Earth is headed for its sixth mass extinction – study

AFP Photo / NASA

The rapid depletion of Earth’s biodiversity indicates that the planet is in the early stages of its sixth mass extinction of life since becoming habitable 3.5 billion years ago, according to a new study published in Science.

Human activity, including a doubling of its population in the past 35 years, has driven the decline of animal life on Earth, the researchers concluded.

There has been a 25 percent average decline rate of remaining terrestrial vertebrates, and a 45 percent decline rate in the abundance of invertebrates. These losses will continue to have innumerable impacts on species that depend on the delicate balance of life on Earth for their own survival.

“We tend to think about extinction as loss of a species from the face of Earth, and that’s very important, but there’s a loss of critical ecosystem functioning in which animals play a central role that we need to pay attention to as well,” said Rodolfo Dirzo, lead author of the study and a biology professor at Stanford University.

“Ironically, we have long considered that defaunation is a cryptic phenomenon, but I think we will end up with a situation that is non-cryptic because of the increasingly obvious consequences to the planet and to human wellbeing.”

The “Anthropocene defaunation,” as some researchers have dubbed this era, is hitting large animals such as elephants, polar bears, and rhinoceroses the hardest, as these megafauna are the subject of some of the highest rates of decline on Earth. This trend matches previous mass die-offs of the Big Five extinction periods.

Megafauna usually have lower population growth rates that need larger habitat areas to maintain their populations, thus they are particularly affected by human growth and desire for their meat mass. Losses among these animals often mean dire impacts for other species that depend on them within an ecosystem.

Past studies have found that the loss of larger animals means a spike in rodents, as grass and shrubs proliferate and soil compaction decreases, all while the risk of predation also declines, Futurity.org notes. As rodent populations increase, so do the disease-transporting ectoparasites that come with them.

“Where human density is high, you get high rates of defaunation, high incidence of rodents, and thus high levels of pathogens, which increases the risks of disease transmission,” said Dirzo.

“Who would have thought that just defaunation would have all these dramatic consequences? But it can be a vicious circle.”

About 16 to 33 percent of all vertebrate species are considered threatened or endangered, the review found.

Invertebrate loss also has far-reaching ripple effects on other species. For example, the continued disappearance of vital honeybee populations across the globe will have bleak consequences for plant pollination, and thus on the world’s food production, as RT has previously reported.

Insects pollinate about 75 percent of the world’s food crops, according to Futurity.

Overall, of the world’s more than 71,000 species, 30 percent of them are threatened, according to the International Union for Conservation of Nature. Based on this assessment – and without drastic economic and political measures to address the current die-off – the sixth mass extinction could be cemented by 2400 A.D., University of California, Berkeley geologist Anthony Barnosky told Harper’s magazine.

Solutions to the die-off are complicated, the study posits, as reducing rates of habitat change and overexploitation of lands must come through regional and situational strategies.

“Prevention of further declines will require us to better understand what species are winning and losing in the fight for survival and from studying the winners, apply what we learn to improve conservation projects,” said Ben Collen, a lecturer at the University College of London and a co-author of the study.“We also need to develop predictive tools for modelling the impact of changes to the ecosystem so we can prioritize conservation efforts, working with governments globally to create supportive policy to reverse the worrying trends we are seeing.”

Researchers from University of California, Santa Barbara; Universidade Estadual Paulista in Brazil; Universidad Nacional Autonoma de Mexico; the Natural Environment Research Council Centre for Ecology and Hydrology in England; and University College London are coauthors of the new study.

Hot spot: Yellowstone road melts, sites closed

Yellowstone National Park.(Reuters / Jim Urquhart)

Yellowstone National Park.(Reuters / Jim UrquharShare on tumblr

The ever-changing thermal geology of Yellowstone National Park has created a hot spot that melted an asphalt road and closed access to popular geysers and other attractions at the height of tourist season, officials said Thursday.

Firehole Lake Drive, a 3-mile-plus offshoot of the park’s Grand Loop that connects the Old Faithful geyser and the Madison Junction, is currently off limits. Park operators say the danger of stepping on seemingly solid soil into severely hot water is “high.”

“It basically turned the asphalt into soup. It turned the gravel road into oatmeal,” Yellowstone spokesman Dan Hottle said.

The affected roadway offers access to the Great Fountain Geyser, White Dome Geyser, and Firehole Lake.

“There are plenty of other great places to see thermal features in the park,” park public affairs chief Al Nash told The Weather Channel. “I wouldn’t risk personal injury to see these during this temporary closure.”

While thermal activity under the park often gives way to temperature fluctuations that can soften asphalt throughout Yellowstone, Hottle said the latest wave seems worse than usual.

“But it’s hard to tell if a thermal area is hotter than normal, because it’s always fluctuating here,” he said,according to the Los Angeles Times. “Road closures are business as usual for us.”

Yellowstone National Park.(AFP Photo / Karen Bleier)

Yellowstone National Park.(AFP Photo / Karen Bleier)

Maintenance workers now must lift the melted asphalt from the roadway, then apply sand and lime to soak up any remains, according to Hottle.

The spokesman said he hopes the road will be reopened by next week, adding that he does not believe the activity will significantly curb visits to the park.

Yellowstone’s supervolcano last erupted about 640,000 years ago, according to US Geological Survey records.

Last December, geologists reported that the magma reservoir under the supervolcano is two-and-a-half times larger than previous estimates.

“That’s not to say it’s getting any bigger,” said analysis team scientist James Farrell of the University of Utah. “It’s just that our ability to see it is getting better.”

The supervolcano has the potential to spew more than 240 cubic miles (1,000 cubic kilometers) of magma across Montana, Idaho, and Wyoming.

“We believe it will erupt again someday, but we have no idea when,” Farrell told National Geographic.

In March, a viral video of bison stampeding through the park gave rise to rumors of an imminent eruption.

In early April, scientists and park officials debunked the fears, saying the bison run was a natural migratory occurrence, not a sign of impending volcanic activity. That very same week, a 4.8 magnitude earthquake shook the northwest section of the park, marking the largest seismic activity at Yellowstone since 1980.

The earthquake occurred near “an area or ground uplift tied to the upward movement of molten rock in the super-volcano, whose mouth, or caldera, is 50 miles long and 30 miles wide,” Reuters reported at the time.

The uplift does not make volcanic activity more likely, though, according to Peter Cervelli, associate director for science and technology at the US Geological Survey’s Volcano Science Center in California.

“The chance of that happening in our lifetimes is exceedingly insignificant,” he said.

 

 

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