The sixth big extinction in Earth's history is under way?

Posted 3/18/2004 2:00 PM
Butterfly, bird loss could be harbinger of major extinction


WASHINGTON (AP) — A detailed survey of birds and butterflies in Britain shows a population decline of 54% to 71%, a finding that suggests the world may be undergoing another major extinction.
Researchers said the study helps support the theory that the sixth big extinction in Earth's history is under way, and this one is caused by humans.

In a series of population surveys that combed virtually every square yard of England, Scotland and Wales over 40 years, more than 20,000 volunteers counted each bird, butterfly and native plant they could find. An analysis of the findings appears this week in the journal Science.

The results showed that populations of the surveyed species are in sharp decline throughout England, Wales and Scotland, with some species gone altogether.

A survey of 58 butterfly species found that some species had experienced a 71% population swoon since similar surveys were taken in 1970 through 1982. Some 201 bird species were tracked between 1968 and 1971, and then again from 1988 to 1991. An analysis showed that that avian population had declined by about 54%.

Two surveys of 1,254 native plant species showed a decrease of about 28% over the past 40 years.

"Population extinctions were recorded in all the main ecosystems of Britain," the authors report in Science. They suggested that the finding strengthens the hypothesis shared by many scientists that "the biological world is approaching the sixth major extinction event in its history."

Scott Miller, a biologist with the Smithsonian's National Museum of Natural History, said the British study was impressive and powerful because it was so thorough.

"The United Kingdom has a monitoring system (for birds, plants and wildlife) that is unmatched," Miller said. "They may not be representative of the world as a whole, but they have the best data."

He said the data supports the idea that the rise of humans over the tens of thousands of years along with climate changes are bringing on an extinction of many species and reshaping the natural world in ways that aren't thoroughly understood.

Scientists have identified five extinction events in Earth's history, with some so severe that more than 90% of all life forms were killed off. The last and most famous extinction was the Cretaceous-Tertiary event some 63 million years ago that killed off the dinosaurs and allowed the rise of mammals. It is thought to have been caused by an asteroid hitting Earth.

The causes of the other extinctions are not well understood. The largest ended the Permian Period some 250 million years ago. All but about 4% of all species disappeared then. There were three other lesser-known events in the Ordovician (435 million years ago), the Devonian (357 million years ago) and the Triassic (198 million years ago) periods.

"We are in the middle of a sixth extinction event that began about 50,000 years ago" with the expanding role in the world of human beings, said Paul S. Martin, a zoologist and geochemist at the University of Arizona in Tucson. "It's happening, but it's slower and it is not clear it will be as severe as some of the others."

Stuart Pimm, an ecologist at Duke University, said in Science that the British study results "show that we have likely underestimated the magnitude of the pending extinctions."

Miller and Martin both point to the hundreds of species, mostly large animals and birds, that already are gone, some wiped out directly through human action.

Martin said the fossil records show that the disappearance of many animals in Australia, Madagascar and North America started about the time that humans arrived at those sites. Gone from the natural North American environment, for instance, are mammoths, camels, giant sloths and saber-toothed tigers.

"For tens of millions of years there were much larger animals on this continent," said Martin. "We have to settle now for deer, antelope and bison. But there was much more" before humans came.

Miller said the most significant thing about the British study is that it makes a detailed survey of insects, specifically the butterfly, and finds that they are in decline.

"They have good evidence of an insect population decline that is at a much higher rate than assumed in the literature," said Miller. "The butterfly may be a good indicator for what is happening to the other insects. We don't even know which factors in our changing environment is affecting the insects more."

The study, conducted by a group of British scientists led by J.A. Thomas of the Natural Environment Research Council, analyzed data collected by an army of volunteers whom Pimm described in Science as "amateurs of a very high level of competence."

http://www.usatoday.com/news/science/2004-03-18-wildlife-gone_x.htm

 

And if that wasn't enough to scare you, I bring you more news of DOOM!!!

Updated 3/18/2004 2:10 PM

NASA: Asteroid to get closer to Earth than any on record


SAN DIEGO (AP) — As far as flying space rocks go, it's as close an encounter as mankind has ever had.
A 100-foot diameter asteroid will pass within 26,500 miles of Earth on Thursday evening, the closest-ever brush on record by a space rock, NASA astronomers said.

The asteroid's close flyby, first spied late Monday, poses no risk, NASA astronomers stressed.

"It's a guaranteed miss," astronomer Paul Chodas, of the near-Earth object office at NASA's Jet Propulsion Laboratory, said Wednesday.

The asteroid, 2004 FH, was expected to make its closest approach at 5:08 p.m. ET, streaking over the southern Atlantic Ocean. It should be visible through binoculars to stargazers across the southern hemisphere, as well as throughout Asia and Europe, said astronomer Steve Chesley, also of JPL.

Professional astronomers around the globe scrambled Wednesday to prepare for the flyby, which could provide an unprecedented chance to get a close look at the asteroid, he added. The asteroid will pass within the moon's orbit.

Similarly sized asteroids are believed to come as close to Earth on average once every two years, but have always escaped detection.

"The important thing is not that it's happening, but that we detected it," Chesley said.

Astronomers found the asteroid late Monday during a routine survey carried out with a pair of telescopes in New Mexico funded by the National Aeronautics and Space Administration. Follow-up observations on Tuesday allowed them to pinpoint its orbit.

"It immediately became clear it would pass very close by the Earth," Chesley said.

Astronomers have not ruled out that the asteroid and our planet could meet again sometime in the future. If the two were to collide, the asteroid likely would disintegrate in the atmosphere, Chesley said.