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Is another mass extinction event on the way?

Why have mass extinctions of species occurred since the late Proterozoic (from 580 million years ago) and repeatedly through the Phanerozoic? Integral to these extinctions were abrupt changes in the physical…

You have to go back to the time of the dinosaurs to see where Earth is heading. Mr Kimberley/Flickr

Why have mass extinctions of species occurred since the late Proterozoic (from 580 million years ago) and repeatedly through the Phanerozoic? Integral to these extinctions were abrupt changes in the physical and chemical properties of the atmosphere, ocean and land, inducing environmental changes at a pace to which many species could not adapt.

The best documented example to date is the 65 million years-old K-T boundary asteroid impact and extinction event. But several other mass extinctions were associated with volcanic eruptions and asteroid/comet impacts (see Figure 1).

Instantaneous effects of impacts (initial fireball flash as the asteroid or comet enters the atmosphere, crater explosion, seismic shock, tsunami waves, incandescent ejecta, dust plumes, greenhouse gas release from carbon-rich limestone and shale) occurred over periods ranging from seconds to weeks and months.

As shown in figure 1, Phanerozoic history (since about 540 million years ago) is marked with a number of mass extinction events. About 80% of genera were lost at the ~251 Ma Permian-Triassic boundary event. This was a consequence of both volcanic eruptions (known as the Siberian Norilsk traps) and an asteroid impact near Araguinha, Brazil (Araguinha: 40 km-diameter; 252.7+/-3.8 Ma).

Figure 1: Phanerozoic genera extinction rates, extraterrestrial impact events (circles denote relative magnitude of impacts) and major volcanic events Andrew Glikson, after Keller (2005)

These mass extinction events came on top of more gradual geological processes. These included plate tectonic movements, continental rifting and associated increases in volcanism and mountain building. There were intermittent build up and precipitation of volcanic aerosols and the longer term accumulation and sequestration of atmospheric greenhouse gases (see Figure 2).

Figure 2. Evolution of atmospheric CO2 over the last 80 Ma as measured by multiple proxies (stomata leaf pores, 13C in phytoplankton, 13C in paleosols) (data after D. Royer, with permission). Main features: (1) a low-CO2 late Cretaceous (~70-65 Ma) period terminated by the K-T impact, raising CO2 to ~1700-6500 ppm; (2) high-CO2 Eocene (~50-32 Ma) period terminated by a ~35 Ma impact cluster followed by opening of the Drake Passage, formation of the circum-Antarctic cold current and the Antarctic ice sheet, leading to low-CO2 (~200-500 ppm) Oligocene to present climates. Andrew Glikson

These past events have much to teach us. But the loss of biodiversity associated with the rise of hominids, and in particular since the onset of the industrial age, constitutes a unique phenomenon in Earth history. It is fundamentally different in origin - although similar in terms of some of its consequences - to previous mass extinction events.

For the first time in planetary history a species has mastered combustion, first of carbon products of the biosphere, then of fossil carbon products hundreds of millions of years old. This has magnified its oxygenating capacities by many orders of magnitude. For example, whereas human respiration uses about two to seven calories each minute, driving a car commonly uses more than 1000 calories a minute and operating a power plant more than one million calories a minute.

Figure 3: The rise in human population and in the number of extinct species between 1800 and 2010. Andrew Glickson/Democracy in Action

The magnitude of current loss of species is portrayed in figures 3 to 5. According to the Centre for Biological Diversity:

“The human population is 6.8 billion and growing every second. The sheer force of our numbers is dominating the planet to such a degree that geologists are contemplating renaming our era the ‘Anthropocene’: the epoch where the human species is the dominant factor affecting land, air, water, soil, and species."

“We now absorb 42 percent of the planet’s entire terrestrial net primary productivity. We use 50 percent of all fresh water. We’ve transformed 50 percent of all land. We’ve changed the chemical composition of the whole biosphere and all the world’s seas, bringing on global warming and ocean acidification. Most importantly, we raised the extinction rate from a natural level of one extinction per million species per year up to 30,000 per year. That’s three per hour.”

Figure 4: Loss of original biomes (major regional group of distinctive plant and animal communities best adapted to the region’s physical natural environment, latitude, elevation, and terrain) by 1950, during 1950 and 1990 and projected loss by 2050. Ecosystems and Human Well-being Synthesis A Report of the Millennium Ecosystem Assessment

The utilisation of solar energy stored in plants through photosynthesis, fossil remains of planets and of marine organisms, increases entropy in nature by many orders of magnitude. The mastery of fire by the genus Homo signifies not only a blueprint for the species, but for much of terrestrial nature.

The splitting of the atom increases potential release of entropy by 14 to 15 orders of magnitude for a 1 megaton TNT-equivalent device. Only a species capable of controlling these devices would be able to avoid the catastrophic consequences of the release of such levels of energy into the biosphere.

Figure 5: Relative Loss of Biodiversity of Vascular Plants between 1970 and 2050 as a Result of Land Use Change for Different Biomes and Realms in the Order from Strength Scenario http://www.maweb.org/en/index.aspx

The rate at which radiative forcing and temperature in the atmosphere are now rising exceeds those of previous events in the atmosphere and ocean system, excepting those associated with mass extinctions of species.

As shown in Figure 6, if we compare the current rise of more than 2ppm/year to the mean rise in atmospheric CO₂ of +0.43 ppm/year since 1750, the only recorded rise of similar magnitude occurred 55 million years ago. At this time, the release of some ~2000 GtC carbon as methane took place at a rate of ~0.1 ppm/year.

Figure 6: Summary of rates of temperature changes, temperature changes per year, CO2 changes and CO2 rates per year during Cainozoic events. Andrew Glikson

In terms of temperatures, the current rise rate of ~0.02 to 0.03 degrees Celsius/year is consistent with the fastest rates recorded in Cainozoic history (see Figure 6).

Throughout geological history many species succeeded in adapting to slow to moderate environmental changes. Some survived the most extreme environmental events. Burning the world’s fossil fuel reserves of more than 2000 GtC, analogous to the magnitude estimated for the 55 Ma-old Paleocene-Eocene Thermal event, is leading Earth’s climate and habitats into uncharted territory.

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  1. Byron Smith
    Byron Smith is a Friend of The Conversation.

    Ministry assistant, ecologcal ethicist and PhD candidate at University of Edinburgh

    Dr Glikson, thanks for another very interesting article with some needed long term perspective on just how novel our little piece of history is. For those of us who have grown up in the last six decades or so, the rate of change in human society and the natural world seems normal, but is really a truly rare even unique period in geological, ecological and biological terms (it is also so in cultural and economic terms, but they are points for another day).

    One small comment. The CBD, whom you quote…

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    1. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Byron Smith

      Recently The Con flagged false "Institutes", and "Academies" (see Simon Chapman's comments at https://theconversation.edu.au/think-tanks-talking-points-deepen-the-divide-over-climate-change-5119) "The most amusing thing about "think tanks" is the way they seem to crave status as genuine seats of scholarship."

      The CBD, is an activist organisation and another example of a lobby group posing as a ,centre for science, no wonder Andrew Glickson believes their spin.

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    2. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Byron Smith

      think you mean science fiction

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  2. Tim Scanlon

    Author and Scientist

    Another good article Andrew.

    Speaking with a geologist last week I was interested in their viewpoint. They, as it seems to be a geologist bias, seem to underestimate the impact of man on the environment and the ability we have to understand the environment. The fact that we are a self aware species that can influence and understand our environment means we have the ability to avoid most disasters, especially those that are of our own creation.

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  3. Mark Carter

    logged in via Facebook

    This is a great article which should be read by absolutely everyone. We are a geological event, and not a happy one.

    Bear in mind when looking at those biomes up for destruction in the coming years that a good chunk of the tropical savannah which will go is in Australia. When you hear half of politics argue in favour of moving agriculture from the flogged out Murray/Darling basin to the 'undeveloped' north then this is what they really mean: ecological destruction on a vast scale. The liberal/nationals are potentially the party of mass extinction...

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  4. Andrew Glikson

    Earth and paleo-climate scientist at Australian National University

    Byron, Tim and Mark - Thank you for your positive feedback to the article.

    Byron - I agree. Whereas there exists a vast literature regarding the current mass extinction, neither the number of species nor the precise rate of extinction can be defined, only the ranges are estimated.

    However, reports by Ecosystems and Human Well-being Synthesis: A Report of the Millennium Ecosystem Assessment are as reliable as any.
    (http://www.eoearth.org/article/Ecosystems_and_Human_Well-being:_Biodiversity_Synthesis:_Key_Questions_on_Biodiversity_in_the_Millennium_Ecosystem_Assessment#gen3

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  5. James Szabadics

    BSc

    This is a good article, thought provoking and information packed!

    I would question the statement that the rate of change in temperature exceeds previous events. The rate of change in the atmospheres temperature is studied in many historical temperature reconstructions from ice cores in the main and also pollen in soil studies, they dont seem to support that position. If you consider the multitude of available reconstuctions of temperature it does not appear the rate of change is unprecendented…

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    1. Byron Smith
      Byron Smith is a Friend of The Conversation.

      Ministry assistant, ecologcal ethicist and PhD candidate at University of Edinburgh

      In reply to James Szabadics

      Check the x-axis. Nothing like a 1ºC change within 100 years is represented by anything on this graph (remember that the colours are local records, the black line is a (non-peer-reviewed)* reconstruction of a global temp). And since we are heading to something like another 3-5ºC in the next 90, then this is like nothing before experienced by human civilisation, indeed, like nothing before experienced by humanity.

      *BTW, "the average shown here should be understood as only a rough, quasi-global approximation to the temperature history of the Holocene"

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    2. James Szabadics

      BSc

      In reply to Byron Smith

      Byron,

      the data is smoothed to 300 year resolution, because for paleo records the noise on 100 year resolution is too great. This in itself is a good reason to cautious with any claim the current changes exceed past events. I also pointed you another reference regards ice age to holocene transition. I'll add another here and appreciate your comment:
      http://www.pnas.org/content/97/4/1331.full

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    3. Byron Smith
      Byron Smith is a Friend of The Conversation.

      Ministry assistant, ecologcal ethicist and PhD candidate at University of Edinburgh

      In reply to James Szabadics

      Sorry to miss this earlier. And to have missed your second paper (I neglected to click "read more" on your comment).

      The PNAS article is very, very interesting paper. And by "interesting", I mean deeply alarming. If anyone wanted evidence of the potential non-linear responses of the climate system to even relatively modest forcings, then here it is. That study puts very serious questions to those who think that changes are likely to be small, slow and benign. The forcings involved in these changes…

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  6. Marc Hendrickx

    Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

    Andrew, I'm interested in your explanation for the apparent massive change in the MWP that saw a 0.5 degree temp increase produced by a mere 5ppm increase in CO2 levels. Based on the figures in your Figure 6 above, if the same level of sensitivity is applied to the modern warm period, for a rise in CO2 of 112 ppm we should currently be at a temperature of about 11.2 degrees C above the MWP. And we seems we are not!
    Is this due to the high level of Sulphur that China is currently emitting?
    Or is something else wrong with your picture?

    The implied range in sensitivity in your figure 6 is between 0.38 to 10 degrees C per 100ppm change in CO2.

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    1. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Marc Hendrickx

      Still waiting for you Andrew. It seems your Figure 6 breaks the back of your own argument.

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    2. Peter Lang

      Retired geologist and engineer

      In reply to Marc Hendrickx

      Yes, I am interestred in Andrew's answer to this question too.

      I am wondering if Figure 6 suffers from the problem of comparing rates of change over different durations. A rate of change over 1 year cannot be compared with a rate of change over 100 years. Similarly, a rate of change over 100 years cannot be compared with the average rate of change over 1000 years. For this reason, I think the Figure 6 is meaningless.

      I'd also refer Andrew to this article which explains "How IPCC invented a new calculus": http://sites.google.com/site/globalwarmingquestions/howtheipccinventedanewcalculus . I'd suggest Andrew's Figure 6 is another example of "IPCC's new calculus".

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  7. Andrew Glikson

    Earth and paleo-climate scientist at Australian National University

    Origin of the Medieval Warm Period:

    As summarized on the basis of the peer review literature using multiple temperature proxies (IPCC AR4 2007 www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter6.pdf Figure 6.13 and related information):

    The figure indicates:

    1. Solar insolation levels during the MWP of between 900 - 1400 AD are high - up to +0.5 to +1.0 Watt/m2 above those of ~1500 AD.

    2. The temperature spike during this interval is approximately 0.3 - 0.4 degrees Celsius above…

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    1. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Andrew Glikson

      these numbers don't gel with your figure 6 Andrew, What's up with that?

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  8. Trevor Ellice

    Geologist

    I'm speechless bit suffice to say I sure glad I do not to have to study under you guys these days - still I guess there are some real geos left like Plimer and Carter. THe carbon paradigm just runs too deep doesn't it. THe idea of the anthropocene to me rates as a massive conceit. I get the feeling mother earth will shake off good ol genus homo like a dog does so-many fleas. If the average life of a species is say about 1million years, Gaia has only 900k years to put up with us. I think she will cope - don't you?

    To be fair however the graph re the extinctions - boy does that need some further study as I have seen these type of things totally debunked - are these all insect species? I could understand if it was biomass, maybe?

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  9. Marc Hendrickx

    Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

    Andrew,
    I'm interested in your figures for carbon addition during the PETM. K. Panchuk et al (ref below) indicate a "6800 Pg (6800Gt) C pulse is the smallest modelled that dissolves enough CaCO3 to reasonably reproduce observations". You use a low figure of 2000GtC. Perhaps it would be fairer on your readers if you correctly indicated the uncertainty in this figure and the bearing it has on climate sensitivity.
    Note that the high temps of the PETM were matched during the Eocene Optimum. Life survived…

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    1. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Marc Hendrickx

      Sadly no response from this by Glickson

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    2. Peter Lang

      Retired geologist and engineer

      In reply to Marc Hendrickx

      Marc,

      Andrew likes to talk only about the subjects he likes to talk about. He doesn't like to discuss matters that, if he did, might throw doubt on his belief in his beliefs. That is why he never answers my questions either. And that is why I keep pointing out that once a scientist becomes and advocate for a cause, he/she loses their ability to be objective.

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  10. Alex Cannara

    logged in via Facebook

    Byron says: "...us who have grown up in the last six decades or so, the rate of change in human society and the natural world seems normal"

    Really? Being from the US, NJ in particular, my decades have been illuminated by vast changes in both the environment and the technology I modestly contribute to myself.

    Byron also admits to not reading the literature, but is willing suggest that total species counts are far lower than previously estimated -- less than "100 million" and more like "10…

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    1. Byron Smith
      Byron Smith is a Friend of The Conversation.

      Ministry assistant, ecologcal ethicist and PhD candidate at University of Edinburgh

      In reply to Alex Cannara

      Alex, I'm afraid you seem to have got the wrong end of the stick. I am in no way saying that the present rate of biodiversity loss is anything short of horrendous and one of the gravest moral failures of humanity (facing plenty of stiff competition!). I did say that whatever the precise figure, it is "catastrophically fast".

      I did not say that I do not read the literature. I said I am not an expert and have not read "widely" in the field. I do try to follow major developments, though this is not…

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  11. Peter Lang

    Retired geologist and engineer

    Andrew Glikson is an advocate for Alarmist causes. He continually preaches "catastrpophe ahead" abd "end of the Earth" scenarios. he holds strongly anti-nuclear causes and is a strong advocate for anti nuclear propoganda. Similarly, he preaches climate catastrophe.

    But he continually dodges answering questions he does no like to answer. Here are some examples of question he continually dodges:

    1. Given that the planet is in a coldhouse phase (rarely has it been this cold in the past 500…

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    1. Peter Lang

      Retired geologist and engineer

      In reply to Peter Lang

      Sadly, no response to these questions by Dr Andrew Glikson. But that is par for the course for advocates for a cause. They do not answer the questions they doo not like.

      Andrew frequently complains about CAGW "deniers and sceptics". He laments that so called "climate scientists" are not trusted. But when they display this habit of avoiding the questions they do not want to answer, of course they are not fully trusted. So called "climate scientiest" who are advocates and activists for a cause, who will not answer questions directly and who provide devious and not fully honest answers, are the reason they are losing credibility.

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  12. Andrew Glikson

    Earth and paleo-climate scientist at Australian National University

    Survival of humans and large mammal under tropical and above-tropical climates.

    Studies by Steven Sherwood (University of NSW), Matt Huber, Bob Beale and other regarding the effects of tropical and humid above tropical climates (termed "wet-bulb tempratures") on the human body demonstrate the following:

    http://www.science.unsw.edu.au/news/global-warming-heat-stress/
    Global warming heat stress could make life intolerable: study By Bob Beale, May 4, 2010:

    "Heat stress would make life intolerable…

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  13. Shirley Birney

    retiree

    From a layperson’s perspective, it disturbs me again to see that geologist/palaeontologist Dewey McLean and his hypothesis (1981) suggesting heat stress on animal embryos from Volcano-Greenhouse/carbon perturbations is fairly well dismissed in the literature while Alvarez’s asteroid theory receives a good deal of attention.

    “Dewey McLean who proposed the Deccan Traps volcano theory in 1981, said the fossil leaf database that Upchurch and colleagues used for their analysis is too small to accurately…

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    1. Andrew Glikson

      Earth and paleo-climate scientist at Australian National University

      In reply to Shirley Birney

      Shirley,

      A 2010 US Geological Society conference, including a larg enumber of impact science specialists, examined the origin of the KT boundary in much detail, concluding as below (Science 5 March 2010: Vol. 327 no. 5970 pp. 1214-1218 DOI: 10.1126/science.1177265)

      The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary

      Peter Schulte1,*, Laia Alegret2, Ignacio Arenillas2, José A. Arz2, Penny J. Barton3, Paul R. Bown4, Timothy J. Bralower5, Gail L. Christeson6…

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    2. Shirley Birney

      retiree

      In reply to Andrew Glikson

      Thank you Dr Glickson and Caroline for your intriguing insights into the K-T extinctions. I imagine it would be difficult to argue with such an impressive array of reputable researchers on the bolide theory coupled with the depositions of iridium.

      Poor old Dewey - I wonder if he’s still with us?

      Nevertheless, Gerta Keller, leader of the Princeton U team’s most recent investigations of the K-T extinctions, adheres to a “one-two punch” theory in that multiple meteorites struck the earth around…

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    3. Andrew Glikson

      Earth and paleo-climate scientist at Australian National University

      In reply to Shirley Birney

      Shirley

      Thank you for your comprehensive comments - showing you are well acquainted with the literature on the KT extinction and related issues.

      Keller assumed the deposits which overlie the Chickxulub crater are normal end-Maastrichtian sediments, since they contain forams of this age and occur below the Iridum-rich impact marker, hence her preference for a double impact. However, other studies have shown that these sediments are tsunami deposits which follow the impact, containing reworked…

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  14. Caroline Copley

    student

    This interesting article coincides with some discussion going on in the Conversation about the "tipping point" where some comments have linked the Permian volcanics causally to the southern Asteroid. I am trained in the biological sciences and not geology, but am familiar with the K-T asteroid event, which is of course the accepted scientific paradigm. HOWEVER the extinctions surrounding that occurred over a long period of time which is well known, therefore such an "act of God" seems unlikely…

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    1. Peter Lang

      Retired geologist and engineer

      In reply to Caroline Copley

      Caroline Copley

      You ask lots of good questions. But many are at the level that I call “down in the weeds”. Some do start with a big picture view of geological time scales.

      I’d suggest it is best to ‘book end’ the problem first, before drilling down into the detail. Some refer it to “start with the satellite view” (or the helicopter view, or start with the large scale aerial photos and drill down, depending what era you worked in).

      If we do start by ‘book-ending’ the problem I suggest…

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  15. Andrew Glikson

    Earth and paleo-climate scientist at Australian National University

    The best way for clarification of questions arising from the article is to refer to the peer reviewed literature.

    I have already provided answers to a number of questions, including:

    1. The nature of the Medieval Warm Period.
    2. The survivability of humans and mammals under extreme tropical conditions of "wet bulb" tempratures.

    Many/most clarifications of other issues are in references indicated in the article, including the comprehensive peer review-based IPCC AR4 Paleoclimate chapter (chapter 6):
    www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter6.pdf

    Further questions can be clarified where raised.

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    1. Peter Lang

      Retired geologist and engineer

      In reply to Andrew Glikson

      Avoidance!

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  16. Andrew Glikson

    Earth and paleo-climate scientist at Australian National University

    Marc writes:

    "I'm interested in your explanation for the apparent massive change in the MWP that saw a 0.5 degree temp increase produced by a mere 5ppm increase in CO2 levels. Based on the figures in your Figure 6 above, if the same level of sensitivity is applied to the modern warm period, for a rise in CO2 of 112 ppm we should currently be at a temperature of about 11.2 degrees C above the MWP. And we seems we are not! Is this due to the high level of Sulphur that China is currently emitting…

    Read more
    1. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Andrew Glikson

      Andrew,
      Glad to extract an admission from you that there's more to climate change than Co2!

      You still choose to directly answering the following....
      1. I'm interested in your figures for carbon addition during the PETM. K. Panchuk et al (ref below) indicate a "6800 Pg (6800Gt) C pulse is the smallest modelled that dissolves enough CaCO3 to reasonably reproduce observations". You use a low figure of 2000GtC. Perhaps it would be fairer on your readers if you correctly indicated the uncertainty…

      Read more
    2. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Marc Hendrickx

      Should read "You still choose to directly AVOID answering the following.... "

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  17. Marc Hendrickx

    Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

    Dear Editors of The Con,
    Thought this might be of interest (link below). Judy Curry's level headed statement
    “Based upon the background knowledge that we have, the threat does not seem to be an existential one on the time scale of the 21st century, even in its most alarming incarnation.” seems worthwhile broadcasting and acts as a counterpoint to the alarmist arguments put forward by Lewandowsky and Glickson on The Con recently. Curry of course unlike your two pretenders is a working climate scientist. Perhaps you can provide an answer as to why this academic's view is not acceptable at The Con.

    On climate change The Con has definitely fallen into the ABC trap. Groupthink reigns. Prove me wrong.

    http://oilprice.com/The-Environment/Global-Warming/The-IPCC-May-Have-Outlived-its-Usefulness-An-Interview-with-Judith-Curry.html

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    1. Shirley Birney

      retiree

      In reply to Marc Hendrickx

      “The Earth’s carbon cycle is not a topic on which I have any expertise” (Judith Curry - 22 September 2011)

      He who obscures Curry’s statement from the readers’ gaze is bound to engage in tomfoolery.

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    2. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Shirley Birney

      And you think Andrew Glickson has that expertise?

      Andrew Glickson, who would you say is more qualified as an authority on climate change Prof. Judy Curry, or yourself? and why?

      See the following link for Judy Curry's CV:
      http://curry.eas.gatech.edu/currycv.html

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    3. Shirley Birney

      retiree

      In reply to Marc Hendrickx

      “I am no expert in logic. My only formal exposure was a course in freshman logic nearly 40 years ago. In the past few years, I’ve wandered randomly through the Wikipedia and the Stanford Encyclopedia of Philosophy.” (Judith Curry)

      30 October 2011: “Climate change presents us with a pressing challenge. A global consensus accepts that human activity is responsible for climate change and its associated dangers. Our challenge is not to consider whether there is climate change, but how best to…

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    4. Marc Hendrickx

      Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

      In reply to Shirley Birney

      "And you think Andrew Glickson has that expertise?"

      Shirley, I'll take your obfuscation and misdirection as a definite No.

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  18. Trevor Ellice

    Geologist

    I respectfully put it to Andrew G that given wet bulbs like that one would expect some thunderstormogenesis, clouds, sunblock and a cool down. I cannot believe you expect these arguments are credible. You seriously believe a naked ape, that can run down a gazelle, because a gazelle cannot regulate it's heat as well as a bushmen is gunna overheat at the tropics - c'mon. The sense check is missing here.

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  19. Holly Luland

    Undergraduate in Conservation Biology (3rd)

    Many a disgruntled geologist

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