The Permo-Triassic Extinction: A Question of Timing

Guest post by Mark Hladik

Introduction

In a 31 August 2011 article A blast from the gas in the past, Anthony Watts and company at Watts Up With That discussed a new paper by Montenegro et al titled, “Climate Simulations of the Permian-Triassic Boundary:  Ocean Acidification and the Extinction Event”.  This paper places the blame for the extinction event on the ‘demon’ gas carbon dioxide which supposedly made the oceanic environment too ‘acid’ for marine critters to make their calcite/aragonite shells.

Standard boilerplate ‘carbon dioxide is dangerous’.  Nothing new here.  Many valid rebuttal points were made by the participants in the ensuing WUWT discussion thread.

In the course of researching this missive, the author found a very similar paper:  Saunders, A.; Reichow, M.; 2009; The Siberian Traps and the End-Permian mass extinction:  A Critical Review; Chinese Science Bulletin v. 54  # 1  pp 20 – 37, (hereafter SR2009).   This paper also points to significant environmental change from the out-gassing during the emplacement of the mafic rocks and their associated by-products, near the Permo-Triassic boundary.

There is no doubt that volcanism on the scale of the Siberian Traps would have a measurable impact on the environment.  The big question is one of timing.  Did the traps form in a time frame which would allow their impact to be a major cause of the extinction event?  Is there another possibility which needs to be explored further, and actually accounts for the likely sequence of events at the extinction?

We do not have perfect knowledge but we can look at data and information which cast doubt on repeated assertions made by those who are convinced that carbon dioxide represents a global danger.

Timing

Geologists have divided the history of the Earth into several time intervals.  For example, most everyone is familiar with the Jurassic Period, thanks to the popularity of the movies bearing the same name.  This is just one of thirteen such Periods, the Permian and the Triassic being the two under consideration here.  A fast and easy download comes from the Geological Society of America (www.geosociety.org/science/timescale) which at this writing has the 2009 Geologic Time Scale, with all of the subdivisions created by the geological community.  This time table is a summary of the monumental work by Gradstein, Ogg, and Smith, called “A Geological Time Scale 2004”, or GTS 2004, which would primarily be of interest to those working in the profession.  Many libraries have copies, and this author will be referring to some of the geochemical charts contained in GTS 2004.

Readers are cautioned that GSA 2009 and GTS 2004 are now somewhat out of date, and this author has recommended revisions to GSA.  While the changes are minor, they have a significant bearing on this article.

At this point, the reader may be asking, ‘why do the dates of geological subdivisions keep changing?’  This is a good question, and requires that the reader understand the origin of the concept of geological time.

Originally, geologic time was subdivided on the basis of the fossils found within the rocks themselves, with older, and often, more primitive life forms, being assigned to older strata.  These “older” strata tended to be deeper in the Earth, so there was little question of the relative ages of the rock layers.

With the advent of radiometric dating, it became possible to assign a time, as measured from the ‘present day’, to a specific rock layer.  Most people are familiar with carbon-14, and how it is often used to determine the approximate age of a sample of organic material, since 14C is present in all living things and the decay rate is well-established.  At the present time, 14C is useable for material less than 100,000 years old.

There are presently several dozen radiometric dating schemes in use, and often multiple methods are employed on a single sample as a cross-check.  As the geological sciences advance in methodology, and more samples are located and accurately dated, the time scale undergoes refinements, but the overall picture remains about the same.

For example, as an undergraduate in the 1970’s, the author memorized certain dates as the beginning times of the various Periods.  At that time, the base of the Cambrian Period was thought to be about 570 million years before present (abbreviated, ‘ma’, which stands for ‘million annua’).  That time was later revised to 540 ma, and in GTS 2004 and the GSA 2009 chart, the date has been further refined to 542 ma, plus or minus 1.0 ma

[i. e., 542.0 ± 1.0 ma].

What comes into play here, however, is the time for the beginning of the Triassic, or the definition of the Permian-Triassic boundary.  In the 1970’s, this time was thought to be about 225 ma, but it has since been refined to about 251.6 , plus or minus 0.4 ma, which is a phenomenal error constraint, considering the difficulties in getting an accurate date.

In the course of researching for this article, however, this author discovered that there has been an even further refinement to the dating of the Permo-Triassic boundary, and a reduction in the uncertainty associated with this important transition.

If the reader has downloaded the free time scale from the GSA, please make the following changes:

base of the Ediacaran:   now thought to be 635 ± 3.7 ma;   (formerly 630 ma)

base of the Triassic:      now thought to be 252.3  ± 0.3 ma;   (formerly 251.6 ma)

base of the Jurassic:      now thought to be 201.5  ± 0.6 ma    (formerly 201.6 ma).

It is likely that there will be further changes, but the trend for the ‘end-of-the-Permian/beginning-of-the-Triassic’ has been a consistent move towards an older time (viz., 225 ma, to 245 ma, and now 252.3 ma).  We are likely to see these revisions continue, especially as the geological community continues to explore this important boundary.

The question under consideration here is, ‘what caused the Permian extinction?’  As noted, numerous authors have pointed to environmental change(s) related to the Siberian Traps.  The most likely scenario put forth (and strongly advocated by SR2009) is that the Siberian Traps outgassed a great deal of carbon dioxide, causing rampant global warming (since, in their view, more carbon dioxide causes global temperatures to rise significantly), and the existing life forms could not adapt.  Montenegro et al carry this idea even further, citing the solution of increased carbon dioxide from the atmosphere into the oceans, changing the oceanic pH closer to a level of ‘acid’, which then inhibited the formation of hard shells of any number of marine invertebrates, causing them to die from predation, lack of food, etc, as well as from increased oceanic temperatures.

While an interesting hypothesis, this may not be the full story.  This author accepts that the Siberian Traps played some role in changing the global environment at the time the eruptions were taking place, but the big questions are, ‘when were those eruptions, and did they play a major role in the Permo-Triassic extinction event?’

Extinction Timing

This author will make reference to Dr. P. R. Janke of PanTerra (Box 556, Hill City, South Dakota 57745), who produces “A Correlated History of the Earth”, and who offers some insights into other possible causes of the Permian extinction event.  While certainly tentative, his hypotheses seem to be gaining ground, especially in light of the recent move of the end of the Permian from 251.6 ma to 252.3 ma.  Dr. Janke finds evidence that ‘global environmental change’ and the Siberian Traps, likely had very little to do with the Permian extinction event(s).

Anthony Watts has also posted an interesting chart on WUWT

which shows that prior to the terminal P/Tr event itself, a significant extinction was already underway.  In the 10 ma leading up to the P/Tr event, the rate of extinction was already greater than the K/T event (largely associated with Chicxulub).  The beginning of the extinction pre-dates the earliest Trap emplacement(s) by millions of years.

We must also ask, how long was the final P/Tr extinction process?  This remains an open question, but the best scientific minds on the planet are in general agreement that the final act was (geologically) rapid, occurring within a time span of 100,000 years, and possibly less (see http://www.le.ac.uk.gl/ads/SiberianTraps/).

This is a significant problem for the suggestion that the Siberian Traps had an effect on the Permian extinction.

The eruption of the traps themselves spanned an estimated 2 ma.  As is the case with many geological phenomena, the event had some beginning (likely at a low level of activity), built up to a crescendo, and then abated.  Even if it did start at a high level of activity, the first 100,000 years of eruptions did not produce 100% of the “extra” carbon dioxide.  If it is found that the terminal extinction occurred even faster than what is currently thought, say, e. g., covering some 50,000 to 75,000 years, then we are forced to question how the (slow-acting) geochemical mechanisms managed to dissolve the initial amounts of “extra” carbon dioxide into the existing oceans, given that the world was in the process of “warming” at the same time, and ‘warmer’ oceans outgas carbon dioxide, instead of taking it into solution.

A warmer world and ocean acidification (all the rage in the CAGW community today) might account for some of the extinction in the marine world, but how do ‘acidic’ oceans cause terrestrial plants and animals to go extinct at the same time?

Two lines of evidence suggest that the “extra” carbon dioxide from Siberia did little to affect the paleoclimate.  Firstly, GTS 2004 has geochemical plots, and the δ18O charts (a widely-used paleotemperature proxy) show little, if any, change across the time boundary.  Secondly, we would expect little change in temperature, even if the amount of carbon dioxide in the atmosphere increased, since carbon dioxide’s ability to cause warming is asymptotic, beyond a concentration of about 300 ppm.  The most widely accepted model of carbon dioxide concentration (Berner et al, GEOCARB III) indicates that the concentration likely changed from ≈3000 ppm to ≈4000 ppm, during the latest Permian and earliest Triassic. It’s a large increase to be sure (approximately 33%), but it should have very close to zero temperature effect, and GTS 2004 bears this out.

The biggest problem with the Siberian Traps hypothesis, however, comes from the dating of the traps themselves.  Recall that the generally accepted time for the end of the Permian (and beginning of the Triassic) has recently been placed at 252.3 ma with a ± 0.3 ma error estimate.  Again referring to the University of Leicester (referenced above), they show a central tendency date for the Siberian Traps as around 250 ma; the earliest radiometric date comes in as just older than 252 ma.  In either case, if these dates are valid, then the majority of the Siberian Traps would seem to POST-date the Permo-Triassic extinction by about a million years, and possibly more!

So how do we explain such a phenomenon, given the magnitude of the event and the questionable evidence for a climate catastrophe?

“A Correlated History of the Earth”

The seventh edition of Dr. Janke’s monumental work is copyrighted 2010; this author is in communication with Dr. Janke regarding some minor revisions to his time chart, especially with the newest base times put into place the previous calendar year.

Dr. Janke shows, among other things, a listing of significant events such as the Siberian Traps, and paleogeographic reconstructions, based on those of Dr. Christopher Scotese (www.scotese.com), which are widely considered to be among the best ever.  He also has a summary of the fluctuations in CO2 concentrations.  If one has not seen this, be prepared for a shock; the amount of information contained within this single chart is exceptional!

A Correlated History of the Earth also contains a column listing extra-terrestrial impact events.  The Chicxulub impact at the Cretaceous/Tertiary boundary (the “K/T Event”) is shown right at 65.5 ma, the now-accepted time for the extinction of the Dinosauria.

The most compelling item about this column on Dr. Janke’s chart is the listing of impacts (yes, plural!) at the end of the Permian.  Within the error limitations of impact event timings (especially older impacts), there are five probable impacts at the Permian/Triassic boundary:

Falkland Islands (part of South America at the time);

Wilkesland (Antarctica)

Gnargoo (Western Australia)

Bedout (offshore Western Australia)

Arganaty (central Kazakhstan)

As remarkable as this possibility is, it gets even better:  the first four events, allowing for the reconstruction of the paleogeography at the time (see Scotese), come suspiciously close to a straight line, not unlike a multiple-impact from a broken-apart celestial body, similar to Comet Shoemaker-Levy 9’s impact on Jupiter in 1994.

The Wilkesland impact structure has an estimated radius of 120 km; for comparison, Chicxulub is about 80 km.  It would seem that the Wilkesland structure, if verified, was potentially sufficient to cause the entire extinction event.  The possibility that there were some “insurance” impacts at the same time suggests that the Siberian Traps were a minor influence, and not necessarily the proximate cause of the extinction.  We have also previously established that the Traps likely post-dated the extinction itself.

In the same vein, we cannot completely rule out antipodal genesis for the Siberian Traps; the four ‘straight-line’ end-Permian impacts could have been an instigator of the Siberian volcanism, if the antipode hypothesis is valid.  Given the proximity, it would seem more likely that the Arganaty impact helped to initiate the Siberian Traps, the event being near the southwest fringe of the Asian LIP (large igneous province).  Perhaps this will become an avenue of further research, free of CAGW dogma.

Obviously, the biggest problem with this suggestion is the lack of an iridium-rich layer, as is associated with the Chicxulub event.  We do know that preservation in the geological record tends to be hit-and-miss, and the older an event is, the less likely that it has been preserved.  The author previously stipulated that there was probably some environmental influence(s) from the Siberian Traps.  If carbon dioxide was outgassed in significant quantities, then it is likely that sulfur and sulfurous compounds were also injected into the atmosphere.  It would take little imagination to see some type of global ‘acid rain’ removing a large part of the fresh iridium-rich layer of impact debris, if the hypothesized impact(s) at the Permo-Triassic boundary occurred.   We know that many land plants were exterminated at this time, so logically, the rate of erosion could have increased substantially, until land plants re-established themselves (in the Triassic), and stabilized soil formation.

(For those who might not otherwise know, groundcovers such as grasses had not evolved yet, so any soil stabilizers would have been restricted to large vascular plants.)

Conclusion

CAGW alarmists seem to be singularly obsessed with carbon dioxide, and its supposed effects on the global environment.  The lengths to which these individuals and groups will go to tie carbon dioxide to absolutely everything, even in the face of contradictory evidence, is something few of us will ever understand.  Even a political agenda as a prime motive does not do justice to the fanaticism on display.

Consider that there is reason to suspect the idea of the Siberian Traps as a prime cause of the Permian extinction, the most extensive, documented extinction on the planet.

Consider that the skeptical side of the argument accepts and knows without doubt that global climate has always changed, that the current change is not unusual (we can  discuss EPICA and Vostok at a later date), and that carbon dioxide emissions have little to do with global climate change.

We can understand that individuals in the Meteorology community might not be aware of the type of data available on the Internet.  Once they are made aware of such data, we could reasonably expect that these individuals might re-examine their positions, and understand the lack of correlation between global temperatures and atmospheric carbon dioxide concentrations.

Members of the geoscience community do not have such an excuse; these individuals are the curators of the knowledge of what has happened in the past, and should know better.  SR2009 makes the blanket assumption that any change in carbon dioxide automatically means a corresponding change in global environment/temperatures, almost in linear lockstep, when we can demonstrate that the levels of CO2 in the Permian atmosphere were such that any change would have had a trivial effect on temperatures.

Montenegro et al fail to recognize that hard-shell organisms evolved at a time when carbon dioxide concentrations were on the order of 6,000 to 7,000 ppm, so that any alleged “ocean acidification” because of the Siberian Traps outgassing would have had a negligible effect on their descendants.  During the preparation and editing of this article, a new post occurred at JoNova’s website, called The Chemistry of Ocean pH and “Acidification”.  [www.joannenova.com.au/2011/11/the-chemistry-of-ocean-ph-and-acidification/#more-18584]   This article summarizes the current information on the effects of increased carbon dioxide on ocean pH, in light of the burning of fossil fuels, and the change in atmospheric chemistry.  It is a worthwhile read.

For much of geologic history, the Earth has been warmer than it is now, with no demonstrable harm to the organisms in existence at the time.  In-so-far as we can tell, life flourished in almost every part of the existing land, and has thrived/survived substantial and innumerable “climate changes”, not to mention impact events.

The reader is free to doubt what you read here, but the geochemical charts contained in Geologic Time Scale 2004 represent the current state of the art.  Even a cursory examination of the δ18O paleotemperature proxy should give pause to even the most die-hard CAGW advocate.  As we know, ‘there are none so blind as those who will not see.’

Appendix

The definitive paper on the radiometric dates for the Siberian Traps is also authored by Reichow and others.  While the University of Leicester summary (above) has an excellent reference to the accepted radiometric dates, this paper

http://le.ac.uk/gl/ads/SiberianTraps/PDF%20Files/Reichow%20et%20al.%202009.pdf

gives the most comprehensive overview of the current research on the dating of the Traps.    With the exception of three dates which come before the newly-accepted boundary between the Permian and Triassic, and three dates which are significant outliers (almost ten million years after the transition), the central tendency of the eruptions of the Traps is about 250.1 ma, well after the terminal Permian extinction was complete.

The specific dates are as follows:

248.1 ma

248.4

248.6

248.7

248.8

248.9

248.9

249.0

249.1

249.2

249.4

249.5

249.6

249.7

249.7

249.8

249.9          [median]

250.1

250.1          [mean and mode]

250.1

250.2

250.2

250.4

250.5

250.5

250.6

250.8

250.8

251.7

251.8

———-   Permo-Triassic boundary at 252.3 ma  (± 0.3)

252.6 ma

253.3

253.4