervals of mass extinctions. The showers, the theory goes, are triggered by the movement of the sun and planets through the crowded mid-plane of our galaxy. As the sun crosses that region, it disrupts great clouds of space dust. Those clouds, in turn, throw off the orbit of comets, sending them careening toward Earth.

    In another theory, planetary scientists suggested that one region of the solar system in particular, known as the Oort comet cloud, plays a key role in mass extinctions.

    Kuiper Belt and Oort Cloud.

    The Oort cloud is a sprawling region at the border of our solar system that contains trillions of icy bodies. Muller put forth a popular hypothesis in the 1980s that said our sun has a sort of evil twin in the Oort cloud. This hypothetical star, he suggested, has an orbital cycle such that it would perturb its neighboring objects, and send 1 billion of them hurtling toward Earth every 26 million years. The star, a binary to the sun, was nicknamed Nemesis, and playfully referred to as the death star. “The binary star, or Nemesis theory, was an alternate to the Galactic-plane story,” Rampino told me. “But the star was looked for, but never found, so Nemesis theory is out of favor now.”

    “[Muller] doesn’t even believe that anymore,” Renne told me.

    If Rampino and Caldeira are correct, the next mass extinction may not be far off—in geologic terms, anyway. Our little corner of the solar system crossed the plane about 2 million years ago, and we are now moving up and through it. “In the Galactic theory, we are near the Galactic plane, and we have been in the danger zone for a couple of million years,” Rampino said. “We are still close to the plane, maybe 30 light years above the plane, [and] a light year is 6 trillion miles … We won’t come back across the plane for about another 30 million years.”

    And while scientists can’t be sure when the next major comet or asteroid impact on Earth will be, the one that is believed to have killed the dinosaurs still stands out as extraordinary, even by mass-extinction standards. The city-sized asteroid that created Chicxulub, for instance, released more energy than 1 billion nuclear bombs when it hit the Earth.

    “There hasn’t been an impact large enough to cause a major mass extinction since the impact 66 million years ago,” Rampino said. “That was a 10-kilometer [six-mile] diameter asteroid or comet. The largest impactor in the last 66 million years was only 5 kilometers [3 miles] in diameter, which only has one-tenth the energy, so it probably wouldn’t have taken out the dinosaurs. In fact, if a 10-kilometer-sized object had hit in the last 66 million years, we wouldn’t be here. Our ancestors probably would have been knocked out.”

    The obvious next question, of course, is how do we prevent the terrible fate the dinosaurs suffered? “These events are so rare in geologic time that the odds of even our great-great-great-great-great-great-grandchildren witnessing them are really low,” Renne said. “The ultimate proof, which is observation, is not going to be available to us, unfortunately.” (Or fortunately, depending on your priorities.)

    In the meantime, scientists are actively scouring the skies, and calculating the orbits of monstrous comets and asteroids. “So far, none are on a collision course, but the work has just begun in earnest,” Rampino said. “Once we know one is coming, then there are several options to divert the object. (You don’t want to blow it up, that will just increase the numbers of impactors.) One possibility is to have a nuclear explosion off to one side of the comet or asteroid, pushing it just slightly off course, or possibly just hitting the object with a rapidly moving space-craft would provide enough of a nudge.”

    See the full article here .

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  • richardmitnick 5:41 pm on September 16, 2015 Permalink | Reply
    Tags: , Mass extinctions, ,   

    From MIT: “Siberian Traps likely culprit for end-Permian extinction” 

    MIT News

    September 16, 2015
    Jennifer Chu

    New study finds massive eruptions likely triggered mass extinction.

    No image credit

    Around 252 million years ago, life on Earth collapsed in spectacular and unprecedented fashion, as more than 96 percent of marine species and 70 percent of land species disappeared in a geological instant. The so-called end-Permian mass extinction ­— or more commonly, the “Great Dying” — remains the most severe extinction event in Earth’s history.

    Scientists suspect that massive volcanic activity, in a large igneous province called the Siberian Traps, may have had a role in the global die-off, raising air and sea temperatures and releasing toxic amounts of greenhouse gases into the atmosphere over a very short period of time.

    Physical map of Siberia with extent of Siberian traps according to http://www.mantleplumes.org/Siberia.html

    However, it’s unclear whether magmatism was the main culprit, or simply an accessory to the mass extinction.

    MIT researchers have now pinned down the timing of the magmatism, and determined that the Siberian Traps erupted at the right time, and for the right duration, to have been a likely trigger for the end-Permian extinction.

    According to the group’s timeline, explosive eruptions began around 300,000 years before the start of the end-Permian extinction. Enormous amounts of lava both erupted over land and flowed beneath the surface, creating immense sheets of igneous rock in the shallow crust. The total volume of eruptions and intrusions was enough to cover a region the size of the United States in kilometer-deep magma. About two-thirds of this magma likely erupted prior to and during the period of mass extinction; the last third erupted in the 500,000 years following the end of the extinction event. This new timeline, the researchers say, establishes the Siberian Traps as the main suspect in killing off a majority of the planet’s species.

    “We now can say it’s plausible,” says Seth Burgess, who received his PhD last year from MIT’s Department of Earth, Atmospheric, and Planetary Sciences and is now a postdoc at the U.S. Geological Survey. “The connection is unavoidable, because it’s clear these two things were happening at the same time.”

    Burgess and Sam Bowring, the Robert R. Shrock Professor of Earth and Planetary Science at MIT, have published their results in the journal Science Advances.

    A singular event

    Around the time of the end-Permian extinction, scientists have found that the Earth was likely experiencing a sudden and massive disruption to the carbon cycle, abnormally high air and sea temperatures, and an increasingly acidic ocean — all signs of a huge and rapid addition of greenhouse gases to the atmosphere. Whatever triggered the mass extinction, scientists reasoned, must have been powerful enough to generate enormous amounts of greenhouse gases in a short period of time.

    The Siberian Traps have long been a likely contender: The large igneous province bears the remains of the largest continental volcanic event in Earth’s history.

    “It’s literally a singular event in Earth history — it’s a monster,” Burgess says. “It makes Yellowstone … look like the head of a pin.”

    This 2013 publication by United States National Park Service at web posting replaces previous USGS map, File:Yellowstone Caldera map2.jpg. The older diagram, File:Yellowstone Caldera map2.jpg, is posted on-line as “fig_03_yellowstone_map.jgp,” dated 14 March 14 2005. Very similar map, but nevertheless some minor changes were made over the elapsed 8 years. Specifically, the northernmost “uncertain boundary” for the 1st caldera has been replaced.

    (2) Note that West Thumb Caldera (44°25′40″N 110°31′57″W) is not to be confused with West Thumb Geyser Basin (44°25′07″N 110°34′23″W). Per the US NPS, West Thumb Lake is itself a smaller caldera. See Figure 22 at US NPS web site. West Thumb Caldera forms West Thumb Lake, and West Thumb Geyser Basin lies on the western shore of West Thumb Lake. Source: US NPS

    It’s thought that as the region erupted, magma rose up through the Earth’s crust, essentially cooking sediments along the way and releasing enormous amounts of greenhouse gases like carbon dioxide and methane into the atmosphere.

    “The question we tried to answer is, ‘Which came first, mass extinction or the Siberian Traps? What is their overall tempo, and does the timing permit magmatism to be a trigger for mass extinction?’” Burgess says.

    Dates pinned

    For the answer, Burgess, Bowring, and colleagues traveled to Siberia on multiple occasions, beginning in 2008, to sample rocks from the Siberian Traps. For each expedition, the team traveled by boat or plane to a small Siberian village, then boarded a helicopter to the Siberian Traps. From there, they paddled on inflatable boats down a wide river, chiseling out samples of volcanic rock along the way.

    “We’d have a couple of hundred kilos of rocks, and would go to the market in Moscow and buy 15 sport duffle bags, and in each we’d put 10 kilos of rocks … and hope we could get them all on the plane and back to the lab,” Burgess recalls.

    Back at MIT, Burgess and Bowring dated select samples using uranium/lead geochronology, in which Bowring’s lab specializes.

    A schematic depiction of the major events in the history of Earth

    The team looked for tiny crystals of either zircon or perovskite, each of which contain uranium and lead, the ratios of which they can measure to calculate the rock’s age. The team dated various layers of rock to determine the beginning and end of the eruptions.

    They then compared the timing of the Siberian Traps to that of the end-Permian extinction, which they had previously determined using identical techniques.

    “That’s important, because we can compare green apples to green apples. If everything is done the same, there’s no bias,” Burgess says. “Now we’re able to say magmatism definitely preceded mass extinction, and we can resolve those two things outside of uncertainty.”

    Richard Ernst, a scientist-in-residence at Carleton University in Ottawa, Ontario, says the new timeline establishes a definitive, causal link between the Siberian Traps and the end-Permian extinction.

    “This paper nails it,” says Ernst, who was not involved in the study. “Given that they have dated a portion of the Siberian Traps occurring just before, during, and only for a short time after the extinction, this is the ‘smoking gun’ for this large igneous province being fully correlated with the extinction. At this point, additional dating and other studies will simply provide more details on the link.”

    Now that the team has resolved the beginning and end of the Siberian Traps eruptions, Burgess hopes others will take an even finer lens to the event, to determine the tempo of magmatism in the 300,000 years prior to the mass extinction.

    “We don’t know if a little erupted for 250,000 years, and right before the extinction, boom, a vast amount did, or if it was more slow and steady, where the atmosphere reaches a tipping point, and across that point you have mass extinction, but before that you just have critically stressed biospheres,” Burgess says. “Now we’ve pinned it down in time, and others can go in with other techniques to get a more fully fleshed out timeline. But we need it to start someplace, and that’s what we’ve got.”

    This research was funded, in part, by the National Science Foundation.

    See the full article here .

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  • richardmitnick 10:39 am on September 4, 2015 Permalink | Reply
    Tags: , Mass extinctions, ,   

    From Vanderbilt: “Evidence that Earth’s first mass extinction was caused by critters, not catastrophe” 

    Vanderbilt U Bloc

    Vanderbilt University

    Sep. 2, 2015
    David Salisbury

    Fossil of frond-like Ediacaran species found in Namibia. (Sarah Tweedt, Smithsonian Institution)

    In the popular mind, mass extinctions are associated with catastrophic events, like giant meteorite impacts and volcanic super-eruptions.

    But the world’s first known mass extinction, which took place about 540 million years ago, now appears to have had a more subtle cause: evolution itself.

    “People have been slow to recognize that biological organisms can also drive mass extinction,” said Simon Darroch, assistant professor of earth and environmental sciences at Vanderbilt University. “But our comparative study of several communities of Ediacarans, the world’s first multicellular organisms, strongly supports the hypothesis that it was the appearance of complex animals capable of altering their environments, which we define as ‘ecosystem engineers,’ that resulted in the Ediacaran’s disappearance.”

    The study is described in the paper Biotic replacement and mass extinction of the Ediacara biota published Sept. 2 in the journal Proceedings of the Royal Society B.

    “There is a powerful analogy between the Earth’s first mass extinction and what is happening today,” Darroch observed. “The end-Ediacaran extinction shows that the evolution of new behaviors can fundamentally change the entire planet, and we are the most powerful ‘ecosystem engineers’ ever known.”

    The earliest life on Earth consisted of microbes – various types of single-celled microorganisms. They ruled the Earth for more than 3 billion years. Then some of these microorganisms [cyanobacteria] discovered how to capture the energy in sunlight.


    The photosynthetic process that they developed had a toxic byproduct: oxygen. Oxygen was poisonous to most microbes that had evolved in an oxygen-free environment, making it the world’s first pollutant.

    But for the microorganisms that developed methods for protecting themselves, oxygen served as a powerful new energy source. Among a number of other things, it gave them the added energy they needed to adopt multicellular forms. Thus, the Ediacarans arose about 600 million years ago during a warm period following a long interval of extensive glaciation.

    “We don’t know very much about the Ediacarans because they did not produce shells or skeletons. As a result, almost all we know about them comes from imprints of their shapes preserved in sand or ash,” said Darroch.

    Simon Darroch (Steve Green / Vanderbilt)

    What scientists do know is that, in their heyday, Ediacarans spread throughout the planet. They were a largely immobile form of marine life shaped like discs and tubes, fronds and quilted mattresses. The majority were extremely passive, remaining attached in one spot for their entire lives. Many fed by absorbing chemicals from the water through their outer membranes, rather than actively gathering nutrients.

    Paleontologists have coined the term “Garden of Ediacara” to convey the peace and tranquility that must have prevailed during this period. But there was a lot of churning going on beneath that apparently serene surface.

    After 60 million years, evolution gave birth to another major innovation: animals. All animals share the characteristics that they can move spontaneously and independently, at least during some point in their lives, and sustain themselves by eating other organisms or what they produce. Animals burst onto the scene in a frenzy of diversification that paleontologists have labeled the Cambrian explosion, a 25-million-year period when most of the modern animal families – vertebrates, molluscs, arthropods, annelids, sponges and jellyfish – came into being.

    “These new species were ‘ecological engineers’ who changed the environment in ways that made it more and more difficult for the Ediacarans to survive,” said Darroch.

    Ediacaran fossil found in the Swartput Farm site. (Sarah Tweedt / Smithsonian Institution)

    He and his colleagues performed an extensive paleoecological and geochemical analysis of the youngest known Ediacaran community exposed in hillside strata in southern Namibia. The site, called Farm Swartpunt, is dated at 545 million years ago, in the waning one to two million years of the Ediacaran reign.

    “We found that the diversity of species at this site was much lower, and there was evidence of greater ecological stress, than at comparable sites that are 10 million to 15 million years older,” Darroch reported. Rocks of this age also preserve an increasing diversity of burrows and tracks made by the earliest complex animals, presenting a plausible link between their evolution and extinction of the Ediacarans.

    The older sites were Mistaken Point in Newfoundland, dating from 579 to 565 million years ago; Nilpena in South Australia, dating from 555 to 550 million years ago; and the White Sea in Russia, dating also from 555 to 550 million years ago million years ago.

    Darroch and his colleagues made extensive efforts to ensure that the differences they recorded were not due to some external factor.

    For example, they ruled out the possibility that the Swartpunt site might have been lacking in some vital nutrients by closely comparing the geochemistry of the sites.

    It is a basic maxim in paleontology that the more effort that is made in investigating a given site, the greater the diversity of fossils that will be found there. So the researchers used statistical methods to compensate for the variation in the differences in the amount of effort that had been spent studying the different sites.

    Simon Darroch in Namibia searching for fossils. (Sarah Tweedt, Smithsonian Institution)

    Having ruled out any extraneous factors, Darroch and his collaborators concluded that “this study provides the first quantitative palaeoecological evidence to suggest that evolutionary innovation, ecosystem engineering and biological interactions may have ultimately caused the first mass extinction of complex life.”

    Marc Laflamme, Thomas Boag and Sara Mason from the University of Toronto; Douglas Erwin and Sarah Tweedt from the Smithsonian Institution, Erik Sperling from Stanford University, Alex Morgan and Donald Johnston from Harvard University; Rachel Racicot from Yale University; and Paul Myrow from Colorado College collaborated in the study.

    The project was supported by grants from the Connaught Foundation, National Science and Engineering Research Council of Canada, NASA Astrobiology Institute, National Geographic Society and National Science Foundation grant EAR 1324095.

    See the full article here .

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  • richardmitnick 8:39 pm on March 22, 2015 Permalink | Reply
    Tags: , , Mass extinctions,   

    From RAS: “Does dark matter cause mass extinctions and geologic upheavals?” 

    Royal Astronomical Society

    Royal Astronomical Society

    19 February 2015

    Media contacts

    James Devitt
    Deputy Director for Media Relations
    New York University
    United States
    Tel: +1 (212) 998 6808
    Mob: +1 (914) 522 3774

    Robert Massey
    Royal Astronomical Society
    Tel: +44 (0)20 7734 3307 x214
    Mob: +44 (0)794 124 8035

    Science contact

    Prof Michael Rampino
    New York University
    United States
    Tel: +1 (718) 578 1442

    NGC 4565, an edge-on spiral galaxy. The stars, dust and gas are concentrated into a thin disc, much like the one in our Milky Way galaxy. NGC 4565 and apparently smaller NGC 4562. 24-inch telescope on Mt. Lemmon, AZ. Courtesy of Joseph D. Schulman

    Mt Lemon 24 inch telescope
    Mt Lemon 24 inch telescope

    Research by New York University Biology Professor Michael Rampino concludes that Earth’s infrequent but predictable path around and through our Galaxy’s disc may have a direct and significant effect on geological and biological phenomena occurring on Earth. In a new paper in Monthly Notices of the Royal Astronomical Society, he concludes that movement through dark matter may perturb the orbits of comets and lead to additional heating in the Earth’s core, both of which could be connected with mass extinction events.

    The galactic disc is the region of the Milky Way galaxy where our solar system resides. It is crowded with stars and clouds of gas and dust, and also a concentration of elusive dark matter – small subatomic particles that can be detected only by their gravitational effects.

    Previous studies have shown that Earth rotates around the disc-shaped Galaxy once every 250 million years. But the Earth’s path around the Galaxy is wavy, with the Sun and planets weaving through the crowded disc approximately every 30 million years. Analysing the pattern of the Earth’s passes through the Galactic disc, Rampino notes that these disc passages seem to correlate with times of comet impacts and mass extinctions of life. The famous comet strike 66 million ago that led to the extinction of the dinosaurs is just one example.

    What causes this correlation between Earth’s passes through the Galactic disc, and the impacts and extinctions that seem to follow?

    While travelling through the disc, the dark matter concentrated there disturbs the pathways of comets typically orbiting far from the Earth in the outer Solar System, Rampino points out. This means that comets that would normally travel at great distances from the Earth instead take unusual paths, causing some of them to collide with the planet.

    But even more remarkably, with each dip through the disc, the dark matter can apparently accumulate within the Earth’s core. Eventually, the dark matter particles annihilate each other, producing considerable heat. The heat created by the annihilation of dark matter in Earth’s core could trigger events such as volcanic eruptions, mountain building, magnetic field reversals, and changes in sea level, which also show peaks every 30 million years. Rampino therefore suggests that astrophysical phenomena derived from the Earth’s winding path through the Galactic disc, and the consequent accumulation of dark matter in the planet’s interior, can result in dramatic changes in Earth’s geological and biological activity.

    His model of dark matter interactions with the Earth as it cycles through the Galaxy could have a broad impact on our understanding of the geological and biological development of Earth, as well as other planets within the Galaxy.

    Rampino said: “We are fortunate enough to live on a planet that is ideal for the development of complex life. But the history of the Earth is punctuated by large scale extinction events, some of which we struggle to explain. It may be that dark matter – the nature of which is still unclear but which makes up around a quarter of the universe – holds the answer. As well as being important on the largest scales, dark matter may have a direct influence on life on Earth.”

    In the future, he suggests, geologists might incorporate these astrophysical findings in order to better understand events that are now thought to result purely from causes inherent to the Earth. This model, Rampino adds, likewise provides new knowledge of the possible distribution and behaviour of dark matter within the Galaxy.

    See the full article here.

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