Comments 1 to 12:

1. Dale H at 05:43 AM on 26 April, 2021

   I am new to the site but have followed climate change as a hobby for over 15 years. For the record I am not a climate denier and have seen data debunking most of the climate myths listed. I am trying to learn more through facts or strong hypothesis as I have spent the last 30+ years working in the food industry convincing Directors to Presidents with data and models on what is driving their businesses.

   My question is there any information that has caused the change in earths temperatures about 1.2 million years ago? We seemed to have been cooling off and then entered a new phase. Is it the sun's orbit?

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2. Doug Bostrom at 06:20 AM on 26 April, 2021

   Dale, we'll need a little more to work with, to help answer your question.

   If you could point us to the source of your query, we could narrow down the nature of the matter.  Was this "new phase" and the time threshold of 1.2 million years ago something you read about, and if so where? 

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3. Dale H at 10:34 AM on 26 April, 2021

   Doug

   Thanks for getting back to me so quickly. It was a number of graphs which included on Wikipedia Geological Temperature record article - chart Temperature of Planet Earth link below.

   On the chart it shows the earths temperature alot warmer for over 250 million years and continuing to drop until say 1.2 to 2 million years it appears more stable. What do we think has caused this, earths orbit, sun strength etc..? Also for the record I have heavily studied all the recent data and believe humans have caused at least some of the warming if not most. 

   

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   Moderator Response:

   [RH] Inserted image from link. You can do this yourself through the edit menu. Just click the "insert" tab, then the tree image icon, and insert the link there. Be sure to limit the image width to 550px.

4. Eclectic at 14:08 PM on 26 April, 2021

   Dale H @3 ,

   it is interesting how (allowing for other input factors) the planetary temperature has broadly declined as the atmospheric CO2 level has declined.  [As might be expected from basic physical principles.]  

   And it appears that a threshold was reached, about a million years ago, when the underlying regular Milankovitch cycle effects have become very prominent.

   The (arguable) stability you mention, may arise from the time-compression appearance of the graph.

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5. MA Rodger at 17:49 PM on 26 April, 2021

   Dale H @3,

   Further to #3, the declining CO2 levels over the last few ten-of-million years are usually put down to errision following the Himilayan mountain-building. The Antarctic ice appeared about 35Mya on the cooling planet. On a shorter time-scale, the shutting-off of the oceans between N & S America 3 Mya ago resulted in the appearance of the Arctic ice which has been fuelling ice ages ever since.

   The frequency of these ice ages swapped from 40,000yr to 100,000yr roughly 1 Mybp (so your 1.2Mya @1). A mechanism for this transition is not entirely nailed down quite yet (eg see Chalk et al 2017 or Willeit et al 2019). However the usual suspect is the level of dust from exposed land during glacial cycles and its reduction of the ice albedo. So when the lands of northern lattitudes have been scoured clean back to the bedrock, the dust is greatly reduced and thus the albedo of the less-dusty ice caps does not decline so much during high glaciation, allowing ice a longer period before destablising into an interglacial.

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6. Dale H at 15:01 PM on 27 April, 2021

   RH, Ecelctic, MA Rodger

   Thank you for the help on where to look for the best articles on the changes in temperature and causes for the last 2 million years. I have read them a few times as well as other articles on the Milanovitch cycles. I am still digesting all of the learning and supporting documents but it gives me a good start on the earth's movement on climate plus some of the other factors that drive change and will have more questions soon.

   It was also very impressive on all of the hard work and thought that has gone into this area and very much appreciate you spending time to help me sort through the numerous studies. As mentioned I have worked in the data and modelling field for 30+ years helping people understand what drives their business and love looking at facts and ideas. You both mention the declining CO2 levels which would lead me to my next question.

   Do we have data or hypothesis on temperature and CO2 levels back to the dinosaur timeframe and how the CO2 levels became so high. Also on temperature do we have mid latitude increases because most of the people live in this area?

   As mentioned I appreciate any of your wisdom you can share and if anyone else has any articles or ideas in the precurrent timeframe that they believe would be of interest please let me know.

   RH I still haven't mastered the pasting of the image to fit into the webpage. Is there somewhere I could learn more about it?

    

    

    

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   Moderator Response:

   [BL] You cannot insert images directly into comments here.

   On the screen for writing comments, you can use the insert/edit image icon (on the Insert tab), to create a link to an image that is located on another publicly visible web page. The Skeptical Science web page will then display that image as part of your comment, but it has to remain accessible on that external web page. This web page does not copy it.

7. Eclectic at 21:29 PM on 27 April, 2021

   Dale H @6 ,

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

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

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

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

   Overall, it's been quite a ride !

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

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

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

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

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8. Dale H at 09:38 AM on 28 April, 2021

   Eclectic

   Thank you for the information above as it was all new to me as my investigation into climate change has mainly been from 1880 to the present with a little bit around the little ice age plus the higher sea levels 1000 to 1250 AD.

   I am sorry about breaking policy guidelines as it wasn't my intent and will adjust my questions. It was just one question lead to another and I didn't see threads with graphs about CO2 and temperature levels in the dinosaur age on the website as I had noticed were higher on google but wanted good data. I also started here because on the newbie page I mainly saw people complaining about deniers and was hoping for some colaboration to help point me to which projects have a greater acceptance.

   As mentioned I have delivered over 1000 projects and workshops in the food business on 4 continents and we always let the facts and models find as close to truth for us and then model out multiple scenarios to help achieve results on their goals and what they can afford. The data has no room for denial but people don't like change so their starting point on most things is denial and we use facts and to help and outcomes to help change them. There is some advantage that the Food business isn't political but there is always different agendas in corporations etc.. on having the results that would benefit them. I found it surprising at the amount of politics on the website which will immediately get the opposing parties backs up and stop the exchange of ideas. I truely believe there is alot more hard work and wisdom in the area that isn't getting out to the public probably on the 5 to 10 fold scale. On deniers one of the reasons I honestly looked at the area at first is I was hearing outrageous claims of what was going to happen. I said maybe but would have to look at as much of the raw data and model outputs myself. Once I looked into it I could see some classic cherry picking the time period, changing the scale etc.. which would give misintented results that is easy for deniers to poke holes in the conclusion and once you lose credibility on the data set it is difficult to get back. I also saw that if you looked at the whole dataset the trend and results show the same result of an increase but maybe on a slightly longer timeframe and was a missed opportunity on changing deniers opinion in some cases. For myself it led to realize that we are affecting climate and I had to tease out the last few questions I had to see any natural increase. (sea level going up before the industrial revolution, why the slow down in the 30's & 40's and a few other things).

   I do think you are selling yourselves a little short and have an opportunity to point out that we have over powered the latest decrease in solar irradiance and sunspot decrease and the temperature is still rising as further proof.

   My hope was to learn more and possibily collaborate on the full picture to help in anyway I could. As you all know in modelling you can predict outside the current data but the model error will go up as leave the data set. My thinking was as we leave the most recent area were CO2 has been the last few million years why not try to learn as much as we can in the dinosaur period when temperatures and CO2 were hotter to help our knowledge and what we are up against. In addition, as you know match your presentations to your audience varying details/complexity to some groups and the big picture with simple reasonable outcomes with executives.

   I will continue to go through the site to look for knowlege on the areas mentioned for question to stay within policy. If you have any good datasets and hypothesis it would be appreciated. Since this may not to policy and not to bore everyone on the site please contact me dale.hansson@verizon.net and I would love to learn and help in anyway.

   Dale

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   Moderator Response:

   [DB] For a discussion of previous climates with high levels of CO2, see this post:

   https://skepticalscience.com/co2-higher-in-past-intermediate.htm

   Over the Earth's history, there are times where atmospheric CO2 is higher than current levels. The planet experienced widespread regions of glaciation during some of those periods. Does this contradict the warming effect of CO2? No, for one simple reason. CO2 is not the only driver of climate. To understand past climate, we need to include other forcings that drive climate.

   http://www.sciencedirect.com/science/article/pii/S0016703706001979
   http://droyer.web.wesleyan.edu/PhanCO2(GCA).pdf

   

   Slide 20
   
   

   Atmospheric CO2 levels have reached extremely high values in the deep past, possibly topping over 5000 ppm in the late Ordovician around 440 million years ago. However, solar activity also falls as you go further back. In the early Phanerozoic, solar output was about 4% less than current levels.

   If climate scientists were claiming CO2 was the only driver of climate, then high CO2 during glacial periods would be problematic. But any climate scientist will tell you CO2 is not the only driver of climate. Climatologist Dana Royer says it best:

   "the geologic record contains a treasure trove of 'alternative Earths' that allow scientists to study how the various components of the Earth system respond to a range of climatic forcings."

   https://link.springer.com/chapter/10.1007/978-94-010-9633-1_4
   https://link.springer.com/article/10.1007/BF00151270

   Past periods of higher CO2 do not contradict the notion that CO2 warms global temperatures. On the contrary, they confirm the close coupling between CO2 and climate. When CO2 levels were higher in the past, solar levels were also lower. The combined effect of sun and CO2 matches well with climate.

9. Bob Loblaw at 10:57 AM on 28 April, 2021

   Dale H:

   You said "As you all know in modelling you can predict outside the current data but the model error will go up as leave the data set."

   Although what you say is very common in statistical fits to data (interpolate, don't extrapolate), it is much less common in models that are based on physics. Climate models have some statistical derivations for small-scale phenomena, but the bulk of the calculations are based on well-defined physical relationships and include things like conservation of energy that controls long-term behaviour. They are much less likely to show extrapolation errors.

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10. Doug Bostrom at 11:38 AM on 28 April, 2021

    A little further to Bob's point, try visiting scholar.google.com and entering "constraining climate models"  (in quotes). That's a primitive search term but will produce a result helpful for understanding the phenomenal effort devoted to keeping models in the paddock labeled "realistic." 

    Models are kept on a tight leash and are not free to run away in imagination.

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11. scaddenp at 07:31 AM on 29 April, 2021

    I agree with Bob - Dale H appears to be confusing physical models with statistical models. Flying a drone on Mars shows you what physics modelling can achieve.

    A good introduction to nature of climate model is here. There is also an old discussion here which explores some of the differences between climate models and other kinds of numerical models.

    Finally, (putting on a moderators hat), discussions about reliability of climate models should be placed here.

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12. Dale H at 09:54 AM on 29 April, 2021

    Moderator

    Thank you for the information. I have read the attached and the climate sceptics link explaining the information and alot of the comments and will look through the rest. It is a big help as well I will follow all the links.

    Bob Loblaw @9, Doug Bostrom @10 & scaddenp @11

    Thanks for reading my ideas and thank you for your time on responding. First I apologize on modelling comment as it was the wrong wording for what I was trying to explain and yes it is about statistical models not physics models. I will study all of the links and information to learn more. As you can tell I am also not a statistician but have used large amounts of data/statistical models to help change the behavior of people in all of the studies delivered which is difficult because people naturally resist change because of the risk involved and sometimes their own agendas so alot start out as deniers.

    My point was we could strengthen our arguement by looking closely at the period when it was higher with all the different forcings and tie it back to the current increases to strengthen the predictions which I haven't seen done that often at least to the public level. In a simple sense it gets to us as the model said so without explaining the different pieces. Once again I come back to the premise that all of you have thought of these things and are not getting near the credit for all of your brillance and hard word.

    I think we have convinced all of the scientists and now maybe broaden the approach with a full view aimed at a larger audience. As with everything else I mentioned you have probably done this already. I was just trying to understand the bigger picture and offer any help on understanding then educating and selling the ideas.

    Thanks again as I have already learned alot in the last week.

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