mass extinction

I estimated that there are about 16 million species of life on Earth. What if 14 million of them suddenly disappeared? Sounds hard to believe, like some dystopian Hollywood summer blockbuster. But that is exactly what seems to have happened at least five times over the past half billion years.

In each instance, a catastrophic event (or combination of events) killed up to 90 percent of the world’s sea and land creatures, and it happened in the blink of an eye – geologically speaking, at least.

Other than the origin of life itself, mass extinctions are the most dramatic and mysterious events in the history of life on Earth.

—  Bill Nye, Evolution and the Science of Creation

Did dark matter kill the dinosaurs?

A thin disk of dark matter running through the Galaxy might be behind the large meteorite strikes that are thought to be responsible for some of Earth’s mass extinctions, including that of the dinosaurs, two theoretical physicists have proposed.

The model is based on a hypothetical form of dark matter described by the authors and their collaborators last year as a means to solve a separate cosmic conundrum. The existence of such a ‘dark disk’ could be tested soon by astronomical observations. […]

Meteorites regularly pepper Earth’s surface. Thirty years ago, physicists suggested that this bombardment intensifies cyclically, pointing to some underlying cosmic cause. One proposed explanation is that the Sun has an as-yet-undetected companion star, dubbed ‘Nemesis’ or ‘Death Star’, that regularly swings by, sending comets from the remote Oort cloud flying into the inner Solar System.

In the latest paper,  theoretical physicists Lisa Randall and Matthew Reece, of Harvard University in Cambridge, Massachusetts, reignite another proposal, which puts the supposed periodicity down to the way the Sun — and the Solar System with it — move inside the Milky Way. As the Sun follows the swirling motion of the Galaxy’s arms, circling around the galactic centre, it also moves up and down, periodically crossing the plane that cuts the Galaxy into a top and a bottom half like the two bread slices in a sandwich. The authors suggest that as the Sun oscillates up and down,  it crosses a denser layer of dark matter — like the ham in the middle — causing a gravitational push and pull that disturbs comets in the Oort cloud.

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It Looks Like an Asteroid Strike Can’t Cause a Worldwide, Dinosaur-Killing Firestorm

For decades, scientists have debated the cause of the mass extinction that wiped out the dinosaurs and other life 65 million years ago. While the majority of researchers agree that a massive asteroid impact at Chicxulub, Mexico is the culprit, there have been some dissenters. Now, new research is questioning just a portion of the asteroid/Cretaceous-Paleogene extinction scenario. While the scientists involved in the study don’t doubt that such an asteroid impact actually happened, their research shows it is just not possible that vast global firestorms could have ravaged our planet and be the main cause of the extinction.

Researchers from the University of Exeter, University of Edinburgh and Imperial College London recreated the vast energy released from a 15-km wide asteroid slamming into Earth, which occurred around the time that dinosaurs became extinct.

They found that close to the impact site — a 180 km wide crater in Mexico — the heat pulse would have lasted for less than a minute. This intense but short-lived heat, the team says, could not have ignited live plants, challenging the idea that the impact led to global firestorms.

However, they did find that the effects of the impact would actually be worse on the other side of the planet, where less intense but longer periods of heat could have ignited live plant matter.

“By combining computer simulations of the impact with methods from engineering we have been able to recreate the enormous heat of the impact in the laboratory,” said Dr. Claire Belcher from the University of Exeter. “This has shown us that the heat was more likely to severely affect ecosystems a long distance away, such that forests in New Zealand would have had more chance of suffering major wildfires than forests in North America that were close to the impact. This flips our understanding of the effects of the impact on its head and means that palaeontologists may need to look for new clues from fossils found a long way from the impact to better understand the mass extinction event.”

Continue Reading.


Biologist warn of early stages of Earth’s sixth mass extinction event | ScienceDaily

The planet’s current biodiversity, the product of 3.5 billion years of evolutionary trial and error, is the highest in the history of life. But it may be reaching a tipping point. Scientists caution that the loss and decline of animals is contributing to what appears to be the early days of the planet’s sixth mass biological extinction event. Since 1500, more than 320 terrestrial vertebrates have become extinct. Populations of the remaining species show a 25 percent average decline in abundance. The situation is similarly dire for invertebrate animal life.

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[Read more on Mass Extinctions]


Severity: 2nd worst

Cause: Some type of C cycle disturbance, not well constrained

Climate: Abrupt ice age followed by rapid warming

Aftermath: Cambrian organisms (e.g. trilobites) decimated

During the End-Ordovician mass extinction, 25% of known marine families and 60% of marine genera were wiped out. Warm-water invertebrates were the hardest hit, as the event was likely caused by a severe cooling event in the world’s oceans triggered by Gondwanan glaciation.However, as with just about all of the mass extinctions, other causes have been offered, such as a gamma ray burst and volcanism and weathering

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The Sumatran Tiger is said to be extinct by 2015, with fewer than 300-400 left in the wild due to large-scale habitat loss, poaching, hunting and human-tiger conflict. Other subspecies are said to follow. 

Stop Tiger Poaching in India 
Save the Tiger 
Save the Sumatran Tiger 
Save the Tigers 
Save the Indian Tiger 
Save the Sumatran Tiger 
Stop Pushing Sumatran Tiger Toward Extinction
Save the Sumatran Tigers from Extinction 
Protect Siberian Tiger Habitat 
Act Now to Save India’s Tiger 
Save the Sumatran Tiger 
Save the Tiger 
Stop Poaching Tigers 
Close Down China’s Tiger Farms 
Save the Siberian Tiger 
Prevent Siberian Tiger Extinction 
Save Endangered Siberian Tigers from Extinction 
Illegal Tiger Trade must End 
Preserve the Bengal Tiger of India 
Save the Malayan Tiger from Extinction 
Save Malayan Tiger by Stopping Logging 

(and sign as many other petitions you can for good karma or to make utopia or whatever reason)

Humans will have wiped out 75% of species by 2250

Humans will wipe out 75% of the species on Earth in around 240 years, a scientist has said. Mike Coffin, a marine geophysicist from the University of Tasmania, has said mankind will cause a mass extinction event between 240 and 500 years from now, which will see most species on the planet going extinct.

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Mod post: if we try harder, we can do that by 2200.

NYT: 'Climate Change and the Exodus of Species'

To most humans, so far, climate change is still more of an idea than an experience. For other species, it is an immediate reality. Many will be left behind as the climate alters, unable to move quickly enough or with nowhere to move to. Others are already adapting. An iconic example of these swift changes is the recent discovery that Atlantic and Pacific populations of bowhead whales — long kept apart by the frozen Arctic — are now overlapping in the open waters of the Northwest Passage. 

A team of scientists from the University of York examined the movement of 2,000 animal and plant species over the past decade. According to their study, published in Science last month, in their exodus from increasing heat, species have moved, on average, 13.3 yards higher in altitude — twice the predicted rate — and 11 miles higher in latitude — three times faster than expected. These changes have happened most rapidly where the climate has warmed the most.

Chris Thomas, an author of the study, says, these changes “are equivalent to animals and plants shifting away from the equator at around 20 centimeters per hour” for the past 40 years. This rate will increase as the pace of climate change increases, bringing with it rapid adaptation but also a rate of extinction and a loss of genetic diversity surpassing anything the fossil record shows us.

A rapid reduction in greenhouse gas emissions is tragically unlikely. We are holding the future of every species on this planet — including ourselves — hostage.

We just can’t seem to stop burning up all those buried trees from way back in the carboniferous age, in the form of coal, and the remains of ancient plankton, in the form of oil and gas. If we could, we’d be home free climate wise. Instead, we’re dumping carbon dioxide into the atmosphere at a rate the Earth hasn’t seen since the great climate catastrophes of the past, the ones that led to mass extinctions. We just can’t seem to break our addiction to the kinds of fuel that will bring back a climate last seen by the dinosaurs, a climate that will drown our coastal cities and wreak havoc on the environment and our ability to feed ourselves. All the while, the glorious sun pours immaculate free energy down upon us, more than we will ever need. Why can’t we summon the ingenuity and courage of the generations that came before us? The dinosaurs never saw that asteroid coming. What’s our excuse?

A team of scientists, in a groundbreaking analysis of data from hundreds of sources, has concluded that humans are on the verge of causing unprecedented damage to the oceans and the animals living in them.

“We may be sitting on a precipice of a major extinction event,” said Douglas J. McCauley, an ecologist at the University of California, Santa Barbara, and an author of the new research, which was published on Thursday in the journal Science.

According to the UN Environment Programme, the Earth is in the midst of a mass extinction of life. Scientists estimate that 150-200 species of plant, insect, bird and mammal become extinct every 24 hours. This is nearly 1,000 times the “natural” or “background” rate and, say many biologists, is greater than anything the world has experienced since the vanishing of the dinosaurs nearly 65m years ago. Around 15% of mammal species and 11% of bird species are classified as threatened with extinction.

[Emphasis mine.] The Guardian, "Protect nature for world economic security, warns UN biodiversity chief"

"We are moving to a more virtual world. Children today haven’t a clue about nature. Children have not seen apple trees. In Algeria, children are growing up who have never seen olive trees. How can you protect nature if you do not know it?"

The New Age of Extinction

Could we be facing the next mass extinction? It won’t come from a massive volcanic eruption or a giant asteroid, it will be from something far more dangerous: humans.

Human interference has driven thousands of species to extinction, over 300 land vertebrates in the past 500 years alone! We’re seeing the worst die-offs since the dinosaurs were wiped out 65 million years ago. Extinction is a natural phenomenon, but it happens at a natural background rate of 1 to 5 species a year. Thanks to humans, we’re seeing that rate increased by a factor of between 1,000 and 10,000.

This rapid rate of extinction is due to hunting/fishing, habitat loss, and climate change, amongst others, but news of this extinction isn’t anything new. In 1998, Joby Warrick of The Washington Post wrote, “A majority of the nation’s biologists are convinced that a ‘mass extinction’ of plants and animals is underway that poses a major threat to humans in the next century, yet most Americans are only dimly aware of the problem.”

On December 14th 2014, the number of Northern White Rhinos fell to just 5, yet these animals have no natural predators. Poachers have decimated their population by killing them for their horns. Other large animals like tigers, elephants, and whales are also being hunted to extinction. Without these large animals, ecosystems can change drastically. Vegetation starts to overgrow, the soil loosens, and rodents take over and spread disease, ultimately infecting humans.

Because of their sensitivity to environmental changes, amphibians are more endangered than any other group. Their habitats are being polluted and destroyed, water temperatures are rising, and exotic species are being introduced, killing them and spreading disease.
Deforestation is wiping out birds by the thousands; water demand, dams, and pollution in our rivers and oceans are destroying fish populations; urbanization and water projects are killing off invertebrates; the disappearance of rainforests and introduction of nonnative species are eradicating mammals; and let’s not forget about plants, which do a wonderful job of supplying us with oxygen and food that keeps us alive. Global warming and the destruction of their ecosystems are rapidly putting a strain on their survival.

So, what can be done to stop this from happening? According to the scientific journal Nature, countries need to continue expanding the areas they shield from destructive human activities and devote more resources to taking stock of life, not to mention reducing our overall carbon footprint ( It will be costly, but the sooner we start the better our chances will be at saving thousands of species from premature extinction.

Planet Earth is home to millions of living creatures that, until humans came along, did a pretty good job at keeping things in balance. Scientists have estimated that, if nothing gets done, we could be facing a mass extinction of 75% of species in the next few hundred years.

~ SW

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Photo Credit: John McColgan