Talk:Holocene extinction/Archive 1

Frogs

Foant added: About half of all frogs (amphibia) have become extinct during the 20th and 21th centuries due to unknown causes but pollution of water, global warming has been proposed as a factor. Three quarters are endangered.

I can't find any support on google for half of either frogs or amphibia having already become extinct. Certainly they are highly vulnerable, but to claim that half are already extinct seems excessive. Unless you have a reference to support this, I am going to remove it. Dragons flight 17:39, Apr 30, 2005 (UTC)

Ok, here is the sources I found (wrote that above from memory): http://www.dn.se/DNet/jsp/polopoly.jsp?d=597&a=344210 (swedish), http://www.washingtonpost.com/wp-dyn/articles/A33569-2004Oct14.html, http://web.archive.org/web/20011129072744/www.oregonlive.com/news/00/02/st021910.html , http://www.worldwatch.org/press/news/1998/05/21/ . Well it seems they are in decline and some are already extinct... After you have read the sources maybe you can phrase it better than I did? Foant 18:06, 2005 Apr 30 (UTC)

The Holocene extinction event is a name customarily given to the widespread, ongoing extinction of species occurring in the modern Holocene epoch.

The statement that there is a "widespread, ongoing extinction of species" is not supported.

What is the current estimated rate of extinction? How does this differ from historical norms? Is there a historically normal rate of extinction or does the rate tend to fluxuate wildly?

How do scientists estimate the current and previous rates of extinction? do these estimates tend to be the same, or do they vary widely depending on the methods used and the scientists conducting the study? What does this imply about the accuracy of these estimates?

The fact that many species of large animals became extinct between 13,000 and 9,000 years ago is troubling. However, comparing it to say, the Late Devonian extinction, where 70% of all species on earth became extinct is a bit overdramatic.

In its attempt to link these extinctions with the presence of human beings, the article also glosses over the fact that the last ice age ended 10,000 years ago, and that climate change is a common cause of extinction. Might it be more accurate to say that human behavior is one of several causes of the current extinction event? (Assuming, of course, that an extinction event is in fact taking place.)

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Well, I can asure you it is taking place! Just visit my website: http://extinct.petermaas.nl Current climate change is different from other periods, that it is caused by human behaviour now! Another site I cn recommend is: http://www.iucn.org/themes/ssc/red_list_2004/main_EN.htm And the 2004 IUCN Red List of Threatened Species - A Global Species Assessment: http://www.iucn.org/themes/ssc/red_list_2004/GSA_book/Red_List_2004_book.pdf In this pdf also more info and data on (frog)extinctions caused by climate change. Pmaas 11:42, 15 December 2005 (UTC)

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From the above mentioned IUCN pdf: Only 34 amphibian species are recorded as having become Extinct by the 2004 IUCN Red List of Threatened Species, 20 of these being endemics to Sri Lanka, most of which disappeared over 100 years ago. It is likely that there have been many undetected amphibian extinctions over the last two centuries, and the concentration in Sri Lanka, although real, is also a reflection of the detailed taxonomic studies of frogs that have taken place there. Nine of the 34 amphibian extinctions have taken place since about 1980. Eight of these nine recent extinctions were sudden disappearances in suitable habitats, and are probably the result of the fungal disease, chytridiomycosis, probably operating in conjunction with climate change (Laurance et al. 1996; Berger et al. 1998; Ron et al. 2003; Burrowes et al. 2004). However, these figures are probably a very large under-estimate of the level of amphibian extinctions since 1980. A total of 122 amphibian species are listed as Critically Endangered (Possibly Extinct), and 113 of these could have disappeared since 1980. Most of these took place in Central and South America, in particular from southern Mexico south to Ecuador, with others recorded from Puerto Rico, Hispaniola, Jamaica, Venezuela, and southern Brazil. Other possible extinctions have been noted in Australia, Indonesia, China, Kenya, and Tanzania. Most of the disappearances happened very suddenly, and it seems increasingly likely that chytridiomycosis, linked to climate change, is the main cause. Proving extinction beyond reasonable doubt is often very difficult. Pmaas 11:48, 15 December 2005 (UTC)

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Regarding "The Ongoing Holocene Extinction", please cite articles from peer-reviewed journals that indicate 1) how current human activity is causing extinction of species 2) the extent to which species will be extinct as a direct result of such activity in the near future. "Those who are skeptical about the impending mass extinction" will need convincing.

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Not very familiar with this topic, and not a native english speaker, I didn't want to edit this myself, but I believe it is a typo of some sort:

For instance, the timing of sudden megafaunal extinctions of large Australian marsupials and a giant lizard, events that followed the arrival of human beings in Australia by many thousand years, need examining.

Shouldn't "followed" be replaced with "preceded" or something? Feel free to remove this comment if you're convinced I'm wrong. --Jacob no. 9 19:58, 26 February 2006 (UTC)

In a word, no. It isn't a typo, it's just a plain old mistake. Current evidence supports the exact opposite conclusion - i.e., the mass extinctions are believed to have immediately followed the arrival of humans on the continent. Tannin 04:53, 6 May 2006 (UTC)

North American Genera/Species

The section on Pleistocene extinctions in North America has the following

Circa 12,000-9000 years BP, 35 to 40 species of large mammals, while only about half a dozen small mammals, disappeared[citation needed].

I changed species to genera, and this change was reverted. I thought I would discuss my reasoning for this change here. I should note that elsewhere in the article, 33 genera of megafauna go extinct in the late Pleistocene.

Generally, the literature I am familiar with (Grayson 2001, J. World. Prehist. 15:1-63 for example, but many others) cite 33 - 35 genera of megafauna which go extinct. Some authors believe (Alroy 2001, Martin 1973, Mosimann and Martin 1975) that the extinctions occured in a short time scale, during Clovis time. Archaeologists who work on this time period (Grayson and Meltzer 2003, for instance), however note that there is little archaeological evidence for this sudden extinction. While biological modelers do recognize this, they can attribute it to the Signor-Lipps effect. Thus it is not uncontroversial to argue that 33-35 genera went extinct in Clovis time (usually about 12,250 - 10,500 rcybp), this is argued by some. This is all analysis done at the genus level.

At the species level, there is little coherance. I don't have an immediate citation off the top of my head (I'll look around later), however the recognition of different species in the same genera is dodgy at best. Experts disagree about what consititutes a new species, and thus they disagree about species counts. Thus most of the analysis is done at the genus level. Thoughts on how to improve this section? --TeaDrinker 22:25, 30 June 2006 (UTC)

i think everything you ve said is on target. the obvious addition we need to make is more on plants and lower life forms in general. As far as your comment on genrera vs species (and you are totally correct of course), the problem here is the lay public is used to thinking in species terms, and has a very difficult time grasping the significance of a lost genus. so we need to have some kind of dialog at the species level. Anlace 22:48, 30 June 2006 (UTC)

I am the one who reverted and asked for a citation. Basically, I was bothered by the 3000 years because I couldn't believe we had that good an age control (and we don't). I've now updated the section based on a 2004 review by Barnosky et. al in Science. According to their figures, only about 1/2 of the genera can be reliably attributed to this interval. While Signor-Lipps might allow more to fall in that interval it is not appropriate on the basis of current knowledge to say for sure that they do. Dragons flight 23:30, 30 June 2006 (UTC)

Great work, I think you hit the nail on the head. I took the liberty of removing the Grayson citation since he does not mention how many smaller animals went extinct. I will try and find a citation for it, however (although I am not certain the number is correct). --TeaDrinker 06:31, 1 July 2006 (UTC)

"Millions" of species

Anlace recently added:

These estimates rely upon an annual loss of up to 140,000 species per year (based on Species-area theory).

based on S.L. Pimm, G.J. Russell, J.L. Gittleman and T.M. Brooks, The Future of Biodiversity, Science 269: 347-350 (1995).

However, while this reference predicts substantially accelerating in the future, they plainly estimate the extinction rate over the last 100 years as 20-200 extinctions per million species year. In other words, given 10-100 million species, that amounts to no more than 20,000 species per year and a more middling value might be 2,000. I don't see how you can possibly get 140,000 from that paper, except possibly by trying to apply the species-area relationship to some numbers not appearing in that paper.

Also, this is not really the kind of citation I'd like to see in support of "millions" of extinctions. It would be much better to point to a reference claiming directly that millions of extinctions have occured. If the middle value is something like 200,000 extinctions during the last century, then while millions of extinctions might be possible, it is not necessarily likely. Hence, the first thing to do is establish that there really are some scientists, somewhere, who plainly estimate there have already been millions of extinctions. Or perhaps we should clarify the existing text to say something like: "Scientists estimate that during the last century, between 20,000 and two million species have gone extinct but the precise total cannot be determined more accurately within the limits of present knowledge." Dragons flight 05:53, 1 July 2006 (UTC)

Cleanup/Split

This article is confusing. It seems to be describing two separate events - the Pleistocene extinction and the Holocene extinction. I'm really not sure how to begin to clean it up, but I feel that as well as being cleaned up it should either be moved to a name which reflects this dual nature or else split into two separate articles. I know I was confused when I clicked on "Pleistocene extinction event" and it redirected here. If anyone has any suggestions please make them known. --72.140.146.246 03:03, 2 August 2006 (UTC)

if there is a split, Pleistocene extinction event would be a sub-article to Holocene Anlace 02:05, 5 October 2006 (UTC)

deleted article link

A link to "The Sixth Extinction" by Niles Eldredge has been thoughtlessly deleted by User:Eagle101, taking action, it seems, against the web host for the article, ActionBioscience.org. I suppose most of the rest of us know who Eldridge is. Even though well-intentioned or intention-less, this deletion has the same effect in this case as vandalism. If the article were mentioned in a note, would it be deleted? Shall we see? --Wetman 19:42, 18 January 2007 (UTC)

Strange emphasis of text

This article has evolved to have a curious emphasis. Most of the article (as one editor pointed out above) is not about the Holocene Mass Extinction at all...but about other previous mass extinctions. This article needs to be re-aligned to focus on the present Holocene event and subordinate the earlier events. In any case the article cries out for much more detail on arthropod, bird, fish, flora and other elements of Holocene. The bias in this article and other biology articles to megafauna is appalling. Anlace 20:41, 30 January 2007 (UTC)

"this current rate of extinction is thus 10 to 100 times greater than any of the prior mass extinction events in the history of the Earth."

I'm strongly tempted to edit this out straight away. The mass extinctions associated with the months immediately following extraterrestrial impact events had rates of extinction orders of magnitude greater than is seen today. Is there a citation for this or perhaps some qualifiers that could be added to make it better reflect the original observation rather than simply deleting it outright?Zebulin 01:37, 5 March 2007 (UTC)

Another similar statement appears in the article:

"Evidence for all previous extinction events is geological in nature, and the shortest scales of geological time are in the order of several hundred thousand to several million years. Even those extinction events that were caused by instantaneous events — the Chicxulub asteroid impact being currently the demonstrable example — unfold through the equivalent of many human lifetimes, due to the complex ecological interactions that are unleashed by the event."

Just because the KT extinction did not completely resolve until thousands of years after the impact does not mean that the extinction rate was uniform. The extinction rate was highest by far in the first year than in any of the subsequent years of that mass extinction.

It is not necessary to pad out the appalling severity of the current mass extinction with unsupportable claims that current extinction rates are unprecedented.Zebulin 01:52, 5 March 2007 (UTC)

I think that the claim that "this current rate of extinction is thus 10 to 100 times greater than any of the prior mass extinction events in the history of the Earth." has been misquoted from something asserted by E O Wilson, that "Before humans existed, the species extinction rate was (very roughly) one species per million species per year (0.0001 percent). Estimates for current species extinction rates range from 100 to 10,000 times that, but most hover close to 1,000 times prehuman levels (0.1 percent per year), with the rate projected to rise, and very likely sharply."

As has been suggested, it is simply not true that the current rate is even as high as it has been during some catastrophic events, so perhaps the claim should be rephrased to something more closely along the lines of what E O Wilson actually said, as quoted in his article .

Foxi tails (talk) 18:38, 19 February 2009 (UTC)foxi_tails

E O Wilson also says something similar here: WILSON, E. 0. 2003. Foxi tails (talk) 18:44, 19 February 2009 (UTC)foxi_tails

Magnitude and rate of loss for current extinction

I've moved this section in from Extinction event because it's far too long and detailed for what is meant to be an overview article. Please integrate the material as you see fit. Philcha 00:35, 20 April 2007 (UTC)

As the material hasn't been properly sourced (or integrated) I've removed it from the article to here for discussion/sourcing.

==Magnitude and rate of loss for current extinction==

Currently, the protected areas in the UNEP-WCMC protected areas database cover between 10% and 12% of the world's land mass. The information assessment is contested, in terms of size and IUCN protection category. Only about half of the area consists of fully protected areas in the IUCN categories I-IV. In the other half, forest exploitation can and usually does take place.

When applying Arrhenius' (1921) "species-area curve", while assuming (1) the optimistic value z=.15 (Dobson 1996) to the protected land mass; (2) a land cover protected effectively and durably of about 9%; (3) all ecosystems represented using a fine distinction in ecosystems (Vreugdenhil et al. 2003) and (4) stable ecological conditions, one may expect the conservation of 70% of the terrestrial species of the planet and according to this model the loss of 30%.

There are no scientifically sound models to predict the effect of climate change on the survival of species. Changing ecological conditions resulting from climate change however, will impact the survival strategies of many species and particularly in the world's most diverse ecosystems, the humid tropical forests. There, the impact may be far reaching if climate change would intensify and prolong the dry seasons. If this would happen, more trees would seasonally shed their leaves, and the sun would penetrate forest levels that previously would never be exposed to direct sunlight. Many species would not be able to survive such conditions for prolonged periods of time. As there are no models to predict the effects, we may only speculate the impact on the species survival on earth, but whatever the outcome, its effect will be accumulated to the minimum species loss of 30%.

Vsmith 14:25, 27 July 2007 (UTC)

YD comet

This was added by a spamming anon:

• Younger Dryas (YD) Comet Catastrophe\Clovis Killer on YouTube

I have removed it as the YD comet hypothesis is not discussed in this article (and despite considerable press coverage has yet to appear in a peer review journal). It might be appropriate here if people want to discuss it the hypothesis in the article. I'll leave that to contributors here to decide. Dragons flight 16:31, 15 June 2007 (UTC)

WP:NPOV

Let's not use this article as a POV tool to make unscientific statements. Most of the extinction event articles are well written and NPOV. Several editors, although I see their point and may agree with it, are trying to make this article a statement on what man is doing to the planet. Let's use verified and reliable sources to write this article. OrangeMarlin ^{Talk• Contributions} 02:01, 27 July 2007 (UTC)

This article seems a little biased to me. I would not argue that there is a large scale extinction, however, that is presented as being unilaterally bad. The loss of some species due to human activity is only bad if the continued existence of those species is more valuable than the benefits we get from the activities we're doing that's causing their extinction. Perhaps it is a tragic loss of biodiversity, or perhaps it is a small price to pay for the benefits humans have received from those activities. I don't know which side is correct, it is hard to quantify the value of those species, but the latter perspective seems to be under-represented in the article. 208.81.43.46 (talk) 23:06, 8 April 2008 (UTC)

Perhaps a scientific definition of extinction and its role in speciation events would be appropriate. Species becoming extinct indicate the existence of and allow for new species to be created and the earth is not a single geologic moment. I'm not suggesting that this article turn into an article about evolution or that it should suggest that species be eradicated in order to promote evolution, but it would probably add to its scientific credibility to include a small section on what role extinction plays in evolution on a whole. Perhaps a short sourced discussion section about how the potential problem of the current extinction rate is not its existence (there is nothing inherently wrong with extinction) but that the problem is that the rate may be so high that nothing is replacing those species' ecological niche (The opposing argument, of course is that there are species replacing the niche, even if it is humans). Britt (talk) 19:04, 12 April 2008 (UTC)

Britt, thank you for your interest in this article, but i think you may be embarking on a slippery slope. We cant make every wikipedia article a tutorial on all the basic sciences. Perhaps a brief mention of speciation is in order, but your tack tends to take one on a POV cornucopian view which appears all too often on wikipedia that "the planet can afford to lose lots of species". Even saying that humans are replacing the "niche" is a gross misrepresentation of the collapse of the ecosystems and simplification of pre_Holocene complexity that originally provided stability and diversity. Anlace (talk) 23:03, 12 April 2008 (UTC)