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Do high levels of CO2 in the past contradict the warming effect of CO2?

What the science says...

Select a level... Basic Intermediate

The Ordovician glaciation was a brief excursion to coldness during an otherwise warm era, due to a coincidence of conditions. It is completely consistent with climate science.

Climate Myth...

CO2 was higher in the past

"The killer proof that CO2 does not drive climate is to be found during the Ordovician- Silurian and the Jurassic-Cretaceous periods when CO2 levels were greater than 4000 ppmv (parts per million by volume) and about 2000 ppmv respectively. If the IPCC theory is correct there should have been runaway greenhouse induced global warming during these periods but instead there was glaciation."
(The Lavoisier Group)

Geologists refer to ancient ice-cap formations and ice-ages as "glaciations." One such glaciation that occurred during the Late Ordovician era, some 444 million years ago has captured the attention of climate scientists and skeptics alike. To get some perspective on timing, that's just over 200 million years before dinosaurs began to roam the Earth.

Unlike other glaciations in the last 500 million years, this one was exceptionally brief (lasting perhaps only a million years or so) but the main reason for generating so much interest recently is because it took place when CO2 levels were apparently sky-high. As Ian Plimer notes in his book, "Heaven and Earth", pp165:

"The proof that CO2 does not drive climate is shown by previous glaciations...If the popular catastrophist view is accepted, then there should have been a runaway greenhouse when CO2 was more than 4000 ppmv. Instead there was glaciation. Clearly a high atmospheric CO2 does not drive global warming and there is no correlation between global temperature and atmospheric CO2."

On the surface, Plimer does seem to have a point: if ice-caps managed to exist back then in an ultra-high CO2 environment, why are the vast majority of climate scientists worrying so much about keeping CO2 levels piddlingly low?

To answer this, we have to fill in some parts of the puzzle that are missing. Let's start with the CO2.

Plimer's stated value of 4000 ppmv or greater is taken from Robert Berner's GEOCARB, a well-known geochemical model of ancient CO2. As the Ordovician was so long ago, there are huge uncertainties for that time period (according to the model, CO2 was between an incredible 2400 and 9000 ppmv.) Crucially, GEOCARB has a 10 million year timestep, leading Berner to explicitly advise against using his model to estimate Late Ordovician CO2 levels due its inability to account for short-term CO2 fluctuations. He noted that "exact values of CO2... should not be taken literally."

What about evidence for any of these short-term CO2 fluctuations? Recent research has uncovered evidence for lower ocean temperatures during the Ordovician than previously thought, creating ideal conditions for a huge spurt in marine  biodiversity and correspondingly large drawdown of CO2 from the atmosphere through carbon burial in the ocean. A  period of mountain-building was also underway (the so-called Taconic orogeny) increasing the amount of rock weathering taking place and subsequently lowering CO2 levels even further. The evidence is definitely there for a short-term disruption of the carbon cycle.

Another important factor is the sun. During the Ordovician, it would have been several percent dimmer according to established nuclear models of main sequence stars. Surprisingly, this raises the CO2 threshold for glaciation to a staggering 3000 ppmv or so. This also explains (along with the logarithmic forcing effect of CO2) why a runaway greenhouse didn't occur: with a dimmer sun, high CO2 is necessary to stop the Earth freezing over.

In summary, we know CO2 was probably very high coming into the Late Ordovician period, however the subsequent dip in CO2 was brief enough not to register in the GEOCARB model, yet low enough (with the help of a dimmer sun) to trigger permanent ice-formation. Effectively it was a brief excursion to coldness during an otherwise warm era, due to a coincidence of conditions.

The following (somewhat simplified) diagram may make this easier to understand:

Ordovician Glaciation

When looking at events such as these from the deep geological past, it is vital to keep in mind that there are many uncertainties, and generally speaking, the further back we look, the more there are. As our paleo techniques improve and other discoveries emerge this story will no doubt be refined. Also, although CO2 is a key factor in controlling the climate, it would be a mistake to think it's the only factor; ignore the other elements and you'll most likely get the story wrong.

Basic rebuttal written by steve.oconnor


Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial

 

Last updated on 6 July 2015 by pattimer. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Further reading

Science magazine have published The Mountains That Froze the World by Phil Berardelli. It explains the work of Seth Young, explaining how the world fell into glacial conditions during the Late Ordovician.

This outstanding lecture by geologist Richard Alley is IMHO considered must-viewing for anyone seeking to understand the role of carbon dioxide throughout Earth's history. The lecture is The Biggest Control Knob: Carbon Dioxide in Earth's Climate History

Comments

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Comments 51 to 100 out of 103:

  1. In my naivistic view of the things science is something that should serve to the people, should improve their quality of life, and should reduce the risks of getting into 'a dead end street'. CO2 is a dead end street from any point of view. Isn't it better to avoid entering this street at all instead of wondering what to do when we come to the 'dead end'. What kind of a science would teach us to close our eye when the disaster of climate change strikes on us? What kind of a science would teach us not to pay attention to the raising acidity of the oceans? What kind of a science would encourage us to expose to risk the only breaks we have so far against CO2 (the plants) and what kind of a science will have no idea of how to proceed (to hinder the processes at least)? Believe it or not but the increase of CO2 in the air (and in the ocean) could not improve our quality of life from any point of view. RE: This 500 MYA-CO2/Temp. Diagram If I am going to trade at the stock exchange with a million moving average in how many nanoseconds I would be Dead on Arrival? BTW: How does the planet look like at 24-25 deg.C ave temp?! What happens with the climate? Why does the temperature stop rising?
  2. Responding to a comment here: The geocraft cartoon graph rises again, with its ominous "... consternation of global warming proponents". And once again, there is no such consternation. The timing of high CO2 and glacial stage onset is critical - and that was always very tough to do on samples that are 450 M yrs old. So one has to wonder about the accuracy of the chronology shown on the geocraft cartoon. Especially in light of Saltzman 2005: ... the evidence suggests that the ice began to build up some 10 million years earlier than when volcanoes began pumping the atmosphere full of the CO2 that ended the Ordovician ice age. Abstract here. Young et al 2010 adds more to this consternation-busting line of research: The integrated datasets are consistent with increasing pCO2 levels in response to ice-sheet expansion that reduced silicate weathering. Ultimately, the time period of elevated pCO2 levels is followed by geologic evidence of deglaciation. -- emphasis added Full paper pdf here.
  3. I want to make sure I have this right. In a statement such as, "Doubling the CO2 increases the temperature 3 degree C (eventually)" are we talking about doubling the CO2 from pre - industrial levels, doubling the CO2 from what we have now, or what?
  4. curiousd @53, across a wide range of CO2 concentrations, including all those that have been experienced on Earth in the last 600,000 years or are projected under anthropogenic emissions, doubling CO2 results in a 2-4 degree increase in temperature if we ignore slow feedbacks such as melting of ice sheets. The IPCC best estimate for that figure is 3 degrees C.
  5. curiousd, The short answer is "both." The way it works (and remember that 3˚C is an estimate that doesn't apply exactly in all cases, but each case could be a little more or less) any doubling will increase temps by 3˚C. So if temps were at 288˚K at 280 ppm (the pre-industrial level), then if we double that to 560 ppm then we should expect temps to be at 291˚K (add 3˚C). CO2 levels are currently at 400 ppm. This implies that we have already committed ourselves to an equilibrium temperature increase of 1.54˚C, or a new "setting" of 289.54˚C. The planet hasn't reached this temperature yet, but if we held CO2 levels constant starting now, that is the temperature we'd expect the planet to reach. Given that, if we then doubled CO2 levels from the current 400 ppm up to 800 ppm, we should expect to add another 3˚C when the planet reaches equilibrium, for a final temperature of 292.54˚C (289.54˚C + 3˚C)... a total increase since pre-industrial levels of 4.54˚C.
  6. Curiousd, There is a nice article on climate sensitivity here by Dana1981. As Spherica said, short term (perhaps 50-100 years) climate sensitivity is about 3C per doubling. Long term (hundreds of years) is estimated at double that. Usually only the short term sensitivity is discussed. If you care about life in 300 years the picture is worse.
  7. There is an excellent article in Science News about new research to figure out exactly what mix of factors was responsible for the greenhouse gas mix being sufficient to overcome the really faint Sun 2.5 to 3.8 billion years ago (the Archean period).  It even involves fossil evidence of raindrops, to infer raindrop shape and speed!

  8. There is a man who lives close to me who is in the Guiness Book of Records for growing the world's largest vegetables.


    He pumps CO2 into his greenhouse.

    Response:

    [TD] Please read the post "CO2 is Plant Food," and comment there, not here.

  9. roscoe:

    Your point being?

  10. If high CO2 levels of the past ages can be discounted by claiming the sun was 4% cooler back then, couldn't the slightly higher temps today be attributed to the sun being that much warmer than in the past? And not necessarily due to the CO2 levels? To discount levels in one scenario and not the current one? That seems like making the science fit a desired result rather than analysing the science to find the results...just an observation...

  11. Eric...  One simple question. Do you honestly think the entire scientific community is fitting science to a desired result? Or, perhaps, might it be that you haven't yet grasped what the science says relative to your question?

    The first act of skepticism should be to ask a question, as you've done, and then see if you can find the answer. 

    Your comment seems more leading than "just an observation." It sounds more like you're headed off into territory where you are forming conclusions based on a lack of knowledge.

  12. eric...  Next, you need to consider what 4% actually means relative to solar output.

    Our sun is a relatively stable star which varies only ~0.1% over the 11 year solar cycle. Solar irradiance is measured at around 1361W/m^2. Four percent of that is 55W/m^2, which is a significant difference of forcing on the climate system.

    The change in solar forcing since ~1900 is on the order of 0.5W/m^2. So, we're talking about 2 orders of magnitude difference.

    Others can check, but I think I have my figures correct.

  13. eric7866:

    First, solar output, on the largest scale, changes extremely slowly over geological timescales, but is extremely significant when it changes. A few % increase in solar output will, in a billion years or so, render the Earth uninhabitable. So it's no surprise that a few % decrease in solar output going back into the geological past requires an immense amount of atmospheric greenhouse gases to compensate. That said, geologically-significant changes in solar output are not something that has the effects consistent with what we have seen of global warming over the last 150 years.

    Second, today's global mean surface temperatures are cold compared to most of the Phanerozoic. (Although given sufficient unabated warming our species may yet have the opportunity to experience surface temperatures consistent with, say, the Late Cretaceous).

    Third, if you think that scientists studying present and paleoclimates are "discounting" any forcing agent in any situation, you are simply mistaken.

  14. "Periods of low CO2 coincide with periods of geographically widespread ice ... This leads to the concept of the CO2-ice threshold - the CO2 level required to initiate a glaciation."

    Sorry for my ignorance, CO2-ice threshold... my understanding is we are around 490 CO2 equivalent right now... Is the converse of deglaciation the same 'number'? Am I also correct that the current 'number' is 500?

  15. Current CO2 is 400ppm, not 490ppm. 500ppm for sufficiently long period of time (1000s of years) is postulated to be enough for it to be more or less ice free at poles, (though Antarctica would likely retain some ice as much higher in altitude than north pole). Note that in Pleistocene we have ice age cycle driven by Milankovich cycles. In Pliocene, there was no such ice age cycle although the Milankovich cycle was almost certainly present (driven by earth orbital mechanics) and CO2 was around 400ppm and solar input roughly the same.

  16. Should have checked before commenting. There is evidence of Milankovich cycles operating in Pliocene and moderating the size of the West Antarctica ice sheet. See here. The milankovich forcing seems to have been operating since at least Oligocene (see here) but in the without low CO2, they did not precipatate ice ages. At 500ppm, our climate would likely be similar to the warmer Miocene.

  17. @ 65

    I'm interested in this comment:

    500ppm for sufficiently long period of time (1000s of years) is postulated to be enough for it to be more or less ice free at poles, (though Antarctica would likely retain some ice as much higher in altitude than north pole).

    How did you come across that idea may i ask?

  18. ooh, also how does comment 66 alter things?

  19. @ 54,

     What happens to the sensitivity predictions if we include the slow feedback of melting ice sheets?

  20. Ravenken @64.

    I feel scaddenp @65/66 is a little quick converting your measure ppm CO2(e) into ppm CO2.

    The use of CO2(e) as a measure of climate forcing also has to take on board the anthroprogenic negative forcings which are less well defined but which will (indeed, can only) reduce the CO2(e) figure.

    The net forcing equivalent to that during time past when CO2=500ppm is a good start point for considering when the globe would lose the southern ice cap. The northern one is more suseptable to increases in temperature. The IPCC suggest in this SLR graphic that a temperature rise above pre-industrial of ≈1.5ºC would see Greenland melt down. (Mind, the ≈ is a worry.) And as the summit drops to warmer altitudes, it would become a tipping point and irreversable outside a renewed ice age. So if Antarctica is 500ppm, Greenland would be 400ppm.

    Of course these are very slow multi-millenia processes. The forcing from methane etc and also the negative forcings are short-lived compared with CO2. And even CO2 will drop over such long time periods. But then melting the very last snow flake on the planet (or just in the NH) is not some target we should be taking as something to avoid. We will be in deep deep do-do far far earlier than the arrival of an ice-free hemisphere or two.

  21. MA Rodgers. Whoops! I did indeed miss the CO2(e). Good point. On that basis, we would indeed be heading for Miocene-type climate (eventually).

    Bozza - based on past climate with assumed similar net forcings. It takes a very long time for icecaps for melt and change in albedo would be very slow till nearly gone.

  22. Until the Faint Young Sun Paradox is resolved we cannot claim that the geological record agrees with holocene climate models.

    Response:

    [PS] You need to tell us more about what you mean. The faint young sun paradox concerns solar output billions of years ago and irrelevant to the holocene. Greenhouse gases give us a good resolution to the paradox from what can be construed about past atmosphere so what is that you think is unresolved of relevance here?

  23. LETS DEBUNK THE GRAPH:

    What sceptics think it shows:

    There is no correlation between temperatures and C02 and that c02 levels was higher in the past, like hundreds of millions of years ago (thus arguing that todays c02 level is nothing to worry about).

    ____________________________________

    But why is there no correlation between c02 and temperature on the graph? Are there another major driver of temperature than C02? And this is so ironic; Deniers favorite mantra is "Its the sun", but what do they do? LOL..

    They use a graph which do not include the sun.

    The assertion that only CO2 drives temperature it's as much a logical falacy as the sun being the only driver of temperature though science considers both. Its amusing that deniers, who say it's the sun which drives the climate, do not consider the sun when they try to demonstrate there is no correlation between CO2 and temperature.

    (The effects of today's global warming are felt by societies and existing ecosystems adapted to the Holocene climate in OUR TIME - NOT the climate and CO2 levels that existed hundreds of millions of years ago.)

    But anyway, can you see the name in the bottom left corner?

    It says C02 after Robert A Berner 2001. Hmm...OK..it refers to a study.

    Lets check this study and see what it says about c02 and temperatures:

    GEOCARB III: A REVISED MODEL OF ATMOSPHERIC CO2 OVER PHANEROZOIC TIME - ROBERT A. BERNER and ZAVARETH KOTHAVALA 2001

    citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.393.582&rep=rep1&type=pdf

    On page 201:

    "Thus, exact values of CO2, as shown by the standard curve, should not be taken literally and are always susceptible to modification. Nevertheless, the overall trend remains. This means that over the long term there is indeed a correlation between CO2 and paleotemperature, as manifested by the atmospheric greenhouse effect"

    WOW. The man behind the C02 graph says there IS a correlation between temps and c02, which is the opposite of what Patrick Moore claims and what deniers thinks of the graph. Berner also confirms the greenhouse effect, which is basic physics many deniers refuse to believe in.

    Full debunk of the graph:

    www.realclimate.org/index.php/archives/2014/03/can-we-make-better-graphs-of-global-temperature-history/

    Can we make better graphs of global temperature history?

    YES, THERE IS A CORRELATION BETWEEN C02, THE SUN AND TEMPERATURES:

    stephenschneider.stanford.edu/Publications/PDF_Papers/shaviv-veizer-03.pdf

     

  24. Poholer54 discusses this from about 3:32.

    https://www.youtube.com/watch?v=FBF6F4Bi6Sg&t=966s

  25. First of all, I do not believe "CO2 does not drive climate". Beside, the word "drive" is way too vague in this context and can easily be used to smuggle in a whole host of possible interpretations the author possibly didn't have in mind at all.

    I prefer classical terms like "correlation" and causation". Let's rephrase the question now:

    We know this planet has experienced CO2 concentrations in the past that exceed the current levels by a magnitude without triggering a runaway greenhouse effect. Now you're making 2 claims:

    1) those, much smaller concentrations will cause a runaway greenhouse effect, and

    2) you can be certain you can understand all the processes and factors involved to such a degree that you can model the mechanism of triggering the runaway effect (I'm not talking about the model predicting the avreage temperatures).

    Those are really, really extraordinary claims. I hope you agree with that assessment. And if so, you already know what I will say about proof levels required.

    If you say, we can't be certain, but the risks involved are too high, thus worth taking seriously, I have no problem with that... but that's not my question.

  26. Norm. First off, no scientist that I am aware of is claiming the putting CO2 into atmosphere could cause a runaway greenhouse. Certainly the consensus opinion is that there is no possibility of a runaway greenhouse. This is a strawman argument. It is best when making a claim that "science is wrong" that you cite science claim that you are disputing. This avoids timewasting with strawman arguments.

    Will adding more CO2 increase temperature? Yes, just a plainly as increasing output from the sun would increase temperature. You can measure it directly. However, figuring out how much it will rise depends on feedbacks which are much harder to determine hence the wide error bars on constraining climate sensitivity. See here for more on runaway feedback

    Reading the IPCC WG1 report or at least the summary for policy makers would help you in understanding what claims the science is actually making.

  27. It would be good to see an explanation of something other than the Ordovician here... the Earth then was so different in a lot of important ways it's difficult to trust any conclusions. What about Cretaceous or Paleogenic Earth? The CO2 levels then are more comparable to where we are headed, and geological and biological factors are likely more similar. 

  28. I am skeptical of the authors conclusions: the argument is that "coincidence of conditions" counteracted the CO2's warning effect at such high levels, at the period in question. But the levels of CO2 are being doubted due to large uncertainties in the extremely ancient evidence, yet the same, if not more, uncertainties exist for the "coincidence of conditions" due to the extremely old evidence. There's lots of evidence to make one skeptical about climate science assertions, not the least of which is all the hysteria around the subject.

  29. Warend @78,

    Ancient evidence can obviously come with uncertainties that can be very large. However you are wrong to suggest that the argument that CO2 levels dipped in the Late Ordovician rests solely on "large uncertainties" or in other words "we don't know that it didn't dip."

    There is evidence cited (Young et al 2008) in the Intermediate version of the OP above showing that, prior to the Late Ordovician, CO2 was high due to high levels of volcanism but not very high due to high levels of rock weathering. And the evidence shows the high levels of volcanism stopped before the rock weathering ended causing CO2 levels to drop to below 3000ppm, a level which would allow glaciation with the weaker sun. This is the "coincidence of conditions" mentioned in the OP summary.

    And the scientific work has continued through the years allowing a more detailed understanding of the events that created the Late Ordovician glaciation. See for instance Ghienne et al (2014) or Pohl et al (2016). Past uncertainty is today reduced to the point of no-longer being uncertainty.

  30. How do you know for certain the sun was "weak" at this period of time? What level of uncertainty has been determined for these studies conclusions. I can assert that - we do not know for certain what happened so long ago, and we do not know what level of uncertainty we are working with. How do you suggest calculating the mathematical level of uncertainty for occurances so far in the past?

    Response:

    [PS] bombing multiple comment threads with weak comments is verging on sloganeering. Stick to where you have the problem, engage with other commentators and move on when resolved please.

    The sun early output is from basic physics of its state as a main-line star. I am unaware of any serious doubt on the physics of stellar evolution that would challenge that conclusion.

  31. I am not challanging the theory or formulations that compose stellar evolution models. But what are the degrees of uncertainty or variance between calculated model results and actual stellar luminosities over time. Because of the time scales this cannot be done directly with observations over time. Looking at published solar luminosities the solar intensity was 11% less during the start of the glaciation event...assuming a 25% forcing contribution due to solar radiation this yields a nominal forcing effect of ~3%. But again what's the uncertainty...I so far have not found a published value. This is understandable given the time frames and the current impossibility to conduct validating experiments. There was some mention of errors in the range of 10 to 15%. If that is the degree of uncertainty in the stellar model results, that would say that there is too much uncertainty relative to the nominal effect. Perhaps there are similar uncertainties, and effect level magnitudes, with the other coincidental conditions/effects?

  32. Warend @81,

    You state that published solar luminosities show "the solar intensity was 11% less during the start of the glaciation event." That seems very high. Are we talking about the same "glaciation event"? Perhaps you could point to the publications you cite. A simple Wikithing reference gives Fig 1 from Ribas (2009) below which suggests a reduction of slightly under 4% in solar intensity for the Late Ordovician.

    I also fail to follow your assessment of that 11% reduction of solar forcing. Perhaps you could set out a more detailed assessment.Ribas (2009) Fig 1

  33. According to this recent study we have a way more accurate view on this issue now:

    Schwark2019

    In the Hirnation Event Summary:

    "Massive perturbations of the atmospheric and hydrosphericcarbon cycle occurred with CO2concentration varying between 8-16 x PAL and near PAL over short periods of time." PAL means Present Atmospheric Level.

    This is quite remarkable, it tells us that a glaciation is capable to absorb even CO2 ammounts of 6000ppm. It does not matter how high CO2 Levels are, a glaciation will happen when the following event occurs:

    Sufficent Landmasses within the Polar Circles (LPC).

    Going through all time periods, we can show how decisive landmasses at the polar circles are. Note that the polar circles represent a very narrow area at the north and south borders on these pictures. Greenland todayis a good example as it forms the only northern ice shield, mainly being within the arctic circle, while edging Canada and Russia are not inland iced.

    Cambrian warm period, Landmasses in the Polar Circles (LPC): 0%-10%

    Cambrian

    Ordovician hirnantion glacial event antarctic LPC 100%:

    HirnantionEvent

    Silurian cold LPC antarctica 90%:

    Silur

    Devonian warming LPC 10% - 40% :

    Devon

    Carboniferus glaciation, Continents drop back to the south pole antarctic LPC: 90%-100%

    Karbon

    Permian Cold with late permian transition towards mesozoic Pangea arctic LPC 80% - 100%:

    Perm

    Triassic warming, antarctic PLC 10%-20%, arctic PLC 70% to 90%. only Southern PLC decisive? Arctic inland ice forming reversed with the jurassic? Triassic north pole contradicton.

    Trias

    Jurassic, Landmasses moved away from the arctic cycle. arctic LPC 10%-20%. antarctic LPC 5%-10%.

    Jura

    Cretateous, sea level rise noticeable, deglaciation at its maximum, transition to upcoming glacial period, Antarctica moving south. Antarctic LPC 80%-100%:

    Kreide

    Today, Cenozoic glacial period Antarctica resting at the pole once again. Greenland LPC 10% -20%, Antarctica 90%-100% LPC.

    With an Ockham attempt i want to make 3 main arguments on why CO2 is not needed and not likely to play any thermal role at all:

    1.Faint Sun Paradox,Snowball Earth and the Hot House Equilibrium.

    The faint sun paradox is not a paradox. It is another evidence of how strong the terrestial force Ice Albedo is and therefore again the continental distribution.

    Even with a 25% lesser sun, Oceans occur,hence the term "paradox".While precambrian snowball effects due to a supercontinent at the south pole, demonstrate the lesser sun effect.

    The so called paradox underlines the trumendos forcings of Albedo and it describes the fundamental drive towards a hot house equilibrium whenever the poles are uncovered by land.

    This Basic heating Trend that is strong enough to even compensate the faint sun paradox puts CO2 further away from having any thermal influence. This basic heat trend is documented by all the terminations of glacial epoches and even more so in the precambrian, with a barrier where no more heating seems possible.

    So we keep in mind that we have a Glacial period during the ordovician to the early silurian, with Co2 levels around up to 6000ppm.

    2. Carboniferous CO2 Levels

    The carboniferous marks the point where the flora takes an increased influence on CO2 levels.

    T°Co2overview

    The late devonian till the middle carboniferus show how CO2 is absorbed while temperatur takes ~90 mio years to "follow".The reason temperature goes down is as usual, the continental drift towards the south pole.

    What we eventualy see is a double decline in CO2.

    The jurassic-cretaceous meeting of CO2 and temperature speaks for itself.

    3. Today,GISS and an estimated CO2 sensitivity of 1,5°C

    The uncertenty itself on the CO2 sensitivity after 30 years of research tells us per se that the science is not settled. IPCC on a global warming of <ahref=https://www.ipcc.ch/sr15/chapter/chapter-1/>1,5°C

    "Past emissions alone are unlikely to raise global-mean temperature to 1.5°C above pre-industrial levels (medium confidence)"

    "1.5°C emission pathways are defined as those that, given current knowledge of the climate response, provide a one- in-two to two-in-three chance of warming either remaining below 1.5°C

    or returning to 1.5°C by around 2100 following an overshoot."

    GISS  actualy does show us a trend towards 1°-1,5°C ~2100 a.d. It is the natural interglacial trend. There is no evidence that our warming period is unique in its rate of warming compared to past medieval epoches

    or to the past 11 Interglacials in our ice cores

    The lowest model called the "russian model"

    What is with Planck and Bolltzmann? my guess is Lüdeckepage19
    and others are right, the saturation is already reached at PAL with 1°C

    Since the Ordovian showed how much CO2 can be absorb in the oceans, acifidication of the ocean  due to human emissions might be the bigger threat. Even though most of the CO2 was embeded in limestone, hence the CO2 "starvation".

     

    Response:

    [DB] Off-topic snipped.

  34. Nyood,

    your presentation of items is jumbled or durcheinander, as the Germans say.  It would be helpful if you could make a succinct summary of the information you wish to convey for this particular thread (and not a Gish Gallop of disparate items belonging to many different threads).

    Please note that the Ordovician sun was about 3% fainter than the modern sun.  The "25% lesser sun" belongs to the very early life of the planet Earth.

    You seem to be suggesting that atmospheric CO2 has no effect on planetary surface temperature.  But that goes against all modern science ~ but still, if you are serious in stating it, then you should present your argument in the appropriate thread here in this SkS website.

  35. Ok i will try to be more structured with future comments.

    You seem to confuse cambrian and precambrian in your criticism. The precambrian is a superaeon before the cambrian era, also called Cryptozoic. Therefore i was talking about the maximum value of a 25% dimmer sun, One of the snowball effects i refered too happend very early in the hadian, the younger double snowball event happen way closer to the cambrian.

    <a href="https://en.wikipedia.org/wiki/Geologic_time_scale"> WikiGeoTime</a>

    Yes my conclusion statement stays:

    The only thing that will cause earth to leave the glacial period of the cenozoic is when Antarctica will move away from the south pole once again.

  36. Nyood @85 , thank you for that comment: <"The only thing that will cause earth to leave the glacial period of the cenozoic is when Antarctica will move away from the south pole once again.">

    I think it is not controversial that Earth will remain in an ice age for a very long time (ice age defined as Earth having substantial ice at one or both poles).

    Even during the warm Eemian period, there was polar ice in the Scandinavian region (at least) plus the huge amount of land ice on the Antarctic continent.

    A small rise in temperature (from today's) might fully melt Greenland ~ but that would likely take  >1000 years.   Still, most of the East Antarctica ice sheet will survive.

    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.

    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].

    All this, within the lifetime of children born in 2019.

  37. "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.

    Response:

    [DB]  Please re-read the entire post before commenting.  As the post notes, CO2 is not the only driver of climate.  No climate scientist makes any such assertion.  So you tilt at windmills of your own building.

    Relevant to this discussion:

    "The evolution of Earth’s climate on geological timescales is largely driven by variations in the magnitude of total solar irradiance (TSI) and changes in the greenhouse gas content of the atmosphere.

    Here we show that the slow ∼50 Wm−2 increase in TSI over the last ∼420 million years (an increase of ∼9 Wm−2 of radiative forcing) was almost completely negated by a long-term decline in atmospheric CO2. This was likely due to the silicate weathering-negative feedback and the expansion of land plants that together ensured Earth’s long-term habitability.

    Humanity’s fossil-fuel use, if unabated, risks taking us, by the middle of the twenty-first century, to values of CO2 not seen since the early Eocene (50 million years ago).

    If CO2 continues to rise further into the twenty-third century, then the associated large increase in radiative forcing, and how the Earth system would respond, would likely be without geological precedent in the last half a billion years."

    Foster et al 2017 - Future climate forcing potentially without precedent in the last 420 million years

    Foster Figure 2

     

    Off-topic and inflammatory snipped.

  38. 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.

    Response:

    [JH] Links activated.

    For future reference, when you include a link in a post, please activate it by using the "Insert/Edit Link" feature of the Edit Box.

  39. Moderator Response:

    "[DB] Please re-read the entire post before commenting. As the post notes, CO2 is not the only driver of climate.
    No climate scientist makes any such assertion. So you tilt at windmills of your own building."

    There seems to be a  missunderstanding here, apologies for my bad writing in my initial post if this is the reason for the confusion.

    I do not contest that or if CO2 is a sole climate driver. I state that CO2 is no driver at all.

    So let me try to give a summary here again:

    The theory is radical. The two equilibriums glacial period (high landmass ratio within polar circles,high LPC) vs Hot House Effect (HHE),
    are that dominat, they neglect all other drivers. low LPC will result in a HHE no matter what.
    General backround HHE forcing is so effective, all other factors do not matter, the warming rate is always rapid, the transition is always within 100 mio years.
    The second largest factors that still have significant forcing are all factors that relate to albedo foremost ice albedo (dust, ashes, sea level).

    Following Orckham we have several situations where neglecting CO2 makes way more sense than assuming any significant forcing.

    Ordovician high disparity of CO2 and T. Carboniferus CO2 drop way before temperature (T) drop. Jurassic CO2-T meeting. Cretaceous all time highest discrepancy.

    TempCo2History to

    The situations where an explanation for CO2 is needed to justify its assumed forcings, is simply and higly objected by Orckham`s razorblade principle.

    So politely i have to say dito: Please re-read my initial post.

    Response:

    [PS] This is heading way into sloganeering territory. You are selecting only observations that support your ideas and ignoring completely all others. Science does not operate that like. You cannot ignore measured increase in downwelling radiation, conservation of energy, nor explain past climate change with hand-wavy statements that violate physics. If you have a theory that can match all observations, simpler and with better precision than current theory and concordant with laws of physics then by all means publish. Meanwhile, current climate theory is the one that matches Occams razor. No more half-baked sophistry please.

  40. Nyood, the importance of CO2 as a driver of climate, is supported by (A) theoretical calculations [Arrhenius and later scientists]; is supported by (B) experimental evidence; is supported by (C) observational evidence; and is supported by (D) geological evidence.  In other words, the mainstream science developed during the past 200 years.

    The principle of Occam's Razor is a often a helpful guide to thinking : it is not in itself evidence and it is not in itself a method of proof.

    Ockham (or Occam) did not support the cutting off or ignoring of evidence.  Newton and Einstein did not ignore evidence.   Nyood, why do you choose to ignore evidence?

  41. Nyood @89,

    You ask that we roll back to your initial comment here, up-thread  @83 where you begin by quoting from a talk by Schwark & Bauersachs [slides] quoting from its summary:-

    "Massive perturbations of the atmospheric and hydrospheric carbon cycle occurred with CO2 concentration varying between 8-16 x PAL and near PAL over short periods of time." (PAL = Present Atmospheric Level.)

    From this you conclude the following:-

    "This is quite remarkable, it tells us that a glaciation is capable to absorb even CO2 ammounts of 6000ppm. It does not matter how high CO2 Levels are, a glaciation will happen when the following event occurs:"

    Your conclusion is incorrect on a number of levels.

    (1) The total climate forcing from 6000ppm CO2 is very roughly 40Wm^-2. There is no evidence to suggest that climate was impacted by such forcings (from any source) during the Ordovician.

    (2) According to your cited reference (slides 11 & 14), the period with elevated CO2 significantly above 4000ppm coincides with the Katian, a period of warming.

    (3) The period following the Katian sees falling CO2 and falling temperature. The period of high glaciation during the Himantian sees CO2 estimates dropping to perhaps 1500ppm. Relative to our recent ice ages with 180ppm CO2, the Himantian CO2 forcing would thus be perhaps +11Wm^-2 while the relative solar forcing would be -8Wm^-2.

    (4) Your assertion @89 is that the major forcing of climate is the tectonic positioning of land over polar regions. Yet there was such land over polar regions throughout the Ordovician when these great swings of climate appear suggesting the climate was being forced by entirely different mechnisms.

    I would therefore suggest you have failed to provide any support for your assertion "CO2 is no driver at all."

  42. "(1) The total climate forcing from 6000ppm CO2 is very roughly 40Wm^-2. There is no evidence
    to suggest that climate was impacted by such forcings (from any source) during the Ordovician."

    (1) The first sentence is axiomaticly using an estimated forcing of CO2 and therefore is a statement, though the consequences you state are true (none).
    I state that CO2 forcing is max 1°C, reaching saturation with roughly PAL levels, pretty much always or already.

    The Second sentence is true, the forcings that Do determine climate Temperature (T) are the two equilibrium forces
    hothouse effect (HHE) and high landmass ratio within polar circles (LPC).
    The faint sun paradox (FSP) underlines the strength and dominance of the terrestial forcings by allowing
    the orrdovician-silurian events, HHE - LPC - HHE, to happen within the same T amplitude of all compareable HHE and LPC events untill today.
    Neglecting CO2 and reducing the FPS or -4% TPI, in its forcings.

    On top of that you devaluate some of your own arguments brought up in the coming sections. According to (1) you do not allow yourself any comparison from there on.

     

    "(2) According to your cited reference (slides 11 & 14), the period with elevated CO2 significantly above 4000ppm
    coincides with the Katian, a period of warming."

    (2)This sentence has no expressiveness. HHE is happening anyways before and after the LPC.
    The Katian documents the late transition state towards an LPC, in fact it doubts CO2 as a driver.
    The discrepancy between assumed CO2 forcing and T is underlined by the general high CO2 level in the atmosphere, the planet will reach a glaciation from here on, to develop extreme ice shields despite CO2 levels this high. The FPS is solved as mentioned.
    Furthermore forces mentioned in the Schwarck study explain the Katian warming already:
    " Bodaevent:
    Continental Flood Basalt Province.Alternatively to a bolide impact, LIPs have been postulated as warming triggers."

    The forcing here that matters is Ice albedo reduction due to dust and ashes.
    We can see this again when younger impacts and events causie warming rather then cooling.
    An accumulation of dust and ashes at the poles are the result of a rather quickly cleanse of the atmosphere.

     

    "(3) The period following the Katian sees falling CO2 and falling temperature.
    The period of high glaciation during the Himantian sees CO2 estimates
    dropping to perhaps 1500ppm. Relative to our recent ice ages with 180ppm CO2,
    the Himantian CO2 forcing would thus be perhaps +11Wm^-2 while the relative solar forcing would be -8Wm^-2."

    (3) "dropping to perhaps 1500ppm". The Schwarck study claims PAL up to x6 till x20. Please specify "perhaps"
    and clarify why it is not PAL but minimum PAL x3 according to you. Where are Schwank et.al wrong ?

    Reminding here that the level of CO2 does not matter in the first place unless it is below PAL (max -1°C), using my axioms.

    Again you apply axiomatical values, which are not needed to explain temperatures, you are still using the FSP as a theory support, or to bring it in an equilibrium with
    CO2 forcing, by trying to "ramp up" CO2 to a minimum of 1500ppm. Ironically this opposites many attempts
    that try to lower CO2 to explain why a glaciation happens, despite ~6000ppm before and after the glaciation, in the first place. These views higlight the needs to explain CO2 forcings as assumed (too high).

     

    "(4) Your assertion @89 is that the major forcing of climate is the tectonic positioning of land over polar regions.
    Yet there was such land over polar regions throughout the Ordovician when these great swings of climate appear suggesting
    the climate was being forced by entirely different mechnisms.

    I would therefore suggest you have failed to provide any support for your assertion "CO2 is no driver at all." "

    (4)This is partly true, as strong as it is the Ice has to build up, which happens very quickly in the hirnation, after the Bodaevent.
    The middle to late ordovician is in transition, the continental drift towards the pole is remarkable.
    Which is documented with the Silurian:

    Ordovizium

    Silur

    Furthermore one has to take in account the varying lengths of time periods. The ordovician has been added historicaly,
    it was included in the silurian before, therefore this interesting periods are "staunched".

    Antarctica shows a trend towards having a "drop back" to the south pole, mentioned in the devonian and possible in the jurassic.
    Maybe this happened here too and we need more accurate paleogeorgraphic data.

     

    Answering two other comments here made by other users:

    89.Moderator response:

    "[PS] This is heading way into sloganeering territory. You are selecting only observations that support your ideas and ignoring completely all others. Science does not operate that like.
    You cannot ignore measured increase in downwelling radiation, conservation of energy, nor explain past climate change with hand-wavy statements that violate physics.
    If you have a theory that can match all observations, simpler and with better precision than current theory and concordant with laws of physics then by all means publish. Meanwhile,
    current climate theory is the one that matches Occams razor. No more half-baked sophistry please."

    My theory already has a better explanation with its radical attempt, that is the whole point. This is not "sloganeering" it is just a very radical attempt so it asks for situations where we have evidence that show CO2 as a significant driver, relating to topic.
    I understand that my radical attempt makes it easy for me but i have to insist on the fairness that i am allowed to show that radical assumptions that i made, make more sense then your axiomatical assumptions.
    There is the inherit problem that we eventualy go off topic but i have to ask you at this point which laws and forcings (radiation, energy conservation) are ignored by me in which way ?
    I ignore factors as far as they allow me, hence ockham.
    I insinuate that your axioms make less sence then mine. Your critisicsm lacks precission at this stage, when it comes to why my radical assumptions are not allowed and where they are not concordant with laws of physics.

     

     

    90. Eclectic:

    "Nyood, the importance of CO2 as a driver of climate, is supported by (A) theoretical calculations [Arrhenius and later scientists]; is supported by (B) experimental evidence; is supported by
    (C) observational evidence; and is supported by (D) geological evidence. In other words, the mainstream science developed during the past 200 years.

    The principle of Occam's Razor is a often a helpful guide to thinking : it is not in itself evidence and it is not in itself a method of proof.

    Ockham (or Occam) did not support the cutting off or ignoring of evidence. Newton and Einstein did not ignore evidence. Nyood, why do you choose to ignore evidence?"

    (A) Arrhenius,Planck Feldmann et.al give a frame, it is known that we can not apply CO2 with a clear value (uncertainty). This leads to a Saturation and or Lindzen et.al and therefore inevitable offtopic, as much as i am willing to discuss it.

    (B) same as (A)

    (C) I clame that observational evidence support my theory today: Dramatic CO2 increase with a moderate warming trend. My initial post was rightfully snipped of modern time references as offtopic.

    (D) Geological evidence is the core of the LPC theory.

    Response:

    [DB] Off-topic, sloganeering and inflammatory snipped.

    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can and will be rescinded if the posting individual continues to treat adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Moderating this site is a tiresome chore, particularly when commentators repeatedly submit offensive, off-topic posts, ignores the refutations of others (sloganeering) or simply makes things up. We really appreciate people's cooperation in abiding by the Comments Policy, which is largely responsible for the quality of this site.  The point of commenting is to further the understanding of the science, using credible evidence and citations to credible sources.  Much of what you are attempting to do would be better-placed on other threads (many exist).  Blanket asserting that the greenhouse effect is not well-documented, well-researched and well-understood is an own-goal and a waste of everyone's time.
     
    Finally, please understand that moderation policies are not open for discussion (complaining about moderation that everyone else has little to no issues with rather than simply adhering to the Comments Policy likewise wastes everyone's time).  If you find yourself incapable of abiding by these common set of rules that everyone else observes, then a change of venues is in the offing.

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

  43. Nyood: "I state that CO2 forcing is max 1°C, reaching saturation with roughly PAL levels, pretty much always or already."

    Earlier you said "The total climate forcing from 6000ppm CO2 is very roughly 40Wm^-2"

    That would suggest then that a 40w/sq.m forcing would produce only a 1 deg C change? What published work is this based on? How did you get the 40 W/sq.m value?

    What is your basis for claiming "reaching saturation with roughly PAL levels, pretty much always or already."

    Current forcings are calculated from radiative physics, Iacono and Clough, and many others have worked on that. So what do you mean by "CO2 forcings as assumed (too high)"? AFAIK, these forcings are not assumed, they are calculated on the basis of the physical properties of the gas.

    Response:

    [PS] "And these forcings are not assumed, they are calculated". And directly observed https://www.nature.com/articles/nature14240. ie observations match theory. By contrast we are seeing wild claims from Nyood with no supporting evidence.

    Argument about CO2 saturation belong in this thread. If nyood wants to make that claim, then present the evidence in that thread please.

  44. Nyood

    continuing with my itemized points of post #90 and your itemized replies in post #92 (subsection) :-

    (A)  Your quote: <" ... can not apply CO2 with a clear value (uncertainty)">

    Here, too much is lost in translation.  You will need to make a re-translation of your idea into English, to achieve a meaningful statement.   Secondly: "Saturation" is invalid, and "Lindzen" is (often) invalid.

    (B)  <"(B) same as (A)">  does not make sense as a reply.

    (C)   <"observational evidence support my theory today">   Yes, but only in part. The full picture of observational evidence (on CO2 greenhouse) renders your theory invalid [ungueltig].

    (D)  Geological evidence supports your theory only in part.  The full picture of geological evidence renders your theory invalid.

    Nyood ,

    in my post #90 , the final and most important question (for you) was: "why do you choose to ignore evidence?"  Note the word choose  [waehlen].

    You have not answered that question.  Please do so, carefully and thoughtfully.  It requires using insight [Einblick; Selbstverstaendnis].

  45. nyood @92,

    (1a) To present a value for CO2 forcing without providing evidential support is not axiomatic, either in the sense of it being self-evident or (probably in the sense you intend) unquestioningly-evident. The evidence can be presented should you so wish and, uncontroversially beyond-question, it is correct.

    You yourself present @92 an unsupported evaluation of CO2 forcing, providing a maximum value which appears novel and controversial in the extreme. You fail to present any evidential support which in the circumstance is turning this discussion into a pantomime. Perhaps you could correct the untenable postion you create for yourself by providing that missing evidence.

    (1b) Your confused statements regarding HHE/LPC appear to contrdict the geographical situation as commonly understood, in that the "Land mass" Gondwawa sits static over the "Polar Circle" throughtout this period. You need to consider how it is your LPC appears then disappears within this period when the contition you say causes LPC remains unchanging?

    (2) Your cut-&-paste from the Schwark & Bauersachs slides appears particularly inept as support for your assertion "in fact it doubts CO2 as a driver." If you, for instance, examine Slide 11 you will see your assertion is fundamentally contradicted.

    (3) Here you really do dip into uncomprehensibility. Do note that the Schwark & Bauersachs slides do not ever say CO2 dropped to present atmospheric levels 400-odd million years ago. The statement you misread from Slide 23 says purely that CO2 varied "between 8-16 x PAL and near PAL." The value 1500ppm can be taken from their Slide 11.

    (4) If it is not land at the polar circle that creates your LPC condition; if it is ice-covered land, you do then reqire to explain the forcing that allows the growth/shrinkage of that ice. And in doing so, your theory now lacking the tectonic element, do consider that you are now describing a climate feedback not a climate forcing.

  46. @MA Rodger

    (1a) "To present a value for CO2 forcing without providing evidential support is not axiomatic,
    either in the sense of it being self-evident or (probably in the sense you intend) unquestioningly-evident.
    The evidence can be presented should you so wish and, uncontroversially beyond-question, it is correct.

    You yourself present @92 an unsupported evaluation of CO2 forcing, providing a maximum value which appears novel and controversial in the extreme.
    You fail to present any evidential support which in the circumstance is turning this discussion into a pantomime.
    Perhaps you could correct the untenable postion you create for yourself by providing that missing evidence."

    (1a) The evidence that i imagine you would provide, will all result in the question: What is missing? This is manifested in the fact that you will get no exact value for CO2 sensitivity, despite known elemental spectral laws regarding infrared absorption. In other words: We are still estimating with 1,5°C - 4,5°C per doubling (?).

    The theory that CO2 reaches a "saturation" already, is just the most likely aproach to me. However the forcings of HHE/LPC could be even that strong
    that they shrink down all other factors making them neglectable, not "needing" any other explanation to temperature.

    The major evidence i can deliver here is the fact that the so called saturation for each GHG is one of the known unkwons and that there are countless debates
    on this issue, underlining how unsolved this whole matter is.

     

    "(1b) Your confused statements regarding HHE/LPC appear to contrdict the geographical situation as commonly understood,
    in that the "Land mass" Gondwawa sits static over the "Polar Circle" throughtout this period.
    You need to consider how it is your LPC appears then disappears within this period when the contition you say causes LPC remains unchanging?"

    (1b)  I see no contradiction, in my former post i gave you the 2 links with the continental distribution, matching my theory.(Ordovizium, Silur)

    I see what you are getting at though wih Schwanck slide 11: The pictures with the "paleo glacial reconstruction". They use a static continental distribution here. It is more likely that the continents were merging towards the hirnation. In a larger perspective the continents definetly move  towards the pole, documented by the ordovician with the silurian as a whole. The ice needs to build up and the Boda event interrupted the glaciation process by reducing ice albedo.

     

    "(2) Your cut-&-paste from the Schwark & Bauersachs slides appears particularly inept as support for your assertion "in fact it doubts CO2 as a driver."
    If you, for instance, examine Slide 11 you will see your assertion is fundamentally contradicted."

    What is contradicted here? Slide 11 shows the Boda event and its CO2 emissions, the CO2 does not matter to me, regarding temperature, the factors that matter are albedo reducing ashes and dust.

    If you are refering to this sentence on page 11: "atmospheric emission of large amounts of CO2 and subsequent climate warming, and.."

    Then i can only tell you that Schwarck et.al are using the neglectable CO2 sensitivity axiomata here. The reason why the Katian doubts ´CO2 as a driver´ is because it marks, with all other epoches preceeding the LPC event, the time where CO2 fails to work as assumed. Where should it show its significant forcing if not here?

     

    "(3) Here you really do dip into uncomprehensibility. Do note that the Schwark & Bauersachs slides do not ever say CO2
    dropped to present atmospheric levels 400-odd million years ago.
    The statement you misread from Slide 23 says purely that CO2 varied "between 8-16 x PAL and near PAL."
    The value 1500ppm can be taken from their Slide 11."

    (3) Well, it does not matter to me, if you want it can be 1500ppm, i would not consider that close to PAL though. PAL would just makes sense to me since the ordovician

    is compareable to all other LPC events.

    Near Pal makes sense to me because it would reach common glacial CO2 levels. I have not enough knowledge of solubility.

    Near Pal is enough for me to support the theory when it comes to: All equilibrium events and the transitions inbetween happen in the same fashion, despite varying CO levels.

    "(4) If it is not land at the polar circle that creates your LPC condition; if it is ice-covered land,
    you do then reqire to explain the forcing that allows the growth/shrinkage of that ice.
    And in doing so, your theory now lacking the tectonic element, do consider that you are now describing a climate feedback not a climate forcing."

    The factor that you are missing here is indeed a fundamental one. It is the fact that snow will not accumulate ice sheets on the sea.
    The double proof for this is the arctic sea, with Greenland within the polar circle.

    In fact with your misunderstanding here it makes me wonder if continental drift as a time dependet factor is included in the prognostications and not only be representd by the, in itself correctly implemented, ice albedo.

    In other words:Fundamently excluding a long term factor of warming.

    Response:

    [DB] The topic of this post is the skeptic claim that "CO2 was higher in the past" (which says nothing about why CO2 levels are high today).  It is not about climate sensitivity or CO2 levels being saturated.  Further, you really need to start citing credible sources appearing in the peer-reviewed literature to support your claims.  This is not optional.

    Simply making things up based on your lack of understanding of the topic means that you pre-concede the scientific portion of the discussion and tacitly admit that you are just venturing your opinions on a topic that you demonstrably lack understanding of and that you have not read the threads on the topics on question.

    Off-topic and sloganeering again snipped.  Those wishing to respond to those snipped points, please do so at a more appropriate thread and link back here.

  47. I want to subsequently deliver a source that confirms what i said with: "Snow will not accumulate ice sheets on the sea"  and therefore is crucial to my theory:

    fuBerlinContinentaldrift

    To not falsify anything with my own translation, i google translated this middle part:

    "Ice ages seem to occur only when there is a larger land mass at least at one geographic pole. Snow has to lie on the continents and not fall into the water, so that a snowpack can form in relatively high latitudes and ice can form over time. Once this is the case, positive ice-albedo feedback occurs due to the high positive albedo values of snow and ice, and further cooling occurs."

     

    Response:

    [DB]  As land-based ice sheets grow (due to snowfall gains in their expanded accumulation zones), sea levels fall.  Land-based ice flows towards the continental edges and extends out over the ocean in the form of ice shelves.  Where sea ice forms next to the ice shelves, snow accumulates, both on the ice sheets, the ice shelves and on sea ice.  This point of argumentation is not germane to the topic of this post.  Please stay on-topic.

    Note that a website by itself is not considered part of the primary literature, especially if it does not belong to a primary producer of research information, such as NOAA, NASA or the like.

  48. Noting that atmospheric CO2 levels have been falling since the Jurassic period and was approaching a level that some scientist claim cannot support plant life (150 ppm)...Is it possible that mankind has evolved to SAVE the living planet instead of DESTROY it? Of course, we may well bring about our own distruction and most of the animal life on the planet...But wasn't the earth headed for a cold death? Carbon and oxygen has been locked away in carbonaceous sedimentary rock, coal, oil, and methane gas. Alas, along comes man to extract all that carbon and oxygen from the ground and breathe new life into a dying planet. 

    What are your thoughts? Am I way off base? (I honestly mean no harm and I certainly do not want to start an angry debate...It has just been a curious thought of mine for over twenty years).

  49. Livinginawe,

    You are way off base.  The world was doing fine before humans evolved.  Wiping out a large percentage of all living creatures (both animals and plants) does not count as "saving" the planet.

    Read some of the historical accounts of how much life existed before humans came to a location.  They describe so many fish on the Grand Banks fishery that ships were slowed by running into them and they could be scooped up in baskets from the surface.  There were so many whales in the Gulf of St. Lawerence that the noise of them breathing at night made it difficult for sailors to sleep.

    Life adapts to slow changes.  The problem with AGW is that the change is way to fast for life to evolve (in addition to the many other harmful pollutants humans release).

  50. LivinginAwe @98

    The plants have already adapted to the long term decline of CO2 in earth history. This is why grasses and other C3 type plants evolved. The most sturdy plants are believed to be able to deal with even 50ppm.

    Eventualy all CO2 should be stored in primerly limestone, yet the decline is very steady and it will take many more million years to completly deplete all CO2 if that ever happens. After our ice age, when Antarctica moves away from the pole again, which is expected to happen in ~90 mio years, the ice age will end and the warming oceans will release the "rest" of the CO2 that is still held by them (1000-2000 ppm).

    My take on this is that earth has already experienced these situations, there is a barrier when it comes to warming that saves us from overheating and there is also a barrier when it comes to cooling and CO2 declining that saves life.

    So in a way you are right, CO2 might help our plants and the greening effect is already documented by Nasa, but we do not know how the plants will deal with this sudden increase of CO2 made by us.

    Response:

    [DB]  "CO2 might help our plants and the greening effect is already documented by Nasa"

    According to the most recent research, the Earth stopped getting greener 20 years ago:

    "the vegetation greening trend indicated by a satellite-derived vegetation index (GIMMS3g), which was evident before the late 1990s, was subsequently stalled or reversed"

    Note that this 2019 research paper was published AFTER the 2016 NASA article on that topic and contains later information.

    Further discussion here:

    "The study published yesterday in Science Advances points to satellite observations that revealed expanding vegetation worldwide during much of the 1980s and 1990s. But then, about 20 years ago, the trend stopped.

    Since then, more than half of the world’s vegetated landscapes have been experiencing a “browning” trend, or decrease in plant growth"

    Further discussion of such is off-topic for this thread, but can be pursued here, "CO2 is plant food".

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