Are we in the midst of the sixth mass extinction?

[Bystander]

"#6? Yes or no?" Mebbe --- I ain't quit yet --- signal:noise is starting to look like one tough problem.

 

[Nereid]

Originally posted by Bystander
"#6? Yes or no?" Mebbe --- I ain't quit yet --- signal:noise is starting to look like one tough problem.

Wasn't it always going to be? That's partly why I think it's well worth the effort to look at this one in some detail.

(In case regular readers hadn't already noticed, I've been rather consumed by a series of discussions in Social Sciences; I just can't help myself there. If you've opinions too, please don't be shy. I really want to keep this thread going, and will put the time in when I can).

 

[Bystander]

To the bitter end. However, I'm stuck at the moment for ways and means to detect 2-3 new species within the 10k or so new identifications per year (consistent with 2-3k appearances per year globally, if we apply a first order rate model to the Lake Victoria cichlids, and extrapolate that to the 10M estimate for total extant species). Doesn't look to be demonstrable, leaving me to argue from order of magnitude rate estimates vs. demonstrable disappearances.

 

[Nereid]

I've got a couple of difficulties with Bystander's approach, apart from the ones he (she?) has already identified:
- a background rate of extinctions that is constant through all between-mass-extinction pairs would seem unlikely. Suppose we got a clear answer at the end of our quest, and the loser was sore; a simple challenge would be 'but the background rate in the pre-Cambrian was quite different than that from 65Mya to 1 Mya!'
- much more difficult - since estimates of the number species of unicellular organisms is at best, very poorly constrained - the two numbers we'd be taking the difference between could be much larger than two or three orders of magnitude.

Avoiding these kinds of problems was partly why I suggested limiting ourselves to a) multicellular critters, and b) only some well-defined subset of all such.

Could I suggest a little side project? What does the fossil record of the last 65 million years say about the prevalence of chordates and magnoliophyta?

 

[Bystander]

Originally posted by Nereid
- a background rate of extinctions that is constant through all between-mass-extinction pairs would seem unlikely.

Uh-huh --- and the distribution of rates about the average is unknown, leaving us in unknown territory as far as stating that an observed rate is not only "high," but of a magnitude that it may be accorded "event" status.

- much more difficult - since estimates of the number species of unicellular organisms is at best, very poorly constrained - the two numbers we'd be taking the difference between could be much larger than two or three orders of magnitude.

Again, uh-huh --- we have no idea what "high" rates are.

Avoiding these kinds of problems was partly why I suggested limiting ourselves to a) multicellular critters, and b) only some well-defined subset of all such.

"Well defined" is going to be open to interpretation: 1M + 10k new IDs/a in a 10M total estimate; some of the anecdotal, or not so anecdotal, information about salmon "picking sides" in a lake; the incomplete nature of the fossil record; and the open questions re. evolutionary mechanisms and selection mechanisms.

Could I suggest a little side project? What does the fossil record of the last 65 million years say about the prevalence of chordates and magnoliophyta?

Or, what's the "party line" on two separate families (depending upon the taxonomy to which one subscribes) evolving/selecting large, hairy, tusked, proboscidean forms during the pleistocene; i.e., just what is the official story on environments and megafauna? Low primary productivity implies megafauna? Or, high primary productivity? It comes and goes as far as fossil record appears to indicate, but what drives the appearances and extinctions of such?

 

[lab rat]

Originally posted by Ivan Seeking
Can anyone name one new species to evolve in the last 100 years?

I can name many species that have gone extinct in the same time. In other words, the times scales discussed seem much too large. If we are creating a mass exinction the applicable time scale is in hundreds of years, not thousands or millions.

Here is a blurb from an article about a new species of whale. I attached the article if anyone is interested.

June 26, 2002 - In the mid-1970s, four rare beaked whales washed ashore dead on the coast near San Diego, California. James Mead, a leading authority on beaked whales from the Smithsonian, examined the skulls of these animals and tentatively identified them as the Southern Hemisphere species Mesoplodon hectori. At that time, there were a dozen named species of beaked whales (Ziphiidae) within the genus Mesoplodon that were diagnosed primarily by the size, shape, and position of an enlarged pair of teeth in the adult males. Two decades later, Merel Dalebout a graduate student from the University of Auckland analyzed DNA sequence data and found that these California animals clustered far apart on a phylogenetic tree from the Southern Hemisphere specimens of Mesoplodon hectori. Working together, Dalebout, Mead, and co-workers are now formally describing this heretofore unrecognized new species in the current issue of Marine Mammal Science (1). The new species, Mesoplodon perrini, is named after William F. Perrin, a preeminent marine mammal systematist and conservationist.

Taken from this article
----> http://www.lam.mus.ca.us/research/mammals/beakedwhale.htm

 

[Bystander]

New? Or, newly identified? Plus, sounding like the last of their species from the description of the discovery --- is it an "appearance," or an "extinction?"

 

[lab rat]

I guess that's open to your interpretation. I read the story and a couple of related stories and [to me] it sounds like it's a new species in the last 25 years.

 

[lab rat]

Oh, Bystander, I do see your point about a few new species and many, many, many disappearing. I'm not trying to stir things up here, I just remembered hearing about the whales a couple of years ago so I posted it.

 

[Bystander]

Not arguing with you on the point --- just echoing the problem with "interpretation," definition, and whatnot that we've been running into in this thread.

It's about boiled down to two possible conclusions: 1) mine, that there is insufficient evidence to reach any conclusions (not likely to budge from it); 2) and Nereid's, whatever it may be.

Do I feel that swapping tigers for 23 new species of cane toads is a fair deal? No. Are we in the middle of a "great extinction?" "Hubris" is a twenty dollar word --- bible thumpers say, "pride" --- funding proposals are successful in direct proportion to the fear that can be generated (Manhattan Project, Cold War, AIDS) --- how many observatories and astronomers are being funded by fear of "great impactors?" Not many --- it's peanuts. How much money can be shaken from the Congressional tree by pointing out changes in flora, fauna, and climate as if they've never been observed before? Tons --- very big business. Ethics and big business? Not in my lifetime.

 

[Bystander]

Actually, we've got big problems here; none of our hypotheses are falsifiable --- I have to have an unbroken global record of species appearances and extinctions to demonstrate that N.'s assertion that the current extinction rate is high enough to count as an "event" is false, and N. has to have an unbroken record to demonstrate that my assertion that appearance and extinction rates are of the order of 10³ is false.

Stalemate.

 

[Nereid]

Bystander wrote:*SNIP Or, what's the "party line" on two separate families (depending upon the taxonomy to which one subscribes) evolving/selecting large, hairy, tusked, proboscidean forms during the pleistocene; i.e., just what is the official story on environments and megafauna? Low primary productivity implies megafauna? Or, high primary productivity? It comes and goes as far as fossil record appears to indicate, but what drives the appearances and extinctions of such?

later:

*SNIP I have to have an unbroken global record of species appearances and extinctions to demonstrate that N.'s assertion that the current extinction rate is high enough to count as an "event" is false *SNIP

Which is partly why I wanted Bystander (and Russ, but he's absconded - sure to get a bad mid-term report) to define (a method for determining) the background rate*!

But wait! Didn't we agree that there have been mass extinctions in the past (step 1 in the proposal)? If we did, how did Bystander (and Russ?) come to be comfortable with the idea that there *was* a mass extinction at the KT boundary, the late Triassic, Permian/Triassic, late Devonian, and late Ordovician?

So, to convince the most skeptical participant, how about we ask Bystander what convinced him that there were five (six, including the Cambrian) mass extinctions? Then we work together to find a way to repeat the steps - as closely as we can - for today's mass extinction (per Nereid's - and Ward's, and ... assertion)?

Hey prodigal child Russ - care to rejoin us? Andre, are you as skeptical as Bystander and Russ? Anyone else?

*My proposal, from the start of this thread:
"1) We all agree on what constitutes a mass extinction.

2) Bystander and Russ propose a definition of the 'normal' or 'background' extinction rate; we discuss it and agree.

3) We agree on what the actual background extinction rate has been, up to 1mya.

4) I propose a means of estimating the present extinction rate; we discuss it and agree.

5) I will make an estimate of the present extinction rate; we discuss it."

 

[Bystander]

Appearance -extinction = 0.01 -0.1 species/a --- there isn't data to plot the difference as a function of time; there is no way to demonstrate a real time modern appearance rate; there is no way to demonstrate a modern real time difference in rates; there are no data to support absolute values of historcal/paleontological rates to much better than 2-3 orders of magnitude.

Two equations (modern extinction rate estimate), the average rate difference over geological time, and three unknowns --- the system is indeterminate.

 

[Nereid]

Originally posted by Bystander
Appearance -extinction = 0.01 -0.1 species/a --- there isn't data to plot the difference as a function of time; there is no way to demonstrate a real time modern appearance rate; there is no way to demonstrate a modern real time difference in rates; there are no data to support absolute values of historcal/paleontological rates to much better than 2-3 orders of magnitude.

Two equations (modern extinction rate estimate), the average rate difference over geological time, and three unknowns --- the system is indeterminate.

Or, in other words, we won't know we've been living through the sixth mass extinction until (a few million years) afterwards. At that future time, it will become obvious there's been a mass extinction.

But, do you consider there have been five earlier mass extinctions? (more?) If so, what was it that lead you to that conclusion?

 

[Bystander]

Paleontological evidence "suggests" extinction events --- alternative explanations have been proposed. What do I find more credible about the idea of abrupt mass extinctions (impactors) than pandemic "creeping crud," or deep freezes, or Siberian or Deccan Traps? Very few extraordinary circumstances and events have to be invoked to explain abrupt changes in globalfloral and faunal distributions in the fossil record.

Parsimony.

 

[Nereid]

Originally posted by Bystander
Paleontological evidence "suggests" extinction events --- alternative explanations have been proposed. What do I find more credible about the idea of abrupt mass extinctions (impactors) than pandemic "creeping crud," or deep freezes, or Siberian or Deccan Traps? Very few extraordinary circumstances and events have to be invoked to explain abrupt changes in globalfloral and faunal distributions in the fossil record.

Parsimony.

A paraphrase: if the cause seems credible, the evidence can be accepted? If not, then the evidence isn't credible??

'abrupt' =~+/- 1 million years?
'global' = >10 sites separated by >1,000 km at the time?
'floral change' = ~>3 Divisions lose >~30% of their Families?
'faunal change' =~>3 Phyla lose >~30% of their Families?

Let's have some numbers please!

 

[Bystander]

Originally posted by Nereid
A paraphrase: if the cause seems credible, the evidence can be accepted? If not, then the evidence isn't credible??

Did I fall off the turnip truck yesterday? Evidence is "credible" regardless; the hand-waving one chooses to use to explain the evidence can be credible, incredible, supported by the evidence, or not supported by the evidence, depending on the gullibility of the audience.

'abrupt' =~+/- 1 million years?

Oh, hell, let's play catastrophist --- I gave you 1Ma earlier, but you want to ask a second time --- let's say it's all over but the shouting in a day, and let the shouting last 30 yrs. for last survivors.

The stratigraphic record doesn't really have a resolution less than 1 Ma --- as a result, the paleo types fall into catastrophist and gradualist schools, and without discovery of mixed ground fish, dinos, and shrubbery in TX or SA turbidites, that argument is never going to be resolved.

'global' = >10 sites separated by >1,000 km at the time?

Tain't likely all the big 5(6) stand up to this test --- evident in all known outcrops of specified age suit you?

'floral change' = ~>3 Divisions lose >~30% of their Families?
'faunal change' =~>3 Phyla lose >~30% of their Families?

OK last time we went through this part.

Let's have some numbers please!

That's the point: we are talking about THREE numbers, appearance rate, extinction rate, and the difference between the two. We can determine an AVERAGE value for the difference over geological time. We CANNOT determine an instantaneous value for historical cases, or for the present. We have no values for appearance or extinction rates historically or for real time. There are ESTIMATES of an extinction rate based on a mix of "specialist" and other type species. If we agree to delete the "specialist" species from the rate estimate, there is still NO basis for concluding anything, because we lack information on the appearance rate, the historical extinction rate, and on the variation of appearance and extinction rates.

I can't state it any more clearly, "There is insufficient information available to conclude a damned thing."

 

[Bystander]

Sole', et al, Nature, vol. 388, 21 Aug., 1997, pp. 764-6.

Might as well get the third horse into this race. Everyone in the "chaos crowd" should like this.

 

[Nereid]

Originally posted by Bystander
Sole', et al, Nature, vol. 388, 21 Aug., 1997, pp. 764-6.

Might as well get the third horse into this race. Everyone in the "chaos crowd" should like this.

I'm pretty sure http://pangea.stanford.edu/Oceans/GES290/SOC/GES290sole1997.pdf is the paper you're referring to.

Nereid: "But, do you consider there have been five earlier mass extinctions? (more?) If so, what was it that lead you to that conclusion?[/color]"

Bystander: "Paleontological evidence "suggests" extinction events --- alternative explanations have been proposed. What do I find more credible about the idea of abrupt mass extinctions (impactors) than pandemic "creeping crud," or deep freezes, or Siberian or Deccan Traps? Very few extraordinary circumstances and events have to be invoked to explain abrupt changes in globalfloral and faunal distributions in the fossil record.

Parsimony.[/color]"

Sorry, I really am in the slow class today, ... your POV is that we can't really discuss a purported sixth mass extinction, because we haven't yet agreed that there've been five mass extinctions (or four, or three, or even one)?

(this is quite separate from any consideration as to whether there is, or could be, sufficient info "to conclude a damn thing")

 

[Bystander]

Originally posted by Nereid
I'm pretty sure http://pangea.stanford.edu/Oceans/GES290/SOC/GES290sole1997.pdf is the paper you're referring to.

Yup.

Sorry, I really am in the slow class today, ... your POV is that we can't really discuss a purported sixth mass extinction, because we haven't yet agreed that there've been five mass extinctions (or four, or three, or even one)?

Nope.

POV is,"Extinction rate, estimated, calculated, divined by Madame Cleo, is meaningless outside a context of historical extinction rates." The only historical information I can see/agree to at the moment is that we can calculate/estimate an average difference in appearance and extinction rates; there is not adequate evidence to support estimates of absolute values for either.

The paper is "grist for your mill" --- you might be able to winkle out an idea of where the current extinction rate estimates fit within the power law distribution, and maybe some idea of absolute rate --- I ain't going to mess with it right now. Their remarks re. power law and the "big 5(6)" as far as them being indistinguishable from other extinctions depend on time frames (stratigraphic uncertainty being a few Ma in all cases for their purposes); more recently (no ref. at hand) the KT(?) has been pinned to something like 100ka for an outcrop in China --- might actually throw that one outside the fit.

Fair 'nuff?

 

[Nereid]

Bystander wrote: *SNIP
The only historical information I can see/agree to at the moment is that we can calculate/estimate an average difference in appearance and extinction rates
*SNAP

How?

 

[Bystander]

Originally posted by Nereid
(snip)The difference between the rate of appearance of species and the rate of extinction of species is then obtained by simple algebra from the above.(snip)

"How?"

You followed it once, seemed to get along with the idea, and now you ask, "How?"

 

[Nereid]

Originally posted by Bystander
"How?"

You followed it once, seemed to get along with the idea, and now you ask, "How?"

Just want to be sure

In terms of my original proposal:
1) We all agree on what constitutes a mass extinction.

2) Bystander and Russ propose a definition of the 'normal' or 'background' extinction rate; we discuss it and agree.

3) We agree on what the actual background extinction rate has been, up to 1mya.

4) I propose a means of estimating the present extinction rate; we discuss it and agree.

5) I will make an estimate of the present extinction rate; we discuss it.

Supplementary topic: if we agree that number six is in progress, then we look for causes.[/color]

We agreed (more or less) on 1).

Bystander decided that 2) was impossible to work with, in any practical sense (and Russ is playing truant).

Which means the end of this little experiment (unless someone would like to suggest how we could continue).

It's been pretty quiet; since 29 Feb, only Nereid and Bystander - have we bored everyone to tears?

 

[Bystander]

Mass extinction of the audience --- no sound but the crickets. Actually been fun --- learned a couple things.

There may be something hiding in the power law distribution material, but that's going to be a while.

Later --- B.

 

[meteor]

The World's No.1 Science & Technology News Service



Earth faces sixth mass extinction


19:00 18 March 04

NewScientist.com news service

The Earth may be on the brink of a sixth mass extinction on a par with the five others that have punctuated its history, suggests the strongest evidence yet.

Butterflies in Britain are going extinct at an even greater rate than birds, according to the most comprehensive study ever of butterflies, birds, and plants.

There is growing concern over the rate at which species of plants and animals are disappearing around the world. But until now the evidence for such extinctions has mainly come from studies of birds. "The doubters could always turn around and say that there's something peculiar about birds that makes them susceptible to the impact of man on the environment," says Jeremy Greenwood of the British Trust for Ornithology in Norfolk, and one of the research team.

http://www.newscientist.com/news/news.jsp?id=ns99994797

 

[Bystander]

Meteor-

Nereid thanks you, and I thank you --- the silence in this thread has been deafening. This is another version of what started this thread ---- sort of "deja vu all over again." We got stalled by my refusal to consider extinction rates alone as sufficient cause for concern, coupled with the fact that "appearances" are difficult to observe.

"--- populations of 71 percent of the butterfly species have decreased over the last 20 years, compared to 56 percent for birds and 28 percent for plants. Two butterfly species (3.4 percent of total) became extinct, compared to six (0.4 percent) of the plant species ----" This isn't too horribly out of line with first order rate estimates based on Lake Victoria cichlids (appearance and extinction rates in my analysis) --- 3x10^-4/a taken over a twenty year interval is 0.6%; compared to observed rates of 3.4, 0.4, and 0.0 for three species groups, I'd have to say, "No surprises here." Nereid may have other conclusions and comments.

The population studies likewise have to be examined in a broader context --- is the island turning a dead brown, or are populations of other species increasing? Population biology is a completely different problem and, excepting the cases where populations crash to zero, unrelated to the extinction problem.

 

[Andre]

OK, some feedback on this old thread based on the alarming hype about extinction that triggered this thread (alliterations allowed?) into existence.

I may have remarked that this was the worst sciencific paper I have ever seen, the model was based almost solely on extrapolating some extinctions of the last few decades that were not caused by changing climate at all. Furthermore, of the some 33 identified major (climate(?) upheavals in the last million years there is only one that is associated with some explicit extinctions (the Pleistocene steppe megafauna Mammoths) around 11,570 years ago.

Well. Here is the retreat .

Charities 'spread scare stories on climate change to boost public donations'
By Elizabeth Day
(Filed: 02/05/2004)

Environmental charities are exaggerating the threat of climate change in an attempt to raise more money from public donations, according to a report by Oxford University academics...

 

[Bystander]

Eeehhhhhhhhh ---- hmmmm. Sloppy science begets sloppy journalism begets sloppy public interest group activities begets sloppy political activism begets sloppy funding of sloppy science? Naaahhh --- people are opportunists --- Svante Arrhenius speculated about "global warming" a century ago, and people have been hunting ways to connect their names with his since then. That, plus the "publish or perish peer review process" has placed a number of speculations into the public record that would have been "edited" to the circular file by the pre-WWII scientific establishment --- violations of first principles and basics of technique, and just plain WRONG science did not get published in them days. Today, 10k journals competing for space on shelves waste a lot of paper and ink publishing "peer-reviewed" pure bunkum --- post WWII/Cold War peer-review is more a matter of "don't trash me and I won't trash you 'cause we're both in the same publish or perish boat."

 

[Andre]

Just for the record another casual opinion on that paper:

http://www.washtimes.com/commentary/20040114-083322-9283r.htm

Massive extinction of logic
By Patrick J. Michaels

Much has been made of a paper published on Jan. 8 in the journal Nature by Chris Thomas and 18 co-authors, claiming global warming will cause a massive extinction of the Earth's biota. Mr. Thomas told The Washington Post: "We're talking about 1.25 million species. It's a massive number."
It turns out that there is a massive number of glaring problems with their study that clearly eluded the peer review process. This is evinced by the rapid turnaround for the manuscript, with acceptance in final form a mere five weeks after original submission. No one can clear revisions through 19 authors in that time unless there weren't many revisions suggested, or, if there were, they were ignored by the journal's editors in a rush to publication.

In fact, acrimonious debates about what should or should not be published about global warming are the rule rather than the exception, simply because papers are being published — on many sides of the issue — that can be shredded after only a cursory review. Unfortunately, the debate may have started with Nature itself.

In 1996, conveniently a day before the U.N. conference that gave birth to the Kyoto Protocol, Nature published a paper purporting to match observed temperature with computer models of disastrous warming. It used weather balloon data from 1963 through 1987. The actual record, however, extended (then) from 1958 through 1995, and, when all the data were used, the troubling numbers disappeared. Since that famous incident, people have been very leery of what major scientific journals publish on global warming. The Thomas extinction paper only throws more fuel on an already roaring inferno.

The work of Mr. Thomas et al. is an interesting exercise in computer modeling showing again that what comes out of a computer is a product of the assumptions that go in. The scientists examined the distribution of more than 1,000 plants and animal species, calculated their current climatic range, and then used a climate model to determine whether the amount of land the species could occupy in the future would shrink or expand. If there was a likely shrinkage, the researchers expected an increased chance of extinction.

etc, etc

Patrick J. Michaels is senior fellow in environmental studies at the Cato Institute.