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FLORA AND FAUNA
'Sixth extinction' of wildlife faster than feared: scientists
By Marlowe HOOD
Paris (AFP) July 11, 2017


Earth's major 'mass extinction' events
Paris (AFP) July 11, 2017 -Most scientists agree that a "mass extinction" event is underway with the Earth's wildlife disappearing at an alarming rate, mainly due to human activity.

But this is not the first time: over the last half-billion years there have been five major wipeouts in which well over half of living creatures disappeared within a geological blink of the eye. All told, more than 90 percent of organisms that have ever strode, swam, soared or slithered on Earth are now gone.

Here are the biggest die-offs, each showing up in the fossil record at the boundary between two geological periods:

Ordovician extinction

When: about 445 million years ago

Species lost: 60-70 percent

Likely cause: Short but intense ice age

Most life at this time was in the oceans. It is thought that the rapid, planet-wide formation of glaciers froze much of the world's water, causing sea levels to fall sharply. Marine organisms such as sponges and algae, along with primitive snails, clams, cephalopods and jawless fish called ostracoderms, all suffered as a consequence.

Devonian extinction

When: about 375-360 million years ago

Species lost: up to 75 percent

Likely cause: oxygen depletion in the ocean

Again, ocean organisms were hardest hit. Fluctuations in sea level, climate change, and asteroid strikes are all suspects. One theory holds that the massive expansion of plant life on land released compounds that caused oxygen depletion in shallow waters. Armoured, bottom-dwelling marine creatures called trilobites were among the many victims, though some species survived.

Permian extinction

When: about 252 million years ago

Species lost: 95 percent

Possible causes: asteroid impact, volcanic activity

The mother of all extinctions, the "Great Dying" devastated ocean and land life alike, and is the only event to have nearly wiped out insects as well. Some scientists say the die-off occurred over millions of years, while others argue it was highly concentrated in a 200,000-year period.

In the sea, trilobites that had survived the last two wipeouts finally succumbed, along with some sharks and bony fishes. On land, massive reptiles known as moschops met their demise. Asteroid impacts, methane release and sea level fluctuations have all been blamed.

Triassic extinction

When: about 200 million years ago

Species lost: 70-80 percent

Likely causes: multiple, still debated

The mysterious Triassic die-out eliminated a vast menagerie of large land animals, including most archosaurs, a diverse group that gave rise to dinosaurs, and whose living relatives today are birds and crocodiles. Most big amphibians were also eliminated.

One theory points to massive lava eruptions during the breakup of the super-continent Pangea, which might have released huge amounts of carbon dioxide, causing runaway global warming. Other scientists suspect asteroid strikes are to blame, but matching craters have yet to be found.

Cretaceous extinction

When: about 66 million years ago

Species lost: 75 percent

Likely cause: asteroid strike

An space rock impact is Suspect No. 1 for the extinction event that wiped out the world's non-avian dinosaurs, from T-Rex to the three-horned Triceratops. A huge crater off Mexico's Yucatan Peninsula supports the asteroid hypothesis.

But most mammals, turtles, crocodiles and frogs survived, along with birds as well as most sea life, including sharks, starfish and sea urchins. With dinosaurs out of the way, mammals flourished, eventually giving rise to the species -- Homo sapiens -- that has sparked the sixth mass extinction.

SOURCES: National Geographic, Encyclopaedia Britannica.

The sixth mass extinction of life on Earth is unfolding more quickly than feared, scientists have warned.

More than 30 percent of animals with a backbone -- fish, birds, amphibians, reptiles and mammals -- are declining in both range and population, according to the first comprehensive analysis of these trends.

"This is the case of a biological annihilation occurring globally," said Stanford professor Rodolfo Dirzo, co-author of a study published on Monday in the peer-reviewed US journal, Proceedings of the National Academy of Sciences (PNAS).

Around a decade ago, experts feared that a new planetary wipeout of species was looming.

Today, most agree that it is underway -- but the new study suggests that the die-out is already ratcheting up a gear.

It provides much-needed data about the threat to wildlife, mapping the dwindling ranges and populations of 27,600 species. For 177 mammals, researchers combed through data covering the period 1900 to 2015.

The mammal species that were monitored have lost at least a third of their original habitat, the researchers found.

Forty percent of them -- including rhinos, orangutans, gorillas and many big cats -- are surviving on 20 percent or less of the land they once roamed.

The loss of biodiversity has recently accelerated.

"Several species of mammals that were relatively safe one or two decades ago are now endangered," including cheetahs, lions and giraffes, the study showed.

Globally, the mass die-off -- deemed to be the sixth in the last half-billion years -- is the worst since three-quarters of life on Earth, including the non-avian dinosaurs, were wiped out 66 million years ago by a giant meteor impact.

On average, two vertebrate species disappear every year.

Tropical regions have seen the highest number of declining species. In South and Southeast Asia, large-bodied species of mammals have lost more than four-fifths of their historical ranges.

- Habitat loss -

While fewer species are disappearing in temperate zones, the percentage is just as high or higher.

As many as half of the number of animals that once shared our planet are no longer here, a loss the authors described as "a massive erosion of the greatest biological diversity in the history of Earth."

There is no mystery as to why: our own ever-expanding species -- which has more than doubled in number since 1960 to 7.4 billion -- is eating, crowding and polluting its planetary co-habitants out of existence.

By comparison, there are as few as 20,000 lions left in the wild, less than 7,000 cheetahs, 500 to 1,000 giant pandas, and about 250 Sumatran rhinoceros.

The main drivers of wildlife decline are habitat loss, overconsumption, pollution, invasive species, disease, as well as poaching in the case of tigers, elephants, rhinos and other large animals prized for their body parts.

Climate change is poised to become a major threat in the coming decades, with some animals -- most famously polar bears -- already in decline due to rising temperatures and changing weather patterns.

"The massive loss of populations and species reflects our lack of empathy to all the wild species that have been our companions since our origins," said lead author Gerardo Ceballos of the National Autonomous University of Mexico.

Beyond any moral imperative, there are practical reasons to rue the eclipse of animals, whether megafauna or smaller and less "charismatic" creatures, the researchers cautioned.

The vanishing of a top-level carnivore or herbivore can have a cascading effect down the food chain, disrupting entire ecosystems.

Other species directly provide "services" to humans, such as honeybees that pollinate crops or birds that ensure pest control.

Previous studies show that ecosystems under stress, while resilient, have a breaking point -- rapid change can lead to collapse.

FLORA AND FAUNA
Three tonnes of ivory seized in Vietnam
Hanoi (AFP) July 9, 2017
Vietnamese authorities have seized nearly three tonnes of ivory hidden among boxes of fruit, officials said Sunday, the latest haul to spotlight the country's key role in the global wildlife smuggling trade. Police in the central province of Thanh Hoa found 2.7 tonnes of tusks inside cartons on the back of a truck that was on its way to Hanoi, according to a report on their website. "Thi ... read more

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