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2021 SkS Weekly Climate Change & Global Warming News Roundup #17

Eclectic at 21:29 PM on 27 April, 2021

Dale H @6 ,

a somewhat brief overview from me as a non-expert :-

The atmospheric CO2 level was very high "from the start", in the sense of Pre-Cambrian times. Fortuitously, the early Sun was significantly lower in output (insolation has been increasing by 1% per 120 million years approx.)

In the long run up to now, exposed rock has very slowly absorbed CO2 by "weathering" to form carbonate which ends up on the ocean floor (and/or subducted by tectonic movement). And part of these carbonates is recycled into the atmosphere by volcanic venting.

The rate of weathering has varied at times. Also, there was a large "plunge" in CO2 level during the fossil-carbon formation in the Carboniferous age (much plant life, and no large herbivores?). A separate plunge during the Ordovician age (somewhat unclear, owing to uncertainty from poor time-resolution). And some major spikes in CO2 (and temperature) owing to Large Igneous Province eruptions such as the Siberian Traps and the Deccan Traps events.

Overall, it's been quite a ride !

The present latitudinal positions of the continents (plus Antarctica at polar position) has predisposed to glacial times for our planet. And likewise, the current "low" CO2. And if I have gathered correctly ~ in about an estimated 15 million years' time, the CO2 level would have become low enough to embarrass the present species of plants (unless they suitably evolve their photosynthetic mechanisms). Obviously the 15 million year time-scale gives the human race considerable leeway in tackling that particular problem.

Dale H , my apologies if you were already aware of much of this broad background. The SkS website has a vast amount of detail available for your self-directed searching.

As you have said you have already spent a goodly amount of time researching climate matters, then it might be advantageously efficient if you gave specific indication of where you feel puzzled or where you feel the mainstream climate scientists might be wrong.

If you need to raise particular questions, then it is standard SkS policy that you place one or two questions in the most appropriate thread . . . and deal with those questions . . . and then progress to the next question you have in mind.

CO2 was higher in the past

Eclectic at 14:36 PM on 3 November, 2019

Nyood @87 , my apologies to you, for my speaking overly-briefly about LIP eruptions.

My example of the Siberian Traps event demonstrated the vast release of CO2 and consequent high temperature rise on Earth. The Deccan Traps event was smaller in effect, and also was complicated by the cooling effect of the Chicxulub asteroid impact.

You are quite right to say LIP events can have a transient cooling effect from the venting of sulphate & other aerosols . . . and also in the much longer term, the exposed silicate rock does gradually draw down the atmospheric CO2 (and hence the lower CO2 will lead to a global cooling, relative to what had gone before).

My essential point with respect to Antarctica, was that a future LIP eruption could be of enough size to produce a major boost in atmospheric CO2 and consequently a major temperature rise for a lengthy period ~ sufficient to melt away the huge Antarctic ice sheet.

We must hope that a major LIP eruption will not occur, for its result could be catastrophic.

The question of Ordovician temperatures and glaciation is a difficult one, for the timing of events & CO2 changes rests presently on low-resolution data. For the relevance to the climate of the modern age, we must rely heavily on the lessons from basic physics.

CO2 was higher in the past

nyood at 06:31 AM on 3 November, 2019

"There are two scenarios where Antarctic ice will disappear:
- (A) the very long term (many millions of years)
as the solar output continues its gradual increase, and
(B) an unexpected Large Igneous Province eruption of CO2,
such as the Siberian or Deccan events. In either of these
circumstances, the South Polar ice would disappear, even if
Antarctica did not move from its present polar position."

(A) This is true the sun will warm for a billion years. If and
when this will melt the poles i do not want to discuss
here,interesting question towards the HHE Hot House Equilibrium though.

(B) The Deccan Traps caused cooling. wikiDeccan
The polar ice would not disappear, you just make an assumption here. The ordovician
tells us the opposite: Even with levels of 6000ppm a glaciation occurs.
You miss the start of my original post: "This is quite remarkable, it tells us
that a glaciation is capable to ABSORB even CO2 ammounts of 6000ppm"
and you ignore the core of my LPC theory, basicly by just saying "it is so, Antarctica would melt"

Please be more carefull with prospective criticism, you can try to go on and find
other arguments pro CO2, like the PETM or the permian-triassic in the past to stay on topic.
Or you can fight my theory and i give you a hint here: i mentioned the "triassic north pole paradox".

"The present day crisis involves the small-magnitude warming which will displace around 200 millon people
as sea level rise approaches 1 metre [Kulp & Strauss, 2019]. And probably a much greater size of refugee problem,
coming from storm surge, land salination, and other agricultural adverse effects
(including low-humidity and high-humidity heat waves]."

What you are doing here is seen very often, you let someone speak for you.
I would have to read the study, check the sources, check the context
and then come back to you. You have to express your thoughts yourself and use studies to back up your argumentation.

First of all what we are seeing here is the common axiomatical acception that CO2 plays a strong role, i would have to argue with Strauss
and confront him with my LPC theory first.
You can check accepted sources like NASA on Sea rise. It will never be that quick that men will not adept let alone react in time.
Furthermore since i see the increase as natural, there is no point to try to change it.

Rebellious Times

ilfark2 at 04:55 AM on 3 May, 2019

Nick Palmer and SkS generally: While Beckwith and McPherson seem a bit out there, there does seem to be an evolving concensus that many things are happening much faster than expected, esp. in the arctic (and, per Beckwith, and you can track down the paper he mentions) they just strated tracking arctic Nitrous Oxide.

Combine this with Richard Alley's work (among others, I'm sure) that abrupt climate change very likely happened before plus the idea in the 1990s that 1.5 might lead to feedback loops and 2 degrees certainly would, wouldn't it be better to err on the side of 0 emissions by tomorrow (which would save lifes via air quality among other causes) ?

Last I checked, methane is increasing in a quite an unexplained, unaccounted for clip (of course Beckwith et al point to the vast area of perma frost not monitored)...

Point being, yes many of the studies of feedback systems in the arctic are in first stages, can we afford to wait the decade it would take to verify their findings?

As Richard Alley said in his presentation to the AGS years ago, there might only be a 5% chance, but there is a 5% the climate flips.

If that happens it very likely could be PETM or post Siberian Traps.

Or am I missing something? Did you guys update this site to include studies that explain the increases in methane and CO2 above the arctic? That wamer soils are starting to be become carbon sources? That warmer oceans are beginning to become a less effective sink possibly leading to a source?

Even if all this is inaccurate, there are something like 122,000 coal fired plants being built around the world now. Tars sands, fracking... all this has to be stopped. How can we get the world to pull together in a democratic way other than deposing market systems and aknowledging we have to plan our resource use and help each other to live sustainably on the planet via changing energy and agriculture?

In terms of material necessity (food, shelter, healthcare), the proportion off the population that does anything is miniscule. If we shared these jobs in a democratic way, expanded education and research, created walking cities we could drop emissions drastically in a day.

Free Catalonia of the 1930s is a good model (among others).

And as XR points out, fear can lead to freeze, flight or fight.

But, again, if you've debunked all this, point me to the article and I'll happily sleep better.

California's response to record wildfires: shift to 100% clean energy

Doug_C at 15:16 PM on 5 September, 2018

Bob Hoye @21

"Those preaching a disaster through climate may have to go a study a little geology. This is a preaching site that has nothing to do with the skepticism of real science."

It's through studying geology that we know how mass extinction is intrinsically linked to climate change primarily through the atmospheric concentration of one gas long identified as the prime persistent radiative forcing agent in the atmosphere - carbon dioxide.

That includes the Great Dying 251 million years ago with a high confidence that it was massive emissions of carbon dioxide from the Siberian Traps that triggered global feedbacks that eventually killed over 95% of life then in the oceans and over 70% of species on land.

The end Triassic extinction was also probably another climate change induced extinction level event.

The Deccan Traps and large scale release of carbon dioxide and other greenhouse gases probably played a significant role in the End Cretaceous extinction.

The fingerprint of CO2 and mass death is all over the geological record, which makes sense when you look at the basic physics. This site has a meter for anyone to consult that indicates how much heat is added to the Earth on a constant basis by the addition of billions of tons of CO2 to the atmosphere.

It now stands at over 2.6 billion Hiroshima bomb heat equivalent units since 1998 alone. There's no way that much heat can be added to the global system without major impacts on climate as most of that heat ends up in the oceans which are the prime driver of climate globally. Able to store vastly more heat than the atmosphere and transport it around the Earth by ocean currents and by determining how atmospheric circulation behaves to a great degree.

"Bob Hoye, B.Sc. geophysics."

Working in the oil and gas sector perhaps...

2018 SkS Weekly Climate Change & Global Warming News Roundup #30

ilfark2 at 02:33 AM on 31 July, 2018

Considering Alley's work on abrupt climate change and the latest Siberian Traps research, global warming should be considered and immediate existential threat.

As such, either keep a quasi market system (like WWII mobilization, but hopefully more equitable) or create a rational society that uses less energy, produces more free time and ensures we don't have this issue in the future (as very likely any market 'solution' would insure since markets have always tended to expand)...

examples of rational societies are Paris Commune (worked well until French allied with German Capitalists to crush it), Catalonia for a few years (until Capitalists crushed it) and Rojova (in process of being crushed by Capitalists)... we know how to have a higher standard of living, using much less energy.

In the US, the vast majority of people pumps tons of carbon to drive in a big circle to an activity that does not need to happen (Finance, Insurance, Real Estate); couple that with Graeber's bullshit jobs and we've a whole lot of folk that can help others do real (material) work. If automate most of this and localize production (Bookchin, et. al.), we could all have much better lives and save this set of evolution's species (what's left of them anyway).

We could do this in a democratic way (as in Catolonia).

Of course, I'm not too hopeful, considering folk on this very site talk about market incentives that might have worked, had they been implented at the turn of the 20th century (and yes folk knew about global warming even then... see Tyndall and others around that time).

We might have 10 or fewer years to get to 0 emissions. Even the overly optimistic Paris Accord depend on carbon extraction that as of now we're not sure will work.

So, yes, using markets, hoping for new technology, might work, but it doesn't seem worth the risk, considering possible scenarios.

Notice also the recent study on the AMOC slowing and speeding up in a natural cycle, which of course means two things. It's going to get hotter in the next few years and we get to see if the paper's contention is true or if the extra heat in the newly claimed altantic (from the arctic) ocean will offset the mechanism from the past (the paper contends that in the past, more melting led to a slowdown which led to less tropical water delivered, which reset the cycle... of course that was before all the extra heat we've beening allowing our emissions to trap)

There are genuine climate alarmists, but they're not in the same league as deniers

ilfark2 at 00:37 AM on 13 July, 2018

It would be nice to have a full debunking of that arctic news blogspot. I went to the "deep dive" on debunking Guy McPherson and the person dismissed the idea that methane could be released on a massive scale by noting sea temps had been about the same 200k yrs ago (and it didn't happen then) and also that Archer does some back of the envelope calcs showing it won't be a problem.

Note though that GHGs were about half what they are now, 200k ago.

Note Alley's work (as someone mentioned above).

Note Archer's history on various parts of artic behavior (e.g., permafrost in which he didn't include the effect of microbes), which he always corrects himself later on. But notice how his timelines have changed over the last 15 years.

The problem with arctic news blog is it's harder to debunk than McPherson. They do cite lots of papers. Some of it is new lines of inquiry, but the direction they point is quite dramatic (Sharkova et. al., e.g.).

Considering PETM and Siberian Traps events happened around 500 — 1500 ppm CO2, and Alley has shown a very good case that global climate can change in a matter of 5 years, and we've trapped a great deal of heat in the ocean that hasn't come out to play yet and we already have 2ce as much CO2 as 200k ago...

They make a good point as to the possibility.

What they don't really flesh out is that, if there is a sudden climate flip and many crops fail along with massive drought, the global capitalist system could grind to a halt for a bit. This could lead to a lot fewer particulates in the air, which could lead to very fast (others have researched this pretty well from what I can tell) warming.

So please, Skeptical Science, fully debunk these guys. Point out what they are missing in your usual ultra thorough manner.

Burning coal may have caused Earth’s worst mass extinction

Doug_C at 09:52 AM on 13 March, 2018

nigelj @1

Large Igneous Provinces such as the Siberian Traps are fissure flow volcanism on a vast scale. This produces fractured surface rock over an extensive area. This could expose coal deposits that could then burn in the presence of lava.

http://www.ldeo.columbia.edu/~polsen/nbcp/lipmc.html

To tweet or not to tweet at Donald Trump? That was the question!

John Mason at 19:02 PM on 10 March, 2017

Chris - yes I think you'll find I've made that abundantly clear. LIPs and human combustion of fossil fuels are rare instances of very rapid perturbations of the slow carbon cycle. Even periods of vastly enhanced weathering of mafic rocks are slow compared to a) the Siberian Traps or b) anthropogenic fossil fuel combustion, although they can be significant nevertheless. Ref. the "weathering goes crazy" tweet and the ones giving figures for the Traps and manmade emissions. The point being that the slow carbon cycle goes along fine and dandy - unless it gets messed with by something of a dramatic nature.

To tweet or not to tweet at Donald Trump? That was the question!

John Mason at 19:17 PM on 9 March, 2017

Doug, the Slow Carbon Cycle is called just that for fairly obvious reasons. Yes it does mostly operate on geological timescales, but there is evidence for periods of highly enhanced weathering. These are considered to be preserved in the Sr isotope record e.g. in the run-up to the Hirnantian glaciation/extinction (ref below). The complex process of Ca-bearing silicate weathering by atmospheric CO2 dissolved in rainwater through to deposition of carbonate sediments is an overall remover of carbon, locking it up within limestone. Since Ca-silicate weathering and limestone deposition are both ongoing processes worldwide, there is a continuous flux of carbon from the air into the lithosphere. The quantity of carbon thus stored away in limestones is phenomenal. You will note that I talk about carbon as opposed to carbon-bearing species, as regardless of your points it cannot be denied that the process begins with carbon in the form of CO2 and its interactions with water and calc-silicates:

2CO₂ + 3H₂O + CaSiO₃ = 2HCO₃ ^– + Ca²⁺ + H₄SiO₄

and ends with calcium carbonate deposition:

2HCO₃ ^– + Ca²⁺ = CO₂ + H₂O + CaCO₃

2 moles of carbon (as CO2) at the start; 1 mole returned as CO2 at the end, 1 mole locked away in calcium carbonate. Overall, that whole bit of the Slow Carbon Cycle results in a net loss of atmospheric CO2.

That's the process going one way. But perturbations of the Slow Carbon Cycle in the opposite sense can occasionally be much more rapid - the Siberian Traps magmas cooking a thick oil/coal-rich sedimentary basin sequence being one example. Mankind's burning of the fossil fuels is another. The point is that the Slow Carbon Cycle both stores and releases carbon continuously, but great big carbon burps can occasionally occur, for which the consequences tend not to be pretty!

Ref: Young, S.A., Saltzman, M.R., Foland, K.A., Linder, J.S. and Kump, L.R. (2009): A major drop in seawater 87Sr/86Sr during the Middle Ordovician (Darriwilian): Links to volcanism and climate? Geology, October 2009, v. 37, p. 951-954.

Increasing CO2 has little to no effect

Rob Honeycutt at 15:08 PM on 27 February, 2017

Try this. Think of a specific observation that would demonstrate that CO2 has a tiny impact on global temperature, as you suggest.

The rest of the scientific community has done this in spades over the past century. Exit from snowball earth events. Early faint sun paradox. Silicate rock weathering. Temperature excursions with the Siberian/Deccan traps. Etc.

Or, alternatively, apply your theory to Venus. Tell us what your equations output for the surface temperature.

US Passenger Vehicle Emissions Comparable to 1980 Mt. St Helens Eruption Occurring Every 3 Days

william at 03:59 AM on 6 November, 2016

The graphic was great. None of the deniers will read the text and few would understand if they did. How about two more graphics. a) The total yearly emissions from all geological sources vs the total yearly emissions of us and b) Our yearly rate of emissions vs the rate of emissions during the laying down of the Siberian traps. Then we can send this to our denier friends in a form they can comprehend.

US Passenger Vehicle Emissions Comparable to 1980 Mt. St Helens Eruption Occurring Every 3 Days

Tom Curtis at 01:43 AM on 6 November, 2016

Joel_Huberman @1, your source suggests the Siberian Traps released 30,000 GtC of CO2 over the period of its erruption, ie, over a period of over a million years, representing an annual emission rate of around 0.03 GtC per annum. In contrast, since 1850 humans have emitted 560 GtC at a mean annual rate of 3.4 GtC. Since 1965 (ie, over the last 50 years for which we have published data), we have emitted 370 GtC at 7.4 GtC per annum. Since 2010 the average annual emission rate has exceeded 10 GtC per annum. In short, we are emitting CO2 at rates that far exceed those during the deposition of large igneous provinces.

Onset of Eocene Warming Event took 3-4 millennia (so what we’re doing is unprecedented in 66 million years)

howardlee at 06:43 AM on 12 February, 2016

To be clear Both Zeebe's and the Kirtland Turner & Ridgwell study are talking about the initial warming of the PETM and the initial pulse of carbon that caused it.

The current thinking is that the PETM is not likely an orbitally forced event even if some of the subsequent hyperthermals may have been. I covered that in an article in 2014 here.

There's very strong evidence for intense volcanic activity associated with the North Atlantic Igneous Province (yes yet another Large Igneous Province associated with a warming event) ocurring at exactly the time of the PETM, See:

Zircon dating ties NE Atlantic sill emplacement to initial Eocene global warming

These papers are also relevant:

Two LIPs and two Earth-system crises: the impact of the North Atlantic Igneous Province and the Siberian Traps on the Earth-surface carbon cycle

Evidence for weathering and volcanism during the PETM from Arctic Ocean and Peri-Tethys osmium isotope records

Large igneous provinces and mass extinctions: An update

Development of intra-basaltic lava-field drainage systems within the Faroe–Shetland Basin

Diachronous sub-volcanic intrusion along deep-water margins: insights from the Irish Rockall Basin

Kimberlite eruptions as triggers for early Cenozoic hyperthermals

However, from an isotope signature point of view the methane hydrate source works according to Zeebe, who told me: " I’m still convinced that this methane hydrate hypothesis is working very well in terms of total amount of carbon and in terms of the isotopic signature that we see. I think there is evidence that there could be mud volcanoes in the North Atlantic that could have contributed exactly to methane release during the PETM."

Whereas Ridgwell told me: " It seems it’s all around the time of a lot of enhanced volcanism going on in the North Atlantic and people have suggested, and I’m coming around to the importance of this, of a particular episode of quite extensive volcanism happening in the North Atlantic just at the time of the PETM. So it seems that maybe [the PETM] is a little bit like some of these older events."

We are the Asteroid - Scientists’ Heighten Concerns About Global Extinctions

tmbtx at 23:48 PM on 6 August, 2015

Ryland,

1. There need not necessarily be a drop in standard of living. Investment in R&D could even enhance it while still addressing the climate. Is it a sure thing? Of course not, but the likely drop in standard of living coming due to our impact on the planet is going to be worse.

2. Not knowing everything about every species is entirely different from doing "pure guesswork". True many of these numbers are estimates but they are well informed estimates.

3. Volcanoes or climate change? Not sure what you mean. Volcanic activity like the Siberian or Deccan traps released lots of CO2, as are we. It's not either/or. But "We are a large igneous province" doesn't make as catchy a statement as "We are the asteroid."

Climate's changed before

Kuni at 05:19 AM on 2 June, 2015

Roamernz - Previous causes are not relevant because they are not the cause today.

Yes it has happened before. When it has happened slowly, life adjusted. When it has happened quickly, it was an extinction event.

Now it is happening quickly yet there are no natural causes that anyone can find that are emitting CO2 above their historical normal levels. There are no Deccan Traps being created. There are no Siberian Traps to be found.

Volcanoes continue to emit around 1% of the CO2 that human are currently emitting via the burning of fossil fuels.

No increase in solar radiation has been detected, the solar cycle is sticking to its regular pattern. Cosmic ray collisions in the upper atmosphere have not increased.

The cause of the greatest mass-extinctions of all? Pollution (Part 2)

howardlee at 04:22 AM on 24 March, 2015

ginckgo @1Methanosarcina may possibly have played a role in the P-T extinction but I'm skeptical of the Rothman et al theory for the following reasons:

It is a one-off explanation, whereas LIPs have a criminal record – they are a serial killer with a consistent “MO”: greenhouse gas release, warming, rising sea levels, ocean acidification and anoxia.

Rothman et al use a 82-million-years-wide time window for the horizontal gene transfer that enabled the runaway methanogenesis. Even if we overlook the often elastic nature of molecular clocks, and that their clock is not calibrated to fossils, that’s a time window extending from the lower Permian to the lowest Jurassic. For the mutation to have happened exactly coincident with the Siberian Traps eruptions is just too fortuitous to be probable. The authors explain the coincidence by citing nickel fertilization by the Siberian Traps eruptions – but that would place the mutation, even more fortuitously, as having occurred between the Emeishan and Siberian LIPs, or else we should have had the Guadeloupian Mass Extinction.

So what did-in the dinosaurs? A murder mystery…

Theorist at 09:02 AM on 21 March, 2015

@Andy Skuce .54 and Tom Curtis .55

As I stated in a prior posting, current gravity anomalies found around the globe are due to variations in crust/upper mantle densities, usually from compression by ice. These are minor and not related to core movement.

There is much evidence to support the GTME. If you viewed the Youtube video referenced earlier, you understand the basic concept:

When the continents, coalesced into larger masses, e.g., Pangea, and especially when that consolidated mass moved latitudinally, the law of conservation of angular momentum comes into play in the same way that it does when a spinning skater moves their outstretched arms close to the body or away from the body. In the case of the skater, their rotational velocity must change. For the Earth, when the coalesced mass moves latitudindally, the distance to the Earth’s axis changes in a comparable manner. Therefore, either the Earth’s rotational velocity changes or something else compensates to conserve angular momentum. GTME posits a movement of the core elements to compensate because there is no rotational change known. The movement of the core elements creates a gravitational gradient around the Earth.

Based on the above, some of the results are:

1. Terrestrial and marine life exhibited a much wider range in physical size than is possible today when the core elements moved away from Earth-centricity.

2. When the core elements moved rapidly toward Earth-centricity, surface gravity increased, flood basalt volcanism began and a massive drop in sea level occurred. The latitudinal movement is supported by a scientific study mentioned in the video which illustrates the latitudinal movement of Pangea over the last 300my.

3.When (2) above happens, methane is disassociated from the sea bottom because of the drop in sea level coupled with the (still) relatively low surface gravity. The volcanism further increases the disassociation because it raises the ocean temperature. In fact, the experts claim that the carbon isotope excursion at the P-T boundary was too large to be accounted for by the Siberian Traps alone.

4. At the Cretaceous-Triassic boundary, marsupials in N.America were almost completely wiped out in contrast to other small mammals.

http://phenomena.nationalgeographic.com/2014/12/24/the-opossums-tale/

This can be explained by a rapid increase in surface gravity. If you have an alternate explanation, I would be interested.

5. The reduction in size and complexity of the forams at the Cretaceous-Triassic transition can be explained by an increase in surface gravity, not only by a change in ocean chemistry. Smaller, less dense forams would be more buoyant and more likely survive if surface gravity increased.

The cause of the greatest mass-extinctions of all? Pollution (Part 2)

ginckgo at 12:49 PM on 20 March, 2015

There's possibly even more to this event than just volcanic 'pollution', and it's even closer to the modern pollution scenario.

Just recently researchers have used genetic clocks to pinpoint the timing when a group of methanogenic bacteria first acquired this trait to produce methane - and it falls just about bang on the end Permian time.

Methanosarcina- Role in the Permian Triassic extinction event

It looks like the isotope patterns favour this source of atmospheric carbon, over the volcanic one. The Siberian Traps, however, may have been the source of important elements, like nickel, allowing for Methanosarcina to bloom massively.

The long hot tail of global warming - new thinking on the Eocene greenhouse climate

howardlee at 05:23 AM on 14 October, 2014

MA Rodger - the accelleration of the Indian Plate seems to have been due to the interaction with the Reunion-Deccan mantle plume which pushed the Indian plate faster for a while. The Indian lithosphere is indeed fairly thin probably due to it's encounter with the plume. The traps are the result of enormous flood basalt eruptions, in common with other traps like the Siberian Traps, which are also associated with abrupt climate change.

So the speed of motion is not due to the thin crust, but both are due to the interaction of the Indian Plate with the Reunion-Deccan Mantle Plume.

Toward Improved Discussions of Methane & Climate

Leland Palmer at 01:25 AM on 23 July, 2014

I do hope that Skeptical Science will revisit this issue. Flood basalt erruptions and release of methane from the methane hydrates seems to be intimately connected, according to the carbon isotope excursions that coincide with a long list of extinction events. This list of flood basalt erruptions, many with coincident carbon isotope excursions corresponding to trillions of tons of methane hydrate dissociation, is from the authors' reply to a more recent article Rapid climate change more deadly in Earth's past than asteroid impacts, study shows. Note that ma= millions of years ago.

Yes we see a pattern of such events. Here's a list grabbed from a couple of papers - note that the dating of some of the events is better than others. The coincidence of LIP and Mass Extinction/Climate event is strongest where the latest high-precision dating has been applied (Permian, Triassic, Mid-Cambrian).
LIP event /extinction or climate event:
Columba River 17ma (Mid Miocene Climate Optimum)
Yemen/Afar 31ma (none?)
North Atlantic 62/56ma ?PETM/Hyperthermals?
Deccan Traps 66ma (Cretaceous extinction precursor)
Sierra Leone 70ma (?)
Caribbean 90ma (Cenomanian/Turonian Anoxic Event);
Madagascar 90Ma (ditto)
Hess Rise 100ma (?)
SE Africa/Maud/Georgia 100ma (?)
Kerguelen 120ma (?Aptian)
Ontong Java 122ma (Aptian Anoxic Event);
High Arctic LIP 130ma
Parana-Etendeka 132ma
Shatsky Rise 145ma
Karoo-Ferrar-Dronning Maud Land 183ma (Toarcian OAE)
Central Atlantic 201 (Triassic Mass Extinction)
Angayucham 210ma (?)
Siberian Traps 252ma (Permian Mass Extinction)
Emeishan traps 260ma (end Guadaloupian extinction)
Tarim 280ma (none?)
Skagerrak- Barguzin–Vitim - Carboniferous Rainforest Collapse (Moscovian and Kasimovian stages);
Viluy - End Tournasian;
Pripyat–Dniepr–Donets - End Famennian–end Frasnian;
Kola/Kontogero - End Frasnian;
Altay–Sayan - End Silurian (?);
Ogcheon S Korea - End Ordovician?;
Central Asian intraplate magmatism - End Late Cambrian;
Kalkarindji - End Early Cambrian;
Volyn - End Ediacaran;

Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.

howardlee at 02:02 AM on 30 May, 2014

Leland @24 from the Jourdan et al paper: "the Stage 4–5 transition is associated with a global sea-level rise and negative δ13C and positive δ34S excursions recorded in stratigraphic sections worldwide (e.g., Montañez et al., 2000; Hough et al., 2006)." [stage 4-5 is the same time as Kalkarindji.]

Yes we see a pattern of such events. Here's a list grabbed from a couple of papers - note that the dating of some of the events is better than others. The coincidence of LIP and Mass Extinction/Climate event is strongest where the latest high-precision dating has been applied (Permian, Triassic, Mid-Cambrian).

LIP event /extinction or climate event:

Columba River 17ma (Mid Miocene Climate Optimum)
Yemen/Afar 31ma (none?)
North Atlantic 62/56ma ?PETM/Hyperthermals?
Deccan Traps 66ma (Cretaceous extinction precursor)
Sierra Leone 70ma (?)
Caribbean 90ma (Cenomanian/Turonian Anoxic Event);
Madagascar 90Ma (ditto)
Hess Rise 100ma (?)
SE Africa/Maud/Georgia 100ma (?)
Kerguelen 120ma (?Aptian)
Ontong Java 122ma (Aptian Anoxic Event);
High Arctic LIP 130ma
Parana-Etendeka 132ma
Shatsky Rise 145ma
Karoo-Ferrar-Dronning Maud Land 183ma (Toarcian OAE)
Central Atlantic 201 (Triassic Mass Extinction)
Angayucham 210ma (?)
Siberian Traps 252ma (Permian Mass Extinction)
Emeishan traps 260ma (end Guadaloupian extinction)
Tarim 280ma (none?)
Skagerrak- Barguzin–Vitim - Carboniferous Rainforest Collapse (Moscovian and Kasimovian stages);
Viluy - End Tournasian;
Pripyat–Dniepr–Donets - End Famennian–end Frasnian;
Kola/Kontogero - End Frasnian;
Altay–Sayan - End Silurian (?);
Ogcheon S Korea - End Ordovician?;
Central Asian intraplate magmatism - End Late Cambrian;
Kalkarindji - End Early Cambrian;
Volyn - End Ediacaran;

(From Kravchinsky 2012 & Bryan and Ferrari 2013) ma= million years ago.

Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.

howardlee at 00:06 AM on 29 May, 2014

Climatelurker - It''s clear that some LIP events have been associated with severe extinctions and others have had more mild extinctions. The Emeishan LIP that occurred just before the Siberian Traps generated global warming and an extinction event much less severe than the Siberian Traps did.

That some LIPs have more severe effects on life than others is a puzzle. It probably relates to eruption rate, presence/absence of organics in the sediments at the LIP location, and other random things. As the authors of one paper noted: "...larger eruptions of flood basalts which clearly had no effect on global ecosystems (e.g. Tarim). The reason why some LIPs are contemporaneous with mass extinctions could be related to random conditions which cannot easily be predicted such as: parental magma composition, geographic location, composition of country rock, or vulnerability of species."

Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.

howardlee at 23:49 PM on 28 May, 2014

Villabolo - you are correct for the Kalkarindji LIP - the authors mention oil specifically. In the Permian Siberian Traps LIP it looks like it was mainly coal. In this generalized figure I used "fossil fuels" as a collective noun and to make clear the parallels between the past and today's climate change. In all cases the heat from the magma baked the organic-rich sediments converting them to methane and CO2 (with a host of other nasties mixed in).

The consequences of climate change (in our lifetimes)

Rob Honeycutt at 08:51 AM on 18 April, 2014

Harry Twinotter... I don't want to give any credence to the boiling oceans idea, but I don't believe the earth has had similar conditions as today. This is specifically because the rate at which we're introducing CO2 into the atmosphere is greater than even the Siberian Traps could have achieved.

I would also add that, eventually the oceans on earth will boil away. It's just not likely to be because of human carbon emissions.

4 Hiroshima bombs worth of heat per second

johncl at 01:44 AM on 3 July, 2013

I do believe that many of us convinced in the seriousness of AGW really is trying to figure out how we can explain this to people so they are able to act upon it. Its really one of humanities biggest challenges, one that could have consequences on a planetary scale if not handled in time. Many believe we are really running of out of time. Talking about CO2 emission cuts of a certain % by 2050 isnt going to cut it. What is needed is for people to wake up and understand that our CO2 emissions through our addiction to fossil fuel burning is really turning up the thermostat of the planet causing a shift that the planet likely only have experienced in rather more cataclysmic events like the big siberian traps vulcanism or asteroide impact. The data shows a dramatic concentration of CO2 in both the air and seas at rates 10x past extinction events. I think its really cause for concern even though we dont really see the big consequences right this second. A tipping point can be passed (and most likely several have been passed now with the Arctic melting fast) where the changes happen so fast that global average temperatures could rise rapidly.

I do believe there is enough evidence now that the planet is absorbing more of the suns energy than it has in the past, and that this amount is significant even on a planetary scale (some are trying to make the 4 abombs per second sound like a small number, just like CO2 is only a small part of the atmosphere - this is a dangerous way of thinking - it only takes 0.25g of arsenic to kill a person). Looking at the broad picture, its really fantastic that life even exists on the planet, and while humans might feel like small gods wielding the power of fossil fuels, we really are quite insignificant and vulnurable, like all living things on this planet. I do believe we should treat our lucky position in this galaxy with some respect and at least acknowledge what we have discovered about simple physics. Sometimes one does not need proof in order to know something is right, if I fall out of a 10 story building, I will likely die - but I dont really need to watch someone fall to their death to understand this is a physical fact. The same way we do know CO2 is a greenhouse gas and that it traps heat. Glenn Tamblyn's line of reasoning perfectly explains a valid reason for the extra heat stored and I my opinion it shouldnt be hard for people to grasp this if they are willing to listen.

Cheers

(Fahrenheit) 451 ppm

pixelDust at 13:11 PM on 12 December, 2011

For me, the biggest fear has been that we're duplicating the conditions that led to the Permian Extinction Event:

Smoking Gun: Greatest Extinction in History was a Volcanic, Coal fired, Greenhouse Event

Sphaerica, how would that fit in with your analysis here? Are the Siberian Traps eruptions the closest natural analogy to modern fossil fuel combustion? If so, assuming worst-case scenarios (human CO2 emissions continuing to grow, Arctic belching methane at an ever-increasing rate, natural carbon sinks overwhelmed or turning to carbon source, etc), how soon could a new, Permian-esque mass extinction start?

_{Apologies for lack of scientific precision in my question; I'm coming at this issue from a layperson's perspective}

Geologists and climate change denial

Tor B at 00:03 AM on 10 June, 2011

Geologists (and others) should watch Richard Alley’s 2009 American Geophysical Union (AGU) lecture on CO2 and climate change over geologic time.

As a student of hard rock geology (BS & MS) in the 70s and early 80s, I learned virtually nothing about paleoclimatology, even as paleoecology was the only part of paleontology that interested me. My relevant climate science education really started a couple of years ago when I intentionally read about how and why CO2 is a greenhouse gas, really basic physical chemistry, I’m embarrassed to admit. I wanted to understand why “some people” were saying “AGW”.

A significant event in Phanerozoic time that may have caused climate to change as rapidly as it is now changing is when the Siberian traps poured out at the end of the Permian. Try Stephen E. Grasby, et. al.’s hypothesis on Catastrophic dispersion of coal fly ash into oceans during the latest Permian extinction or an article based on it titled Massive volcanic eruptions + coal fires = the Great Dying.

Christy Crock #3: Internal Variability

Rob Honeycutt at 04:08 AM on 15 April, 2011

Jay @ 55... Yes. Absolutely. Life can exist, and has existed, in much warmer climates than today. Everyone understands that. But go back and look at the Siberian Traps. Rapid changes in global climate have disastrous results on the existing life of that time.

I always like to say: You know, the planet is going to be just fine. It's going to still be here in a million years, and in a billion years, and several billion years beyond that. Survival of the human species has nothing to do with survival of the planet.

The Earth's Sixth Mass Extinction May Be Underway

idunno at 19:32 PM on 13 March, 2011

Hi all,

I am posting in support of Agnostic@47. I recommend rereading that post rather than this. This is just a footnote.

We are all aware that the surface Arctic Sea Ice is disappearing.

As the surface sea ice disappears, the heat accumulating in the ocean has to do something.

It is quite likely to begin to melt the seabed. This is composed of sea water that has frozen in the presence of an abundance of methane. When it freezes, it the water traps the methane in a chemical lattice. This substance is called a methane clathrate.

When surface sea ice melts, 1 litre of frozen water (ice) becomes one litre of liquid water. This matters in various ways that are discussed all over the net...

When the frozen seabed melts, 1 litre of frozen seabed releases 0.8 litres of liquid water, and 168 litres of methane.

For "litre" substitute "cubic kilometre" in the sentence above, and you are then staring at the scale of this problem.

I should note that, b-----r the greenhouse effect of methane. It is a poisonous gas, and explosive.

Furthermore, if the East Siberian shelf does begin to melt, it is very possible that there are very very large, very shallow deposits of gaseous methane which have been capped for some millenia by the solid methane clathrates above them.

Should any one of these gas fields collapse, and vent into the atmosphere then:

1. there would be some danger of the atmosphere becoming anoxic for the purposes of mammalian respiration;

2. there would be a near certainty of an Arctic ocean tsunami, which would be highly likely to cause much more extensive damage to the sea bed...

For any Republicans on here who are now delighted to learn that their vehicles will shortly be working better due to a greater level of methane in the atmosphere, I should perhaps point out that the infernal combustion engine also requires an abundant intake of oxygen to work at maximum efficiency...

The Earth's Sixth Mass Extinction May Be Underway

littlerobbergirl at 02:01 AM on 10 March, 2011

oops 'nutrient' cycling web.

dana, it's possible all the extinctions are down to co2, even the impact(s);
the deccan traps were opposite the k/t impact site, and there seems to be a depression in eastern antarctica that might be a truly huge crater directly opposite to where the siberian traps were at the time of the permian extinction.

Blaming the Pacific Decadal Oscillation

Timothy Chase at 12:51 PM on 7 March, 2011

I had written in 56:

We can't explain the warm interglacials and ice ages without the amplification due to carbon dioxide (which is released by the oceans when they warm like a warming soda losing its fizz but absorbed when the oceans cool), ice sheets (due to their melting and growth) and water vapor feedback.

RW1 responded in 61:

Sure we can. The glacial and interglacial periods in between are driven by changes in the Earth's orbit around the Sun, which in turn changes the distribution of the incoming solar energy immensely. This is enough to overcome what appears to be a very strong net negative feedback operating on the system. CO2 lags or follows these cycles - it does not coincide or precede them.

CO2 lags warming by no more than 1000 years, likely as the deep ocean gives up carbon. And when I stated that carbon dioxide (under these circumstances) is a feedback that implied a lag of sorts. The warming from a glacial to interglacial takes several thousand years. Therefore the carbon dioxide actually coincides with much of the warming. Which is why the curves appear to be almost on top of one-another.

Looking at just the warming due to solar insolation you can't explain the saw tooth structure of the temperature and CO2 trendlines. Things warm rapidly, with the warming period appearing to be perhaps 7000 or 8000 years. But the cooling takes perhaps 100,000 years. Orbital forcings can't explain why this asymmetric pattern appears time and time again. But the rapid decay and slow growth of ice sheets as well as the rapid degassing but slow absorption of carbon dioxide by the oceans and ultimately it minearlization can.

For the sawtooth structure please see Figure 1 here:

CO2 lags temperature - what does it mean?
http://www.skepticalscience.com/co2-lags-temperature-intermediate.htm

In the review article:

C. Lorius (13 Sept 1990) The ice-core record: climate sensitivity and future greenhouse warming, Nature, Vol 347

... Hansen and coauthors state:

The orbital forcing is, however, relatively weak when considered on an annual globally averaged basis (the total insolation received by Earth has varied by 0.7 W m^-2 over the past 160 kyr). The amplification of this forcing, the observed dominant 100-kyr cycle and the synchronized termination of the main glaciations and their similar amplitude in the Northern and Southern Hemispheres cannot easily be explained despite developments including the nonlinear response to ice sheets to orbital forcing.

Solar forcing is weak. You can't even explain the extent to which warming to place even when you include the nonlinear response of ice sheets. And you can't explain the synchronicity of the warming of both hemispheres. Both GCM studies and multivariate studies of paleoclimate data suggest that roughly 40% of the warming of the Antarctic from glacial to interglacial was due to the increase in CO2 from 200 to 300 ppmv. (See page 144.)

Furthermore, while recognizing that orbital forcing was responsible for the Milankovitch cycles, they predicted that through the analysis of upcoming ice core samples it would be possible to identify the lag time between the initial warming and the rise in carbon dioxide.

Please see:

This objective is part of the GRIP (Greenland Ice Core Project) and GISP II (Greenland Ice Sheet Project) now being conducted in north central Greenland by Eurpopean and American scientists. These dirllings are expected to reach the bedrock (ice thickness is 3.2 km) in 1992 and to cover the last climate cycle and hopefully more. These cores will allow further documentation of the rapid climate changes discussed here. With a snow accumulation higher than at Vostok they should also allow a better determination of the relative timing (phase lag) of climate and greenhouse forcing.

pg.145

But just as importantly there were times when carbon dioxide rose first.

The ice cores from Greenland and Antarctica have taken us back the better part of a million years now. During this time temperature always seems to rise first. However, if you look back further in the case of supervolcanoes and their flood basalt eruptions carbon dioxide rose first, then temperature.

Examples of where continental and submarine supervolcanoes gave rise to Large Igneous Provinces resulting in mass extinction include:

55 Mya, Paleocene-Eocene Thermal Maximum – North Atlantic Basalts
65 Mya, end-Cretaceous event resulting from a supervolcano that gave rise to the Deccan basalts in India as it collided with Asia at the time of the formation of the Himalayas
183 Mya, Toracian Turnover (a lesser warming and extinction event in the Early Jurassic period) – Karoo Basalts (Africa)
201 Mya, End Triassic Extinction – Central Atlantic Magmatic Province
251 Mya, Permian-Triassic Extinction that resulted from a supervolcano that left behind the Siberian basalts during the breakup of Pangaea.
360-375 Mya, Late Devonian Extinction – Viluy Traps (Eastern Siberia, more tentative according to Rampino below)

For a more extensive list, please see:

Vincent E. Courtillot and Paul R. Renne (2003) On the ages of ﬂood basalt events, C. R. Geoscience 335, 113–140

For a recent commentary:

Michael R. Rampino (April 13, 2010) Mass extinctions of life and catastrophic ﬂood basalt volcanism, PNAS, vol. 107, no. 15, pp. 6555-6556

Here is recent study showing that the eruption of the Central Atlantic Magmatic Province occured simultaneously with the end Triassic Extinction 201 Mya:

Jessica H. Whiteside (April 13, 2010) Compound-specific carbon isotopes from Earth's largest flood basalt eruptions directly linked to the end-Triassic mass extinction, PNAS, vol. 107, no. 15, pp 6721-6725

In recent times temperature generally rose first. But if you look further back, in some cases carbon dioxide rose first, then temperature. And those times that carbon dioxide rose first are strongly associated with sudden changes in climate and the resulting major and minor extinction events.

Animals and plants can adapt

Karamanski at 14:16 PM on 2 February, 2011

Hydrogen sulfide is thought to have been a major player in the Permian mass extinction 250 million years ago, because CO2 emissions from the Siberian Traps warmed the atmosphere and oceans, causing the oceans to lose oxygen. With less oxygen, the anaerobic bacteria produce hydrogen sulfide that spreads through the ocean and into the atmosphere and poisons most of the animals on the planet. When we hear about the potentially dire consequences of global warming, why don't we ever hear about hydrogen sulfide emissions from the warming oceans as a result of decreasing oxygen?

Positive feedback means runaway warming

Leland Palmer at 08:41 AM on 2 January, 2011

Thanks, muoncounter, it's a very interesting paper.

Glaciations tend to start gradually, but end abruptly.

Various people, referenced in the your paper and the Wikipedia article on the clathrate gun hypothesis, suspect that lower sea levels during those glaciations can cause pressure induced release of methane from hydrates, rapidly increasing atmospheric methane levels leading to an increase in temperatures and higher sea levels.

If true, this does demonstrate one thing: large scale methane releases from oceanic hydrates can reach the atmosphere.

This is supported by the carbon isotope data from events like the PETM and the End Permian- although direct intrusion of magma from the Siberian Traps volcanism into methane hydrate deposits may have been necessary to trigger the End Permian mass extinction.
These carbon isotope data suggest that two to five or more trillion tons of isotopically light methane from the hydrates entered the active carbon cycle during those events.

Can our greenhouse driven pulse of heat, which is working its way inexorably downward into the oceans, stimulate a similar rapid release of methane?

It's cosmic rays

LizR at 06:15 AM on 23 December, 2010

Den siste mohikanen said:

"For sure, neither the sun nor CO2 nor the two together make up for the only climate forcing. So your argument is a bit weak by itself, but even if we assume that all the unexplained difference is due to CO2, that doesn't give as much room for IPCCs +6°C forecast that you seem to imply."

This is only true if there are no "tipping points" involved. However, if the current temperature rise is sufficient to bring trapped methane out of solution in the oceans, permafrost, clathrates etc, then there could be a feedback effect. Or there are other possibilities that could have the same effect.

Here is a comment from Michael Benton, a paleontologist at Bristol University. He says that evidence points to the cause of the Permian extinction being prolonged and violent eruptions from the Siberian traps, a huge region of volcanic rock. In this scenario, mass eruptions triggered environmental catastrophe by belching an overwhelming quantity of gas into the atmosphere for half a million years.

"The main follow on was a flash warming of the Earth. That caused stagnation in the oceans, as normal circulation shut down. On land, the consequence of all the carbon dioxide and other gases appears to have been massive acid rain that killed the forests and stripped the landscape bare," Benton said. "This was the greatest of all mass extinctions, the time when life was most nearly completely wiped out."

Positive feedback means runaway warming

Leland Palmer at 01:14 AM on 5 December, 2010

Wow, thanks for the quick and thoughtful response.

Any thoughtful person would be thankful to be wrong about such a scenario, of course.

The fact that we are coming out of an ice age, and starting from a cooler starting point might not save us from such a scenario, though. Our methane hydrate deposits are in equilibrium at ice age temperatures.

The speed at which we are introducing CO2 is absolutely unprecedented, so far as I know. Also, the forcing from fossil fuel use is entirely non-random, unlike most past naturally occurring events. So, our methane hydrates could be particularly susceptible to disruption, and have had no chance to gradually lose methane, and have it safely oxidized into CO2 and sequestered via the rock weathering cycle over many thousands of years.

Yes, there were warmer periods in the past, but we may have gotten to those warmer periods in a safer manner, more gradually, allowing harmless oxidation of methane at reasonable rates.

The permafrost decay positive feedback is a similar concern. If this permafrost loses its frozen plant matter to decay into CO2 and methane gradually, there is no problem. If the accumulated frozen plant matter from thousands of years of ice age conditions decays within a century, though, this might add to warming in an unprecedented manner.

The yedoma and thermokarst of Siberia are a similar concern. These ice age accumulations of methane and methane hydrate could also be susceptible to anomalously rapid dissociation.

The PETM is worrisome, but the event that really worries me is the End Permian. As you point out, the PETM was nasty, but the End Permian mass extinction was the big one, extinguishing on the order of 90 percent of species existing at that time. Direct intrusion of the Siberian Traps volcanism into methane hydrate deposits may have been necessary to cause that one, but we don't know this for sure, so far as I know.

So, I worry that our "clathrate gun" and associated ice age relics might be cocked and loaded, so to speak.

Some things that might save us, as you point out, are the logarithmic nature of the greenhouse effects from the various greenhouse gases, and the diminishing returns positive feedback phenomenon. Also in favor of stability are the endothermic nature of methane hydrate dissociation, and the Planck radiation feedback.

One thing that really worries me is the unpredictable nature of positive feedback phenomena. I frankly doubt the ability of anyone to predict the outcome of such a complex interlocked series of positive and negative feedbacks. If anyone could do it, it would be someone like Hansen- and Hansen is worried, too.

Another thing that worries me is that estimates of the total quantity of methane hydrates differ by at least an order of magnitude.

The sun is a couple of percent hotter than it was during the PETM, but several percent hotter than during the End Permian, I think.

If we take the End Permian event, and add in a more rapid triggering event, a buildup of ice age methane hydrates, and a sun that is five percent or so hotter, what do we end up with?

Ocean acidification threatens entire marine food chains

Ned at 22:34 PM on 28 August, 2010

thingadonta writes: A volcanic event such as a flood basalt event associated with a emerging hotspot or Siberian Traps event exceeds rate and magnitude of human C02.

From Saunders 2009:

However, if we consider the province as a whole, the eruption of between 2×10^6 and 3×10^6 km3 of basalt could release 12000 to 18000 Gt of C, enough to significantly change the carbon content of even a Permian atmosphere. Note that the eruption of 18000 Gt of C over 1 million years equates to only 0.018 Gt per year, a fraction of the current output from burning of fossil fuels (~ 7 Gt C/a).

There's lots of other useful information in Saunders 2009, if you're interested in flood basalt episodes.

Ocean acidification threatens entire marine food chains

Rob Painting at 21:39 PM on 28 August, 2010

Thingadonta @ 18 - " I dont think so. A volcanic event such as a flood basalt event associated with a emerging hotspot or Siberian Traps event exceeds rate and magnitude of human C02."

That's simply your non expert opinion, not supporting evidence. Read the study I linked, it actually addresses such issues.

Ocean acidification threatens entire marine food chains

thingadonta at 21:29 PM on 28 August, 2010

#16: dappledwater

"...rate of CO2 release that makes the current great experiment so geologically unusual, and quite probably unprecedented in Earth history. "

I dont think so. A volcanic event such as a flood basalt event associated with a emerging hotspot or Siberian Traps event exceeds rate and magnitude of human C02.

Volcanic events such as the Siberian Traps emitted more c02 than humans ever will. Oceans did not acidify for tens of thousnds of years from this kind of output, in both rate nor magnitude greaer than human c02 emissions, so they wont acidify from human emissions of c02 on short time scales.

The geological record indicates that these sort of amounts of c02 are buffered in the oceans-which is why oceans take a long time to acidify. Some researches acknowledge this but twist this around and say such and such rates of acifidication haven't happened in such and such million years; this actually provides good evidence that the oceans are buffered.

#15

Boba10960

There is a vast and dynamic interplay between c02/c03 and the ocean subsurface. Most limestone in the world is in fact formed as a result of precipitation of c03 from ocean waters, and not from coral reefs. How his actually occurs/rate has been a matter of debate for decades.

An example is the dolomites in Italy, which is the type area for dolomite rock. Tese formed from ocean precipitation.

Currently I am engaged (along with other work) in analysing/reviewing thousands of metres of carbonate-enriched sediments formed close to the ocean/subsurface interface. These sort of carbonate- saturated sediments are everywhere. The interface of c03/c02 in eg volcanic realms extends thousands of metres beneath the sea floor, eg along much of the Mid Ocean Ridge system.

One question: has David Archer and the IPCC, along with coral reef researchers, factored in the thousands of metres of c03/c02 interaction/interface along all the world's ocean ridges?

I bet the answer is, they haven't.

(Note: some NASA sceintists think the world's ocean water comes from comets-they know nothing about crustal geology and how granites expel water when they cool-which is how the world's oceans formed when the earths crust first cooled; the point is they are ignorant of what goes on in the subsurface.

Couldn't coral reef researchers be making the same sort of mistake?)

How Jo Nova doesn't get past climate change

thingadonta at 21:47 PM on 23 June, 2010

The paper by Beerling et al 2002 calculates an increase in c02 at the K-T boundary, and then infers a large amount of short term warming (~7.5degrees) by this increase. As such, it doesn't provide any direct evidence of short-term warming, all of the supposed warming is modelled.

In your description of the end of the K-T, you completely leave out the Deccan Traps Volcanics, in order to come to the conclusion that T rises, and other associated effects were short term. The Deccan Traps volcanic episode is probably the largest series of long term volcanic eruptions in the last 65 million + years (I'll have to check it with the age of the basalt province in the West Pacific oceanic basin), about the time Inida separated from Africa (?). Beerling et al 2002, concludes that modelling of the Deccan Traps fails to account for an inferred large c02 rise at the end of the K-T. In other words, modelling, by non volcanologists, fails to account for an inferred C02 rise, which then fails to account for an inferred T rise. It's therefore so much easier just to leave out the major causative factor in the demise of 75% of the world's species about the K-T boundary-volcanism, which even Tim Flannery points out that the major extinction rates from the bolide impact only occurred about the North America continent, not globally. The rest of the extinctions, over a longer time period, were largely caused by Deccan Traps volcanism, much the same as at the End Permian (Siberian Traps Volcanism), when there was also, no bolide impact. Volcanoes are the major culprite in both extinction events, and both caused major c02 rises, and major T rises, over very long, not short, time periods.

The evidence of the very long time (millions of years +)periods involved with eg hanges in T, which you fail to mention or discuss, is provided by: eg long term deposition of red beds at both the K-T and End Permian periods (and also the end Triassic as well-Gondwana break up volcanism-eg Karoo red beds), which occurred over intervals spanning at least several million years, which therefore can't relate to short term c02 rises. The red beds indicate hot house conditions of several million years, even about the poles, as a direct result of extensive volcanic episodes, not short term bolide impacts, and associated short term c02 rises.

How climate skeptics mislead

Rob Honeycutt at 14:09 PM on 16 June, 2010

johnd said... The misleading part comes about by declaring that these are signs of AGW and dismissing that they may be due to natural warming.

I'm sorry but I have to take exception to this. If we look at almost any combination of proxy temp records of the past few thousand to million years I think it becomes obvious that something is extremely different now. I fail to see how such a dramatic change in temp could occur naturally. It "may" be natural but that is an extremely small possibility because if it were natural one would expect that we would be just as dramatically aware of the natural cause. The Siberian Traps have not reasserted themselves last I heard.

What we do face is the reality that humans and technology have dramatically changed over the past 150 years.

The significance of past climate change

thingadonta at 21:50 PM on 21 April, 2010

I agree with pretty much all of what you say above except for one major point-the issue of the time scales involved.

The past geological record indicates that changes on a global scale are invariably very slow. We're talking tens of thousands, to hundreds of thousands and even millions of years in the vast majority of cases. For something like acidification of global oceans by volcanoes, and indeed the majority of mass extinction events (except in rare cases of eg bolide impacts), that is the sort of time frame the geological record indicates is invariably required.

To take a few examples, the output of greenhouse and other gases by Siberian Traps volcanism at the end of the Permian occurred on a major scale over several hundred thousand to several million years, and that is how long it took to cause major climate changes such as (possibly) acidifying the oceans, the collapse of coral reef ecosystems, and mass extinction. It was not a ‘rapid process’ when compared to the scale of human lifetimes. The break-up of the Gondwana supercontinent is likely implicated in eg the Mid-End Triassic mass extinction-continents do not break up 'rapidly'. This occurred over millions of years - with possible stress-related tipping points etc, as rift-related volcanism increased over very long time periods. Many other examples from the geological record indicate much the same thing, (eg oceans don't ‘acidify’ within short human timescales when similar amounts of c02 have been added to the atmosphere in the sort of time scales involved as is currently the case).

This is also the major reason people such as the gradualist Charles Darwin were so skeptical of the presence of 'mass extinction' events in the geological record in the first place, and also I suspect why the person on the street is with current climate change and the extreme predictions around it as well. It's like worrying about continental drift changing the climate within this century.

This is one of the major skeptical arguments, that major global changes such as those predicted by the IPCC to occur within the next century by human emissions of greenhouse gases will NOT occur, not so much because the concepts and theory is wrong, but because the scale of time involved is far too short, and that the geological record provides very good support for this contention. Academics and other pro AGW advocates get the concepts largely right, but get the time scales involved largely wrong.

Earth's five mass extinction events

Philippe Chantreau at 04:32 AM on 18 April, 2010

As for the volcanic CO2, that should also be put in context. Currently, anthropogenic emissions are approximately 150 times larger than volcanic. So, from the CO2 change point of view, we are mimicking periods when volcanic activity was 150 times greater than now. To be honest, I don't really know how it would compare to the Dekkan traps or Siberian traps but that would still be rather impressive. I don't know what kind of oceanic "high resistance to pH change" it would take for that to go unnoticed.

Earth's five mass extinction events

thingadonta at 16:17 PM on 17 April, 2010

#45 Chris:

The extinctions you refer to are not 'rapid' (KT/ POTM). They occur over tens of thousands or years+. This is the main issue, and why papers such as Veron are wrong/misleading.

Verons article on 'coral reef crisis' is an exercise in exageration. Have a look at his language designed to produce the greatest exageration possible:
"degraded water-quality and increased severe weather events." Both not true. Severe weather has not increased. When reefs are impacted by severe weather, they always recover, you would think they have evolved to, after millions of years of 'severe weather'. Opportunistc species rebuild them, as in after volcanic eruptions in the Pacific, Krakatoa etc.

"other environmental impacts." ie if you run out of enough 'disaster' words, just say 'other environmental impacts', that way you don't have to explain it.

"Perhaps most importantly, there is no evidence that reefs have ever experienced true parallels to today’s anthropogenically-driven combination of stressors." Baloney. End Permian, end K/T, POTM. All 3 took tens of thousands of years. All 3 worse than now. Veron wants us to believe that puny humans can outbeat the Siberian Traps several hundred thousand years of explosive volcanism.

His statement that we have lost 19% of reef since 1970 is a gross distortion. (We should get Macintyre and Lomborg onto these coral reef exagerators). What's more, if temperatures have risen, this promotes coral reef growth at the margins of their range: eg Southern Barrier reef etc, I know this partly becuase I studied this area and this issue in my honours thesis.

Nowhere does he mention that the ocean has buffering mechanisms which cannot be easily reproduced in the laboratory, and which make oceans VERY resistant to rapid chemical change, as the geological record shows (which is why it takes tens of thousands of years to change them and for marine species to go extinct in geological time periods). Veron completely ignores this, because it is in his interest to promote as much 'quick catastrophism' as possible.

Mass coral bleachings are a natural event that occured before the 1970s, there is 'little record of it' before this because no one was looking. Communities in the Pacific have recorded it for hundreds/thousands of years.

"The 1997/1998 mass bleaching event killed approximately 16% of coral communities globally (Berkelmans and Oliver, 1999; Wilkinson,
2004). It was also the start of a decline from which there has been no significant long-term recovery." Incorrect, corals are used to such events, it occurs seasonally all the time including at the margin of their range, and they get over it all the time, Veron does not.

The article link by Caldera shows he doens't know much about the K/T exinction. He doesnt even mention the delcine of marine organisms from well before Chicxulub about 70Ma. He doesnt mention the Decaan Traps either, and yet this were the major cause of the maine extinctdions (not the impact), the bolide impact was too short to produce long lasting marine effects.

He also mentions that the earth was warmer in the Cretaceous because volanoes were spewing out more c02. But I thought volcanic c02 was so minor as to be irrelevant? So it's only important when convenient. IE Volcanoes can change climate on long time scales, but not short ones, humans can change climate on short time scales, but they cant take a geological long time to do it, even though volcanoes have to. (Somebody tell the volcanos because they arent listening).

If Veron and co. are the measure of 'well informed scientists' regarding the next announcement of impending doom, then I don't think we have much to worry about.

Earth's five mass extinction events

thingadonta at 19:02 PM on 16 April, 2010

A few points:
re 39 Steve L.
"I think you are misinterpreting #35. Or maybe I am. It seems that #35 says that less total CO2 released, but released quickly over a short period of time, cannot have a similar impact as a lot of CO2 released over a longer time period. I believe this is wrong. "

I am skeptical when you want to change an entire ocean's chemistry in less than tens of thousands of years, taking the geoligical record as a starting point. This is how long the geological record generally says it takes, even under extreme scenarios. So I dont know how pro AGW people use the past geological record to scare us abvout short human lifetimes. It's like a biologist scaring us about our rate of speciation.

This is one of the main skeptic arguments -ie the time it takes to change the oceans, warm the planet etc etc (add it to the list), and is similar to the arguments in palaeontology and biology over gradual evolution versus punctuated equilibrium. That is, how fast is 'rapid/punctuated' versus 'gradual' when you are referring to geological time periods? It's a question of semantics really, eveyone agrees that the rate of evolution can change, but gradualists are very skeptical of any 'jumps' or 'jerks' or 'rapid' rate changes. (It also harks back to the days of the catastrophists and the uniformitarians in the 19th century -Darwin was a a uniformatirian and got it wrong with regards to 'mass extinction' events (he thought they were just gaps in the fossil record), Cuvier was a catastrophist- like nearly all pro-AGW people, and got it right with to mass extinction events).

But as for mass extinctions, we are talking in most cases, of hundreds of thousands of years. Skeptics, therfore, contend that for somnething like ocean acidification by C02, it will take about that long to do it, which makes current humnan activities regarding ocean acidification, irrelevant. We can never release the kind of amount of gases that Siberian and Decaan Traps volcanism can do over several hundred thousand years in order to change ocean chemistry. Skeptics contend that various pro AGW researchers have vastly ignored and downplayed the time periods involved with most mass extiction events, and exagerated their own figures to scare people (like Jones with Siberian temperature data). Skeptics also contend that by the time the ocean acidifies (if it does at all, it is well buffered in many other respects in its interactions with volcanoes, sediments, Mid oceanic ridges etc etc?) from human c02, say in about 10,000++ years
(?), we will have long ago given up our reliance on fossil fuels. (If this figure seems way too long, that is what is usually meant by 'geologically rapid', conveniently distorted by some coral reef researchers).

As for K/T and #34,
bolide impact pushed species over the edge after Decaan Traps volcanism had already weakened many ecosystems and which had begun several hundred thousand years earlier. Species were already in decline, especially marine species. This is well established. It was not one or the other (volcanism or bolide impact), it was both.

re #32
The Chicxulub impact did not cause Decaan Traps volcanism, becuase it was already well underway (several hundred thousand years) before the asteriod/comet hit Mexico. Species were in decline already for about the previous few million years (including the dinosaurs-have a look at eg the "Walking With Dinosaurs" series-this is well established in peer reviewed literature, volcanic gases/effects were already killing the eg dinosaurs before they were pushed over the edge to oblivion by the asteroid. It was a one-two punch, which is why it was such a major extinction event).

You can understand it this way, mass extinctions are by nature worse when a combination of factors are involved. There have been many large impacts in earth hoistory with no mass extinctions.

re#36
"Accelerated release is not contingent upon causation being either "natural" or "human induced". What matters is the chemistry/physics. "

What matters is the time periods involved. Mass extinction events take hundreds of thousands of years to change the chemistry of the oceans. Ask a volcanologist (which is one reason why Plimer is such a skeptic-one of his pet topics is volcanology-and he is more informed about what they do to oceans, as Veron is not).

If someone wants to counter most of the above, they have to show how the past geological record shows the oceans can acidify in a few hundred years from changes in c02 levels. As far as I know, it says no such thing.

Earth's five mass extinction events

watchingthedeniers at 17:07 PM on 16 April, 2010

@ 39

I may have misinterpreted. Here is the para I focused on:

"But my point is, all this took hundreds of thousands- to millions of years of vast amounts of c02 etc from Siberian Traps volcanism-oceans didn't,and probably won't, acidify quickly-ie less than tens of thousands of years?, if they do from humans at all."

I read that to imply he/she questioned how human activity could result in acidification. He posits time periods and natural processes and contrasts (by implication) possible human interactions with the climate. That's how I read it.

(see last sentence)

It could be we are *both* reading the different things into the post because the argument is muddled and attempting to argue both points?

Earth's five mass extinction events

thingadonta at 10:50 AM on 16 April, 2010

#23 Steve RL.

"So apparently conditions not conducive to coraline growth (low pH) persisted". IE for ~10Ma.

In the case of coals, there is a 'coal gap' between 250 Ma to ~240 Ma, the plant species that produced most of the coal in The Late Permian went extinct at the end of the Permian and had to re-evolve-, so there is virtually no coal on the East Coast of Australia from about 250-240Ma(ie from the Sydney-Bowen Basin-which royalties pays a reasonable proportion of East Coast academic salaries-you don't hear much appreciation though).

Coal produced after 240Ma was from different plant species than previously, you also get a lot of red beds at this time indicating hothouse conditions.

But my point is, all this took hundreds of thousands- to millions of years of vast amounts of c02 etc from Siberian Traps volcanism-oceans didnt,and probably won't, acidify quickly-ie less than tens of thousands of years?, if they do from humans at all.

Earth's five mass extinction events

thingadonta at 10:39 AM on 16 April, 2010

Thanksfor the link paper,

One question before I may respond more fully (I am in the remote field at the moment using VSAT satellite collecting real data in the real world, and not making up pretty coloured models on a computer screen, and of course, who am I having to deal with right now, people using pretty coloured maps on a computer screen which are wrong and exagerated and which I am fixing in the field with real data, but I digress). my question:

-the Siberian Traps ejected vast volumes of eg c02 over several hundred throusand years+, and it took coral reefs to collapse over hundreds of thouands of years (and possibly, oceans to acidify-although this is not clear) hso how can less amounts of c02 from humans acidiy the oceans in a few decades-hundreds of years??

Earth's five mass extinction events

Philippe Chantreau at 09:02 AM on 16 April, 2010

There is new research suggesting that the major factor in the Cretaceous extinction was the Chixculub impact, not the Deccan volcanoes. I'm trying to find the Science article mentioned here: LINK

I recall reading that bolide impacts could also be triggers for the kind of activity that left behind the Dekkan Traps and Siberian Traps, but can't find the reference at the moment. In any case, things must be considered in context. The pressure of Human activity and the size of the population alone are enough to drive numerous species to extinction. Rapid environmental changes happening at the same time won't help.

Earth's five mass extinction events

thingadonta at 20:53 PM on 15 April, 2010

You and Veron (2008) are inferring rapid C02 changes and ocean acidifications at mass extinction periods by looking at coral reef extinctions. This inference has little/no evidence to support it, other than circumstantial.

Corals reef extinctions and coral reef 'absences' in the fossil record occur for other reasons than by rapid C02 changes and inferred ocean acidification.

"Throughout Earth's history, there have been periods where climate changed dramatically" Wrong/selective.

Most mass extinction events occurred in geological times of tens of thousands of years. This is not what is generally meant by "change dramatically".

Your point 2 above should say 75 million years later, not "ago". This Later Devonian event didn’t 'turn hostile’; it was a slow process, with multiple waves, that occurred over millions of years.

The Mass extinction at the end of the Permian was caused by cascading factors that occurred over several hundred thousand to a few million years, related to Siberian Traps volcanism. Most genera took about 10 Ma years to recover, the corals were not in any way special.

The End Triassic mass extinction (I think it is actually Mid Triassic) was associated with Gondawana continental breakup and injection of vast rift-related volcanism in South America, Australia, South Africa and Antarctica. Most of the hard rock aggregate on the East Coast of Australia, the towering cliffs in Tasmania, South America and so on are associated with this. It was volcanic, and slow, like most mass extinctions.

The End Cretaceous was associated with Deccan Traps volcanism in India (not long after it separated from Africa) and bolide impact. This is the only certain mass extinction event associated with bolide impact, but volcanism played a major part as well (a one two punch).

“The fossil record shows coral extinction occurred over much longer periods." This is because it was a result of slow, gradual, volcanically active periods. They were not periods of 'quickly changing atmospheric c02'. They were periods of slow increases in volcanism.

Veron is not a volcanologist. Neither was Alvarez, who rejected both the stratigraphers and the volcanologists who informed him his bolide impact theory in 1980 at the K/T boundary wasn't all that was going on at the time. Time proved the volcanologists right, and as usual, the physicists who like to dabble in earth history got it wrong eg:
• Kelvin and the age of the earth early 1900s, when stratigraphers told him the earth was much older than his calculations-he wouldn’t listen ;
• the geophysicists and other non-earth physicists -including Albert Einstein-who rejected plate tectonics in the 1920s-1950s - the stratigraphers told them the rocks proved the continents moved well before plate tectonics was discovered,
• Alvalrez and bolide impact 1980s, and
• John Cook solar physicist 2008- now inferring mass extinctions of corals were rapid and associated largely with rapid c02 changes, I suspect most volcanologists would say this is a gross oversimplification, or at worst invalid.

There is little/no evidence that slow volcanic processes were associated with inferred ocean acidifications, and corresponding reef extinctions. The reefs went extinct, like most other things, because of slow sea level changes (there is good correlation betwen sea level changes and marine extinctions), changes in volcanism (producing a variety of slow effects-again a very good correlation, but importantly-generally not with C02 changes), bolide impacts (really the only one that is 'rapid'), continental break ups (eg Triassic), continental joinings (well known to reduce biodiversity as previously separate and endemic species compete with and then extinguish each other), and many other factors. C02 change is slow, doesn’t follow these other factors or most mass exticntions, and plays a relatively minor part in the history of the earth.
You're selective references to the vast peer reviewed literature on mass extinctions does not give readers the full picture of the state of understanding and history of debate in this field.

New observations find underwater Arctic Shelf is perforated and venting methane

4 billion at 15:53 PM on 8 March, 2010

In 2007 Shakhova et al wrote,

"Until recently, due to slightly negative annual temperatures within the water column and the lid-type coverage of shelf sediments by sub-sea permafrost, old organic carbon buried on the Siberian Arctic shelf was considered completely isolated from the modern carbon cycle."

So it seems fair to say the observed venting is a new phenomenon.

Shakova et al 2010, wrote,

"The release to the atmosphere of only one percent of the methane assumed to be stored in shallow hydrate deposits might alter the current atmospheric burden of methane up to 3 to 4 times"

The East Siberian Arctic Shelf covers a similar area to the Siberian traps which has been linked to a large increase in GHG's in the past.

As the potential volume of GHG's from the ESAS is so large, perhaps similar to levels released by the Siberian traps, isn't it reasonable to suggest that the effects of ongoing and near complete venting of ESAS Methane will be similar to the effects of the Siberian traps event?

The upcoming ice age has been postponed indefinitely

Jim Eager at 03:53 AM on 30 January, 2010

But neither a Toba/Yellowstone nor a Siberian/Deccan traps event are happening right now, so Plimer's point is just another distraction.

The upcoming ice age has been postponed indefinitely

Ned at 01:52 AM on 30 January, 2010

I think there's some confusion there between (a) a huge explosive event at, say, Yellowstone, which could potentially inject a lot of aerosols into the stratosphere, and (b) a broad-scale, multi-century flood basalt event like the Siberian traps or Deccan traps, which would outgas a lot of CO2. Yes they're both catastrophic volcanism but the climate impacts are quite different.

CO2 has been higher in the past

chris at 06:56 AM on 5 November, 2009

re #29; Disclaimed

There's a decent amount of recent research/reviews on the subject of CO2 levels and extinctions. Here's a selection of papers/reviews that address this. It might be about a year out of date, and I wrote this in a slightly different context elsewhere....I had a quick look at the literature earlier, and didn't find anything that substantially adds to this.

The major extinction events of the past 300 million years are generally associated with rapid onset and long term warming events, and tectonic processes are considered the most likely causes of the rise in greenhouse gases and warming associated with these (especially massive flood basalt events; e.g. the Serbian Traps at the end-Permian extinction; the Deccan Traps at the end-Cretaceous extinction; the tectonic events resulting in plate boundary separation and opening up of the N Atlantic at the Paleo-Eocene Thermal Maximum)

Major extinctions are associated with long lived perturbation of the climate system and the atmosphere. For example the early Jurassic extinction is associated with events (greenhouse gas induced warming) lasting 200,000 years

Svensen H et al (2007) Hydrothermal venting of greenhouse gases triggering Early Jurassic global warming Earth Planetary Sci Lett 256 554-566

Abstract: The climate change in the Toarcian (Early Jurassic) was characterized by a major perturbation of the global carbon cycle. The event lasted for approximately 200,000 years and was manifested by a global warming of similar to 6 degrees C, anoxic conditions in the oceans, and extinction of marine species. The triggering mechanisms for the perturbation and environmental change are however strongly debated. Here, we present evidence for a rapid formation and transport of greenhouse gases from the deep sedimentary reservoirs in the Karoo Basin, South Africa.......

likewise comprehensive analyses of the coincidence of major tectonic events, and resulting elevation of greenhouse gas levels, are associated with several of the major extinctions of the last 300 million years. Note that CO2 isn't the only player. Methane is implicated in several of these events (see especially the PETM below) and sulphurous oxides and their effects on ocean acidity and oxygen content are also implicated:

Wignall P (2005) The link between large igneous province eruptions and mass extinctions Elements 1, 293-297

Abstract: In the past 300 million years, there has been a near-perfect association between extinction events and the eruption of large igneous provinces, but proving the nature of the causal links is far from resolved. The associated environmental changes often include global warming and the development of widespread oxygen-poor conditions in the oceans. This implicates a role for volcanic CO2 emissions, but other perturbations of the global carbon cycle, such as release of methane from gas hydrate reservoirs or shut-down of photosynthesis in the oceans, are probably required to achieve severe green-house warming. The best links between extinction and eruption are seen in the interval from 300 to 150 Ma. With the exception of the Deccan Trap eruptions (65 Ma), the emplacement of younger volcanic provinces has been generally associated with significant environmental changes but little or no increase in extinction rates above background levels.

R. J. Twitchett (2006) The palaeoclimatology, palaeoecology and palaeoenvironmental analysis of mass extinction events
Palaeogeog., Palaeoclimatol., Palaeoecol. 232, 190-213

concluding paragraph: "Mass extinction studies have enjoyed a surge in scientific interest of the past 30 years that shows no sign of abating. Recent areas of particular interest include the palaeoecological study of biotic crises, and analyses of patterns of post-extinction recovery. There is good evidence of rapid climate change affecting all of the major extinction events, while the ability of extraterrestrial impact to cause extinction remains debatable. There is growing evidence that food shortage and suppression of primary productivity, lasting several hundred thousand years, may be a proximate cause of many past extinction events. Selective extinction of suspension feeders and the prevalence of dwarfed organisms in the aftermath are palaeoecological consequences of these changes. The association with rapid global warming shows that study of mass extinction events is not just an esoteric intellectual exercise, but may have implications for the present day."

Notice that greenhouse environments are associated with the very delayed (millions of years) recovery of biota following thse extinctions;

Fraiser ML et al. (2007) Elevated atmospheric CO2 and the delayed biotic recovery from the end-Permian mass extinction Palaeogeog. Palaeoclim. Paleoecol. 252, 164-175

Abstract: Excessive CO2 in the Earth ocean-atmosphere system may have been a significant factor in causing the end-Permian mass extinction. CO2 injected into the atmosphere by the Siberian Traps has been postulated as a major factor leading to the end-Permian mass extinction by facilitating global warming, widespread ocean stratification, and development of anoxic, euxinic and CO2-rich deep waters. A broad incursion of this toxic deep water into the surface ocean may have caused this mass extinction. Although previous studies of the role of excessive CO2 have focused on these "bottom-up" effects emanating from the deep ocean, "top-down" effects of increasing atmosphere CO2 concentrations on ocean-surface waters and biota have not previously been explored. Passive diffusion of atmospheric CO2 into ocean-surface waters decreases the pH and CaCO3 saturation state of seawater, causing a physiological and biocalcification crisis for many marine invertebrates. While both "bottom-up" and "top-down" mechanisms may have contributed to the relatively short-term biotic devastation of the end-Permian mass extinction, such a "top-down" physiological and biocalcification crisis would have had long-term effects and might have contributed to the protracted 5- to 6-million-year-long delay in biotic recovery following this mass extinction. Earth's Modern marine biota may experience similar "top-down" CO2 stresses if anthropogenic input of atmosphere/ocean CO2 continues to rise.

The lesser extinction associated with the Paleo-Eocene-Thermal Maximum (PETM) 55 MYA is probably the best characterised (not surprisingly since it's the most recent!) example of massive tectonic processes (the opening up of the N. Atlantic as the plates seperated) associated with enhanced atmospheric greenhouse gases, ocean acidification etc.:

M. Storey et al. (2007)Paleocene-Eocene Thermal Maximum and the Opening of the Northeast Atlantic Science 316, 587 - 589

abstract: The Paleocene-Eocene thermal maximum (PETM) has been attributed to a sudden release of carbon dioxide and/or methane. 40Ar/39Ar age determinations show that the Danish Ash-17 deposit, which overlies the PETM by about 450,000 years in the Atlantic, and the Skraenterne Formation Tuff, representing the end of 1 ± 0.5 million years of massive volcanism in East Greenland, are coeval. The relative age of Danish Ash-17 thus places the PETM onset after the beginning of massive flood basalt volcanism at 56.1 ± 0.4 million years ago but within error of the estimated continental breakup time of 55.5 ± 0.3 million years ago, marked by the eruption of mid-ocean ridge basalt–like flows. These correlations support the view that the PETM was triggered by greenhouse gas release during magma interaction with basin-filling carbon-rich sedimentary rocks proximal to the embryonic plate boundary between Greenland and Europe.

And even the end-Cretaceous extinction (that did for the dinosaurs) seems to have had at least a significant component from massive flood basalt events (that resulted in the Deccan Traps in what is now India). In fact there is increasing evidence that the impact that resulted in the Chicxulub crater in the Yucatan post-dates the onset of the extinction by several 100,000's of years, and the extinction is associated with global warming (including a sudden contribution from the impact into limestone-rich deposits that vapourized massive amounts of carbonate (limestone) back into CO2):

Keller G (2005) Impacts, volcanism and mass extinction: random coincidence or cause and effect? Austral. J. Earth Sci 52 725-757.

Abstract: Large impacts are credited with the most devastating mass extinctions in Earth's history and the Cretaceous - Tertiary (K/T) boundary impact is the strongest and sole direct support for this view. A review of the five largest Phanerozoic mass extinctions provides no support that impacts with craters up to 180 km in diameter caused significant species extinctions. This includes the 170 km-diameter Chicxulub impact crater regarded as 0.3 million years older than the K/T mass extinction. A second, larger impact event may have been the ultimate cause of this mass extinction, as suggested by a global iridium anomaly at the K/T boundary, but no crater has been found to date. The current crater database suggests that multiple impacts, for example comet showers, were the norm, rather than the exception, during the Late Eocene, K/T transition, latest Triassic and the Devonian-Carboniferous transition, but did not cause significant species extinctions. Whether multiple impacts substantially contributed to greenhouse worming and associated environmental stresses is yet to be demonstrated. From the current database, it must be concluded that no known Phanerozoic impacts, including the Chicxulub impact (but excluding the K/T impact) caused mass extinctions or even significant. species extinctions. The K/T mass extinction may have been caused by the coincidence of a very large impact ( > 250 km) upon a highly stressed biotic environment as a result of volcanism. The consistent association of large magmatic provinces (large igneous provinces and continental flood-basalt provinces) with all but one (end-Ordovician) of the five major Phanerozoic mass extinctions suggests that volcanism played a major role. Faunal and geochemical evidence from the end-Permian, end-Devonian, end-Cretaceous and Triassic/Jurassic transition suggests that the biotic stress was due to a lethal combination of tectonically induced hydrothermal and volcanic processes, leading to eutrophication in the oceans, global warming, sea-level transgression and ocean anoxia. It must be concluded that major magmatic events and their long-term environmental consequences are major contributors, though not the sole causes of mass extinctions. Sudden mass extinctions, such as at the K/T boundary, may require the coincidence of major volcanism and a very large Impact.

Beerling DJ et al. (2002) An atmospheric pCO(2) reconstruction across the Cretaceous-Tertiary boundary from leaf megafossils Proc. Natl. Acad. Sci. USA 99 (12): 7836-7840

Abstract: The end-Cretaceous mass extinctions, 65 million years ago, profoundly influenced the course of biotic evolution. These extinctions coincided with a major extraterrestrial impact event and massive volcanism in India. Determining the relative importance of each event as a driver of environmental and biotic change across the Cretaceous-Tertiary boundary (KTB) crucially depends on constraining the mass of CO2 injected into the atmospheric carbon reservoir. Using the inverse relationship between atmospheric CO2 and the stomatal index of land plant leaves, we reconstruct Late Cretaceous-Early Tertiary atmospheric CO2 concentration (pCO(2)) levels with special emphasis on providing a pCO(2) estimate directly above the KTB. Our record shows stable Late Cretaceous/ Early Tertiary background pCO(2) levels of 350-500 ppm by volume, but with a marked increase to at least 2,300 ppm by volume within 10,000 years of the KTB. Numerical simulations with a global biogeochemical carbon cycle model indicate that CO2 outgassing during the eruption of the Deccan Trap basalts fails to fully account for the inferred pCO(2) increase. Instead, we calculate that the postboundary pCO(2) rise is most consistent with the instantaneous transfer of approximate to 4,600 Gt C from the lithic to the atmospheric reservoir by a large extraterrestrial bolide impact. A resultant climatic forcing of +12 W(.)m(-2) would have been sufficient to warm the Earth's surface by approximate to7.5degreesC, in the absence of counter forcing by sulfate aerosols. This finding reinforces previous evidence for major climatic warming after the KTB impact and implies that severe and abrupt global warming during the earliest Paleocene was an important factor in biotic extinction at the KTB.

Note that there may be some question over the absolute concentrations of atmospheric CO2 calculated using the plant stomatal frequency index.

Note also that since these processes all occurred in the deep past, we obviously don't know exactly all the contributions to all the extinctions. However the associations between tectonic/mantle plume breaching/flood basalt eruptions/global warming and extinctions are increasingly supported by the evidence.

Climate time lag

chris at 17:57 PM on 29 July, 2009

re #288

Not realy thingadonta. The notion that biodiversity thrives under high CO2/warm-hot periods is one of those fallacies that one thinks must be true, but actually seems not to be. We've already seen that most of the major extinction events through the Phanerozoic are associated (where this is characterized) with greenhouse gas enhancement through tectonic processes, high temperatures, ocean acidification/anoxia etc. (see my post #257).

In the more general case, high temperaures are associated with low biodiversity and vice versa, as indiated by detailed examination of the fossil record:

*PJ Mayhew et al. (2007) A long-term association between global temperature and biodiversity, origination and extinction in the fossil record Proceedings of The Royal Society B 275, 47–53.

Abstract: The past relationship between global temperature and levels of biological diversity is of increasing concern due to anthropogenic climate warming. However, no consistent link between these variables has yet been demonstrated. We analysed the fossil record for the last 520Myr against estimates of low latitude sea surface temperature for the same period. We found that global biodiversity (the richness of families and genera) is related to temperature and has been relatively low during warm 'greenhouse' phases, while during the same phases extinction and origination rates of taxonomic lineages have been relatively high. These findings are consistent for terrestrial and marine environments and are robust to a number of alternative assumptions and potential biases. Our results provide the first clear evidence that global climate may explain substantial variation in the fossil record in a simple and consistent manner. Our findings may have implications for extinction and biodiversity change under future climate warming.

Hollywood films with Sophia Loren are simply not a good means of informing oneself on the subject of biodiversity. One really has to address the evidence !

Likewise, high temperatures seem to have the effect of greatly delaying for long, long periods, the recovery of biodiversity following greenhouse-induced extinction events; e.g. :

Fraiser ML et al. (2007) Elevated atmospheric CO2 and the delayed biotic recovery from the end-Permian mass extinction Palaeogeog. Palaeoclim. Paleoecol. 252, 164-175

Abstract: Excessive CO2 in the Earth ocean-atmosphere system may have been a significant factor in causing the end-Permian mass extinction. CO2 injected into the atmosphere by the Siberian Traps has been postulated as a major factor leading to the end-Permian mass extinction by facilitating global warming, widespread ocean stratification, and development of anoxic, euxinic and CO2-rich deep waters. A broad incursion of this toxic deep water into the surface ocean may have caused this mass extinction. Although previous studies of the role of excessive CO2 have focused on these "bottom-up" effects emanating from the deep ocean, "top-down" effects of increasing atmosphere CO2 concentrations on ocean-surface waters and biota have not previously been explored. Passive diffusion of atmospheric CO2 into ocean-surface waters decreases the pH and CaCO3 saturation state of seawater, causing a physiological and biocalcification crisis for many marine invertebrates. While both "bottom-up" and "top-down" mechanisms may have contributed to the relatively short-term biotic devastation of the end-Permian mass extinction, such a "top-down" physiological and biocalcification crisis would have had long-term effects and might have contributed to the protracted 5- to 6-million-year-long delay in biotic recovery following this mass extinction. Earth's Modern marine biota may experience similar "top-down" CO2 stresses if anthropogenic input of atmosphere/ocean CO2 continues to rise.

The contemporary situation is potentially very serious due to the rapid rate of change, combined with the equally problematic (if not more serious right now), confounding issues of massive deforestation, more generalised habitat destruction/degradation and over-exploitation:

Brook BW (et al. (2008) "Synergies among extinction drivers under global change" Trends in Ecology and Evol. 23, 453-460

Abstract: If habitat destruction or overexploitation of populations is severe, species loss can occur directly and abruptly. Yet the final descent to extinction is often driven by synergistic processes (amplifying feedbacks) that can be disconnected from the original cause of decline. We review recent observational, experimental and metaanalytic work which together show that owing to interacting and self-reinforcing processes, estimates of extinction risk for most species are more severe than previously recognised. As such, conservation actions which only target single-threat drivers risk being inadequate because of the cascading effects caused by unmanaged synergies. Future work should focus on how climate change will interact with and accelerate ongoing threats to biodiversity, such as habitat degradation, overexploitation and invasive species

Climate time lag

thingadonta at 22:55 PM on 27 July, 2009

re 255:
Chris:

I can't comment about the relationship between co2 and climate sensivity etc throughout geological periods without having a more detailed look at the papers and data you mention. So thanks for the papers. But I DO know that glacial periods occur where there is eg:

1) restricted ocean current circulation (eg in the last 37 Ma-Australia's increasing separation from Antartica, Africa crashing into Asia and eliminating almost the the Tethys Sea-only the small Meditterranen Sea is left, and South America joining North America in the last few million years), and
2) where continents are bound together near the poles (eg Permo-Carboniferous).

The general reduction in ocean circulation causes cooling in the oceans and subsequent lowering of c02 (higher solubility), the relative effect of lowering c02 on T itself is likely small-once again I suspect the reserchers have enhanced co2's relative effect in such cases. Its a chicken and egg argument, c02 drops because the ocean and earth cools, not the other way round.

I also know from experience that it can be very difficult to nail-down cause(s) of geological-age climate changes, and the sometimes associated minor/mass extinction events; the usual trend is that the latest research 'fad' usually dominates the debate- eg K-T boundary extinction event in the 1980s with bolide impact, as opposed/coupled with strong volcanism in the Deccan traps in India (very likely a combination of both). Also, I mention the end Permian with its very strong volcanism in Siberia which widespread hothouse-(but what caused the Siberian volcanism in the first place?). Note also: there are no coals in the early Triassic, coal-forming plants went extinct at end Permian for around 10Ma and had to re-evolve, but was this due to greenhouse gases?.

I suspect, but I am not familiar with all this more recent geological-greenhouse gas literature, that relative greenhouse gas effects can be 'adjusted' to produce whatever effect on climate and/or extinction events in the geological past is desired to produce a preconceived outcome. This happened with bolide impacts (with few real major or minor extinction events correlated); researchers have also probably overshot the mark with greenhouse gases and the geological past, with more chicken and egg-type arguments (co2 causing T to change or T causing c02 to change).

eg: "When atmospheric CO2 levels drop below thresholds, the levels of which are modulated by the solar output, cold/glacial periods result".

But how do you know that T didnt drop naturally first, with the drops in ocean T leading to drops in atmospheric c02 from higher solubility of c02 in cooler oceans? And one more thing, is the geological record at sufficient resolution to resolve this? I suspect it isnt, in the vast majority of cases.

I'll have to read the stuff sometime.

It's the sun

Patrick 027 at 03:04 AM on 28 April, 2009

Well, I can't really argue with you so much about the PT extinction except to say that the role of the Siberian traps' CO2 emissions over a million(s?) years(even if caused by an impact) might be expected to be significant.

"Nothing to do with CO2 or temperatures. The PETM was roughly 55 million years ago, we evolved from primitive primates to prosimians in Asia, this was a benefit to our own ancestors."

PETM seems to have been caused either by a large CO2 release, a large CH4 release (that would eventually oxidize to CO2), or maybe both. It might have been triggered by volcanism but may have involved destabilization of CH4 hydrates, rather than being direct geological emissions of CO2. There was a temperature increase. It was not a mass extinction on the scale of KT or PT, but there was at least some ecological disruption (I just don't know the magnitude offhand as suggested by the evidence). Sure, we may owe our existence to it. We also owe our existence to KT and PT mass extinctions. We don't need to replicate those things to continue our existence.

"And of course their is the constantly evolving bacteria. The largest part of the biomass by far in the air, on the surface and below it, in the water and in the muck below it, all do well in warm conditions."

In terms of biomass, they might have some competition from krill (?). They certainly do evolve, but the plethora of metabolic pathways (photosynthesis types..., fermentation, respiration, methanogens and methanotrophs, sulfate reduction...) has not changed much for a long time.

It's the sun

Quietman at 12:11 PM on 27 April, 2009

Re: "(PETM, end-Permian mass extinction (?) )."

Nothing to do with CO2 or temperatures. The PETM was roughly 55 million years ago, we evolved from primitive primates to prosimians in Asia, this was a benefit to our own ancestors.

The PT extinction was an ocean impactor near Antarctica destroying nearly 90% of marine species. Like the KT impact we had the creation of traps on the opposite of the impact (Deccan Traps), in this case the Siberian Traps. The subsequent terrestrial extinction was not quite as bad at roughly 70% of species. There is good reason to suspect the Bedout crater but this is as large an argument as the KT extinction.

I could go on but this is not the right thread for it, I think "Climate Changed Before" would be more appropriate.

But don't let me interfere with your discussion with Gord. In the mean time I'll go through my notes and find some references for you (to post in the other thread as mentioned).

Climate's changed before

Quietman at 06:54 AM on 3 March, 2009

I did not copy the link but I did keep the article:

With surprising and mysterious regularity, life on Earth has flourished and vanished in cycles of mass extinction every 62 million years, say two UC Berkeley scientists who discovered the pattern after a painstaking computer study of fossil records going back for more than 500 million years. Their findings are certain to generate a renewed burst of speculation among scientists who study the history and evolution of life. Each period of abundant life and each mass extinction has itself covered at least a few million years — and the trend of biodiversity has been rising steadily ever since the last mass extinction, when dinosaurs and millions of other life forms went extinct about 65 million years ago.

The Berkeley researchers are physicists, not biologists or geologists or paleontologists, but they have analyzed the most exhaustive compendium of fossil records that exists — data that cover the first and last known appearances of no fewer than 36,380 separate marine genera, including millions of species that once thrived in the world’s seas, later virtually disappeared, and in many cases returned. Richard Muller and his graduate student, Robert Rohde, are publishing a report on their exhaustive study in the journal Nature today, and in interviews this week, the two men said they have been working on the surprising evidence for about four years. “We’ve tried everything we can think of to find an explanation for these weird cycles of biodiversity and extinction,” Muller said, “and so far, we’ve failed.” But the cycles are so clear that the evidence “simply jumps out of the data,” said James Kirchner, a professor of earth and planetary sciences on the Berkeley campus who was not involved in the research but who has written a commentary on the report that is also appearing in Nature today. “Their discovery is exciting, it’s unexpected and it’s unexplained,” Kirchner said. And it is certain, he added, to send other scientists in many disciplines seeking explanations for the strange cycles. “Everyone and his brother will be proposing an explanation — and eventually, at least one or two will turn out to be right while all the others will be wrong.”

Muller and Rohde conceded that they have puzzled through every conceivable phenomenon in nature in search of an explanation: “We’ve had to think about solar system dynamics, about the causes of comet showers, about how the galaxy works, and how volcanoes work, but nothing explains what we’ve discovered,” Muller said. The evidence of strange extinction cycles that first drew Rohde’s attention emerged from an elaborate computer database he developed from the largest compendium of fossil data ever created. It was a 560-page list of marine organisms developed 14 years ago by the late J. John Sepkoski Jr., a famed paleobiologist at the University of Chicago who died at the age of 50 nearly five years ago. Sepkoski himself had suggested that marine life appeared to have its ups and downs in cycles every 26 million years, but to Rohde and Muller, the longer cycle is strikingly more evident, although they have also seen the suggestion of even longer cycles that seem to recur every 140 million years. Sepkoski’s fossil record of marine life extends back for 540 million years to the time of the great “Cambrian Explosion,” when almost all the ancestral forms of multicellular life emerged, and Muller and Rohde built on it for their computer version. Muller has long been known as an unconventional and imaginative physicist on the Berkeley campus and at the Lawrence Berkeley Laboratory. It was he, for example, who suggested more than 20 years ago that an undiscovered faraway dwarf star — which he named “Nemesis” — was orbiting the sun and might have steered a huge asteroid into the collision with Earth that drove the dinosaurs to extinction. “I’ve given up on Nemesis,” Muller said this week, “but then I thought there might be two stars somewhere out there, but I’ve given them both up now.” He and Rohde have considered many other possible causes for the 62- million-year cycles, they said. Perhaps, they suggested, there’s an unknown “Planet X” somewhere far out beyond the solar system that’s disturbing the comets in the distant region called the Oort Cloud — where they exist by the millions — to the point that they shower the Earth and cause extinctions in regular cycles. Daniel Whitmire and John Matese of the University of Louisiana at Lafayette proposed that idea as a cause of major comet showers in 1985, but no one except UFO believers has ever discovered a sign of it. Or perhaps there’s some kind of “natural timetable” deep inside the Earth that triggers cycles of massive volcanism, Rohde has thought. There’s even a bit of evidence: A huge slab of volcanic basalt known as the Deccan Traps in India has been dated to 65 million years ago — just when the dinosaurs died, he noted. And the similar basaltic Siberian Traps were formed by volcanism about 250 million years ago, at the end of the Permian period, when the greatest of all mass extinctions drove more than 70 percent of all the world’s marine life to death, Rohde said.

The two scientists proposed more far-out ideas in their report in Nature, but only to indicate the possibilities they considered. Muller’s favorite explanation, he said informally, is that the solar system passes through an exceptionally massive arm of our own spiral Milky Way galaxy every 62 million years, and that that increase in galactic gravity might set off a hugely destructive comet shower that would drive cycles of mass extinction on Earth. Rohde, however, prefers periodic surges of volcanism on Earth as the least implausible explanation for the cycles, he said — although it’s only a tentative one, he conceded. Said Muller: “We’re getting frustrated and we need help. All I can say is that we’re confident the cycles exist, and I cannot come up with any possible explanation that won’t turn out to be fascinating. There’s something going on in the fossil record, and we just don’t know what it is.”

Climate's changed before

Quietman at 15:13 PM on 27 February, 2009

David
Someone essentially called John a liar (in a nice enough way) in the Arctic melt thread and he has been very quiet since. I side with John but I'm a liar too.

The Permian extinction is obviously the most interesting. I'll assume that you have read "Gorgon" already since it is so pertinent.

OK, the obvious factor is the Siberian traps. Large volcanic fields erupting for a very long time spewing all sorts of poisons into the atmosphere. But (from Gorgon) the sea extinctions (something like 90%) happened in a different time fram from the land extinctions (Somewhere around 75%). Sorry I don't remember the exact numbers.

Well what caused the traps to erupt? In both the PT and KT extinctions we have evidence for very large impactors on the opposite side of the earth preceding the eruption of the traps. The reason for the extinctions is fairly obvious (two incidents and two extinction events, the second event caused by the first).

BTW the same actually happened at the KT, Bakker points out that the dinosaurs were already in trouble by the KT event.

Volcanoes emit more CO2 than humans

Quietman at 08:49 AM on 16 January, 2009

Also you might want to read Peter Ward's work on the PT extinction (not the media coverage that assume CO2). While Ward does not recognize the importance of the Antarctic impact, he does cite the Siberian Traps that it created as releasing METHANE and poisionous gas. While the gas may have caused a GH condition, the GHG did not cause the extinction event, which (as he points out in Gorgon and elsewhere) was a two stage extinction. First the oceans died (90% of all ocean species) and was followed by land species (70%). What most forget when reading about the PT extinction is that the Pennsylvanian-Permian Ice Age had just closed and the planet had warmed (naturally) prior to the extinction event, just like right now after 12000 years of interglacial (the average length of an interglacial BTW).

What does CO2 lagging temperature mean?

chris at 10:08 AM on 3 October, 2008

Re #27 Mizimi

When presented with a ludicrous and blatantly incorrect paleotemperature "graph" of unknown provenance you consider it a "beautiful example to show there IS a limit to which CO2 can effect temperature changes.....(your post #16).

However when presented with copious scientific data on the straightforward relationship between atmospheric paleo CO2 levels and paleotemperature (see my post #25) you suddenly lose your enthusiasm. Apparently you prefer nonsense that supports some sort of agenda position in preference to the science...try re-reading my post #26 on the nature of skepticism.

Your "sub" point about paleo-warmth is unfortunately misplaced. In fact the evidence indicates that the warm periods in the past have been associated with lower biodiversity [***] and that it is the rapid increases in global warmth, largely associated in the past with tectonic events, that have been the drivers of major extinctions throughout Earth's history[*****]:

[***]PJ Mayhew et al. (2007) A long-term association between global temperature and biodiversity, origination and extinction in the fossil record Proceedings of The Royal Society B 275, 47–53.

Abstract: "The past relationship between global temperature and levels of biological diversity is of increasing concern due to anthropogenic climate warming. However, no consistent link between these variables has yet been demonstrated. We analysed the fossil record for the last 520Myr against estimates of low latitude sea surface temperature for the same period. We found that global biodiversity (the richness of families and genera) is related to temperature and has been relatively low during warm 'greenhouse' phases, while during the same phases extinction and origination rates of taxonomic lineages have been relatively high. These findings are consistent for terrestrial and marine environments and are robust to a number of alternative assumptions and potential biases. Our results provide the first clear evidence that global climate may explain substantial variation in the fossil record in a simple and consistent manner. Our findings may have implications for extinction and biodiversity change under future climate warming."

[*****]Major extinctions are associated with long lived perturbation of the climate system and the atmosphere. For example the early Jurassic extinction is associated with events (greenhouse gas induced warming) lasting 200,000 years:

Svensen H et al (2007) Hydrothermal venting of greenhouse gases triggering Early Jurassic global warming Earth Planetary Sci Lett 256 554-566

Abstract: "The climate change in the Toarcian (Early Jurassic) was characterized by a major perturbation of the global carbon cycle. The event lasted for approximately 200,000 years and was manifested by a global warming of similar to 6 degrees C, anoxic conditions in the oceans, and extinction of marine species. The triggering mechanisms for the perturbation and environmental change are however strongly debated. Here, we present evidence for a rapid formation and transport of greenhouse gases from the deep sedimentary reservoirs in the Karoo Basin, South Africa......."

likewise comprehensive analyses of the coincidence of major tectonic events, and resulting elevation of greenhouse gas levels, are associated with several of the major extinctions of the last 300 million years. Note that CO2 isn't the only player. Methane is implicated in several of these events (see especially the PETM below) and sulphurous oxides and their effects on ocean acidity and oxygen content are also implicated:

Wignall P (2005) The link between large igneous province eruptions and mass extinctions Elements 1, 293-297

Abstract: "In the past 300 million years, there has been a near-perfect association between extinction events and the eruption of large igneous provinces, but proving the nature of the causal links is far from resolved. The associated environmental changes often include global warming and the development of widespread oxygen-poor conditions in the oceans. This implicates a role for volcanic CO2 emissions, but other perturbations of the global carbon cycle, such as release of methane from gas hydrate reservoirs or shut-down of photosynthesis in the oceans, are probably required to achieve severe green-house warming. The best links between extinction and eruption are seen in the interval from 300 to 150 Ma. With the exception of the Deccan Trap eruptions (65 Ma), the emplacement of younger volcanic provinces has been generally associated with significant environmental changes but little or no increase in extinction rates above background levels."

R. J. Twitchett (2006) The palaeoclimatology, palaeoecology and palaeoenvironmental analysis of mass extinction events
Palaeogeog., Palaeoclimatol., Palaeoecol. 232, 190-213

concluding paragraph: "Mass extinction studies have enjoyed a surge in scientific interest of the past 30 years that shows no sign of abating. Recent areas of particular interest include the palaeoecological study of biotic crises, and analyses of patterns of post-extinction recovery. There is good evidence of rapid climate change affecting all of the major extinction events, while the ability of extraterrestrial impact to cause extinction remains debatable. There is growing evidence that food shortage and suppression of primary productivity, lasting several hundred thousand years, may be a proximate cause of many past extinction events. Selective extinction of suspension feeders and the prevalence of dwarfed organisms in the aftermath are palaeoecological consequences of these changes. The association with rapid global warming shows that study of mass extinction events is not just an esoteric intellectual exercise, but may have implications for the present day."

Notice that greenhouse environments are associated with the very delayed (millions of years) recovery of biota following these extinctions;

Fraiser ML et al. (2007) Elevated atmospheric CO2 and the delayed biotic recovery from the end-Permian mass extinction Palaeogeog. Palaeoclim. Paleoecol. 252, 164-175

Abstract: Excessive CO2 in the Earth ocean-atmosphere system may have been a significant factor in causing the end-Permian mass extinction. CO2 injected into the atmosphere by the Siberian Traps has been postulated as a major factor leading to the end-Permian mass extinction by facilitating global warming, widespread ocean stratification, and development of anoxic, euxinic and CO2-rich deep waters. A broad incursion of this toxic deep water into the surface ocean may have caused this mass extinction. Although previous studies of the role of excessive CO2 have focused on these "bottom-up" effects emanating from the deep ocean, "top-down" effects of increasing atmosphere CO2 concentrations on ocean-surface waters and biota have not previously been explored. Passive diffusion of atmospheric CO2 into ocean-surface waters decreases the pH and CaCO3 saturation state of seawater, causing a physiological and biocalcification crisis for many marine invertebrates. While both "bottom-up" and "top-down" mechanisms may have contributed to the relatively short-term biotic devastation of the end-Permian mass extinction, such a "top-down" physiological and biocalcification crisis would have had long-term effects and might have contributed to the protracted 5- to 6-million-year-long delay in biotic recovery following this mass extinction. Earth's Modern marine biota may experience similar "top-down" CO2 stresses if anthropogenic input of atmosphere/ocean CO2 continues to rise.

The lesser extinction associated with the Paleo-Eocene-Thermal Maximum (PETM)55 MYA is probably the best characterised (not surprisingly since it's the most recent!) example of massive tectonic processes (the opening up of the N. Atlantic as the plates seperated) associated with enhanced atmospheric greenhouse gases, ocean acidification etc.:

M. Storey et al. (2007)Paleocene-Eocene Thermal Maximum and the Opening of the Northeast Atlantic Science 316, 587 - 589

abstract: "The Paleocene-Eocene thermal maximum (PETM) has been attributed to a sudden release of carbon dioxide and/or methane. 40Ar/39Ar age determinations show that the Danish Ash-17 deposit, which overlies the PETM by about 450,000 years in the Atlantic, and the Skraenterne Formation Tuff, representing the end of 1 ± 0.5 million years of massive volcanism in East Greenland, are coeval. The relative age of Danish Ash-17 thus places the PETM onset after the beginning of massive flood basalt volcanism at 56.1 ± 0.4 million years ago but within error of the estimated continental breakup time of 55.5 ± 0.3 million years ago, marked by the eruption of mid-ocean ridge basalt–like flows. These correlations support the view that the PETM was triggered by greenhouse gas release during magma interaction with basin-filling carbon-rich sedimentary rocks proximal to the embryonic plate boundary between Greenland and Europe."

And even the end-Cretaceous extinction (that did for the dinosaurs) seems to have had at least a significant component from massive flood basalt events (that resulted in the Deccan Traps in what is now India). In fact there is increasing evidence that the impact that resulted in the Chicxulub crater in the Yucatan post-dates the onset of the extinction by several 100,000's of years, and the extinction is associated with global warming (including a sudden contribution from the impact into limestone-rich deposits that vapourized massive amounts of carbonate (limestone) back into CO2):

Keller G (2005) Impacts, volcanism and mass extinction: random coincidence or cause and effect? Austral. J. Earth Sci 52 725-757.

Abstract: "Large impacts are credited with the most devastating mass extinctions in Earth's history and the Cretaceous - Tertiary (K/T) boundary impact is the strongest and sole direct support for this view. A review of the five largest Phanerozoic mass extinctions provides no support that impacts with craters up to 180 km in diameter caused significant species extinctions. This includes the 170 km-diameter Chicxulub impact crater regarded as 0.3 million years older than the K/T mass extinction. A second, larger impact event may have been the ultimate cause of this mass extinction, as suggested by a global iridium anomaly at the K/T boundary, but no crater has been found to date. The current crater database suggests that multiple impacts, for example comet showers, were the norm, rather than the exception, during the Late Eocene, K/T transition, latest Triassic and the Devonian-Carboniferous transition, but did not cause significant species extinctions. Whether multiple impacts substantially contributed to greenhouse worming and associated environmental stresses is yet to be demonstrated. From the current database, it must be concluded that no known Phanerozoic impacts, including the Chicxulub impact (but excluding the K/T impact) caused mass extinctions or even significant. species extinctions. The K/T mass extinction may have been caused by the coincidence of a very large impact ( > 250 km) upon a highly stressed biotic environment as a result of volcanism. The consistent association of large magmatic provinces (large igneous provinces and continental flood-basalt provinces) with all but one (end-Ordovician) of the five major Phanerozoic mass extinctions suggests that volcanism played a major role. Faunal and geochemical evidence from the end-Permian, end-Devonian, end-Cretaceous and Triassic/Jurassic transition suggests that the biotic stress was due to a lethal combination of tectonically induced hydrothermal and volcanic processes, leading to eutrophication in the oceans, global warming, sea-level transgression and ocean anoxia. It must be concluded that major magmatic events and their long-term environmental consequences are major contributors, though not the sole causes of mass extinctions. Sudden mass extinctions, such as at the K/T boundary, may require the coincidence of major volcanism and a very large Impact."

Beerling DJ et al. (2002) An atmospheric pCO(2) reconstruction across the Cretaceous-Tertiary boundary from leaf megafossils Proc. Natl. Acad. Sci. USA 99 (12): 7836-7840

Abstract: "The end-Cretaceous mass extinctions, 65 million years ago, profoundly influenced the course of biotic evolution. These extinctions coincided with a major extraterrestrial impact event and massive volcanism in India. Determining the relative importance of each event as a driver of environmental and biotic change across the Cretaceous-Tertiary boundary (KTB) crucially depends on constraining the mass of CO2 injected into the atmospheric carbon reservoir. Using the inverse relationship between atmospheric CO2 and the stomatal index of land plant leaves, we reconstruct Late Cretaceous-Early Tertiary atmospheric CO2 concentration (pCO(2)) levels with special emphasis on providing a pCO(2) estimate directly above the KTB. Our record shows stable Late Cretaceous/ Early Tertiary background pCO(2) levels of 350-500 ppm by volume, but with a marked increase to at least 2,300 ppm by volume within 10,000 years of the KTB. Numerical simulations with a global biogeochemical carbon cycle model indicate that CO2 outgassing during the eruption of the Deccan Trap basalts fails to fully account for the inferred pCO(2) increase. Instead, we calculate that the postboundary pCO(2) rise is most consistent with the instantaneous transfer of approximate to 4,600 Gt C from the lithic to the atmospheric reservoir by a large extraterrestrial bolide impact. A resultant climatic forcing of +12 W(.)m(-2) would have been sufficient to warm the Earth's surface by approximate to7.5degreesC, in the absence of counter forcing by sulfate aerosols. This finding reinforces previous evidence for major climatic warming after the KTB impact and implies that severe and abrupt global warming during the earliest Paleocene was an important factor in biotic extinction at the KTB."

Can animals and plants adapt to global warming?

Quietman at 02:46 AM on 5 May, 2008

chris

On cycles and explanations for previous extinctions:

I used those 2 articles simply because they were the most recent, not actually the most relavent. As you are aware the idea of extinction cycles is just hypotheses,
while the idea of climate cycles has good evidence. In the case of the KT event, some paleontologists have pointed out that the dinosaurs were in decline from about 70 million years ago due to climate stress. The effect of the Deccan Traps and the Yucatan impact seem to be a fatal blow but most likely not within a cyclic extinction (my view). The PT event also involved an impact and the Siberian Traps but did they actually cause the climate change or again were they a coincidence that simply made things worse?

The issue of clarity in climate cycles is simply that there are too many of them and not all of them identified as yet. Why do ice ages occur? Of the 4 major iceages why are they of different lengths and what causes their end. Are we now coming out of an ice age of merely within an interglacial? There are definate cycles involved but we still have a long way to go in understanding them.

And I agree, Global warming does seem to be directly related to extinctions and I believe that it is the speed not the temperatures that are relavent. The warming slopes are much steeper than the cooling slopes, not allowing enough time for species to adapt.
I simply disagree that mankind is the direct cause. But I feel that our mistakes have only made things worse.

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