More on Climate Feedback

On a number of occasions, I have emphasized that the key scientific hypothesis that drives catastrophic warming forecasts is not greenhouse gas theory, but is the theory that the climate is dominated by strong positive feedbacks:

The catastrophe comes, not from a mere 1 degree of warming, but from the multiplication for this warming 3,4,5 times or more by hypothesized positive feedback effects in the climate.   Greenhouse gas theory gives us warming numbers we might not even be able to find amidst the natural variations of our climate;  it is the theory of strong positive climate feedback that gives us the apocalypse.

So when I read the interview with Jennifer Marohasy, I was focused less on the discussion of how world temperatures seemed sort of flat over the last 10 years  (I have little patience with climate alarmists focusing on short periods of time to "prove" a long term climate trend, so I try not to fall in the same trap).  What was really interesting to me was this:

The [NASA Aqua] satellite was only launched in 2002 and it enabled the collection of data, not just on temperature but also on cloud formation and water vapour. What all the climate models suggest is that, when you’ve got warming from additional carbon dioxide, this will result in increased water vapour, so you’re going to get a positive feedback. That’s what the models have been indicating. What this great data from the NASA Aqua satellite … (is) actually showing is just the opposite, that with a little bit of warming, weather processes are compensating, so they’re actually limiting the greenhouse effect and you’re getting a negative rather than a positive feedback."

Up to this point, climate scientists who argued for strong positive feedback have relied mainly on numbers from hundreds of thousands of years ago, of which our understanding is quite imperfect.  I have long argued that more recent, higher quality data over the last 50-100 years seems to point to feedback that is at best zero and probably negative [also see video here and here].  Now we have better data from the satellite NASA launched in part to test the strong positive feedback hypothesis that in fact feedback may be negative.  This means that instead of multiplying a climate sensitivity of 1 (from CO2 alone) to numbers of 3 or more with feedback, as the IPCC argued, a climate sensitivity of 1 from CO2 may actually be reduced to a net sensitivity well less than 1.  This would imply warming from CO2 over the next century of less than 1C, an amount likely lost in the noise of natural variations and hardly catastrophic.

Marohasy: "That’s right … These findings actually aren’t being disputed by the meteorological community. They’re having trouble digesting the findings, they’re acknowledging the findings, they’re acknowledging that the data from NASA’s Aqua satellite is not how the models predict, and I think they’re about to recognise that the models really do need to be overhauled and that when they are overhauled they will probably show greatly reduced future warming projected as a consequence of carbon dioxide."

  • Scientist

    Two comments.

    1. Where is this research published? The Aqua satellite web pages mention nothing of it.
    2. You keep saying you don’t believe in positive feedback Does the cycle warming -> ice melting -> lower albedo -> more sunlight absorbed -> warming really not make sense to you?

  • morganovich

    anyone have a link to the actual spencer data on the relationship of co2 and water vapor? having trouble finding it. nothing much on the aqua project website.

  • Doug Foss

    Scientist:

    Question #1 is a good one. Let’s see the data and make some assessments about its provenance and its import.

    Question #2 allows only one agreement as to feedback cycles as a result of your phrasing, but there may be other feedback cycles depending on the data. I can easily envision: additional CO2 leads to slight warming, leads to greater cloud cover, leads to higher albedo even before ice melts appreciably, leads to less light reaching Earth’s surface, leads to compensating cooling, resulting in hardly detectable change in global temperatures. That’s why your first question is so important. Absent hard data on correlations among and between CO2, water vapor and clouds, how could the modelers write their code?

  • Scientist

    Doug – certainly I can imagine negative feedbacks as well, and clearly they do exist because when the planet enters an ice age, the cooling eventually stops and a new equilibrium is reached, just as when an ice age ends, the rapid warming ends and a new equilibrium is reached. However, the author of this blog really thinks that positive feedback do not exist. He’s said this repeatedly. He never responds to comments so I can’t tell if he even reads them, let alone understands, but hello? Ice ages? Clearly tipping points and so on exist, otherwise we’d never have ice ages or interglacials.

  • morganovich

    spencer discusses it here in his testimony to the house (starting on page 7).

    http://oversight.house.gov/documents/20070320152338-19776.pdf

    as the lead on this project for NASA, he certainly ought to have had a good look at the data.

    full article from geophys research letters here:

    http://www.agu.org/pubs/crossref/2007/2007GL029698.shtml

    abstract:

    We explore the daily evolution of tropical intraseasonal oscillations in satellite-observed tropospheric temperature, precipitation, radiative fluxes, and cloud properties. The warm/rainy phase of a composited average of fifteen oscillations is accompanied by a net reduction in radiative input into the ocean-atmosphere system, with longwave heating anomalies transitioning to longwave cooling during the rainy phase. The increase in longwave cooling is traced to decreasing coverage by ice clouds, potentially supporting Lindzen’s “infrared iris” hypothesis of climate stabilization. These observations should be considered in the testing of cloud parameterizations in climate models, which remain sources of substantial uncertainty in global warming prediction.

    so, more water vapor = more rain = net cooling

    lots of theories (like warming/reduced albedo/warming) can sound plausible. the test is in the evidence. this evidence seems to point to negative feedback.

    given that the earth’s overall temperature has remained for 500 million years in a range smaller that the annual variation in many places, is it so hard to imagine a negative feedback dominated system? how, in the face of that, can you argue for a positive feedback dominated ecosystem, particularly when co2 levels in earth’s atmosphere have been at levels over 20 times those currently prevailing in the past? why did we not warm uncontrollably then?

    and given that there is 80-100 times the water vapor in the atmosphere as co2, is it so hard to imagine how small changes in the dominant greenhouse gas could swamp anything created by the smaller one if they are in are in opposition? why are you so confident that co2 is the driver of a system in which it is such a small part?

  • Papertiger

    It’s a shame really. I was lookng forward to living in a tropical rain forest world.
    Have you ever visited the Trinity forest, with it’s eternal mists, shafts of sunlight sneaking between the boughs of towering redwoods?
    It would have been nice.
    Ah well. Amber waves of grain are cool too.

  • coveman

    Proving the existence (much less the validity) of the data Marohasy discusses is only half the battle. Getting the Global Warm-mongers to accept it is the other half. Given the McCarthyist tactics of the IPCC and gang, it would not surprise me if it takes awhile to get this data (if it indeed exists) released and peer-reviewed.

    I am interested not so much in the science Marohasy discusses (a no-brainer as far as I’m concerned), but in her comments such as “The head of the IPCC has already acknowledged it” and so on. Now THIS I gotta see.

    Could it be that the “fat lady” is finally singing for the AGW movement?

  • TCO

    Very cool. For once. You. Motherfucker.

  • Larry Sheldon

    What kind of “Scientist” asks over and over again “Don’t you believe….”

    Some things I take on faith, among them “A is A”. But stuff from the realm of science I don’t expect to be interrogated on in terms of faith.

    Warren needs a banhammer.

  • Larry Sheldon

    And why do I have to put up with TCO’s sewer mouth.

    I sometime refer people here who do not want to read that juvenile garbage.

  • Mike D

    Scientist:
    Do the letters ENSO,PDO,SOI,NAO,AO,MJO and all the other O’s related to the ocean atmosphere interactions mean anything to you! Show me papers in the climate science world where they can now accurately predict these events more than 6 months in advance and maybe I would consider there might be some truth in what you are pushing. These are mostly MDO’s (multi decadal ocilations) they are the primary regional climate drivers of the earth. What drives them to swith is still being hashed out and they can be seen in the past but we still cannot predict the flips until after they have flipped for a period of time. Have you heard the term Natural Climate Fluctuation. It has only been occuring since the earth has had an atmosphere. It is a simple idea. The temperature goes up the temprature goes down. It is sunny It is cloudy.

    I will take this time to dedicate a couple of songs.
    “To everything there is a season and a time for every purpose under heaven” The song is “Turn Turn Turn” by the Byrds
    How about ” I really don’t know clouds at all” From “Both sides now” Joni Mitchell. This on is for the AGW crowd

  • dreamin

    Sez Scientologist: “However, the author of this blog really thinks that positive feedback do not exist.”

    Sez me: When you misrepresent other peoples’ positions, it only undermines your credibility.

    What the blog author says is that one should assume that the climate system IS NOT DOMINATED by positive feedbacks.

    Nobody is saying that positive feedbacks don’t exist or that negative feedbacks don’t exist. The question is whether the system is dominated by positive or negative.

    Anyone who gives it a moment of critical thought would realize that the climate system is almost certainly dominated by negative feedbacks. That’s the key insight that Warren has shared in this blog.

  • Scientist

    dreamin – you’ve got comprehension problems. Did you read the bit in this post which says I have long argued that more recent, higher quality data over the last 50-100 years seems to point to feedback that is at best zero and probably negative? If so, how do you come up with Nobody is saying that positive feedbacks don’t exist?

    morganovich – given that the earth’s overall temperature has remained for 500 million years in a range smaller that the annual variation in many places – interesting you should characterise it like that. Your statement is correct, and you could extend your 500 million years to the entire history of the earth, but weirdly you’re neglecting to mention the extremes this actually indicates – from glaciers covering all of Europe to tropical forest at the poles, and the fact that the climate can switch from one extreme to the other rather quickly.

    when co2 levels in earth’s atmosphere have been at levels over 20 times those currently prevailing in the past? why did we not warm uncontrollably then? – we? Humans weren’t around then. But you know what? When CO2 was higher, the earth was hotter! Are you surprised by that?

  • Alan D. McIntire

    And even when the earth was much warmer, there were still large ice sheets

    http://www.sciencemag.org/cgi/content/abstract/319/5860/189

    - A. McIntire

  • Industry Insider

    Scientist – You state, “when CO2 was higher, the earth was hotter.” One may be able to cherry-pick some periods when higher CO2 levels and higher temperatures coincided, but statistically, higher CO2 does not mean higher temperature. See Rothman, D.H. 2002. “Atmospheric Carbon Dioxide Levels for the Last 500 million Years.” Proceedings of the National Academy of Sciences. USA 99: 4167-4171, which concludes that variations in CO2 levels exhibit “no systematic correspondence with the geologic record of climatic variations at tectonic time scales.”

    Also, you mentioned, “Does the cycle warming -> ice melting -> lower albedo -> more sunlight absorbed -> warming really not make sense to you?”

    Sure, it makes sense regionally only, but let’s talk globally. I would not expect the ice melting feedback loop to be a globally dominant feedback loop since it only applies near the poles. I would expect the globally dominant feedback loops to be those operating near the equator and in the middle latitudes, that is, the areas of the planet accounting for most of the surface area and the areas receiving the most sunlight. Spencer’s analysis of the tropics shows that positive feedbacks do not dominate there.

  • Scientist

    Cherry picking? I don’t think so. Hotter temperatures have corresponded with higher levels of CO2 over the whole history of humanity and far further back. When considering which time period we can learn most from, when studying today’s prevailing conditions, the most recent 500,000 years is much more useful than some arbitrary time within the last 500 million years.

    And do you think tectonic time scales useful for us, when considering the causes and effects of climate change over decades and centuries?

  • morganovich

    “scientist”-

    if the world has varied in temperature by less than 15 degrees c over 500 million years ,how does that support a positive feedback dominated system of temperature? THAT is my point. and funny you should mention the range. are you aware we are currently in an ice age? sure, we are in an interglacial within that ice age, but current temps are at the LOW end of the long term range.

    the implied statement in being worried about GW is that warming is bad. but would an incremental degree of warming really be worse than a degree of cooling? the last time the world was a degree colder, crops failed and ice surged. drought and extreme weather were more common than now. we are much closer to a glaciation than a departure from an ice age. to my mind, a glaciation would harm us far more than further warming.

    and given the negative feedbacks being demonstrated around warming, the runaway CO2 warming scenario seems less likely.

    so long as the isthmus of panama stays closed (this is what froze the antarctic) and a continent remains at a pole, the world is likely to stay fairly cold.

    and you comment about CO2 is not correct. yes, the world has been warmer. but it has also been this cold with a co2 level 8 times this high.

    take a look at this chart:

    http://icecap.us/images/uploads/Monckton2.jpg

    the correlation of co2 and temp is just not that high.

    why are you so sure that such a tiny part of the climate system dominates? you always duck that question. you insist on seeing everyone else’s evidence, so where is yours? where is the empirical evidence that CO2 can drive climate?

  • morganovich

    oh, and if tectonic time scales are too long, how about a century of time scale?

    as this analysis shows, co2 correlates poorly to temperature over the last 100 years.

    http://wattsupwiththat.wordpress.com/2008/01/25/warming-trend-pdo-and-solar-correlate-better-than-co2/#more-597

    and if we look at co2 for 500,000 years as you suggest, the vostok cores etc show a clear lag – co2 rises 500-800 years AFTER a temperature rise, making it seem like an effect and not a cause. might it add some incremental warming? perhaps. but where is the evidence? show it to me. show me why any effect it has is not swamped by precipitation systems. show me why temps start to cool, and then co2 drops.

  • dreamin

    “Did you read the bit in this post which says I have long argued that more recent, higher quality data over the last 50-100 years seems to point to feedback that is at best zero and probably negative? If so, how do you come up with Nobody is saying that positive feedbacks don’t exist?”

    Easily. Because the statement you quote is referring to NET feedback.

    Claiming that net feedback is zero or negative is not the same thing as claiming that positive feedbacks do not exist.

    Seriously, what does it mean that the best arguments you can come up with rely on misinterpreting and misrepresenting peoples’ statements? To me, it means you don’t have any real arguments left.

  • Industry Insider

    Scientist – Your statement that higher CO2 means hotter earth was made in response to this comment:

    “when co2 levels in earth’s atmosphere have been at levels over 20 times those currently prevailing in the past? why did we not warm uncontrollably then?”

    As I’m sure you realize, CO2 levels have not been 20 times the present levels during the past 500,000 years, which is why my response focused on tectonic timescales. The question you never addressed was, why did we not warm uncontrollably when CO2 levels were 20 times the present levels? If CO2 were actually the dominant climate forcing the AGW crowd believes, I would think that a CO2 concentration 20 times today’s levels would have to lead to runaway warming, regardless of the other forcings at work, but that did not happen.

  • Keith

    The thing I love best about the Climate Warming Alarmists’ concepts of positive feedbacks are their magical qualities. CO2 levels have increased about 100 ppm in the past century, but that wasn’t enough to cause huge positive feedbacks. However, the Alarmists are just certain that any day now, if we don’t quickly mend our evil ways, positive feedbacks will kick in and raise temperatures by several degrees.

  • Scientist

    “morganovich” – A system which switches abruptly between states is one in which positive feedbacks certainly do dominate, at those times. How can you ever switch between states if negative feedback dominates? The graph you didn’t even bother to link to (and why is it that not a single one of the deniers here has the very basic ability to make an HTML link?) is pure fiction. Read the literature.

    Do you really think that anyone has ever said that CO2 is the only thing affecting the climate? It certainly looks like it. And you also seem to be stupid enough to suggest that because CO2 is a small fraction of the atmosphere that its effect must be small. Empirical evidence that CO2 can drive the climate? The fact that it is responsible for 10-25% of the entire greenhouse effect should surely be enough to start with. The fact that you can’t explain the temperature trends observed over the last 100 years without including its effect is another good bit of evidence.

    Industry Insider – what do you mean by ‘uncontrollably’? Do you think that if CO2 had been at today’s concentrations instead of 20 times them, the temperature would have been the same? You say ‘I would think…’ – are these thoughts backed by any science, or are they just thoughts? Why would you think that CO2 would dominate other effects, when we know that the sun was cooler half a billion years ago?

  • Industry Insider

    Scientist –

    Re: “uncontrollably.” Please go back and re-read my post. Feel free to ask morganovich about the definition of “uncontrollably” since I was quoting his comment.

    Re: “I would think.” Again, go back and re-read my post. To quote myself:

    “If CO2 were actually the dominant climate forcing the AGW crowd believes, I would think that a CO2 concentration 20 times today’s levels would have to lead to runaway warming…”

    Note the “if” statement. If CO2 were the dominant factor driving climate (note I do not believe it is, based on the evidence), would it not be logical to presume that CO2 concentrations 20 times those seen today would be strongly correllated with temperature? However, the correllation is not there.

    To this point, you have focused on semantics and have not addressed the substance of the points I have raised.

  • morganovich

    “scientist” if you think that this:

    “Empirical evidence that CO2 can drive the climate? The fact that it is responsible for 10-25% of the entire greenhouse effect should surely be enough to start with. The fact that you can’t explain the temperature trends observed over the last 100 years without including its effect is another good bit of evidence.”

    is empirical evidence, then i fear that those calling you “scientologist” are likely correct.

    would you accept that answer from me? and did you even look at the correlations for the last 100 years? both currents and solar output explain temperature changes much better than co2. co2 may influence climate, but that influence is likely minor and offset by other factors. it does not “drive” climate. increases in co2 don’t cause interglacials, they are the result of them. nor do reductions in co2 cause coolings. there is just no evidence of co2 changes leading temperature nor causing “tipping points”. you are likely looking at the speedometer of the car and assuming it controls speed.

    and a system that changes abruptly from state to state can quite certainly be dominated by negative feedback. the fact that such a shift stops means it must be. if it were not, why would the trend not continue? you mistake imbalance and adjustment for positive feedback.

    and you never answered the question (again): why so worried about a bit of warming when we are in an ice age and a degree drop in temperature would probably harm us more than a degree of increase.

    look at when species die off. cold periods. and when do they thrive and multiply? warm periods. it’s very cold by historical standards right now (500 million years)

    what are you so concerned is going to happen?

    and stop picking nits about wording when you start losing the agument.

    no one is fooled.

  • Scientist

    Industry Insider – you answered none of my questions. Why not?

  • Industry Insider

    Okay – here goes:

    You inquire: “And do you think tectonic time scales useful for us, when considering the causes and effects of climate change over decades and centuries?”

    Yes, tectonic timescales are useful for us because we can examine long-term CO2 levels in parallel with temperature and rigorously show there is no correlation between the two variables. Later on in your questions, you bring up solar variation. If you can correct the temperature vs. CO2 data for solar variation and show a statistically significant correlation between CO2 and temperature over the past half-billion years, go ahead and do it. Your study would have no problem getting published, and you would be well-received by the media and the rest of the AGW establishment.

    You inquire: “what do you mean by ‘uncontrollably’?”

    See my post above. I was quoting morganovich. I would guess morganovitch was referring to a temperature increase that, driven by positive feedbacks, would increase to some maximum value and could not be reversed due to the positive feedbacks in play, but this would be speculation on my part – you would have to ask morganovich yourself.

    You inquire: “Do you think that if CO2 had been at today’s concentrations instead of 20 times them, the temperature would have been the same?”

    I am not going to speculate what the temperature would have been at some point hundreds of millions of years in the past based on changing one single variable when the climate feedback mechanisms are so poorly understood. I could describe potential scenarios that would support a higher temperature or a lower temperature, but I won’t waste my time. I concur with the quote by morganovich: “co2 may influence climate, but that influence is likely minor and offset by other factors.”

    You inquire: “You say ‘I would think…’ – are these thoughts backed by any science, or are they just thoughts?”

    Follow the logic in my post above. I do not subscribe to the first part of the “if” statement, so I do not take the position in the second part of the statement.

    You inquire: “Why would you think that CO2 would dominate other effects, when we know that the sun was cooler half a billion years ago?”

    I do not think that CO2 would dominate other effects. As I said above, co2 may influence climate, but that influence is likely minor and offset by other factors. I expect you might reply with something to the effect of, “well, CO2 did not drive climate under the conditions 100 million years ago, but it does drive climate under the current conditions.” If that is your position, the only support you have are the climate models, which rely on these hypothesized positive feedbacks which are not being observed in the real world.

    I have now answered all your questions. You answered none of my questions. Why not?

  • Chris Christner

    The sun’s energy output has increased 6% since atmospheric CO2 was 7000 ppm 600 million years ago. During that time when CO2 levels were up to 20 times higher than today (albeit with a Sun that was slightly less energetic), the planet never experienced runaway greenhouse effects–so much for positive feedback. Over the 600 million years while CO2 levels have dropped to their current level, average global temps have remained within a +12 to +22 degree C range (53 to 71 degree F). Either CO2 has a negligible effect on global temps or negative feedback is overwhelmingly more powerful, or both.

  • Scientist

    Industry Insider – bit busy right now, will come back to you shortly.

    Chris Christner – How about a little bit of maths? Step one is easy – the forcing due to a 6% increase in solar output. Solar radiation averaged over the surface of the earth today is 240W/m². So, 6% of that is 14.4 W/m².

    Step two is slightly less easy as it involves logarithms. The forcing due to a change in CO2 concentration is given by this formula:

      ΔF = αln(C/C0)

    where α is 5.35. The graph you link to really is pure fiction, but let’s take 7000 ppm as representative. Then, the forcing due to a decline in CO2 concentrations from 7000 to 385 ppm is -15.5 W/m².

    Step three is really easy. Add the two numbers. The net forcing since 600 million years ago due to increasing solar output combined with decreasing CO2 concentrations is -1.1 W/m². Climate sensitivity is generally estimated at about 0.75 °C/W/m², so all else being equal, the temperature 600 million years ago would have been 0.8°C higher than it is today.

    So, your final sentence is completely, totally wrong. Do you think you should have checked out the numbers yourself before coming to such a conclusion?

  • Scientist

    Actually Industry Insider, I think that post answers your points as well. Please tell me if you think it doesn’t.

    If you think CO2 has a minor effect on climate, I wonder what explanation you’d give for why temperatures are not 10°C higher than they were 600 million years ago, given the 14 W/m² increase in solar insolation.

  • Industry Insider

    Scientist – the reason: other climate forcings and feedbacks.

    The arbitrary point “600MM years ago and 7,000 ppm” just represents a snapshot in time. Over the intervening period, the overall trend has been more solar insolation, and both CO2 concentrations and temperatures have fluctuated significantly without any systematic correspondence between the two variables. There have been periods when CO2 increased but temperature decreased. This would indicate the presence of other forcings that dominated any effect of CO2 during these periods.

    As I indicated before, you have a chance to contribute to climate science here. If you can prepare a detailed analysis of paleoclimate temperature, CO2, and insolation; correct/adjust for insolation; and show (in a statistically significant way) that changes in CO2 concentration induce changes in temperature, you will have something worthy of publishing. Otherwise, we can just continue to waste our time trading antecdotes.

  • Scientist

    It’s very well known that CO2 can induce changes in temperature. No point in me reinventing the wheel. However, if you’ve never heard of the wheel there’s a lot to be said for learning about it. If you genuinely don’t think that CO2 is not a driver of climate change, you’ve got some basic physics revision to do.

  • morganovich

    ahh, the “everyone knows” argument.

    show me one conclusive piece of evidence that CO2 was the primary cause/precipitator of a past warming.

  • Industry Insider

    **Crunch** (That’s the sound of the strawman you just built and then knocked over.)

    I never said CO2 cannot induce changes in temperature. CO2 may influence climate, but that influence is likely minor and offset by other factors. If CO2 were the driver of climate change, then there would be statistically significant trend information indicating that CO2 increases cause temperature increases and CO2 decreases cause temperature decreases. This is not the case over the last 500MM years, the last 500k years, or even the last century. Throw out predictions based on the climate models (and discarding them seems appropriate, considering how well the feedbacks in the models have been shown to match reality), and the AGW crowd is left with nothing but a few paleoclimate antecdotes where CO2 and temperature changes coincide.

  • Scientist

    You’ve offered nothing to back your claim that CO2 is only a minor factor and is offset by other factors. It’s pure supposition and extremely vague, as shown by the very hopeful sounding ‘likely’ you threw in there. There is indeed statistically significant trend information indicating that CO2 increases cause temperature increases. I know of no scientist who has managed to explain that pattern of 20th century temperature trends without CO2 concentrations rising.

  • Industry Insider

    Scientist – you state “There is indeed statistically significant trend information indicating that CO2 increases cause temperature increases.”

    Please cite references. Show me the statistically significant proof in the paleoclimate record.

  • Industry Insider

    Scientist – Now you’re hassling me for saying “likely?” Are you serious?

    Maybe I should include a table of probability percentages in my posts like the IPCC uses (“probably” = >50% chance, etc.). Heck, if I go the IPCC route, I could justify my conclusions based on “expert judgement” without any rigorous justification and not get called out on it. That would be fun!

  • Scientist

    You want paleoclimate evidence? Start by doing a search for ‘paleocene-eocene thermal maximum’. But what’s wrong with looking at the last century? We can calculate the solar forcing, the aerosol forcing, and the greenhouse gas forcing, and if we don’t include the greenhouse gas forcing we cannot explain the temperature pattern. Physics tells us that more CO2=hotter atmosphere; observations verify that.

    I criticise your use of the word ‘likely’ because it is extremely vague and you haven’t offered any evidence of why you think CO2 is a minor influence.

  • Neil Wilkins

    It is utterly impossible for the planet to have positive feedback for the warming and CO2 level. All earth scientists know that the earth has a history of much higher CO2 and temperatures than now. If positive feedback was even slightly possible then earth wouldve warmed up and life extinguished at one of many warming events since the time at which the current atmosphere dominated by N and O developed about 2 billion years ago. Before that the earth was dominated by methane CO2 and N and H2O – even more potent greenhouse gases. since the last 2 billion years of our current atmospheric regime there have been many many rises in CO2 yet all were eventually followed by cooling. This is the ultimate proof.
    No wonder the very great majority of earth scientists regard climate “scientists” as sad jokes. They are like phrenologists in the 19th century – they dress their own preconcieved beliefs and political agendas up as scientific proofs.