With the steep decline in populations of many animal species, from frogs and fish to tigers, some scientists have warned that Earth is on the brink of a mass extinction like those that occurred only five times before during the past 540 million years. Each of these 'Big Five' saw three-quarters or more of all animal species go extinct.
In a study to be published in the March 3 issue of the journal Nature, University of California, Berkeley, paleobiologists assess where mammals and other species stand today in terms of possible extinction, compared with the past 540 million years, and they find cause for hope as well as alarm.
"If you look only at the critically endangered mammals those where the risk of extinction is at least 50 percent within three of their generations and assume that their time will run out, and they will be extinct in 1,000 years, that puts us clearly outside any range of normal, and tells us that we are moving into the mass extinction realm," said principal author Anthony D. Barnosky, UC Berkeley professor of integrative biology, a curator in the Museum of Paleontology and a research paleontologist in the Museum of Vertebrate Zoology.
"If currently threatened species those officially classed as critically endangered, endangered and vulnerable actually went extinct, and that rate of extinction continued, the sixth mass extinction could arrive within as little as 3 to 22 centuries," he said.
Nevertheless, Barnosky added, it's not too late to save these critically endangered mammals and other such species and stop short of the tipping point. That would require dealing with a perfect storm of threats, including habitat fragmentation, invasive species, disease and global warming,
"So far, only 1 to 2 percent of all species have gone extinct in the groups we can look at clearly, so by those numbers, it looks like we are not far down the road to extinction. We still have a lot of Earth's biota to save," Barnosky said. "It's very important to devote resources and legislation toward species conservation if we don't want to be the species whose activity caused a mass extinction."
Coauthor Charles Marshall, UC Berkeley professor of integrative biology and director of the campus's Museum of Paleontology, emphasized that the small number of recorded extinctions to date does not mean we are not in a crisis.
"Just because the magnitude is low compared to the biggest mass extinctions we've seen in a half a billion years doesn't mean to say that they aren't significant," he said. "Even though the magnitude is fairly low, present rates are higher than during most past mass extinctions."
"The modern global mass extinction is a largely unaddressed hazard of climate change and human activities," said H. Richard Lane, program director in the National Science Foundation's Division of Earth Sciences, which funded the research. "Its continued progression, as this paper shows, could result in unforeseen and irreversible negative consequences to the environment and to humanity."
The study originated in a graduate seminar Barnosky organized in 2009 to bring biologists and paleontologists together in an attempt to compare the extinction rate seen in the fossil record with today's extinction record. These are "like comparing apples and oranges," Barnosky said. For one thing, the fossil record goes back 3.5 billion years, while the historical record goes back only a few thousand years. In addition, the fossil record has many holes, making it is impossible to count every species that evolved and subsequently disappeared, which probably amounts to 99 percent of all species that have ever existed. A different set of data problems complicates counting modern extinctions.
Dating of the fossil record also is not very precise, Marshall said.
"If we find a mass extinction, we have great difficulty determining whether it was a bad weekend or it occurred over a decade or 10,000 years," he said. "But without the fossil record, we really have no scale to measure the significance of the impact we are having."
To get around this limitation, Marshall said, "This paper, instead of calculating a single death rate, estimates the range of plausible rates for the mass extinctions from the fossil record and then compares these rates to where we are now."
Barnosky's team chose mammals as a starting point because they are well studied today and are well represented in the fossil record going back some 65 million years. Biologists estimate that within the past 500 years, at least 80 mammal species have gone extinct out of a starting total of 5,570 species.
The team's estimate for the average extinction rate for mammals is less than two extinctions every million years, far lower than the current extinction rate for mammals.
"It looks like modern extinction rates resemble mass extinction rates, even after setting a high bar for defining 'mass extinction,'" Barnosky said.
After looking at the list of threatened species maintained by the International Union for Conservation of Nature (IUCN), the team concluded that if all mammals now listed as "critically endangered," "endangered" and "threatened" go extinct, whether that takes several hundred years or 1,000 years, Earth will be in a true mass extinction.
"Obviously there are caveats," Barnosky said. "What we know is based on observations from just a very few twigs plucked from the enormous number of branches that make up the tree of life."
He urges similar studies of groups other than mammals in order to confirm the findings, as well as action to combat the loss of animal and plant species.
"Our findings highlight how essential it is to save critically endangered, endangered and vulnerable species," Barnosky added. "With them, Earth's biodiversity remains in pretty good shape compared to the long-term biodiversity baseline. If most of them die, even if their disappearance is stretched out over the next 1,000 years, the sixth mass extinction will have arrived."
Explore further:
Extinction alert issued for 800 species

ereneon
1.3 / 5 (15) Mar 02, 2011jjoensuu
1.1 / 5 (15) Mar 02, 2011No surprise. This is just a beginning to bolster something else later.
hunter3
4.6 / 5 (12) Mar 02, 2011I would criticize the authors' choice of mammals, however. Mammals are among the most vulnerable to human activities, like hunting, habitat fragmentation, and invasive species. Australia and North America have very few of the mammal species they once had before man. On the other hand, mammals are more resistant to natural mass extinctions, considering they can accept a higher range of environmental conditions than other animal classes and phyla (they did survive the dinosaurs, after all).
Kikeros
1 / 5 (3) Mar 02, 2011epsi00
2.6 / 5 (25) Mar 02, 2011sstritt
1.9 / 5 (19) Mar 02, 2011What species are you, meatbag?
StillWind
1.1 / 5 (11) Mar 02, 2011Although it has been surmised that humans had a hand in the extinction of megafauna in North America, this is far from settled.
It is also important to note that while a few subspecies may have become extinct (eastern elk and eastern woodland bison), no complete mammal species have gone extinct since Europeans settled N.A., and those who were previously reduced, are increasing in numbers, and some dramatically.
In fact, mammal species would seem to have increased in N.A., thanks to introduction of cattle, hogs, horses, cats, and other domestic species.
Doom1974
3 / 5 (2) Mar 02, 2011Misanthrope
2.8 / 5 (19) Mar 02, 2011Absolutely. Eliminate the one and only species that actively and knowingly participates in its own undoing and everything else will fall into place. From an evolutionary standpoint our "intelligence" has yet to prove it has any real survival value.
Caliban
4.6 / 5 (11) Mar 02, 2011Shelgeyr
2.7 / 5 (17) Mar 02, 2011Generally, I think I'd rather be trapped with a room full of Global Warming Alarmists than with a single Eliminationist.
And yes, this is because I'm selfish.
However, since this "6th extinction" will likely leave enough still alive for my offspring to eat, I'm just not going to worry about it.
And by the way... "other species can live at peace"??? Really? Have you spent ANY time with Nature at all? I mean, without rose-colored glasses over squinting-in-anger eyes?
You apparently know nothing of herd management in the wild, nor the broad spectrum of extinction scenarios (which includes resource depletion), nor the concept of "hot" viruses. But thanks for the heads-up with the nickname. Gracious of you.
MorituriMax
3.7 / 5 (12) Mar 02, 2011I'm hoping the next extinct species will be the fundamentalist religious types and the ignorant people like you, then the remaining humans can actually get along with long term plans to make the planet a wonderful place to live for EVERYONE.
You do know other species also eat each other(?), and they're not pretty to watch while they rip their prey limb from limb.
Shelgeyr
1.8 / 5 (9) Mar 02, 2011Please, please, let's not go lumping ignorant fundamentalist religious types like myself in with the Eliminationists!
Don't you detect a bit of a conflict between your "remaining humans can actually get along..." with "other species also eat each other" statements?
If you eliminated humanity down to the last two people, and if they were anywhere near each other, they'd eventually fight over something. Probably something stupid, like "the comfy chair". No reason to eliminate them though...
By the way, you are aware, aren't you, that "Morituri" itself is from a little old eliminationistic (is that even a word???) i.e. "genocidal" resource war recorded in the Irish "Book of Invasions"? I just thought that ironic...
Firecat
4.2 / 5 (5) Mar 02, 2011I'm an orc! :)
epsi00
2.7 / 5 (15) Mar 02, 2011Sadly, the same species as you, a crass uneducated human who, because he lacks arguments, resorts to name calling.
Sleepy
3.5 / 5 (2) Mar 02, 2011stealthc
1 / 5 (12) Mar 03, 2011LivaN
4.4 / 5 (7) Mar 03, 2011Unfortunately other species do not 'live at peace'. They fight it out and only the strongest survive. We were the result of species at peace, as were the previous 5 mass extinctions. You see, in the real world, if you don't have a will to live then you're just fuel for something else that does. Currently you're freeloading on your species will to live, while proclaiming that species deserves to become extinct. One could almost equate you to a 'cancer of your species'.
Misanthrope
Because you have to fight every day to survive right? You've grown accustom to the protection that your species provides for you, and have no real understanding of the harsh reality that exists beyond that protection.
Shelgeyr
1.6 / 5 (11) Mar 03, 2011Although frankly, why I'd bother arguing with something that's 70% water is beyond my understanding. I must be getting way too ancient... this newfangled interweb tubething...
---
You know normally, when someone asks what species you are, it is understood that's it is a "rhetorical question", and you really aren't supposed to answer. But thanks for clearing that up for those of us who might have not been 100% sure.
---
“Ray, if someone asks if you're a god, you say YES!” - Dr. Peter Venkman
(just to bring it back around to the whole "mass extinction" topic, you know...)
Sinister181
2.3 / 5 (9) Mar 03, 2011What kind of f--ing ignorant statement is that? How the hell do you know? Were you around, during the last 5 mass extinctions?
epsi00
3 / 5 (8) Mar 03, 2011Other species do fight it out but you will never see a lion killing 10 antelopes just because he can and stashing them somewhere for lean days. He will kill only when he is hungry and/or when he has little ones to feed.
The same lion will never buy himself a private jet or park 3 to 5 cars or have a whole collection of fancy cars while other lions are starving.
Modernmystic
2.2 / 5 (10) Mar 03, 2011Or at least enviro-extremists who's idea of a good day is 7 billion people dead.
Not even sure Hitler was that off his nut.
Modernmystic
2.5 / 5 (11) Mar 03, 2011I don't know about lions but I have SEEN wolves kill three Elk for fun (I'm assuming) and leave ALL the meat on the field. I've seen video of killer whales using seals like ping-pong balls...
I think you need a healthy dose of perspective and actual facts.
No, but he will kill rival males and let his kids starve so he can survive...
epsi00
2.6 / 5 (10) Mar 03, 2011L'intelligence au service du mal
and this is my final answer to those who think we are noble, or better than our cousins the animals or whatever else they may write on this thread.
Sinister181
2.5 / 5 (8) Mar 03, 2011More animals are killed by Humans than Humans are killed by animals. I think it is you, sir, who needs a new perspective.
I also think that everyone is being a little hard on epsi00. And, to be fair, no other species of animal has screwed up the Earth as much as what Humans have done (and that's a fact). I'm not trying to be a misanthrope or anything here. But some people are just unwilling to accept reality.
Monarch
1 / 5 (8) Mar 03, 2011Modernmystic
2.1 / 5 (11) Mar 03, 2011And nature views this how? Are you attempting to insert your morality into a system that is by definition amoral? Get a grip.
Screwed up by WHO'S standards? Yours? Natures?
Nature has ONE standard...success...period. Nature doesn't care how many animals we slaughter or how many go extinct. YOU might, but don't pretend you speak for nature or have some objective stance on how things OUGHT to be, because you DON'T.
Shelgeyr
1.4 / 5 (9) Mar 03, 2011We ARE better. Better at thinking, and better at surviving (which is relevant to this thread).
That's not a fact. That's an opinion, and a very species-centric one at that. And IMHO mistaken.
Considering all of the animal species that have ever gone extinct, do you think mankind is the ONLY one that has caused the demise of another? Isn't the problem with invasive species (man-introduced or not) is that they wipe out extant populations?
Imagine that you're some variant of prairie rodent, trying to make due in a part of Africa where the blasted elephants have - again! - torn down all the good covering vegetation. Here comes the hawk! Darn those elephants! They sure have screwed up the Earth, and that's a fact! Squeek!
Sinister181
2.3 / 5 (6) Mar 03, 2011I wasn't aware that there was a standard. But clearly, you and I have very different definitions. Therefore, we must agree to disagree.
I might not speak for nature, but apparently you do when you say that it DOESN'T care. Maybe when a couple of million species of animals (or plants) go extinct and everything else starts dying (due to the ecosystem's balance being thrown out of whack), then maybe, just maybe nature will start caring then. But I suppose it's all a matter of "success". And maybe when we've finally succeeded, then it will be our own undoing.
Shelgeyr
2.4 / 5 (10) Mar 03, 2011How? "Nature" is what is. "Nature" itself is a human conceptual abstraction. Do you think a carbon atom "cares" if it is part of a diamond, a CO2 molecule, a sugar cube, or a pencil lead? If all life on Earth was destroyed, Nature wouldn't care - because Nature CAN'T care. This thing we call Nature has no ability to reason, weigh, measure, evaluate, or value. And since that which can't care, doesn't care, Modernmystic is correct (and not "speaking for Nature") in saying that Nature doesn't care.
Certainly there are things IN Nature that care - namely us, people with minds who have the capacity for reason, a desire for things to be certain ways, and the will to impose our desires upon our surroundings - traits shared to a lesser degree by many (most? all?) animals.
But the part is not the whole. Nature doesn't care.
epsi00
2.3 / 5 (6) Mar 03, 2011And of course you DO, because you know nature better than the rest of us. So you can speak on behalf of nature but at the same time deny others the same right.
What arguments do you have? what is the scientific basis of your statements? Making a statement is easy. any idiot can do that. supporting a statement with facts is a bit harder so not any idiot can do that.
Modernmystic
2.6 / 5 (9) Mar 03, 2011You should know.
The facts behind my statement are blatantly self evident. Nature rewards success with survival and you get to pass on your genes, if you fail you die and so do your genes. Ever hear of a fella by the name of Darwin? Ever read a book beyond the level of Dr. Seuss?
You should...
Modernmystic
2.5 / 5 (8) Mar 03, 2011Then on what basis do you assert that humans have "screwed up the planet"? A statement like that presupposes a standard of some kind. Are you re-canting, or are you trying to weasel out of your own argument?
Like was previously said, it not only doesn't care, it CAN'T. It doesn't hold values, or make judgments. Objectively it's a set of chemicals cycling via the laws of thermodynamics. Not exactly a machine of morality.
Human beings don't need the biosphere of this planet to survive, or at least very very shortly we won't. If it's going to survive the biosphere needs us though, or in about 500 million years it will be ash.
epsi00
2.6 / 5 (5) Mar 04, 2011and a^n + b^n = c^n is also self evident to you, right. Maybe now you should switch field and help mathematicians with all the " yet to be solved problems " they have been working on for centuries. Maybe even The Riemann hypothesis is self evident to you.
too bad you did not live in Darwin time, you would have come up with the idea of evolution itself. Now you can only explain with your self evident statements.
As to Dr Seuss, I let the millions of kids and adults who enjoyed reading him, myself included, respond to you. In his own field, he is a giant and it is self evident to me that you are not, in any field.
You should...
Modernmystic
1.5 / 5 (8) Mar 04, 2011Sinister181
3 / 5 (6) Mar 05, 2011How do you know that this even true? Are you saying that if we destroyed the biosphere of this planet, that we won't perish along with it? Do you at least agree that we need certain PARTS of the biosphere? We are biological, after all. It just seems to baffle me. Unless you're working on something to turn Human beings into immortal cyborgs, then I guess we're stuck with the Earth, the biosphere, and our biological requirements.I can't understand your reasoning
Moebius
3 / 5 (8) Mar 05, 2011What he really meant was the less than human portion of our species that is responsible for this problem. They are the greedy, the skeptics, the over-populaters, the religious, the uncaring, the unknowing, the people that use the term tree hugger, the new republicans (the old republican party understood conservation), the fishing industry, developers, poachers, etc. The despoilers and their enablers are a significant portion of us. Yes, I think it is already too late to stop this because all these people can't be stopped.
MM: no, nature doesn't care what we do or how many species we drive extinct, and it doesn't care if in so doing we drive ourselves extinct. You are the kind of person I am describing above. An arrogant fool who thinks we have some kind of divine mandate to survive anything we do.
kaasinees
2.1 / 5 (7) Mar 05, 2011You are assuming we have the technology, that can compensate for the loss of trillions of living organisms? How naive is that? If the biosphere dies, so do we, common sense.
MorituriMax
1 / 5 (7) Mar 05, 2011Eventually we'll build our own biospheres and planets, screw "nature." "Nature" hasn't done anything for us anyway, we're only here because we've been able to adapt to anything "she" throws at us. The species that can't hack it, well they had their chance.
Skultch
4.2 / 5 (5) Mar 05, 2011The depth and breadth of the ignorance revealed in these statements is truly amazing. "We" didn't survive those mass extinctions, because "we" weren't around. The last mass extinction was ~65 million years ago. Our ancestors that survived that were tiny furry creatures; nocturnal, I think.
And it was a VERY BIG DEAL to them and us. We are the result of the survivors.
I guess, to you, individuals don't matter. Have many friends? Care if they survive or not?
Skultch
4 / 5 (4) Mar 05, 2011That said, there is no objective morality to govern whether we deserve to survive or not. Human survival is not a moral issue, it's a pragmatic one, because survival of our INDIVIDUAL genes is every person's highest priority, whether they realize it or not. Morals were selected in intelligent animals because it lowered the risks involved in reproduction, among other benefits. We must protect biodiversity for the same reason, survival of each of our genomes. It just happens to be the case at this time that human and inter-species cooperation is essential for this end.
The feelings every individual animal has that motivate survival are simple. If you had to choose between the survival of your child and a stranger's, how many milliseconds would it take you to decide?
We only cooperate because it is in our self interest to do so.
MorituriMax
1.8 / 5 (5) Mar 05, 2011Sorry, my comments were meant for someone smart enough to realize that yes, I know "I" personally wasn't around 65 million years ago.
And really, all of those previous extinctions didn't wipe out species as "bad" as we are to the environment. Or did the dinosaurs do to the environment what we are being accused of doing?
If none of the previous species wiped out by those 5 or more previous extinctions were doing such bad things to the environment, then how exactly am "I" supposed to feel guilty of how we live today? Living clean and in harmony sure didn't help out all the previous recipients of the extinction-level-event of the day did it?
Further, how exactly would we prevent an asteroid from wiping us off the face of the earth by driving green cars and getting all of our energy from solar power? Do the oil deposits somehow act as an anti-asteroid defense?
MorituriMax
1.8 / 5 (5) Mar 05, 2011Skeptic_Heretic
4.3 / 5 (6) Mar 05, 2011The immediate issue is that the energy production required to sustain ourselves will skyrocket. Having to preserve our food and the various systems that ensure easy health will skyrocket until we adapt, which could be a very slow process considering our propensity to control our environment rather than adapt. Life will get very hard, and a reduction in our intellect could follow, leaving us in a dire state indeed.
kaasinees
1.6 / 5 (7) Mar 05, 2011Johannes414
1 / 5 (7) Mar 05, 2011Skeptic_Heretic
4.2 / 5 (5) Mar 05, 2011And this is why religion, when taken to extremes, is harmful.
MorituriMax
1 / 5 (2) Mar 06, 2011Amen.
Stone_in_the_Void
1 / 5 (2) Mar 06, 2011otthole88
2 / 5 (4) Mar 06, 2011Soon the godman and all similar gods will leave this earth, and humanity will again be able to live in peace. It will truly be heaven on earth without religion.
Moebius
3.7 / 5 (6) Mar 06, 2011This statement is why religion is a sickness. Many who believe this will try to make it happen if given the opportunity. Motivated by the misinterpreters on TV and in their churches who twist the words of the bible to stoke the masses.
epsi00
3 / 5 (2) Mar 06, 2011exactly.
Thanks
MorituriMax
1 / 5 (3) Mar 06, 2011Hmmm, epsi, moebius?
rynox
1 / 5 (5) Mar 06, 2011Well... we're all still here...
Modernmystic
1.8 / 5 (6) Mar 08, 2011How do you think we live in space for months on end? We can recycle air, we can purify water, and in a few years we'll be able to actually manufacture food from raw materials. There are NO theoretical problems with this. All we'll need is power and a few years of technological advancement and we will have absolutely ZERO need for the biosphere...none, zip, nada.
Read a book on nano-technology...