Weather, or climate change?

I start teaching again tomorrow, so it’s going to be a busy few months and posting will probably be light. I also don’t really have much to say at the moment, but that will probably change :-). I did, however, want to post this video that I found recently (see below). It discusses the link between weather events and climate change. It includes Kevin Trenberth making the point that the environment in which all events occur is different today, than it was in the past. Consequently, every event is different.

What I particularly like about the video is that those being interviewed regularly refer back to basic physics; evaporation, energy, increasing water vapour in the atmosphere, etc. We do have a very good understanding of the basic physics associated with climate change. Just because we have not definitely found some signal in a dataset, does not suddenly bring this understanding into question. Of course, if we would expect to have seen a signal, and do not, it might. Not seeing something in incomplete, or noisy, data does not.

Of course, there are certain aspects that are complicated and where the impact of climate change may not be obvious. There are others, however, where it would be extremely surprising if climate change did not increase the frequency and intensity of the most extreme events; as Kevin Trenberth says “at the high [is] when you start breaking records”. Maybe I’m biased, but I think it’s important to realise that our basic understanding of the underlying physics is very strong and that gives us a very good understanding of what – in general – we might expect. I’ll leave it there, and I recommend watching the video.

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77 Responses to Weather, or climate change?

  1. Gingerbaker says:

    ” it would be extremely surprising if climate change did not increase the frequency and intensity of the most extreme events…”

    Yet it is the prosaic which is more telling: Climate change effects even the least extreme weather events. There is no longer any weather which could be considered “normal” if normal refers to weather typical of the middle 19th or 20th century, because the climate system now contains significantly higher energy and atmospheric water.

    A beautiful clear 70 degree day in June 1850 feels the same as a beautiful clear 70 degree day in June 2016 – but it is not the same day at all, because the baseline conditions have changed.

    A 400-foot home run swat by a ballplayer on steroids is not the identical performance of that same player hitting a 400-foot home run while not on steroids.

  2. Gingerbaker,
    In a sense that is Kevin Trenberth’s point. The climate environment now is different to what it was in the past, due to anthropogenically-driven warming. Hence all events are different. Of course, in some sense, what is really relevant is the changes that we will have trouble dealing with, which is likely to be things like an increase in the intensity and frequency of the extreme events.

  3. BBD says:

    I mentioned this on a previous thread, but it’s arguably interesting enough to merit another go here: ongoing research in the Lake District on lake bed sediment deposition appears to show that recent flooding is exceptional even on a multicentennial timescale.

    No surprises there, I hear you say, but some contrarians have tried very hard to claim that there’s nothing unusual about the frequency and severity of recent flooding.

  4. Magma says:

    @BBD, to summarize the abstract linked in that article, the two most extreme flooding events in that Lake Country watershed over the past 600 years occurred in 2009 and 2015. As I noted on a previous thread, sooner or later the signal of increased number or intensity of global warming-driven extreme weather events will emerge from the background noise of ‘normal’ weather variation… and that sooner or later may already have occurred.

  5. angech says:

    ” it would be extremely surprising if climate change did not increase the frequency and intensity of the most extreme events…”.
    The climate change referred to here is that of increasing entropy, increased heat in the oceans and atmosphere. but some extreme events do become less frequent.
    The extreme events referred to are clearly all extra heat related effects.
    If the earth were cooling the same statement would be true for extreme events due to cooling.
    More ice, more snow, more extreme droughts, less rainfall.
    But look at the flipside in an earth where the extra heat is accounted for by negative feedbacks.
    How do we tell the two scenarios apart?
    On the one hand we have AGW, on the other natural Climate change.
    What is the incidence of extreme weather events?
    Where do they occur?
    And most important what is the range of natural Climate change?
    Looking for attribution in entrails is always satisfying when you find some, I think we got 3 examples.
    I have just been through one of the worst droughts in recorded Australian History in Victoria.
    It will never rain again, the dams will be always less than half full. This is the new norm. Build desalination plants were the catch cries.
    Like California now, except it has passed.
    I look outside my window at the River. Moderate flood level , fourth time in 3 months, 2 meters off the house going under. My wife likes living near the river, we are in the town.It is a flood plain that goes under every 20-40 years.
    The video is full of information but also contradiction. Why?

  6. Angech,

    Like California now, except it has passed.

    We had an almost normal winter rain season here in the SF Bay Area which was quite nice, but the drought is most certainly not over …

    … particularly in the southern/central parts of the state where much of the agriculture is. Not getting a La Nina might also be good news for this winter, but nobody I know in these parts is counting chickens yet. Finding long-term timeseries is difficult …

    … but that puts the past 15 years into perspective.

  7. angech,
    I really don’t quite follow what you’re getting at.

    What does this imply

    On the one hand we have AGW, on the other natural Climate change.

    The current evidence suggests that – absent something like an asteroid strike or major volcanic eruption – the dominant driver of climate change in the coming decades will be anthropogenic. Are you really suggesting otherwise.

    The video is full of information but also contradiction. Why?

    I don’t think it is. Your comment – I think – is just an example of how it is impossible to write – or say – something that someone can’t find reason to criticise.

  8. angech says:

    ATTP,
    The whole thrust of the Climate change debate is your and most others expectation and belief that the dominant driver of climate change in the coming decades will be anthropogenic.
    Pre anthropogenic influences the Climate did change naturally, we can agree on that.
    The degree of change was determined by natural variation.
    There are people other than myself who do suggest otherwise, that is why they are known as deniers.
    The substance of the counter arguments may seem trivial to you but do attract some scientific attention Curry, Pielke 1 and 2 and Christie.
    Your opening statements are quite correct. Where would the discussion be if we all just agreed in toto. I was adding a little bit of contrarian perspective.
    I cannot and would not criticise what you wrote but I can criticise the video contradictions.

  9. angech,

    The whole thrust of the Climate change debate is your and most others expectation and belief that the dominant driver of climate change in the coming decades will be anthropogenic.

    It’s not just belief.

    Pre anthropogenic influences the Climate did change naturally, we can agree on that.
    The degree of change was determined by natural variation.

    Except a lot of these past changes were driven by physical processes similar to what is driving it today. For example, the warming/cooling during the Milankovitch cycles was largely a consequence of changes in atmospheric CO2 and albedo. Hence, even though these were natural, they still allow us to understand what might happen if we cause CO2 and albedo to change.

    The substance of the counter arguments may seem trivial to you but do attract some scientific attention Curry, Pielke 1 and 2 and Christie.

    They might receive a lot of attention, but I don’t think they do within the scientific community.

    I cannot and would not criticise what you wrote but I can criticise the video contradictions.

    You’re, of course, free to criticise what I write. My point was more that some criticism appears to be nit-picks, rather than something substantive.

  10. Hyperactive Hydrologist says:

    Warmer cities tend to have higher frequency and more intense (convective) rainfall than cooler cities and this is taken into considerations when the drainage systems are designed. As the climate warms why won’t the intense (convective) rainfall events in the cooler cites become more like the events experienced by warmer cites?

    I know this is simplistic but I am only considering localised convective rainfall which predominately causes flooding in urban areas due to lack of capacity of the drainage systems. The flooding last week in Manchester and the South East are examples of this type of event.

    http://www.manchestereveningnews.co.uk/news/greater-manchester-news/recap-manchester-city-centre-streets-11484778
    http://www.bbc.co.uk/news/uk-england-sussex-37382361

    This paper suggests that summer downpours will intensify with warming:
    http://www.nature.com/nclimate/journal/v4/n7/full/nclimate2258.html#ref2

  11. Willard says:

    > The substance of the counter arguments may seem trivial to you […]

    What’s less trivial is the fishing expedition of your “may seem,” angech.

    Here’s the matrix of the “counter arguments”:

    https://contrarianmatrix.wordpress.com/

    If you know of any other with published citations, I’d gladly add them.

    ***

    From now on, please try to have a point in your comments. Raising concerns is not good enough anymore.

  12. Angech says:

    Willard I was replying to ATTP’s comment.
    CO2 is the question, Attribution is the answer.
    Without definite attributions the answer to the sensitivity to CO2 is unknown.
    Rising baseline surface air temperature anomaly independent of El Niño in conjunction with CO2 increase is needed.
    We had it then we lost it.
    Will become a believer when/if it comes back.
    Could you say the same if the temperatures fall for the next 5-10 years or will you play the Natural variability card, again?
    Meanwhile the video, while pleasing to the believers, carries threats and warnings of disasters while the messages are contradictory.
    Increased droughts that will go on for extremely long times accompanied by more frequent massive flooding events.
    Ignoring the fact that both are normal extremes of the Climate and cannot happen at the same time.
    Re hurricanes and I stand to be corrected as usual, my understanding is that they should become less common but more severe, yet the insistence on more severe and more frequent to appeal to people’s fear, leads to the need for more hurricanes even as there are less of them.
    To have less would run counter to the theme of more frequent events with higher heat in the system.

  13. angech,

    Without definite attributions the answer to the sensitivity to CO2 is unknown.

    No, I disagree with this very strongly. In principle we can never “know” anything, but we have a good understanding of many things as a result of years of research and basic physics. Even without definitive attribution, we can still “know” within what range the sensitivity is likely to lie.

  14. BBD says:

    Rising baseline surface air temperature anomaly independent of El Niño in conjunction with CO2 increase is needed.
    We had it then we lost it.
    Will become a believer when/if it comes back.

    OHC never stopped increasing. You make the simple mistake of treating the troposphere as if it were the entire climate system instead of only a small part of it. Most is ocean.

  15. angech wrote “Without definite attributions the answer to the sensitivity to CO2 is unknown.”

    This is complete nonsense (and I suspect angech knows that perfectly well), there is always going to be uncertainty in any statement regarding the real world, and there is a lot of ground between “known” and “unknown” than angech is disregarding. Particular incidences of cancer very rarely have “definite attributions”, but that doesn’t mean we don’t know by how much different risk factors increase our susceptibility to different types of cancer (i.e. the sensitivity of the risk factor).

  16. Hyperactive Hydrologist says:

    Angech wrote:

    “Increased droughts that will go on for extremely long times accompanied by more frequent massive flooding events.
    Ignoring the fact that both are normal extremes of the Climate and cannot happen at the same time.”

    No one is claiming that these will happen in the same place at the same time. We currently have prolonged drought in California, however we have just seen significant flooding in Louisiana. We expect to see a general intensification of the hydrological system with the basic theme being wet getting wetter dry getting drier. However, this does not mean that a drought might not be broken by a period of exceptionally wet weather. A good example of this is from the UK in 2012. Below is a summary from the CEH May-July Hydrology bulletin which can be found here http://nrfa.ceh.ac.uk/node/110.

    “2012 thus far has been remarkable in hydrological terms – the scale of the
    transformation from severe early spring drought conditions to widespread and
    sustained flooding through June and much of July is without modern parallel across
    much of the country.”

    2012 turned out to be one of the wettest years in the UK records, which date back to 1910, despite drought condition and rainfall deficiency in the first 3 months.

  17. BTW I made the same point on a previous thread and angech responded to it, and so must have been aware of it, and yet is making the same sort of argument again. Looks to me like angech is a Markov process ;o)

  18. Willard says:

    > CO2 is the question,

    What’s the question, again?

    ***

    > Meanwhile the video, while pleasing to the believers, carries threats and warnings […]

    Whatever the question, the CAGW meme you’re trying yet again to peddle begs it.

  19. izen says:

    @-“Without definite attributions the answer to the sensitivity to CO2 is unknown.”

    That there is SOME effect is undeniable.
    There is no definite attribution of a Lance Armstrong win to steroid use.
    But ALL of his records have been declared void.

  20. Windchaser says:

    Rising baseline surface air temperature anomaly independent of El Niño in conjunction with CO2 increase is needed.
    We had it then we lost it.
    Will become a believer when/if it comes back.
    Could you say the same if the temperatures fall for the next 5-10 years or will you play the Natural variability card, again?

    Well, natural variability doesn’t go away just because we add an anthropogenic signal. Instead, you then have both: natural variability around a rising trend.

    You can look at the last 30 years, remove the ENSO signal, and what do you get? A rising baseline surface air temperature anomaly independent of El Nino.

    That is what you say we need, and we already have it. Have had it for quite some time.

  21. rconnor says:

    Angech wrote:
    “Rising baseline surface air temperature anomaly independent of El Niño in conjunction with CO2 increase is needed.”

    Further to Windchaser’s point, try looking at Foster and Rahmstorf 2011, which attempts to remove natural variability from the temperature data (link at end) and shows an even stronger, cleaner warming single. Or simply review El Nino years only, La Nina years only and/or ENSO neutral years only from any data set. All three show steady warming, even throughout the “pause”. (example from NASA at the end)

    http://iopscience.iop.org/article/10.1088/1748-9326/6/4/044022/pdf

  22. Angech said on September 19, 2016 at 1:44 pm,

    “CO2 is the question, Attribution is the answer.
    Without definite attributions the answer to the sensitivity to CO2 is unknown.
    Rising baseline surface air temperature anomaly independent of El Nino in conjunction with CO2 increase is needed.”

    Cause and effect relationships in nature can manifest as nonmonotonic functions with even large fluctuations, since there can be competing cause and effect relationships. Regardless, there are many ways to see the clear cause and effect relationship between CO2 and temperature. One simple and easy-to-see way for even the general public is the graph of the 60 year running mean. This graph nicely tracks along a slightly upward bending curve. This graph shows a filtering out of almost all the natural variation, including the most general one, the roughly half-century long one of the NMO of Steinman, Mann, and Miller (2015). (See Mann’s article
    http://www.realclimate.org/index.php/archives/2015/02/climate-oscillations-and-the-global-warming-faux-pause/
    for a graph showing the NMO, the PMO, and the AMO. Also, Google “60 year running mean” with the quotation marks, for All and for Images.)

    I’ve already presented this graph of the 60 year running mean here at this blog along with a graph of the 30 year running mean, to compare them. In this comment
    https://andthentheresphysics.wordpress.com/2015/11/24/one-graph-to-rule-them-all/#comment-67531
    on November 25, 2015 at 5:10 am under ATTP’s post, “One graph to rule them all”, I wrote this:

    “See my comment
    https://andthentheresphysics.wordpress.com/2015/05/03/the-impact-of-the-hiatus/#comment-54920
    on May 4, 2015 at 7:26 am and some of the subsequent comments by other commenters under ATTP’s post “The impact of the “hiatus”?”, specifically the first of the three graphs I presented, this first graph being of a 60 year running mean covering the warming since the late 1800s, which shows this 60 year moving average tracking the path of a positively accelerated curve (the curve of a convex function on a given interval). That is, all the multidecadal variations are essentially filtered out, exposing that the warming since the late 1800s underneath all those multidecadal variations follows a relatively smooth (and positively) accelerated track. (The other two graphs support this.)

    I also have pointed out that Tamino at his blog Open Mind has shown that the warming is accelerating. I give a link to the details…”
    [continue reading the comment for more]

    “We had it then we lost it.”

    False. A nice and clear relationship is there underneath the fluctuations. As I said before, there are many ways to see it, but for the general public the simplest way to see it is the graph of the 60 year running mean I linked to above.

    To give something that could be used in a high school algebra class to try get the general point across as to what is going on – to see the cause and effect more clearly – underneath the fluctuating behavior: The above linked-to graphs of the 30 year and 60 year running means relate to each other very roughly similarly to how the first parts of the graphs of the functions f(x) = x^1.9 + 17cos(x) and g(x) = x^1.9 relate to each other. In each case, just by looking at them, the former graph seems to cycle for a couple of cycles around the latter graph that follows along an upward bending curve. (Function f actually cycles exactly around g.) For f and g, use the zoom function of the graphing utility – the Google search engine works nicely – to see the larger behavior as x increases. Note that the “down” parts of the cycles become less “down” and then become mere slowdowns, which in turn then essentially vanish. Note how this aspect of this analog we can use for students fits the findings of such studies as the one highlighted here:

    “Warming hiatus periods to become increasingly unlikely”
    http://agupubs.onlinelibrary.wiley.com/agu/article/10.1002/2014GL060527/editor-highlight/

    Quote:

    “Running their model ensemble under two scenarios (the Intergovernmental Panel on Climate Change’s representative concentration pathway (RCP) 4.5, which sees anthropogenic emissions taper off by the end of the century, and RCP 8.5, which sees unconstrained greenhouse gas emissions), the authors found that as emissions increase, hiatus periods become increasingly rare. Under RCP 8.5, they found that past the year 2032, hiatus periods are unlikely to occur, and by the end of the century, even a large Krakatoa-style volcanic eruption would be unlikely to cause enough cooling to counteract accumulated warming and trigger a hiatus.”

  23. angech says:

    Dikran, you and ATTP make the point that we can work out expected climate sensitivity for CO2 under known conditions and that attribution is not* necessary for this, though I would point out that I would certainly like to see attribution occur.
    The problem is that you both believe you know all the conditions which I disagree with, this being the basis of the feedbacks involved and here the lack of definite attribution is not helpful even if it is not conditional.
    Leaving that issue your comments on cancer and causation I left alone but since you insist on repeating them I would point out the following.
    Much of our background cancer risk is due to known radiation, for all cancers.
    Radon exposure is listed as the most likely other cause for non smoking lung cancer. Sunshine is a cause for skin cancer and melanoma. Wart virus is a cause of multiple human epithelial cancers from cervical, intestinal throat and even breast duct cancer. Tobacco for lung and throat and ?? renal cancer. Chemicals in the rubber industry and hair dyes for bladder cancer. In the animal world there is a virus for breast cancer in mice and the Tasmanian a Devil has a particularly nasty viral face cancer.
    Genetic cancers are well known.
    So many particular cancers commonly do have definite attributions contrary to your claim.
    Many more will be found as our knowledge base increases, just as the true sensitivity to CO2 increase in the world we live in.
    You and ATTP could well be proven right in your claims.
    I hold that you have called it too soon and on insufficient information, a theme from Willard in the previous thread, which he may not appreciate being used here.

  24. > which he may not appreciate being used here.

    Again with the mental attributions, angech.

    Everything you said about cancer can be said about AGW, so that you find the evidence of cancer attribution sufficient while AGW insufficient may be contradictory, something you disapproved earlier.

    Just like are cancers we know better than others, there are types of events we can expect with more confidence that others. There’s no contradiction between expecting more extreme events but less normal events overall, btw. Also, Clifford’s sufficient condition is more relevant to the duty of inquiry more than the sufficiency of the evidence. Good enough should be good enough even for Cliffordians.

  25. angech,

    I hold that you have called it too soon and on insufficient information, a theme from Willard in the previous thread, which he may not appreciate being used here.

    The current evidence suggests that we’ll warm by around 2C per 1000 giga-tonnes of carbon, and that the changes will be essentially irreversible on human timescales. Your “let’s wait and see, and let’s be more certain” has the potential to result in some severe and damaging changes, if you’re wrong. So, your strategy is essentially based on a view that the science is probably wrong.

  26. angech wrote “The problem is that you both believe you know all the conditions which I disagree with, this being the basis of the feedbacks involved and here the lack of definite attribution is not helpful even if it is not conditional.”

    I’ll start with this bit. You are not a mind reader angech, and yet again you demonstrate it by getting it wrong. I don’t believe we know all the conditions, and nowhere have I indicated that we do. We do know enough of the conditions to make a useful estimate though and to put a credible interval on those estimates, which is the way science normally operates in situations where there is uncertainty. So that disposes of that straw man.

    “though I would point out that I would certainly like to see attribution occur.”

    Yes, this is an example of “impossible expectations”, that allows you to ignore what the science actually says by requiring standards of evidence that science (if you understand the issues) can’t reasonably be expected to provide:

    “Much of our background cancer risk is due to known radiation, for all cancers.
    Radon exposure is listed as the most likely other cause for non smoking lung cancer.”

    That is precisely my point: If someone gets lung cancer, we generally don’t know whether it is from smoking or radiation (e.g. inhalation of radon) even if they smoke. Those who smoke can still get lung cancer where the direct cause is radon rather than their smoking. Yet we advise people not to smoke even though we can’t definitely attribute specific cases of cancer to smoking. Likewise we can’t attribute individual incidences of extreme weather to CO2, but we can show a statistical relationship. So just as we advise people to stop smoking to reduce their risk of lung cancer, we can advise reducing CO2 emissions to reduce the risks of extreme weather. However this advice is based in both cases on statistics, rather than direct attribution of particular events.

    “I hold that you have called it too soon and on insufficient information, “

    Impossible expectation again.

  27. “I hold that you have called it too soon and on insufficient information“

    actually, given that our best estimate of climate sensitivity has hardly changed over the last 100 years, this comment is rather amusing ;o)

  28. angech says:

    “given that our best estimate of has hardly changed over the last 100 years”
    “Known unknowns and all?
    Our best estimate.
    Would you care to share that estimate and it’s range now?
    Or is this what you mean
    the IPCC Fifth Assessment Report (AR5) “there is high confidence that ECS is extremely unlikely less than 1°C and medium confidence that the ECS is likely between 1.5°C and 4.5°C and very unlikely greater than 6°C.”

    the IPCC Fourth Assessment Report (AR4), which said it was likely to be in the range 2 to 4.5 °C with a best estimate of about 3 °C, and is very unlikely to be less than 1.5 °C

  29. angech, I note that you ignore the substantive post and respond to the non-serious one, how typical.

    Responding by pointing out a small change at the bottom end of the range between AR4 and AR5 rather makes my point. Svante Arrhenius’ estimate in 1908 (4C) is consistent with the IPCC range, hence hardly changed over the last 100 years. Give it a rest angech.

  30. angech says:

    “Responding by pointing out a small change at the bottom end of the range between AR4 and AR5 rather makes my point”
    With a range that extends from 1.0 to 6.0 degrees a small change at the bottom end of the range between AR4 and AR5 is not important.
    The elephant in the room is the 5 degrees range of uncertainty.
    To say 1.0 to 6.0 degrees per doubling is possible does not make a useful estimate, your words, as it implies a range in years to worry from 500 to 50.
    A massive difference in whether the changes will be essentially irreversible on human timescales.
    To put a credible interval on those estimates one would have to define a much more narrow range.
    Svante Arrhenius’ estimate in 1908 (4C) is not consistent with the IPCC best estimate 2.5 C it is a massive 1.5 degrees off though you can safely claim it is in the IPCC range.
    I may not be a mind reader but a post that highlights “5 Characteristics of science denial” as part of an answer certainly fits with playing the man rather than discussing the question.
    I don’t mind if you wish this approach but you could try to be more constructive.
    My figures and comments on the range and the change over the last 100 years seem both reasonable and scientific

  31. angech is still avoiding the substantive point that you don’t need definite attribution to estimate sensitivity, and rather than admit that the estimates of climate sensitivity have not changed much in 100 years, is now trying to make something out of the range being too broad instead. Sorry angech, you evasion is too transparent to be effective.

    “My figures and comments on the range and the change over the last 100 years seem both reasonable and scientific”

    LOL, angech didn’t actually given any figures for the “change over 100 years”, the time between AR4 and AR5 was afterall rather less than 100 years!

  32. angech do you agree that we can’t generally attribute specific cases of lung cancer in smokers to smoking (i.e. the mutation leading to the cancer could have been initiated by radon)? Yes or no?

  33. Incidentally the spread of estimates of climate sensitivity is hardly “the elephant in the room”, given that it is explicitly stated in the clearest possible terms and is the subject of most discussions of climate sensitivity on blogs, given that the risk is largely dominated by the high impact outcomes that would result from CS at the high end of the range (which is why expanding the range a bit at the low end really isn’t a big deal). It is more the “elephant in the safari park” where it is an attraction that everybody goes to look at.

  34. BBD says:

    angech

    You are treating the range as if every value from lowest to highest is equally likely. This is a mistake (another one). The most likely value is about 3C per doubling of CO2. Has been for decades. There is *far* less uncertainty about this than contrarians pretend.

  35. rconnor says:

    Angech,

    Allow me to expand on the lung cancer analogy a little further:

    I go to the doctor to check out a bad cough I’ve been having. The doctor says that I’m showing early signs of lung cancer. Luckily, we caught it early enough that if I stop smoking now, I can reduce my risk of it developing further and avoid the need for chemo.

    Two possible responses:
    (1) Take the expert opinions advice, which is backed up by piles of research and evidence, that stopping smoking will greatly reduce my risk of lung cancer.

    Or

    (2) Reject the doctors claim about the correlation smoking and my health issues. Do you know how complicated the body is and how many factors go into your health! How does he REALLY know my smoking is responsible for my cough? We just don’t know enough to justify me stopping smoking (after all, nicotine patches will result in economic ruin, I tellz ya!).

    Are you suggesting that you’d lean more towards the second response?

    (I also see you quickly dropped your “non-rising baseline” point. Good call.)

  36. angech says:

    rconnor says:
    “Allow me to expand on the lung cancer analogy a little further:
    I go to the doctor to check out a bad cough I’ve been having. The doctor says that I’m showing early signs of lung cancer. Luckily, we caught it early enough that if I stop smoking now, I can reduce my risk of it developing further and avoid the need for chemo
    (2) Reject the doctors claim about the correlation smoking and my health issues. “.

    This is an argument, Willard.
    “Have I stopped being a contrarian” variety, so complex.
    Get a real doctor and get your bronchitis treated with an antibiotic as this is the correct procedure.
    I don’t want advice on treating a potential risk many years in the future.That is on my cigarette packet. I want to stop dying from pneumonia now.
    The treatment for lung cancer is removal of the cancer, chemo and radiotherapy, not stopping smoking.
    Having a cough, like having extra CO2 in the atmosphere, might be a sign of many other things than cancer or a runaway greenhouse effect.
    Rather than cut your lung out for a cough I would get a proper diagnosis first and then act on the facts.
    Mind you reducing your smoking would always be better for your health and CO2 reduction would be similarly helpful, just not an imperative if the Climate sensitivity is low.

  37. angech says:

    BBD says: angech”You are treating the range as if every value from lowest to highest is equally likely. This is a mistake (another one)”.
    No,your assertion is not correct. I am just pointing out that there is a very large range. There is always a possibility of an asymptotic range and in a Bell curve the values vary in likelihood in both directions from the midpoint.
    “The most likely value is about 3C per doubling of CO2. Has been for decades”
    Tell Dikran. He said.
    “Svante Arrhenius’ estimate in 1908 (4C) is consistent with the IPCC range, hence hardly changed over the last 100 years” and ” the estimates of climate sensitivity have not changed much in 100 years”
    25% change down then is not much?
    Change in decades or 100 years?
    “angech is still avoiding the substantive point that you don’t need definite attribution to estimate sensitivity”
    On the other hand I agree with your comment totally. It is exactly what ATTP said in the start of this post. I did not avoid it, I said ” I would certainly like to see attribution occur.”
    “Looking for attribution is always satisfying when you find some”
    If you do not confirm some attribution at some stage however your estimate will inevitably be wrong.

  38. Marco says:

    “Get a real doctor and get your bronchitis treated with an antibiotic as this is the correct procedure.”

    Err….no. Get yourself a real doctor and most likely do NOT get treated with antibiotics, unless a bacterial infection is actually identified (the vast majority, as in >85%, of all cases of bronchitis are NOT related to bacterial infection, and antibiotics will then do much more harm than good).

  39. anoilman says:

    Angech: Your Lung Cancer analogy is preposterous. One doesn’t go in with a cough and walk out with a crisp diagnosis for cancer. What you claim is ludicrous.
    https://andthentheresphysics.wordpress.com/2015/07/31/guest-post-what-would-you-do/

    One goes in with a cough, and the doctors (your GP) start analyzing it. They go through the usual battery of tests guided by a list of symptoms to figure out what it is. Generally its process of elimination looking at all the data, and trying things. Lets face it, they try the cheapest things first. If they think it might be serious, you get a CT, etc…

    Where I live the radiologist can immediately elevate the diagnosis to Cancer to jump you right in to see a specialist. This is what happened to me. That means I’m not talking to just a doctor… I’m talking to a specialist in cancer of the lungs who’s also seen thousands of people go by his desk, and who publishes in his field, and who has patents on various technologies used in treatment.

    When my wife saw what was growing in my lungs, she burst into tears. Yet the first thing my specialist said to me, was, “I don’t think its cancer, you don’t fit the profile for cancer, and you don’t have the right symptoms. If you were 30 years older, and a smoker, we’d be having a very different conversation. Either way, we’re still guessing. We need to do more tests, I can do a lung biopsy next week.” (FYI, I was hoping for TB since I lived in Africa in the 80’s.)

    To get evidence, they take a sample of the tissue from your lungs. They then run the genetic profile of that sample against what they know of cancer, and obviously a host of other ailments. Everyone in that process are also specialists in exactly identifying the tissue sample.

    Now the specialist in diagnosing lung cancer has very detailed information, and armed with that, the latest data in treatment possibilities, and knowledge of the results, he will recommend treatment. [This is not precise. Its trail and error based on what works with what you have. Doing nothing is of course a bad idea.]

    If I had ignored my doctor, and even my specialist I would live on average 20 years less. I would still have violent coughing fits, and be physically depleted. Sometimes what I have will clear up for a while, then return. More commonly though, it will spread, and get worse. A few people who’ve ignored their doctors and lived, are probably walking around saying, “They don’t know nuttin. I survived cancer with vitamin pills.” These people are a big source of bad advice, and doing their fellow humans a real disservice. 🙂

  40. anoilman says:

    Marco says:
    ” …. and antibiotics will then do much more harm than good….”

    Its only the unfortunate few who get explosive diarrhea as a side effect;
    http://www.uptodate.com/contents/antibiotic-associated-diarrhea-caused-by-clostridium-difficile-beyond-the-basics

    Sadly hospitals are a good place to get infected with CDiff, and of course bring out the symptoms. (Please don’t ask why I’ve read the latest papers on this.)

  41. I note angech has not answered my question, surprise surprise. Of course not, because he knows perfectly well that he can’t without showing his argument is wrong.

    Instead there is more sophistry:

    “The most likely value is about 3C per doubling of CO2. Has been for decades”
    Tell Dikran. He said.
    “Svante Arrhenius’ estimate in 1908 (4C) is consistent with the IPCC range, hence hardly changed over the last 100 years” and ” the estimates of climate sensitivity have not changed much in 100 years”
    25% change down then is not much?

    Over the course of 100 years, when you consider the improvements in the theory and in observational technique (for instance Arhenius wouldn’t have been able to use satelites to measure the Earth’s albedo and would have had to estimate it from earthshine) then yes, 25% down is remarkably small figure. Of course angech would realise that if he spent a moment thinking about it.

    “I did not avoid it, I said ” I would certainly like to see attribution occur.”

    wriggle, wriggle, wriggle.

  42. Just to put the change in our estimate of climate sensitivity into perspective, Thompson’s 1897 estimate for the age of the Earth was between 20 to 40 million years. Over the last century that has crept up by a very small amount to about 4.4 billion years. I’d say a 25% change is pretty small compared to that! ;o)

  43. angech says:

    anoilman says: September 21, 2016 at 5:50 am
    Angech: Your Lung Cancer analogy is preposterous.
    Note ; The lung cancer analogy was not mine,Dikranmarsupial and rconnor started sand ran with it.
    Note I should thank you for correcting Marco, “in >85%, of all cases of bronchitis are NOT related to bacterial infection [many are the common clod and influenza which the doctor would also diagnose and not treat with antibiotics], and antibiotics will then do much more harm than good”
    As you kindly point out not useful is different to doing harm.
    I also wrote ” I want to stop dying from pneumonia now.”
    The most important condition to rule out is acute pneumonia. This can be difficult to diagnose but a bad cough is a good starting point”
    A good doctor will do a CXR, take a temp check the FBE, ESR, CRP, WCC looking for neutrophilia and listen to the chest. Not all pneumonia can be heard by auscultation.
    He would also consider the outside risk of lung cancer with the history of smoking but a simple CXR would be the first step there as well.
    He would check out the patient medication to make sure he was not on an ACE 1 antihypertensive which causes coughing.
    He would check for history and signs of asthma and treat that if present.
    I thought a logical comment on treating the symptom of a bad cough was appropriate for this thread but I am quite happy to go through every little part of a diagnostic visit if needed

  44. angech says:

    anoilman says: ” One doesn’t go in with a cough and walk out with a crisp diagnosis for cancer.”
    I see I left several comments trying to help with your predicament at that time, you may have forgotten.
    “angech says: August 3, 2015 at 10:38”
    I have also had a very close friend go through the same problem in the last 8 weeks. Very upsetting and why I chose not to respond to the analogy originally.
    One goes in with a cough, another goes in with a bad cough.
    Lung cancer is more likely to present with a mild chronic cough and other non specific symptoms. A bad cough of short duration is more suggestive of a chest infection [which needs identifying and treating].
    CXR does not always show up cancer so if the symptoms persist, particularly in a cancer CT is next [Along with sputum for TB and Cytology x3 and MCS etc,etc]
    Trans thoracic biopsy if a lesion is identified and it is accessible , bronchoscopy and samples, mediastinoscopy in the old days for a tissue sample.
    PET Scan is very good in helping see if localized.
    Sometimes one can be lucky with treatable illnesses like sarcoidosis etc.
    I am very relieved to read your entry which cleared you of the really nasty stuff and hope your health stays good for the next 20 years so I can apologize to you if my beliefs prove unfounded.
    “One doesn’t go in with a cough and walk out with a crisp diagnosis for cancer.”
    Not me.
    Try rconnor says: September 20, 2016 at 3:46 pm
    “Allow me to expand on the lung cancer analogy a little further: I go to the doctor to check out a bad cough I’ve been having. The doctor says that I’m showing early signs of lung cancer”

  45. angech says:

    Dikranmarsupial
    You can have the last word[s].
    I cannot beat your logic.
    “Over the course of 100 years, when you consider the improvements in the theory and in observational technique (for instance Arrhenius wouldn’t have been able to use satellites to measure the Earth’s albedo and would have had to estimate it from earthshine) then yes, 25% down is remarkably small figure.”

    ” the estimates of climate sensitivity have not changed much in 100 years”

    By 1904, Arrhenius became concerned with rapid increases in anthropogenic carbon emissions and recognized that “the slight percentage of carbonic acid in the atmosphere may, by the advances of industry, be changed to a noticeable degree in the course of a few centuries.” He eventually made the suggestion that an increase in atmospheric carbon dioxide due to the burning of fossil fuels could be beneficial, making the Earth’s climates “more equable,” stimulating plant growth, and providing more food for a larger population.

  46. LOL, so angech admits that he was wrong and that the estimate of climate sensitivity has indeed not changed much over the last 100 years, but still can’t admit that we do have a good enough basis for action and instead points out that Arrhenius’s opinion (he wasn’t an expert on biology or economics as far as I am aware) was that increased temperatures might be beneficial. Of course if you actually perform some research into the likely impacts (e.g. IPCC WG2 report) then you draw a different conclusion. You really are clutching at straws angech.

    It is funny that angech still hasn’t answered the question ” do you agree that we can’t generally attribute specific cases of lung cancer in smokers to smoking (i.e. the mutation leading to the cancer could have been initiated by radon)? Yes or no?” and yet continues to try an keep the analogy going with anoilman.

  47. BBD says:

    angech

    BBD says: angech”You are treating the range as if every value from lowest to highest is equally likely. This is a mistake (another one)”.

    No,your assertion is not correct.

    Yes, it is. Most likely = about 3C. Least likely = either end of the range.

  48. angech says:

    dikranmarsupial says:
    LOL, so angech admits that he was wrong and that the estimate of climate sensitivity has indeed not changed much over the last 100 years”
    No I said you could have the last words,not that I was wrong.
    I will put them up again
    “Over the course of 100 years, when you consider the improvements in the theory and in observational technique (for instance Arrhenius wouldn’t have been able to use satellites to measure the Earth’s albedo and would have had to estimate it from earthshine) then yes, 25% down is remarkably small figure.”
    ” the estimates of climate sensitivity have not changed much in 100 years”

  49. angech also wrote “I cannot beat your logic.” which would appear to have been an acknowledgement that he couldn’t find a fault in the argument that showed he was wrong, but is wriggling out of it again now.

    Angech, do you agree that the change in climate sensitivity over the last 100 years has not changed much? Given that climatology was in its infancy 100 years ago, can you give another example of a numeric estimate from a science that was also in its infancy that changed substantially less in its first 100 years? I’ve given one already that changed by several orders of magnitude in a shorter span of time, so if you are right you should have no problem finding examples.

  50. angech says:

    BBD
    – “The most likely value is about 3C per doubling of CO2. Has been for decades.”
    The 1990 IPCC First Assessment Report estimated that equilibrium climate sensitivity to CO2 doubling lay between 1.5 and 4.5 °C, a “best guess in the light of current knowledge” of 2.5 °C.
    the IPCC 1996 Second Assessment Report t “No strong reasons have emerged to change” these estimates. 2001 the third, cannot see a best estimate, range 1.5 to 4.5
    the IPCC Fourth Assessment Report (AR4),2007 which said it was likely to be in the range 2 to 4.5 °C with a best estimate of about 3 °C, and is very unlikely to be less than 1.5 °C
    the IPCC Fifth Assessment Report (AR5) 2013 “there is high confidence that ECS is extremely unlikely less than 1°C and medium confidence that the ECS is likely between 1.5°C and 4.5°C and very unlikely greater than 6°C.” could not see a best estimate.
    BBD says: angech”You are treating the range as if every value from lowest to highest is equally likely. This is a mistake (another one)”.
    Your assertion is not correct. I did not treat the range as if every value is equally likely.
    I pointed out that there is a very large range for most probabilities in AR4 of 1.0 to 6.0 degrees. In a Bell curve the values vary in decreasing likelihood in both directions from the midpoint.
    ECS is not a Bell curve.
    -“The most likely value is about 3C per doubling of CO2. Has been for decades”
    Factually the ECS was 2.5 for a decade. You would have to show the estimate as 3C for 2001, 2007 and 2013 to convince me of the comment and you would have to explain mathematically why an asymmetric curve in 2001 should be most likely 3 range 1.5 to 4.5 when a 2007 2.0 to 4.5 curve has 3 and a 2013 1.5 -4.5 median confidence curve should retain the figure of 3.
    This extremely odd occurrence, the ECS of 3.0, if it was 3.0 in all 3 reports, is a worry.
    -Decades would be correct, if this is the case but certainly not a 100 years. At least 2.5 going to 3 is only a 16.67% change in 20 years, though that might be worse than 25% in 100 years , actually 83.333% come to think of it.

  51. BBD says:

    The most likely value for ECS is ~3C.

    I don’t care how much obfuscatory waffle you post. It doesn’t change anything.

  52. rconnor says:

    Angech,

    The point of the analogy is not the accuracy of the medical part (I’m aware it’s fictitious – it’s an analogy), rather it’s how you seem to be tackling the risk assessment problem given evidence from a credible source.

    The point is that, when faced with a strong consilience of evidence, from multiple, credible sources (climate scientists/doctor), claiming that there is high risk of future hardships (impacts of global warming/cancer) unless we change our current actions (emissions/smoking), you’d advocate for not changing our current actions (reduce emissions/stop smoking) because you feel the uncertainty is too high to justify the actions.

    In a risk assessment exercise, uncertainty is not your friend. You don’t decide that because something *might* be less damaging, then preventative measures are not justified, that would be absurd. Especially when the risk is right skewed. Eli Rabett had a great term for this sort of terrible risk assessment – luckwarmers (my apologies if someone coined it before him). They bank on getting lucky that sensitivity is on the (really) low end, where the probability distribution function says is much less likely, and use that to justify inaction or less action.

    Furthermore, even if sensitivity is on the low end, that doesn’t really change our need for mitigation substantially. Myles Allen stated, “A 25 per cent reduction in TCR would mean the changes we expect between now and 2050 might take until early 2060s instead…So, even if correct, it is hardly a game-changer…any revision in the lower bound on climate sensitivity does not affect the urgency of mitigation” (Source). So, yes, *if* sensitivity is on the low end, then we get a little more time but we still need to reduce emissions significantly.

    The following are two good posts on this topic:
    http://theidiottracker.blogspot.ca/2010/09/between-science-and-hard-place.html
    http://theidiottracker.blogspot.ca/2010/09/between-science-and-hard-place-part-two.html

  53. BTW Angech still hasn’t answered the question “do you agree that we can’t generally attribute specific cases of lung cancer in smokers to smoking (i.e. the mutation leading to the cancer could have been initiated by radon)? Yes or no?” This seems like evasion to me.

  54. > Factually the ECS was 2.5 for a decade.

    I thought you said there was no best estimate in the 1996 report.

  55. > This is an argument, Willard.

    Promises, Doc.

    You only repeated the usual lukewarm line about the lack of imperative to reduce CO2 if sensitivity was low. You need to connect that with the idea that CS is a range, that there’s no way we can exclude the possibility of a less lukewarm sensitivity, and that there are many other good reasons to stop smoking, I mean dumping CO2 like there’s no tomorrow.

    Connect all this and you got yourself an argument, no just some throw line a Lord can cast.

  56. Marco says:

    I’m not sure who Angech is thanking and for what, but it appears he thinks that giving antibiotics is merely not useful in most cases, rather than doing harm. I really hope I got this wrong, though, because there is no doubt that antibiotics do harm, even in the process of doing good. AOM points out a specific direct example, but let’s also not forget the current problems with antibiotic resistance.

  57. anoilman says:

    Angech: You still haven’t even vaguely made a reasonable point.

    My point is that if you have an issue, you escalate and bring in the experts until you can decipher what it is. Everyone is looking at all the evidence they can. You’re certainly free to question the experts, but you are incredibly unlikely to find them outright wrong. If you are in earnest, you are likely to learn why you are wrong.

    Cherry picking and grasping at wrong conclusions is what you are recommending as a matter of course, and that is an incredibly silly stance to take on anything. This is so blatantly obvious, that you know you’re in the wrong.

    We still haven’t even gotten into the mountains of data, experience and science that put those experts there for you. Like Climate Science, this is immense, and it crosses all boundaries of science, math and physics.

    willard: My father was a heavy smoker (3 packs a day), and as his health declined (without cancer) he was told to stop by his doctor. Which he did. His health improved immediately.

  58. Willard says:

    Keep calm and play ClimateBall ™ like a gentleman would, Oily One.

  59. Magma says:

    @anoilman: Mine didn’t, and suffered debilitating illnesses that left them partial invalids and led to their painfully protracted early deaths. But on the bright side, they never smoked again after the onset of terminal COPD and a catastrophic stroke and ruined CV system. In a lucid moment my father told me he started smoking at 12 to look older. “It worked,” he said. (He had a finely honed sense of irony.)

    There’s a possibility this could affect the way I view some fossil fuel companies’ adoption of the tobacco industry’s strategy of delay, deny and obfuscate.

  60. anoilman says:

    Magma: I’m sure everyone has different experiences. Probable versus actual outcomes will never be perfect. Some people just blow it off and keep doing what they want to do.

    However with global warming, we only have one globe. I don’t feel its wise to just blow that fact off.

  61. Magma says:

    No argument here. I was extending your point.

    I figure people can do whatever they like if they have their very own personal atmosphere (or planet). So far, though, it looks like we’ve still just got the single shared one.

  62. angech says:

    anoilman says: September 21, 2016 at 4:23 pm
    “Angech: You still haven’t even vaguely made a reasonable point.”
    Fair enough.
    When I tried to post the differing ICCP assessment sensitivities it was described as obfuscatory waffle though I felt it made several reasonable points.
    The large range of sensitivities is a reasonable concern

    “Cherry picking and grasping at wrong conclusions is an incredibly silly stance to take on anything.”

    Agreed

    I can see where you are coming from when you accept 3C, and the consequences you foresee flowing from that and why you are so concerned and thank you for that.

  63. “The large range of sensitivities is a reasonable concern”

    it was also a goalpost shift to avoid admitting that the estimate of sensitivity had not changed much in 100 years.

    “I can see where you are coming from when you accept 3C, and the consequences you foresee flowing from that and why you are so concerned and thank you for that.”

    angech again misses the point, since impacts rise non-linearly in climate sensitivity, it isn’t a matter of accepting 3C, the problem is also the possibility of 4C or 4.5C. The lower tail of the interval is less of a concern because imacts rise non-linearly with climate sensitivity. Of course this has been pointed out already.

    Reminder:

    “BTW Angech still hasn’t answered the question “do you agree that we can’t generally attribute specific cases of lung cancer in smokers to smoking (i.e. the mutation leading to the cancer could have been initiated by radon)? Yes or no?” This seems like evasion to me.”

  64. angech says:

    dikranmarsupial says:
    “BTW Angech still hasn’t answered the question “do you agree that we can’t generally attribute specific cases of lung cancer in smokers to smoking (i.e. the mutation leading to the cancer could have been initiated by radon)? Yes or no?” This seems like evasion to me.”

    Seems like a trick question to me. Yes or no? I agree entirely with both since it lets you “win” whatever little point you wish to make.

    Do you agree that we can’t generally attribute specific rises in the earths surface temperature to CO2 level increase [the rise in temperature could be caused by natural variation’? Yes or no?
    Try not to evade the question Dikran].

    Well?

  65. angech says:

    dikranmarsupial says: September 22, 2016 at 1:36 pm
    “The large range of sensitivities is a reasonable concern”
    it was also a goalpost shift to avoid admitting that the estimate of sensitivity had not changed much in 100 years”.-
    No, it is a valid, non obfuscatory,legitimate and reasonable comment.
    Not a goalpost shift.
    Your comment is to distract from the fact that the central estimate of sensitivity has changed a lot in 100 years, from 4C to 2.5 C, then 3C and currently not estimated by the IPCC.
    How many people here have a concern about such a large range. None?
    I would suggest most would have some concern and that most should have a lot of concern about such a wide range, and am disappointed that it is denied so strongly.

  66. Windchaser says:

    I would suggest most would have some concern and that most should have a lot of concern about such a wide range, and am disappointed that it is denied so strongly.

    “Concern” how?

    I mean, yeah, we’d like the range to be smaller. That’s part of the point of ongoing research.

    Do you agree that we can’t generally attribute specific rises in the earths surface temperature to CO2 level increase [the rise in temperature could be caused by natural variation’? Yes or no? Try not to evade the question Dikran].

    We use a probabilistic attribution. Same as with cancer. It’s not “yes/no, smoking did/didn’t cause your cancer”. More like “there’s a 90% chance that smoking caused your cancer”.

    In the case of global warming, it’s “there’s a X% chance that at least Y% of the warming was anthropogenic”.

  67. angech wrote “Seems like a trick question to me. Yes or no? I agree entirely with both since it lets you “win” whatever little point you wish to make.”

    nice way to bullshit out of answering the question. The question was

    ““BTW Angech still hasn’t answered the question “do you agree that we can’t generally attribute specific cases of lung cancer in smokers to smoking (i.e. the mutation leading to the cancer could have been initiated by radon)? Yes or no?” This seems like evasion to me.””

    You either can do this, or you can’t, there is no “yes and no”, but unfortunately angech knows he can’t answer correctly without showing that he was wrong, but his intention appears to be trolling, so he can’t just let it go, so he has to say something to keep it going a bit longer.

    “Do you agree that we can’t generally attribute specific rises in the earths surface temperature to CO2 level increase [the rise in temperature could be caused by natural variation’? Yes or no?
    Try not to evade the question Dikran].”

    Pathetic attempt to wind me up by highlighting his evasion of my question by suggesting that I evade questions. Sorry angech, you are a troll, and not even a subtle one. If you want to know my answer, read the chapter on attribution in the IPCC WG1 report.

  68. To answer angech’s question, some temperature changes can be attributed directly to a particular forcing or to internal variability. For instance the cooling following the eruption of Mt Pinatobo was due to aerosol cooling from the ejected material. The peak in 1998 was due to ENSO. These mechanisms are well understood and their effects can be attributed fairly unequivocally. However, there are many forcings that affect climate, and on shorter timescales, internal variability dominates. On a thirty year timescale, the effects of internal variability are quite small. In order to attribute temperature variations to the forcings and internal variability, you need a model. This is what scientists do, rather than just looking at the data and saying what they think. One way of going about the attribution is to see what the model would predict in the absence of e.g. anthropgenic forcing, which is what the IPCC did to illustrate this point:

    If we can’t make a model that can explain the rise in temperature using only natural forcings, then that rather implies (to a rational person) that to the best of our understanding, the rise is anthropogenic. There you are, a full answer to your rhetorical question.

  69. BBD says:

    and currently not estimated by the IPCC.

    Only because what are now understood to be understimates based on EBMs made it difficult to synthesise a best estimate from the various lines of evidence. Now the problem with EBM estimates is understood, we are back to the canonical ~3C again. Not that we actually ever left it, but that’s the IPCC for you. Very conservative.

  70. Angech wrote “How many people here have a concern about such a large range. None?”

    I pointed the concern out to you in the very comment you are responding to, where I wrote:

    “angech again misses the point, since impacts rise non-linearly in climate sensitivity, it isn’t a matter of accepting 3C, the problem is also the possibility of 4C or 4.5C. The lower tail of the interval is less of a concern because imacts rise non-linearly with climate sensitivity. Of course this has been pointed out already.”

    The breadth of the credible interval is indeed a big concern, because of the non-linearity of impacts as a function of CS, and what we really need is constraints that rule out high climate sensitivity, rather than arguments that climate sensitivity may be low.

    So not only is angech engaging in evasion, and sophistry, and rhetorical mockery, he isn’t even bothering to read the responses to his comments before replying.

  71. Magma says:

    Apropos of nothing in particular, “The amount of energy needed to refute bullshit is an order of magnitude larger than to produce it.”
    (source: various, including Alberto Brandolini)

  72. rconnor says:

    “the rise in temperature could be caused by natural variation’? Yes or no”

    If you’re referring to the current rise in temperature from 1900-present, then the answer is “No”. No natural occurring physical mechanism can account for the magnitude, rate and timing of the rise in surface temperature. Anthropogenic CO2 emissions can. What’s more, it can account for other observations, which many natural physical mechanisms (ex. solar activity) cannot:
    – Less outgoing longwave radiation along wavelengths associated with CO2 (Source)
    – Increased downward infrared radiation along wavelengths associated with CO2 (Source)
    – Nights warming faster than days (Source)
    – Cooling stratosphere, warming surface (Source)
    – Rising tropopause (Source)
    – Cooling and contracting ionosphere (Source)

    Regarding the evolution of sensitivity estimates, see the following graph which plots sensitivity estimates over time from various papers. The papers and sensitivities were taken from Barton Paul Levenson’s website and I added on EBM papers (Otto 13, Lewis 13 and LC14) near the end to make it as lukewarmer-friendly as I possibly could.

    The “trend line” is a bit of joke considering the R^2 is 0.055. But a few things can be said:
    – There is no evidence to suggest the sensitivity is “settling” to a lower value
    – The vast majority of papers fall within the IPCC range
    – The range of estimates is not noticeably shrinking

    So what’s “concerning” about the evolution of sensitivity estimates? Well, there’s no “concern” of estimates plummeting to lower values. There’s very little “concern” of estimates rising to higher values. There is a “concern” that the range isn’t shrinking – but lots of very smart people are working hard on this.

    From a risk assessment standpoint, the major and real concern is that we cannot eliminate the upper, more dangerous end of the IPCC range. In fact, looking at the long view of the sensitivity estimates, we have to treat a 3 K sensitivity very seriously and cannot discount a 4.5 K sensitivity. Of course we cannot discount a 2 K sensitivity, despite the PDF showing lower likelihood but, again, you don’t do a risk assessment by hoping that the damages will be on the low end of your probability range.

    Until we can discount the upper end and shift the most likely estimate much lower, we should be very concerned about the sensitivity range – by concerned I mean act to mitigate possible future damages. Anything else would be terribly stupid risk assessment in the face of the data and evidence.

  73. Magma says:

    @rconnor: There is no evidence to suggest the sensitivity is “settling” to a lower value

    The eight post-2010 ECS estimates shown are between 1.5 °C and 3.5 °C and span a lower temperature range than covered by any given ten-year period from 1970 to 2005. That could be taken as evidence of convergence.

  74. rconnor says:

    Magma,

    BPL’s list ended in 2006. I added on a few more recent papers (Schmittner et al 2011 (2.3 K), Hargreaves et al 2012 (2.5 K), PALAEOSENS Project 2012 (3.5 K), Bitz et al 2012 (3.2 K) and Masters 2013 (3.15 K)) and specifically included the 3 EBM papers listed before.

    Thus the post 2010 sensitivity estimates are heavily influenced by the 3 EBM papers, as was the IPCC’s decision to lower the lower bound of the estimate range. However, the EBM papers have a number of factors that may make their estimates artificially low.

    (1) The reference periods of EBM’s have a large impact on the sensitivity estimate. Most of the EBM’s end around periods influence by La Nina’s. If they were updated to include data up to 2015, their estimates would increase.

    (2) LC14 stated they selected the end period of 1995-2011 to “avoid major volcanic activity”. However, as noted by Vernier et al 2011, the post 2000 period was influence by several smaller volcanoes. This suggests that the end reference period may have been impacted by volcanic activity, thus lowering the sensitivity estimate.

    (3) EBM’s are also strongly influenced by OHC data. These papers were published before Durack et al 2014 which noted “observed estimate of 0-700 dbar global warming since 1970 are likely biased low”. Gavin Schmidt, in a tweet, stated that incorporating Durack et al 2014 into LC14 would increase their sensitivity estimates by 15%.

    (4) Cowtan & Way 2013 and Karl et al 2015 have indicated that there was a slight cooling bias in recent temperature data. Incorporating this new research would likely increase the sensitivity estimates of EBMs.

    (5) Inhomogeneities in aerosol forcing, as noted in Shindell 2014 and Kummer & Dessler 2014 (both too recent to have been included in any of the EBM papers listed), may cause EMBs to underestimate sensitivity.

    (6) EBMs ignore all non-linearities in feedbacks and inhomogeneities in forcings. This accounts for some of the reason they show lower sensitivities than other methods.

    (7) See Marvel et al 2015.

    None of this is meant to say these EBM papers are wrong, as most of these notes come from research/data that came out after the papers were published. However, when incorporating the newest research and data, it’s very likely that EBMs would lead to higher sensitivities, more in-line with other methods. Therefore I don’t believe one should take the post 2010 papers as evidence of convergence to a lower estimate – especially in light of Marvel et al 2015.

  75. angech says:

    rconnor says:
    “the rise in temperature could be caused by natural variation’? Yes or no”
    If you’re referring to the current rise in temperature from 1900-present, then the answer is “No”
    Thank you for the graph of the evolution of sensitivity estimates [The papers and sensitivities were taken from Barton Paul Levenson’s website].”
    Very helpful reference for this debate.
    Also Magma for
    “The eight post-2010 ECS estimates shown are between 1.5 °C and 3.5 °C and span a lower temperature range than covered by any given ten-year period from 1970 to 2005.”
    And Dikran for pointing out that internal variability [aka natural variation] is a factor, even if not in his opinion important due to time scale.
    “To answer angech’s question, some temperature changes can be attributed directly to a particular forcing or to internal variability. However, there are many forcings that affect climate, and on shorter timescales, internal variability dominates.
    willard (@nevaudit) summend up Dikran’s point thus
    ” Everything you said about cancer can be said about AGW, so that you find the evidence of cancer attribution sufficient while AGW insufficient may be contradictory, something you disapproved earlier. ”
    Thanks.
    That is the trouble with analogies, they are not the same thing. The evidence for smoking and lung cancer is strong and multi factorial, The evidence for AGW is still weak and multi-factorial in my and other skeptic’s opinion.
    The argument to produce sufficient proof is different to arguing a consensus exists. ATTP will argue that for some skeptics there is never enough proof and he is right.
    However when putting up your proofs they have to be logical, cohesive, supportive and non contradictory.
    The range of ECS is just one of a number of legitimate sticking points to discuss refine and remove from dispute which is why this discussion is worthwhile.

  76. angech says:
    September 21, 2016 at 8:29 am

    Dikranmarsupial
    You can have the last word[s].

    LOL. ;o)

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