Tag Archives: mass extinction

Artist's rendering of the landscape during end-Permian extinction. Credit: José-Luis Olivares/MIT.

Ozone-depleting chemicals may have caused the largest mass extinction in history

Artist's rendering of the landscape during end-Permian extinction. Credit: José-Luis Olivares/MIT.

Artist’s rendering of the landscape during end-Permian extinction. Credit: José-Luis Olivares/MIT.

Living organisms haven’t always had it easy and throughout their multi-billion-year-old history, they have frequently been threatened with annihilation. But there was no greater challenge than the Great Dying, a mass extinction event that occurred 250 million years ago. For almost a million years, a huge volcano in Siberia continuously erupted, wiping out 90% of all species. The scale of extinction was unprecedented but it was never clear what made this massive volcanic eruption so deadly — after all, it wasn’t the first nor the last event of its kind. Now, a new study explains what may have driven the Great Dying: reactive chemicals released from stockpiles beneath the crust that destroyed the ozone layer.

The Permian-Triassic extinction took place at the end of the Permian period, and in those times, living on our planet was hellish: global warming, ocean acidification and ocean anoxia (lack of oxygen) all worked together to wipe out most of life on Earth. According to a 2014 study performed by MIT researchers, the extinction event likely lasted for 60,000 years, with an uncertainty of 48,000 years. In geological terms, this is like the blink of an eye — too fast for most life on Earth to adapt. The samples also confirmed what was known for a while: the extinction was preceded by a sharp increase of carbon dioxide in the oceans.

The long-lasting volcanic eruptions from the Siberian Traps, a region of Russia whose steplike hills are a result of repeated eruptions of magma, released volatile chemicals, including carbon dioxide, into the atmosphere and oceans, covering an estimated five million cubic kilometers. Most of the carbon was absorbed by the oceans which act like huge heat-sinks, increasing sea temperatures by as much as 10 degrees Celsius – too hot for anything to survive. Around 96% of marine species and 70% of terrestrial species were obliterated by the Permian-Triassic extinction and it took life on Earth ten million years to recover from this event.

But the conditions life had to face in these dire times may have been even more challenging than previously hypothesized.

In a new study published in Nature Geoscience, Michael Broadley, a postdoctoral researcher at the Centre for Petrographic and Geochemical Research in Vandœuvre-lès-Nancy, France along with colleagues examined rocks from the lithosphere — the solid, outer part of the Earth sandwiched in between the crust and the mantle — which were captured by passing magma during the ancient eruption.

These samples provide a snapshot of the lithosphere’s composition prior to the event that brought them to the surface of the Earth. Before the eruption of the Siberian Flood Basalts, the researchers found that the lithosphere contained significant amounts of chlorine, bromine, and iodine. These elements, present in the halogen group on the periodic table, have since disappeared after the volcanic eruption.

The breakthrough was identifying these elements which were presented in extremely low concentrations — just a few parts per billion in the case of bromine and iodine.

“These rocks were a complete surprise. The level of halogens was much much higher than we were expecting. When we got these results we realised that we had something interesting. The level of enrichment is so high that we knew that even if only a small percentage was released to the atmosphere it could have potentially devastating effects for the Earth’s ozone layer,” Broadley told ZME Science.

Once these elements flooded the atmosphere, they reacted with the ozone layer, destroying it. The ozone layer cushions the planet’s surface from harmful UV radiation and exposure to higher levels of UV radiation (such as those associated with a thinned ozone layer) significantly raise the risks of developing cataract and skin cancer. Wide-scale exposure to UV levels expected in the absence of the ozone layer would drastically impact whole ecosystems.

Human activity recently made a huge, gaping hole in the ozone layer due to pollution with chlorofluorocarbons and hydrochlorofluorocarbons (CHCs and HCHCs), chemicals used in old refrigerators and spray cans. However, thanks to remarkable international collaboration, that hole is almost plugged now. Unfortunately, creatures living more than 250 million years were in no such luck.

Coupled with acid rain and gloomy sky, a thin ozone layer must have been quite a dramatic sight on the planet at the time.

“We knew from fossil evidence that there seems to be a high level of mutated spores and pollen around the time of the eruption of the halogens. These high level of mutation is considered to be related to higher levels of UV radiation at the time. We, therefore, consider that the huge amounts of halogens released from the lithosphere led to the destruction of the ozone layer and therefore led to high levels of solar UV radiation reaching the surface. Whilst potentially not immediately noticeable, the high levels of UV would have damaged DNA and led to plant sterility. Therefore if humans had been around at this time they may have witnessed the large scale deforestation and the collapse of the food chain,” Broadley said.

In the future, Broadley and colleagues are planning to study diamonds from the lithosphere. During their formation, the diamonds trap some lithospheric fluids, which may help answer how the Siberian lithosphere became so enriched with halogens in the first place. In the meantime, the study serves as a stark reminder of how fragile life can be.

“This study has parallels to modern times. During the 70s and 80s, scientists discovered the ozone hole, caused by the release of halogen-bearing compounds to the atmosphere. Thankfully global action was taken to reduce the emission of these compounds but our study shows the importance of the ozone layer and the potential consequences that can come about from its destruction,” Broadley said.

Mass extinctions don’t come out of the blue — and we’re seeing some of the signs today

An incoming mass extinction isn’t as hard to spot as we’d believed, new research suggests.

sign-slippery-wet-caution.

Image via Pexels.

Paleobiologists from the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) say that the build-up to the largest mass extinction event ever recorded was a lot less inconspicuous than anyone assumed. Armed with this knowledge, they also make a worrying remark: some of the tell-tale signs are unfolding today.

Mass extinctions are like really deep economic crises, but for life — which is why such events are also referred to as ‘biotic crises’. They’re rare, dramatic events, reaping life with terrifying efficiency: the ‘tamest’ mass extinctions cull around 70% to 75% of all species. The largest such event we know of, the Permian-Triassic extinction event, claimed an estimated 83% of all genera and 90% to 96% of all species. Such is their effect that geologists actually use these events as separators between whole geological eras.

Draw of the curtain

Needless to say, such events completely alter the course of evolution, usually on a planetary scale. The Permian-Triassic event made the rise of the dinosaurs possible, and a subsequent mass extinction 65 million years ago threw them off their throne — allowing mammals, and ultimately humans, to move in. There have been five such events that we know of so far.

Given their sheer ability to stir things up — especially for the dominant species (used to be dinosaurs, now it’s us) — mass extinction events are certainly something we’d want to avoid. Thus making the fact that a sixth one is likely incoming a very, very scary prospect. However, a new paper suggests that our view of how these events unfold don’t necessarily correspond to reality.

It’s widely believed that they start relatively abruptly and unfold quickly (in geological terms); most estimates of the Cretaceous-Paleogene extinction, the one with the meteorite that wiped out the dinosaurs, pin its duration around the 60,000-year mark.

The new paper, published by researchers from Germany and Iran, suggests that this crisis unfolded over a longer period of time. Led by Prof. Dr. Wolfgang Kießling, Chair for Palaeoenvironmental Research at FAU, the team examined fossils from largely unresearched geological profiles in Iran. According to their findings, the first indicators of a mass extinction became apparent as early as 700,000 years prior to the event itself — several species of ammonoids disappeared around that time, and the remaining species became increasingly smaller and less complex closer to the extinction event.

“There is much evidence of severe global warming, ocean acidification and a lack of oxygen [today],” says Kießling. “What separates us from the events of the past is the extent of these phenomena. For example, today’s increase in temperature is significantly lower than 250 million years ago”.

The team further reports that some of the processes they observed towards the end of the Permian Period (close to the extinction event) can also be seen today. Most notably, they point to the “increased rate of extinction in all habitats” that can be linked directly to human activity “such as the destruction of habitat, over-fishing, and pollution”. Another worrying sign is the “dwarfing” of ocean species, which they note is “clearly attributed to climate change”.

“We should take these signs very seriously,” he adds.

And I daresay he’s right.

The paper “Pre–mass extinction decline of latest Permian ammonoids” has been published in the journal Geology.

Credit: Pixabay.

Five periods of mass extinction on Earth. Are we entering the sixth?

Credit: Pixabay.

Credit: Pixabay.

Our Earth is very old. Based on the estimation of the oldest rock, it’s around 4.5 billion years of age.

Scientists from all over the world use astronomy, geology, chemistry, biology, archaeology and other sciences to investigate the Earth’s formation as well as the emergence and extinction of life on Earth.

…Then there’s life!

Around 13.8 billion years ago, an enormous explosion that scientists call the Big Bang spurred the formation of our planet. The explosion produced increasingly dense, cloud-like masses of hydrogen dust; the biggest turned into our sun, while smaller ones became planets. One of those planets is our Earth.

Some scientists believe around 600 to 700 million years later, meteor showers bombarded the earth, carrying with it large volumes of water and amino acids. Life, in the form of single-cell bacteria, began.

Since then, bacteria has evolved into more complex forms, though different beings have also become extinct.

Geological eras

Geologists divide the periods from the Earth’s formation up until now into a number of eras based on the changes that happened in each of them.

We are currently in the Holocene era, which started around 11,700 years ago when the Ice Age ended.

More recently though, a number of scientists have argued that because of the nuclear bomb testings of the 1950’s and population explosion, humans have entered a new era, called the Anthropocene.

They argue that with more than seven billion people, human activity has drastically influenced nature and the extinction of a number of wildlife.

The Earth is no stranger to disappearing life forms. There are have been many periods of extinction, from when the first organism emerged on Earth until today.

However, according to fossil records, only five eras have drastically reduced the population of living beings on earth to warrant the label of mass extinction.

First period of extinction

Entering early to mid period of the Ordovician Era, the Earth was still warm with an ideal humidity level for living. However, towards the end of the period – around 443 million years ago – everything changed suddenly, when the old continent Gondwana reached the South Pole. The temperature dropped drastically and ice formed everywhere, lowering the water level.

Subsequently, the level of carbon dioxide in the atmosphere and in the sea dropped, causing the number of plants to decrease dramatically and an ecosystem chaos ensued because certain plants, used as sources of food, became scarce.

Some 86% of the population of living beings disappeared within three million years. Some of the organisms affected by the first extinction were Brachiopods, Conodonts, Acritarchs, Bryozons, and also Trilobites that lived in the ocean.

Second period of extinction

The second period of extinction, during the Devon Age, happened around 359 million years ago. A relentless meteor shower is believed to be one of the causes of mass extinction. Other causes include a drastic decrease in oxygen levels globally, the increased activity of tectonic plates, and climate change. These changes caused around 75% of living creatures to die.

Extinction in this period impacted life in the sea which, at the time, was dominated by corals and stromatoporoids.

Third period of extinction

The third period of extinction, around 251 million years ago, during the Permian Age, was the biggest and worst that ever happened on Earth.

The formation of the giant continent Pangea caused immense changes in geology, climate and the environment. Volcanic eruptions that continued for 1 million years released around 300 million square kilometres of lava while more than 1750 metres of sediment was formed in the Siberian Traps.

The eruptions burned forests four times the size of Korea. It produced large volumes of carbon dioxide that caused global warming. As a result, frozen methane below the sea melted, producing a global warming effect 20 times more powerful than carbon dioxide.

The global warming lasted for approximately 10 million years. A terrible mass extinction was inevitable. Only 5% of the population of life on Earth survived and 95% perished from massive drought, lack of oxygen and acid rain that made plants unable to survive.

Fourth period of extinction

The fourth period of extinction happened around 210 million years ago, during the Late Triassic Age.

The slow splitting of Pangea caused volcanoes to form in the Central Atlantic Magmatic Province. After a spike in atmospheric carbon dioxide, global warming started again, with scientists speculating it lasted as long as eight million years.

This caused coral and conodonts, an eel-like ancient sea creature to face serious crisis. Coral-based creatures did not survive.

A meteor rain also hastened the destruction in this period: Around 80% of living creatures, including reptiles died, with some 20% of the creatures that became extinct sea-based lifeforms.

Additionally, a number of creatures that lived on land that died in this period were pseudosuchia, crocodylomorphs, theropods and several large amphibians.

Fifth period of extinction

The fifth period of extinction happened around 65 million years ago and is more popularly known as Cretaceous-Tertiary extinction. It was the fastest period of mass extinction, occurring over one to 2.5 million years.

It’s possibly the most known period of mass extinction because this was when dinosaurs were wiped out from the face of the earth. Scientists believe a meteor fall in today’s Gulf of Mexico compounded with high volcanic activity which produced a significant amount of carbon dioxide, killed half of the earth’s living population.

How does the future look?

Some scientists believe that we have entered the sixth period of extinction since 2010. The massive emission of carbon dioxide from fossil fuels has affected the lives of many plants and animals. Scientists predict that this will affect many life forms on Earth in the next three to four decades. Who knows?

Mirzam Abdurrachman, Lecturer at Department of Geology, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung; Aswan, Lecturer in Geology, Institut Teknologi Bandung, and Yahdi Zaim, Professor in Geology, Institut Teknologi Bandung

This article was originally published on The Conversation. Read the original article.

humpback whale

Selective wipe out of large marine species sets the stage for an unprecedented sixth mass extinction

humpback whale

Credit: Pixabay

The past five mass extinctions known to paleontologists follow no preferential pattern on which marine species were lost. For some time, scientists have warned that wildlife is headed for a sixth major extinction, one that may have already started and is caused primarily by humans. A new study suggests that this mass extinction is unprecedented on a couple of levels, among which the way marine species are wiped out. Namely, larger ones are favorably lost which could disrupt marine ecosystems for millions of years.

A consequential bias

“If this pattern goes unchecked, the future oceans would lack many of the largest species in today’s oceans,” said Jonathan Payne, associate professor and chair of geological sciences at Stanford University.

“Many large species play critical roles in ecosystems and so their extinctions could lead to ecological cascades that would influence the structure and function of future ecosystems beyond the simple fact of losing those species.”

Payne and colleagues note that human activities, particularly fishing, are targeting large species like great white sharks, blue whales, and southern bluefin tuna because these are easier to catch and yield a better return. The danger posed to large species of marine life is, thus, disproportionate as smaller species are less targetted. Losing large marine species could have a cascading effect on the local ecosystem as these keep smaller species in check. Payne cites the loss of tritons, large predator snails, which have made room for the crown of thorns starfish to flourish by eating coral.

To assess how the current species loss compares to previous mass extinction events, Payne and colleagues combed through a database of 2,497 groups of marine vertebrate and mollusc over the past 500 years, then compared extinctions to those from the ancient past using a fossil database.

Unlike today, the researchers could find no pattern in ancient times of discriminatory extinction among large or small species. In fact, over the past 66 million years, the researchers found a small link between a species small body size and going extinct — that’s a strong reversal to the present situation.

“We see this over and over again. Humans enter into a new ecosystem, and the largest animals are killed off first. Marine systems have been spared up to now, because until relatively recently, humans were restricted to coastal areas and didn’t have the technology to fish in the deep ocean on an industrial scale,” said Noel Heim, co-author of the new study published in the journal Science.

Though it was surprising for the researchers not to find any strong link between body size and extinction over the last millions of years, the present situation is anything but. That’s because humans have caused many extinctions of large land animals, which are often the first to go. For instance, there’s the Late Quaternary extinction event which followed in the footsteps of the last ice age and saw humans wipe out many megafauna species like the giant short-faced kangaroo, the wombat-like ‘diprotodon’, or the Genyronis Newtoni bird.

Ending on an optimistic note, Payne says that at least the current of species loss among large marine animals is not at the same level as that of lost large land species. “I think there are a lot of reasons to be optimistic about the oceans, because we haven’t impacted them much yet,” he told the Washington Post. 

The study couldn’t have been timed better. The U.S. State Department will soon open the door to its third annual Our Ocean conference which gathers heads of state and environmentalists from all over the world in an effort to find the best solution to the ocean’s most complex problems.

World’s first mass extinction might have been caused by animals

The world’s first mass extinction might have been caused by animals called “ecosystem engineers,” a term that refers to organisms that create, modify or maintain habitats. In the case of the current study, the fossil evidence from Namibia suggests that newly evolved animals modified the environment so drastically that they drove older species to extinction.

Fossilized evidence of the relationship between Ediacarans and animals. Credit: Simon Darroch, Vanderbilt University

Fossilized evidence of the relationship between Ediacarans and animals. Credit: Simon Darroch, Vanderbilt University

Approximately 540 million years ago, the Earth experienced the end-Ediacaran extinction, the world’s first mass extinction. Ediacarans were the first multicellular organisms, which evolved from various types of single-celled organisms. Shaped like discs and tubes, they were largely immobile and inhabited marine environments.

After 60 million years of the Ediacarans spreading around the Earth, the world’s first animals – the metazoans – evolved. With the ability to move spontaneously and independently, animals burst onto the Earth in what is now known as the Cambrian explosion, a 25-million-year period when many of the modern animal families evolved.

“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 Simon Darroch, assistant professor of earth and environmental sciences at Vanderbilt University and lead author of the study.

Previous research by Darroch and his team revealed communities of Ediacarans that appeared to be stressed. The fossils examined in the current paper represent a community of both Ediacarans and animals right before the Cambrian explosion, providing the best evidence thus far of the unique ecological association between these groups and highlighting the struggle of the Ediacarans as animals began to diversify.

“With this paper we’re narrowing in on causation; we’ve discovered some new fossil sites that preserve both Ediacara biota and animal fossils (both animal burrows – ‘trace fossils’ – and the remains of animals themselves) sharing the same communities, which lets us speculate about how these two very different groups of organisms interacted,” Darroch said.

Darroch also suggests that modern humans can learn from what is observed in the new fossil evidence given what is happening in the world today.

“The end-Ediacaran extinction shows that the evolution of new behaviors can fundamentally change the entire planet, and today we humans are the most powerful ‘ecosystems engineers’ ever known,” he said.

Journal Reference: A mixed Ediacaran-metazoan assemblage from the Zaris Sub-basin, Namibia. 4 July 2016. 10.1016/j.palaeo.2016.07.003

Ancient rocks reveal causes of Earth’s greatest mass extinction event

The Oman rocks that were used to reveal the causes of the Permian-Triassic Boundary extinction event. Credit: Matthew Clarkson
The Oman rocks that were used to reveal the causes of the Permian-Triassic Boundary extinction event.
Credit: Matthew Clarkson

Around 252 million years ago, the Earth experienced the biggest mass extinction event in its history. Referred to as both the Permian-Triassic extinction event and the Great Dying, it wiped out over 90 percent of marine life and approximately two-thirds of land-dwelling animals. Now, a new study sheds light on the causes of this event and reveals why the Earth’s marine creatures took so long to recover from it.

Although previous research pointed to a lack of dissolved oxygen and increase in sulphides in the Earth’s waters as the main cause of the mass extinction and the planet’s delayed recovery, the new study suggests that these anoxic conditions were complex and the high sulphide levels were not ubiquitous.

Using chemical techniques to analyze data from six sampling sites in Oman – spanning a range of shallow regions all the way to the deeper ocean – the team revealed that despite the lack of oxygen in the water, no toxic sulphides were present. Instead, the team noticed an increase in iron levels.

Contrary to previous beliefs, the new findings suggest that low oxygen in combination with high levels of iron – not sulphides – were the main causes of the delayed recovery of marine life that occurred following the Great Dying. Furthermore, the data suggests that some shallow waters did not suffer from the low oxygen levels present in other bodies of water, which likely helped increase the diversity of life in these areas.

“The neat point about this study is that it shows just how critical an absence of oxygen, rather than the presence of toxic sulphide, was to the survival of animal life,” said Simon Poulton of the University of Leeds and co-author of the study. “We found that marine organisms were able to rapidly recolonize areas where oxygen became available.”

Researchers believe that the anoxic conditions behind the Permian-Triassic extinction event likely stemmed from a combination of run-off from land rock erosion and high temperatures, although the exact causes of the extended recovery period are still not known.

“We knew that lack of oxygen in the oceans played a key role in the extinction and recovery processes, but we are still discovering how exactly it was involved,” said Matthew Clarkson of the University of Edinburgh’s School of GeoSciences and lead author of the study. “Our findings about the chemistry of the ocean at the time provide us with a clearer picture of how this complex process delayed the recovery of life for so long.”

Journal Reference: Dynamic anoxic ferruginous conditions during the end-Permian mass extinction and recovery. 19 July 2016. 10.1038/ncomms12236

Ancient supernovae might have contributed to Earth mass extinction

Radiation from two ancient supernovae that exploded millions of years ago might have contributed to Earth mass extinction.

Image credit ALMA/NASA

Image credit ALMA/NASA

Back in April, a team of researchers used core samples from the Atlantic, Indian and Pacific Oceans to suggest that two ancient supernovae led to the distribution of radiation around the world in the form of iron-60 radionuclides. Although the effects of these explosions on the Earth’s climate and organisms were not known at the time, a new study suggests that they likely exposed the Earth’s biology and atmosphere to long-lasting cosmic radiation.

“I was surprised to see as much effect as there was,” said Adrian Melott, a physics professor from the University of Kansas and co-author of the new paper set to be published in Astrophysical Journal Letters. “I was expecting there to be very little effect at all. The supernovae were pretty far way – more than 300 light years – that’s really not very close.”

Melott claims that the two stars behind the supernovae exploded 1.7 to 3.2 and 6.5 to 8.7 million years ago approximately 300 light years from the Earth. In addition to disrupting animals’ sleep patterns for a few weeks, the data suggests that the events exposed every creature on the surface of the Earth and the shallow regions of its oceans to radiation that was equivalent to one computed tomography (CT) scan per year.

“The big thing turns out to be the cosmic rays,” Melott said. “The really high-energy ones are pretty rare. They get increased by quite a lot here—for a few hundred to thousands of years, by a factor of a few hundred. The high-energy cosmic rays are the ones that can penetrate the atmosphere. They tear up molecules, they can rip electrons off atoms, and that goes on right down to the ground level. Normally that happens only at high altitude.”

The team suggests that the increased radiation would have been enough to affect the terrestrial atmosphere and biota, including an increase in the mutation rate and frequency of cancer.

Most interestingly, a minor mass extinction took place on the Earth approximately 2.59 million years ago. Melott and his team claim that it is possible that these ancient supernovae could have been connected to this extinction event through an increase in cosmic rays. Such an increase could alter the lowest layer of the Earth’s atmosphere – the troposphere – and lead to significant climate changes.

“There was climate change around this time,” Melott said. “Africa dried out, and a lot of the forest turned into savannah. Around this time and afterwards, we started having glaciations – ice ages – over and over again, and it’s not clear why that started to happen. It’s controversial, but maybe cosmic rays had something to do with it.”

Although the findings have yet to be published officially, they can be read at the pre-print site arXiv.org here.

An imagined post-extinction scene, when the ocean was filled with tiny fish. Illustration: Bob Nicholls

It pays to be a small fish in a big pond after a mass extintion

Some 360 million years ago, the oceans were teeming with big fish, some as big as a school bus. Then something terrible happened, the causes of which still escape scientists today: the Hangenberg Event. This was the last peak in a streak of mass extinctions known as the  Late Devonian extinctions which wiped out 97% of all marine vertebrate species. In the aftermath, it paid to be small, a new study suggests. The researchers at University of Pennsylvania found that small fish dominated the ecological niches for nearly 40 million years. This tremendous rebound time is relevant today when overfishing is threatening countless large fish species. Once these disappear, it might be a very long time before we get tuna-sized fish back on our plates.

An imagined post-extinction scene, when the ocean was filled with tiny fish. Illustration: Bob Nicholls

An imagined post-extinction scene, when the ocean was filled with tiny fish. Illustration: Bob Nicholls

The researchers studied 1,120 fossils of sort of ancient fish species  dating back 419 to 323 million years ago, pre and post Hangenberg. Over time, the fish had increased in size, echoing Cope’s Rule –  the generalization that most animal groups have evolved toward larger body size. Once 97% of all vertebrate species died off, that body sized plummeted. That itself isn’t surprising. During mass extinction events, the big guys are first to go. They require more food, resources, take longer to breed and parent. Only the small fish which needed little food and were quick to reprodue survived. What’s surprising, however, is how long it took for large fish to return to the scene.

“[T]he end result is an ocean in which most sharks are less than a meter and most fishes and tetrapods are less than 10 centimeters, which is extremely tiny. Yet these are the ancestors of everything that dominates from then on, including humans,” said University of Pennsylvania’s Lauren Sallen.

Two fish from the Mississippian, post-extinction, immortalized in a fighting pose. Credit: Carnegie Museum

Two fish from the Mississippian, post-extinction, immortalized in a fighting pose. Credit: Carnegie Museum

The researchers mapped body-size trends with known climate models of the time. They found there were no atmospheric oxygen or temperature limitations that would have forced big fish out – it’s all based on ecological factors, the researchers note.

“Before the extinction, the ecosystem is stable and thriving so that organisms can spend the time to grow to large sizes before they reproduce, for example,” Sallan said. “But, in the aftermath of the extinction, that ends up being a bad strategy in the long term. So tiny, fast-reproducing fish take over the entire world.”

So far, life on Earth went through five major extinction events, each stressing life to the brink of obliteration. The most devastating blow came 252 million years ago when the Great Dying snuffed out about 90 percent of the world’s species, both on land and in the oceans. Some experts fear we’re beginning to enter the phase of a new, sixth extinction event – this time driven by humans. For instance, plants and animals are going extinct 1,000 times faster than they did before humans walked on Earth’s surface. Studies like this one at UP show how fragile the ecosystem can really be.

Some models no longer available: Earth enters its 6th mass extinction phase, humans accelerate the losses

Geological evidence indicates that our planet has seen five mass extinction cycles since life first appeared on the planet. While they sound like the kind of cataclysmic events that only beardy men with huge boats survive through (read that in a book once, so it must be true), they are actually an integral part of life. The cycles free up ecological niches or entire ecosystems for new species to evolve into, much in the same way wildfires clear old, dry, dead plant matter so that fresh, green, happy plants have access to enough sunlight and nutrients to grow.

And if there’s one thing we here at ZME Science know, its beer mass extinctions. We’ve seen it coming, wrote about our role in it, and about how long some systems will need to recover from such an event. But even we were surprised when a new study, headed by National Autonomous University of Mexico’s Gerardo Ceballos revealed that we had come to start the 6th wildfire not with a box of matches, but with Apocalypse-Now amounts of napalm.

“The evidence is incontrovertible that recent extinction rates are unprecedented in human history and highly unusual in Earth’s history,” the study states.

“If it is allowed to continue, life would take many millions of years to recover and our species itself would likely disappear early on,” said Ceballos.

The authors of the study, published in Science Advances, compiled data obtained from geologic evidence, modern extinction records and other sources to determine the average rate at which species disappear. They point out that the study was done using extremely conservative assumptions, such as a background extinction rate of “2 mammal extinctions per 10,000 species per 100 years (that is, 2 E/MSY)” -twice as high as widely used previous estimates- and stringent criteria for when a species can be considered extinct . Even working under these very restrictive conditions, they have found that our planet’s ecosystems are breaking down at a terrifying rate.

“The average rate of vertebrate species loss over the last century is up to 114 times higher than the background rate. Under the 2 E/MSY rate, the number of species that have gone extinct in the last century would have taken […] between 800 and 10,000 years to disappear” they write. “These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way.”

The study looks at the anthropic related extinction of species rather than the number of individuals, meaning that the data mined by the team consists of whole populations, whole species or genera of animals that go extinct, not how many individuals of which species disappear. They calculated a “highly conservative modern extinction rate” by using the data exclusively on species listed as extinct (EX), and a “conservative extinction rate” by that also includes both extinct in the wild (EW) and presumed-extinct (PE) species. In terms of biological impact and the provision of ecosystem services, they consider EW and PE species to be functionally equivalent to EX species: even if some individuals still exist, their abundance is not sufficient to have a substantial influence on ecological function and processes, and it’s unlikely that the species will recover.

The findings show that current extinction rates vastly exceed what the team considered as being the natural average. This is especially troubling as they set the average value at double what was previously estimated, and the data on vertebrate extinctions was treated in the “most conservative plausible way”. The paper goes on to say that it’s very likely that the calculations underestimate the severity of the extinction crisis, as the team aimed to place a realistic “lower bound” on humanity’s impact on biodiversity, so they were looking for the best-case scenario of what is happening to ecosystems around the world.

Problems related to this declining biodiversity and environmental degradation may already be upon on us in significant ways. Insurer Lloyd’s of London assessed the possibility of food shocks in its 2015 “Emerging Risk Report,” released before the academic study. The report determined that the global food supply is “under chronic pressure to meet an ever-rising demand, and its vulnerability to acute disruptions is compounded by factors such as climate change, water stress, ongoing globalization and heightening political instability.”

“Our analysis emphasizes that our global society has started to destroy species of other organisms at an accelerating rate, initiating a mass extinction episode unparalleled for 65 million years.”

“Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing.”

And we should not let it pass us by. The Starks were right, winter is coming, and if we don’t do something about it now, we’ll spend it by ourselves around the campfire. We’ll have to explain to our kids that there once really were lions living and roaring in the savannah, not rust on the Lannister coat of arms, and exactly what a “wolf” is. Because they might end up just as real to them as the dragons in the book are to us.

marine_life extinction

Marine life might need 1,000 years to recover from climate change

Marine life is on the brink of experiencing its sixth mass extinction, a disruption that is expected to occur very rapidly once the gears are set in motion (cataclysmic chain events). Now, a new study suggests that it might take a full millennium for marine life to recover from a potential climate change-driven die off, not hundreds as previously suggested.

marine_life extinction

Image: Wikimedia Commons

 

When ice melts from the base of an ice shelf, for instance, the oxygen contained within the air bubbles trapped in the ice goes into solution (ocean). However, the dissolved oxygen levels that result from this process are significantly lower than those obtained by equilibration with the atmosphere. To find out how this affects marine life, researchers at  University of California, Davis wanted to see how ancient life reacted to sudden melting periods like those following an ice age. To this end, they carved fossilized marine fauna samples from from the ocean floor off Santa Barbara, California. They recovered some 5,400 invertebrate fossils, including those of spanning a period between 3,400 and 16,100 years ago. During this time the climate abruptly warmed, akin to what we’re currently experiencing because of greenhouse gas emissions. According to the researchers, the fauna “nearly disappeared from the record during those times of low oxygen,” according to the study.

The damage was made in only a couple of decades, however it took thousands of years for marine life to rebound back to previous levels.

“There’s not a recovery we have to look forward to in my lifetime or my grandchildren’s lifetime,” said lead author Sarah Moffitt, a scientist from the Bodega Marine Laboratory and Coastal and Marine Sciences Institute at the University of California, Davis.

“It’s a gritty reality we need to face as scientists and people who care about the natural world and who make decisions about the natural world.”

 

Image credit: PIXGOOD

Plants are much better at adapting to mass extinction than animals

Life has found our blue gem planet as a welcoming host, but it hasn’t always been all fun and games. To our knowledge, life has gone through five major mass extinctions over the past couple hundred millions of years. During this time countless species and even families were wiped out in a heart beat, but geological time frame standards. When faced with overwhelming odds, nature favors those who can adapt. According to researchers at the University of Gothenburg plants have always been surprisingly resilient to these challenging times, compared to animals. That’s not to say that plants didn’t go extinct as well – sure, countless as well, but others soon filled their space at a much great pace than animals could.

Image credit: PIXGOOD

Image credit: PIXGOOD

More than 20,000 plant fossils were carefully analyzed to see how dramatic events effected their place in the ecosystem. As expected, dramatic events had different consequences depending on the plant group. The key insight however is that negative rates of plant diversification – that is, more species died out than new ones formed – was never sustained for long periods of time, unlike the case of most animals.

 

“In the plant kingdom, mass extinction events can be seen as opportunities for turnover leading to renewed biodiversity,” says leading author Daniele Silvestro.

As an example, the Cretaceous-Paleogene mass extinction, caused by the impact of an asteroid off the Mexican coast some 66 million years ago, caused the extinction of the dinosaurs – a group of animals that had dominated the planet for millions of years and which had survived other major extinctions prior. Following this extinction, animals had to wait a long time before the ecological niches could be filled again. Yet plant diversity was minimally  affected.

[READ ABOUT] The most devastating mass extinction in Earth’s history

Dr. Daniele Silvestro, University of Gothenburg finding fossils. Image courtesy of University of Gothenburg

Dr. Daniele Silvestro, University of Gothenburg finding fossils. Image courtesy of University of Gothenburg

Some important plant groups, such as the gymnosperms (including pines, spruce and firs) lost a great deal of their diversity through extinction. Flowering plants (angiosperms), on the other hand, thrived and quickly grew in diversity. Today,  flowering plants dominate global diversity above all other plant groups. Findings appeared in the journal New Phytologist.

“Mass extinctions are often thought as a bad thing, but they have been crucial in changing the world into how we know it today,” says senior author Alexandre Antonelli.

By studying this sort of things, researchers hope to identify which plants are most vulnerable and sensitive to change to aid in conservation efforts. Nevertheless, it’s interesting to learn about just how resilient plants are in the face of adversity. But in a way, this shouldn’t surprise us. Wildfires, lightning even droughts are welcoming events for plants since these flush the ecosystem and make room for more diversity.

We’re heading towards a sixth major extinction

Species on Earth are disappearing at a never-before seen rate in human history. The stark threat hangs over all species – mammals, reptiles, birds, insects – and researchers are still trying to figure out the extent of this potential mass extinction. Now, a new analysis conducted by Naturfound that 41% of all amphibians on the planet now face extinction while 26% of mammal species and 13% of birds are similarly threatened.

Image via Nature. Download a PDF for the graphic.

Major Extinctions

The most devastating extinction ever took place some 252 million years ago, during the Permian – the last period of the Paleozoic. In the Permian extinction, an estimated 96 percent of marine species and 70 percent of life on land became extinct following a yet unconfirmed series of cataclysmic events. In Earth’s history, there have been five major mass extinctions – periods when the extinction rate is much higher than the natural, background rate. The first one to occur was the Ordovician–Silurian extinction about 440 million years ago, and the last one is Cretaceous–Paleogene extinction event, 66 million years ago – the extinction that wiped out the dinosaurs. All the major extinctions are associated with catastrophic events. This time, it’s different.

extinction species

The five major extinctions. Many scientists believe we may be heading towards a sixth, man-drive mass extinction. Image via University of New England.

Never in the history of the Earth has a species been so dominant as humans; we are changing the entire planet accoring to our needs, and this is having a huge effect on other species. From the massive deforestation to intensive agriculture which are destroying millions of square miles of animal habitat and to the introduction of invasive species and driving climate change, humanity is pushing the Earth towards a sixth great extinction.

“Habitat destruction, pollution or overfishing either kills off wild creatures and plants or leaves them badly weakened,” said Derek Tittensor, a marine ecologist at the World Conservation Monitoring Centre in Cambridge. “The trouble is that in coming decades, the additional threat of worsening climate change will become more and more pronounced and could then kill off these survivors.”

Human Driven Extinction

The endangered Indian pangolin, or thick-tailed pangolin (Manis crassicaudata), lives in south Asia, where hunters have targeted the animal for its meat and scales, which are used in traditional medicines.
Francois Savigny/NPL

Some 1.7 million species described by scientists, but we still don’t know exactly how many species there are in total. Estimates range from 2 to 50 million. The problem is that researchers have so far sampled only a sliver of Earth’s biodiversity, and most of the Earth’s species reside in a limited habitat – often times the very habitats which are most threatened, like the Amazon rainforest or areas of the ocean. It’s very hard to paint an accurate broad picture.

“That is the real problem we face,” added Tittensor. “The scale of uncertainty is huge.”

In other words, we know that we’re driving a huge chunk of animal and plant biodiversity extinct… we just don’t know exactly how big that chunk is. However, it’s clear that we need to change our ways if we want to prevent this disaster. Conservation policies could slow down extinctions, but this is not the long term solution we should be looking for.

“In general, the state of biodiversity is worsening, in many cases significantly,” says Derek Tittensor, a marine ecologist with the United Nations Environment Programme’s World Conservation Monitoring Centre in Cambridge, UK.

This means that what we should be looking for is sustainable change. In other words, we need to change our ways for good, and not just do things to mend our wrongdoings. The two main areas we should focus on are agriculture and overfishing – because this time it’s not a meteorite, it’s not a volcano, it’s not a cataclysm – we’re basically overeating biodiversity, with climate change being the icing on the cake.

The golden-crowned sifaka, or Tattersall’s sifaka (Propithecus tattersalli), of Madagascar is critically endangered. Habitat destruction and hunting have caused its population to decline since it was first discovered in 1974.
Nick Garbutt/naturepl.com

“In the case of land extinctions, it is the spread of agriculture that has been main driver,” added Tittensor. “By contrast it has been the over-exploitation of resources – overfishing – that has affected sealife.” On top of these impacts, rising global temperatures threaten to destroy habitats and kill off more creatures.

The analysis published in Nature paints a grim picture, but it also highlights what we need to do. First of all, we need to get an accurate picture of what’s happening – for this, governments and international organizations like the International Union for Conservation of Nature have to start a giant census; it may not be the exciting step, but we have to do it – only then can we understand what are the most adequate and effective measures.

Also, it’s vital to remember that we are not just harming biodiversity – we’re harming ourselves. As ecologist Paul Ehrlich puts it:

“In pushing other species to extinction, humanity is busy sawing off the limb on which it perches.”

 

The Quaternary period saw the extinctions of numerous predominantly larger, especially megafaunal, species, many of which occurred during the transition from the Pleistocene to the Holocene epoch. Among the main causes hypothesized by paleontologists are natural climate change and overkill by humans. Image: Wikimedia Commons

The Sixth Grand Extinction Will Be ‘Invisible’

Life on Earth has so far passed through five distinct crises that threatened to wipe it out, typically referred to as mass extinctions. The direst one was some 252 million years ago when 96 percent of marine species and 70 percent of life on land became extinct following a yet unconfirmed series of cataclysmic events known as the end-Permian extinction. Mass extinction is an alarming, scary term, but while it’s natural to shiver at the idea, it’s worth considering that we’re actually living through a mass extinction, the sixth so far. This one is different though. While past mass extinctions were triggered by cataclysmic events, the sixth great extinction will be the only one caused single-handedly by a singular species: us. If this wasn’t sad enough, the sixth extinction might be remembered (if there’s anyone left to recollect) as the ‘invisible’ extinction.

The sixth grand extinction

The Quaternary period saw the extinctions of numerous predominantly larger, especially megafaunal, species, many of which occurred during the transition from the Pleistocene to the Holocene epoch. Among the main causes hypothesized by paleontologists are natural climate change and overkill by humans. Image: Wikimedia Commons

The Quaternary period saw the extinctions of numerous predominantly larger, especially megafaunal, species, many of which occurred during the transition from the Pleistocene to the Holocene epoch. Among the main causes hypothesized by paleontologists are natural climate change and overkill by humans. Image: Wikimedia Commons

Humans can be beautifully creative, yet brutally inconsiderate at the same time of the world they live in and share with other creatures. It’s precisely our uncanny intellect and creativity – which we’re so proud of and which are often trumpeted as key differential qualities that separate us from beasts – that is dooming this planet. Because our technology and means of manipulating resources have evolved so rapidly, few species can keep up. A growing number of ecosystems are faced with situations where the environment is no longer predictable, either because of direct human interference (deforestation, loss of habitat, pollution) or indirect, through global warming (shorter seasons, droughts, ocean acidification, and so on).

great_extinction

Biologists and paleoecologists estimate that humans have driven roughly 1,000 species extinct in our 200,000 years on the planet. Since 1500 we have killed off at least 322 types of animals, including the passenger pigeon or the Tasmanian tiger. Only yesterday ZME Science reported how the Northern White Rhino is down to only five specimens as a result of human poaching. Another 20,000 or more species are now threatened with extinction according to the International Union for the Conservation of Nature, which keeps a list of all the known endangered plants and animals on the planet. The population of any given animal among the five million or so species on the planet is, on average, 28 percent smaller, thanks to humans.

extinction

A thought experiment

As if this wasn’t bad news enough, there’s another chilling prospect that might make the whole event even more frustrating: no one might ever know that most of these species existed. Say a doomsday event was to shatter human knowledge and civilization as we know it, forcing the survivors to start from square one. Within a couple of generations, common knowledge about the world we take for granted today (like the existence of lions, rhinos or turtles) might vanish. No problem, post-meltdown paleontologist will be able to piece together the puzzle of past existence on Earth by studying fossil remains. According to Roy Plotnick, a palaeontologist at the University of Illinois at Chicago, this might be useless for most animals on Earth.

extinction1

One study found that although human population has doubled in the past 35 years, the number of invertebrate animals – such as beetles, butterflies, spiders and worms – has decreased by 45% during that same period. “We were shocked to find similar losses in invertebrates as with larger animals, as we previously thought invertebrates to be more resilient.” said Ben Collen of the U.K.’s University College London, one of the study authors. Image: Science

 

Of the 715 mammal species listed on the International Union for the Conservation of Nature (IUCN) Red List only 90 of them are represented in the fossil record or 13%. The rest of them will be gone without a trace.

“We assume a lot about the persistence of human recordings. Who can read an 8-inch floppy disk these days? The rock record is a much more persistent way of recording information. I’m a reader of science fiction, and I think about post-apocalyptic worlds. What would we make of what had happened in the long-ago past?” said Plotnick in an interview for Nature.

According to Plotnick, rodents and bats are the most vulnerable at becoming completely forgotten. Body size is an important factor as far as fossils go, but geographical distribution is by far the most significant. You have much less chance of getting caught in the fossil record if you’re only found in one place. Birds and reptiles are also particularly vulnerable, especially island species.

“As a palaeontologist I think about the appearance and extinction of species — that shows how we do geological time. One big signal is the mass extinction of mammals in North America, Europe and Australia, when hunters arrived. That would be the stratigraphic marker.” Plotnick says.

Plotnick ends his interview by striking a humorous chord – we’ve bred so many pigs all over the world and, consequently, scattered their bones all over the place that a post-current era civilization might conclude this planet was once dominated by hogs. They wouldn’t be that far away from the truth.

Iberian lynx mother and cub.

World’s most endangered wild cat embryos frozen and stored in hope of restoration

Iberian lynx mother and cub.

Iberian lynx mother and cub.

The Iberian lynx is the only wild cat listed as  critically endangered by the International Union for Conservation of Nature (IUCN), numbering no more than 200 specimens, all of whom are entirely confined to southern Spain. Researchers from the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin recently salvaged embryos and egg cells from a pair of captive Iberian lynxes before the animals were sterilized for their own safety. These life carrying eggs were then frozen and stored to this day in hopes that sometime they’ll be able to foster life once more in a surrogate parent.

Azahar, one of the two Iberian lynxes, recently  underwent two emergency Caesarean sections in two consecutive pregnancies, so the researchers decided not to put her up for breeding anymore due to health hazards. Before Azahar was sterilized, though, the cat’s ovaries were removed by castration.

Now, castration might seem like an odd-ball idea considering it’s the opposite of conservation efforts, however right after surgery, the researchers managed to extract embryos and ovarian pieces from the feline through an adapted process the German institute had pioneered for domestic cats.

“Seven days after mating we expected to flush embryos from the uterus,” Katarina Jewgenow, a specialist from the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin, said in a statement.

Saliega, the other female lynx also held in captivity, already gave birth to 16 cubs and at an age of twelve was too old to mate anymore. From Saliega, the researchers extracted a batch of unfertilized egg cells.

“The next step we are discussing right now is to implant these embryos into a foster mother, which might be an Eurasian lynx female,” said Jewgenow.

The closet related cat is the Eurasian lynx, which the researchers hope to use as a foster mother for the Iberian lynx eggs currently stored in liquid-nitrogen vats at Madrid’s Museo Nacional de Ciencias Naturales de Madrid.

The news comes only days after a highly publicized TEDx event in Washington D.C. called TEDxDeExtinction – a forum where ethical and practical questions related to reviving extinct animals were discussed and highlighted.

source

The Takahe is a flightless bird that was previously thought to be extinct in New Zealand until it was discovered in the 1950s in a remote region of the South Island.(c) Tim Blackburn

Humans caused ancient Pacific bird extinction that killed 10% of world bird population

The Takahe is a flightless bird that was previously thought to be extinct in New Zealand until it was discovered in the 1950s in a remote region of the South Island.(c) Tim Blackburn

The Takahe is a flightless bird that was previously thought to be extinct in New Zealand until it was discovered in the 1950s in a remote region of the South Island.(c) Tim Blackburn

A new study sheds new light on the impact humans had on the local aviary fauna in the Pacific, after the authors conclude that human colonization of the Pacific Islands is the main driving factor that wiped out some 1,300 bird species in the area or roughly 10% of the entire bird population on the planet.

The study also shows that winged birds were 30 times far more likely to survive colonization, and larger birds went extinct far more often, demonstrating the the main cause for extinction was hunting, along with habitat destruction. One might want to remember the  dodo and Sylviornis; huge flightless birds, which weighed about 66 pounds (30 kilograms) and that were wiped out within a few mere years.

Previous estimates of human impact on Pacific bird extinction ranged 800 to up to 2000 bird species, however this most recent research by the team of scientists, lead by Professor Richard Duncan of the Institute for Applied Ecology at the University of Canberra, is the first to provide an accurate snapshot.

According to Duncan, incomplete fossils records have been hampering research efforts concerning human settlement impacts on the local biosphere.

“Consequently, many extinct bird species remain to be discovered, confounding attempts to quantify more precisely the number and type of species lost across the region,” write Duncan and colleagues Dr Alison Boyer from the University of Tennessee and Tim Blackburn, of London’s Institute of Zoology.

To estimate the toll taken by the Pacific birds, the researchers devised a mathematical model that analyzed bird species on 41 different Pacific Islands. A total of 618 populations of 193 nonpasserine landbirds were identified on the 41 islands, comprising 371 populations present at the time of European contact and 247 populations known only as fossils. In total some 1,300 bird species went extinct in the Pacific islands between 3,500 to 700 years ago.

The present study seems to substantiate recent claims that suggest bird populations around the world are plummeting.  A report released in late 2012 found bird populations in the U.K. declining to near record lows, as it was found that there were 44 million fewer birds in 2012 than in 1966, a rate of decine of one nesting pair every minute for almost 50 years.

Findings were published in the journal Proceedings of the National Academy of Sciences,

Triassic fossil of an eel-like conodont. (c) Yadong Sun.

During the greatest mass extinction in Earth’s history the world’s oceans reached 40°C – lethally hot

Between 247 to 252 million years ago, Earth life was going through quite possibly its most dire time. During this period some 90% of world’s species were wiped out, but what puzzled scientists for so long is the fact that it took five million years for life to recover after this apocalypse. A new study conducted by an international team of scientists found why it took so long – it was literally too hot to survive.

During what’s now commonly known as the end-Permian mass extinction, the Earth was a massive barren landscape. The die-off not only wiped out most marine and terrestrial animals, but plants too, which ensued a vicious circle. Plants absorb carbon dioxide, preventing the atmosphere from getting warmer, but as these died off in term as well, temperatures rose even higher too lethal levels. Other mass extinction periods took a few hundred thousand years for life to recover to previously similar levels, however this pre-Triassic extinction trialed life on Earth like never before – it needed five million years to surface.

pre-permian mass extinction

Earth at this time was a very peculiar world. The tropics would have a wet climate, much like today, but with no forests, only shrubs and ferns. Shellfish were the only marine creatures in the oceans. Virtually no land animals existed because their metabolisms would not have withstood such high temperatures. Only the polar regions offered a habitable refuge from the baking heat.

Too darned hot to survive!

Triassic fossil of an eel-like conodont. (c) Yadong Sun.

Triassic fossil of an eel-like conodont. (c) Yadong Sun.

Scientists from the University of Leeds, the China University of Geosciences and the University of Erlangen-Nurnburg (Germany) analyzed fossil records of some of the few life-forms that had survived the Permian extinction – sturdier species like snails and clams. After studying the oxygen isotopes in 15,000 conodont fossils extracted from rocks in South China, which serve as ancient seawater temperature records, the researchers found that oxygen isotopes water temperatures close to the ocean’s surface could reach 40°C.

“Global warming has long been linked to the end-Permian mass extinction, but this study is the first to show extreme temperatures kept life from restarting in equatorial latitudes for millions of years,” said Yadong Sun, lead author of a new study that documents the team’s findings.

Could it happen again?

Until now, climate modelers have assumed sea-surface temperatures cannot surpass 30°C. The modern average for the same area is between 77 and 86 degrees Fahrenheit (25 and 30 degrees Celsius).

Since 1880, global temperatures have increased by 1.4 degrees Fahrenheit (0.8 degree Celsius), two thirds of which have occurred after 1975. Despite this alarming trend, scientists assure that we’re far from witnessing a similar dire time falling upon us. Still, the pre-Permian extinction serves as a reminder of just how tough life on Earth had it, and how close it was to obliteration.

“Nobody has ever dared say that past climates attained these levels of heat. Hopefully future global warming won’t get anywhere near temperatures of 250 million years ago, but if it does we have shown that it may take millions of years to recover,” noted co-researcher Paul Wignall, from the University of Leeds.

Findings were presented in the journal Science.

In China, the Meishan Geopark sits on the outcrop (gray wall, right) containing the most famous record of the greatest mass extinction (inset). (c) Shuzhong Shen

Eruption responsible for greatest mass extinction on land and sea

In China, the Meishan Geopark sits on the outcrop (gray wall, right) containing the most famous record of the greatest mass extinction (inset). (c) Shuzhong Shen

In China, the Meishan Geopark sits on the outcrop (gray wall, right) containing the most famous record of the greatest mass extinction (inset). (c) Shuzhong Shen

Paleontologists have found a link between cataclysmic volcanic eruptions around 252 million years and greatest mass extinction the Earth has ever seen, responsible for wiping out 90% of the biosphere in both land and sea.

Paleontologists, led by Shu-zhong Shen of Nanjing Institute of Geology and Palaeontology in China, analyzed nine rock outcrops across Southern China which they dated back 252 million years ago, at the end of the Permian period. In the outcrops, the scientists found volcanic minerals left behind from the eruptions, which spewed deadly CO2, sulfur and methane into the atmosphere and oceans.

These volcanic minerals were of invaluable importance for the researchers, as it allowed them to pinpoint the eruptions with an error of less 100,000 years. In their study, the group used the steady decay of radioactive uranium to lead, coupled with an improvement in the sample preparation procedure, which reduced the dating error by a factor of four.

[RELATED] 200 million years ago, half of all life on Earth went extinct from a methane eruption

“What’s striking is how fast the extinction was,” says paleontologist Douglas Erwin of the Smithsonian National Museum of Natural History in Washington, D.C., a co-author on the paper. The event had been seen as lasting half a million years, but the new dating limits it to no more than 200,000 years and quite possibly less than 100,000 years, Erwin says. “We’re paleontologists studying events 250 million years ago,” he adds, so “a hundred thousand years sounds like overnight to us.”

This makes for the most accurate dating of the mass extinction, at this point, putting it right on par with the lava outpourings that formed large deposits of volcanic rock known as the Siberian Trap, the later date just a few tens of thousands of years away from the mass extinction.  “We think the timing is consistent with the Siberian Traps eruptions being the major cause of the extinctions,” Erwin says

methane eruption undersea

200 million years ago, half of all life on Earth went extint from a methane eruption

methane eruption underseaAround 200 million years ago, the Earth was still one big continent – the great Pangaea. Around that time came, what’s commonly referred to as, the End-Triassic mass extinction period in which half of all marine life on the planet went extinct. For years, scientists believed that this came as a result of a mass volcanic eruption across the world, as the massive continent split into multiple segment-continents.

A new study, published just recently in the journal Science, concludes, however, that responsible for the mass extension is actually a deadly methane eruption in the sea floor. Researchers at the Nordic Center for Earth Evolution at the University of Copenhagen claim that as a huge quantity of methane being released into the atmosphere, it killed off much of the species on Earth and paved the way for the age of dinosaurs.

Earth scientist Micha Ruhl and colleagues examined ancient plant fossils sampled from the bottom of the Tethys Ocean, and based on their molecular analysis it appears that “at least 12,000 gigatons of methane was injected into the atmosphere over just 10- to 20,000 years of the end-Triassic extinction.”

The sea floor eruption seems to have went on “burping” for at least 600,000 years, scientists observed. Although it stays in the atmosphere for a briefer period, methane is a more potent greenhouse gas than carbon dioxide and when released outside in the atmosphere, it triggers the release of more methane. A snow-ball effects is thus achieved, which might explain the prolonged duration of the emissions.

According to a release about Ruhl and his team’s findings:

The researchers suggest that this short-lived burst of methane was more likely responsible for the mass extinctions. Changes in vegetation at the end of the Triassic Period also provide evidence of strong warming events and an enhanced global water cycle at the time, they say. Ruhl and his colleagues also say that their findings may help scientists plan ahead, since humans could potentially contribute 5,000 gigatons of carbon or more to the atmosphere if we were to burn all of our known fossil fuel reserves.

However, this doesn’t change any theories about how the dinosaurs went extinct. Just last week the youngest dinosaur fossil was found, which added considerable weight to the already prevailing asteroid mass extinction theory.

via

The shores of Canada saved animals from climate change

One of our planet’s most significant misteries is the one concerning the massive extinction that took place about 252 million years ago. As it turns out, the shores of ancient Alberta, British Columbia and the Canadian Arctic were a very important refuge for the ancient animals that were threatened; most of the animals that lived at that period were wiped out.

A team of researchers (that included Charles Henderson, a geoscience professor at the U of C, Tyler Beatty, a PhD candidate at the U of C and J-P Zonneveld, an associate professor at the U of A) conducted the research that led to this conclusion. They claim this may not be the only refuge for life during the mass extinction, but it is the only one they have found until now.

“The boundary between the end of the Permian and beginning of the Triassic period saw unparalleled species loss in the marine realm, and biotic recovery was delayed relative to other mass extinctions,” says Henderson, in a paper published in the October edition of Geology. “A major unresolved question has been discovering where the marine organisms that recovered from the extinction were housed.”

“The boundary between the end of the Permian and beginning of the Triassic period saw unparalleled species loss in the marine realm, and biotic recovery was delayed relative to other mass extinctions,” says Henderson, in a paper published in the October edition of Geology. “A major unresolved question has been discovering where the marine organisms that recovered from the extinction were housed.”

“The boundary between the end of the Permian and beginning of the Triassic period saw unparalleled species loss in the marine realm, and biotic recovery was delayed relative to other mass extinctions,” says Henderson, in a paper published in the October edition of Geology. “A major unresolved question has been discovering where the marine organisms that recovered from the extinction were housed.”

What happened is that during the Perminan, the land masses collided to form a supercontinent called Pangeea. Near the end of that period, during the mass extinction, about 95 out of every 100 marine animals were extinct, and the same thing happened to 70 in 100 from the land. There are several theories, but none seems to give a full explanation to what happened; but it’s for sure that the recovery time for life on Earth was huge, longer than any such period our Eart has encountered.



How to recover from a mass extinction

saber tooth
About 250 million years ago, at the end of the Permian, and event caused a mass extinction which killed over 90 percent of the life on Earth. Ecosystems were destroyed and organisms were left to recover; it was the closest life came to being wiped out ever.

The full recovery of those ecosystems took at least 30 million years, according to new research from the University of Bristol. Previous studies indicated that life just bounced back relatively quickly in the form of ‘disaster taxa’ (opportunistic organisms that filled the empty ecospace left behind by the extinction), such as the hardy Lystrosaurus, a barrel-chested herbivorous animal, about the size of a pig.

But this latest research led by Sarda Sahney and Professor Michael Benton at the University of Bristol and recently published in Proceedings of the Royal Society B indicates that rich ecosystems with a big diversity of species emerged only after 30 million years. Sahney said:

“Our research shows that after a major ecological crisis, recovery takes a very long time. So although we have not yet witnessed anything like the level of the extinction that occurred at the end of the Permian, we should nevertheless bear in mind that ecosystems take a very long time to fully recover.”

They analyzed the recovery of tetrapods – animals with a backbone and four legs, such as amphibians and reptiles – and found that the dramatic restructurations which took place took a lot longer than initially anticipated. Professor Benton explained:

“Diversity is most commonly assessed by tallying the number of taxa on a global scale, but these studies are subject to the vagaries of sampling. By examining well-preserved and well-studied faunas, the taxonomic and ecological recovery of communities after the Permian extinction event can be examined more accurately, and the problems of geological bias are largely avoided.”