Why Climate Sensitivity is Not Policy-Relevant

First of all, we all owe Joe Romm thanks for being quick to draw up the natural extension to the Marcott et al. graph showing the consensus picture of the near future global temperature in the light of this new result:

Carbon-Final

JOE ROMM’S ALARMING GRAPH

After duly boggling about how horrible this looks on this particular time scale, a second thought hits.

A number of commentators are very interested in debating how sensitive the climate is to CO2 (the equilibrium climate sensitivity, usually expressed as temperature change per doubling of CO2 consentration). A great deal of talk goes toward discussion that this number may be as little as half of the consensus best estimate. This is highly unlikely, and if true it’s very interesting as a matter of science. But is it policy-relevant?

Given that on this time scale the warming pulse is essentially vertical, it’s easy to modify the plot to be a good approximation of the trajectory if the consensus is actually so badly wrong that it is more than double the real sensitivity. It looks like this:

THE LUKEWARMERS' WISHFUL ALTERNATIVE

THE LUKEWARMERS’ WISHFUL ALTERNATIVE

 

Given that this change still takes us well outside the experience of humanity in range, and well outside the normal experience of the biosphere in rapidity, such an outcome offers no grounds for complacency. And the data themselves plainly argue against a sensitivity smaller than that.

Clearly we are already in trouble and need to stop accumulating carbon in the atmosphere as soon as possible. No plausible sensitivity argument can change this enough to cut us any slack.

No plausible sensitivity-related argument is policy relevant.

UPDATE: Send in the trolls! This article was linked by Morano:

Screen shot 2013-03-11 at 12.11.05 AM

 

(some comments were moved to the borehole.)

 

Comments:

  1. According to Joe Romm, his graph is projected to 2100.

    These really are powerful graphs. Of course, most of us knew this already, but sometimes seeing it laid out so plainly over the course of human civilization brings it home with a thud.

    http://thinkprogress.org/climate/2013/03/08/1691411/bombshell-recent-warming-is-amazing-and-atypical-and-poised-to-destroy-stable-climate-that-made-civilization-possible/

    • Well yes, *these* graphs are powerful because of those extensions, but I truly don't understand why this paper has attracted much interest since the basic shape of Holocene global surface temps has been known for over a decade. Any explanation would be appreciated.

      • As with Mann et al, the reason the graph is captivating and the reason it is scientifically valuable are distinct. Scientifically it presents a higher resolution record than heretofore existed, and shows a general absence of high frequency variability of the sort being seen now. Polemically, though, it is hard to see it as other than a reinforcement of the idea that we are in big trouble.

      • One reason the new paper attracted a lot of attention is because it appeared in Science and this journal put its powerful publicity machine in high gear to promote the story. Also, deliberately calling the graph a 'hockey stick' seems to have been a calculated move to attract attention. All this is good, in my opinion. The bad thing is that Science makes it hard for people to get free access to the actual paper. Someday pirated versions of the PDF file will hit the net, but I haven't seen one yet.

    • I think Joe may be overstating the case regarding 2100, but the fact remains that the curve is essentially vertical compared to past results.

  2. It's the effect of variable frequency attenuation. Over most of the history, the data is sparsely sampled and any lumps and spikes shorter than a millenium are blurred out. So you get a nice smooth line. Then at the end you include the high-frequency modern reconstructions which *do* show spikes. (Does anyone know which ones?) The result is that it looks like the modern period is acting differently to the past. You could take any red noise series and do the same.

    Climate/weather is experienced at a local level. Sea level may be affected by the global average, but for everything else you're only interested in the weather at the place where you are, right now. So to assess impact, you need to plot not only the global millenial average, but the *range* of variation too. How much does it vary decade-to-decade, year-to-year, day-to-day, place-to-place? And how much has that changed, and how much will/might it change?

    It matters whether cold times/places are getting warmer, or hot times/places are getting hotter. The effects on human welfare are opposite. Show us *that* data. (Or if you don't know, show us where our ignorance extends.) Tell us the nearest place to us that currently has our future climate. Then less educated people will understand what you're talking about at more than the most shallow intellectual level, and might therefore be more inclined to do something about it.

    • It’s the effect of variable frequency attenuation. Over most of the history, the data is sparsely sampled and any lumps and spikes shorter than a millenium are blurred out. So you get a nice smooth line. Then at the end you include the high-frequency modern reconstructions which *do* show spikes.

      A fair point, certainly, at least to some extent. But the excursion we are now seeing is sufficient that it most likely would have been resolved at least in part. Any comparable spike would have had to subside very quickly to not appear in the record. And we have neither evidence nor proposed mechanism for such a spike. What we do see is that global mean surface temperature in the Holocene is a stable quantity.

      How much does it vary decade-to-decade, year-to-year, day-to-day, place-to-place? And how much has that changed, and how much will/might it change?

      The extent to which the past local holocene variations were already anthropogenic is hard to constrain - it is still a plausible hypothesis that the drying of the Sahara was anthropogenic, for example. That said, what we are now seeing in any given place is not yet solidly outside the recent preindustrial variation of the particular place, with the notable exception of the Arctic. On the other hand, taken globally, the prevalence of anomalies is starting to emerge from the noise, more or less on schedule.

      Tell us the nearest place to us that currently has our future climate.

      Dr. Donald Weubbles likes to show maps of Illinois sliding down to the latitude of Texas. But I suggest this badly misses the point.

      We are moving the system very far from equilibrium. We can expect very large transients at many characteristic time scales. As time progresses, places will have less and less of a characteristic we are used to calling a "climate". There is no reason to expect a smooth transition to a new statistical distribution. The concept of "climate", to be technical, implies stationary or near-stationary statistics of weather. But we will not see stationary statistics again in our lifetimes.

      The dominant effect on human welfare will be via decreased predictability. I expect the dominant effects of that will be to drive agriculture into wholly or partially controlled environments and will grossly impoverish biodiversity in the wild. Also predictable is that we can anticipate sea level rising by meters per century for centuries to come, and that the base of the ocean food chain will be drastically changed and probably reduced by ocean acidification.

      Whether we can get through this without a dramatic increase in mortality is the real adaptation question.

      I for one would have preferred not to do the experiment but it is to some extent too late. I would like, as a second choice, to minimize how far into this diminished prospect we risk venturing.

      • " But the excursion we are now seeing is sufficient that it most likely would have been resolved at least in part. Any comparable spike would have had to subside very quickly to not appear in the record."

        Judging by Marcott's bandwidth estimate, anything less than 300 years would vanish, and anything less than 2000 years would be significantly attenuated. Yes?

        "And we have neither evidence nor proposed mechanism for such a spike."

        There are proposals, but I agree insufficient evidence as yet. (e.g. Dansgaard-Oeschger/Bond speculations...)

        "What we do see is that global mean surface temperature in the Holocene is a stable quantity."

        Again, can we conclude this from just the low-frequency component?

        "The extent to which the past local holocene variations were already anthropogenic is hard to constrain – it is still a plausible hypothesis that the drying of the Sahara was anthropogenic, for example."

        Agreed.

        "We are moving the system very far from equilibrium."

        I assume you mean far from the current equilibrium to a new one?

        "The concept of “climate”, to be technical, implies stationary or near-stationary statistics of weather. But we will not see stationary statistics again in our lifetimes."

        That sounds interesting. Do you have any more on that?

        I understand 'stationary' to mean the statistical distribution is invariant to translations in time. If climate changes, it can't be invariant. But I assume you mean something more than simply that the climate changes over time - which I'd agree with anyway.

      • Attenuated, sure. Invisible? Not logically excluded but quite unlikely. If such excursions were common the smoothed record would still be unlikely to be THAT smooth.

        Dansgaard etc., not in the Holocene. Agreed there were large excursions during the postglacial shift. But that's the point. We've abruptly entered an unstable period.

        Holocene climate changes slowly enough over time that "climate change" seems meaningful to us. But it's likely that will change.

        see http://planet3.org/2012/04/09/disequilibrium-is-not-your-friend/

      • > And we have neither evidence nor proposed mechanism for such a spike.

        I just made the same argument with Moshpit:

        > The Earth might not move that fast [I'm referring to a quote by the authors who mainly blame the Sun] and handwaving unknown abrupt forcings might be suboptimal here.

        http://judithcurry.com/2013/03/11/lets-play-hockey-again/#comment-301869

        Since I've discovered this independently, I made my point in a most obscure way.

    • "Sea level may be affected by the global average, but for everything else you’re only interested in the weather at the place where you are, right now."

      Think about feeding a population of 9 billion as formerly productive regions become too hot and dry for large scale agriculture, populations have to relocate, sea level causes very large coastal populations to move inland quicker than new high rise housing can be built (but the land is needed for crops) and so on. Don't be so self-centered ;)

      "It matters whether cold times/places are getting warmer, or hot times/places are getting hotter. The effects on human welfare are opposite."

      Assertion, no basis given, don't forget precipitation and agriculture again, and it matters big time if the tundra and permafrost melts. Nullius, are you by any chance just saying stuff to argue? :)

      "Show us *that* data."

      Here it is.

      • "Think about feeding a population of 9 billion as formerly productive regions become too hot and dry for large scale agriculture, populations have to relocate, sea level causes very large coastal populations to move inland quicker than new high rise housing can be built (but the land is needed for crops) and so on. Don’t be so self-centered"

        I find this stuff interesting, but isn't it diverting off topic?

        I see three main distinct claims here:

        1. Large areas will become hot and dry.
        2. This will render them unsuitable for agriculture.
        3. Sea level rise will displace coastal populations faster than new housing can be built.

        First, I thought the prediction was more usually that precipitation will increase, and that much of the strongest warming will be in the cooler parts of the world. I realise that at the regional level it is more complicated than that, but it seems to me that the story people tell about the future isn't consistent, except that it's consistently always whatever sounds worse at that point in the conversation, or more of whatever bad weather has most recently happened. If it's hot and dry it's going to get hotter and dryer. If it's cold and wet it's going to get wetter. After a while the pattern becomes tedious and it starts to stick out. :-)

        Second, we know what happens to crops when we try to grow them in greenhouses! :-)

        I've seen several papers trying to make this argument, and none of them successfully. As 20th century temperatures have risen, crop yields have gone up. Technology is moving faster than climate change. Studies usually ignore the adaptability of farmers, who can change crop choices and methods to suit. We already farm over a huge range of climates. In the worst case, we already have the technology to grow food more or less independently of the surroundings, with desalination, greenhouses and hydroponics - it's just more expensive.

        Thirdly, discussion of sea level rises usually neglects any discussion of the dynamic geology of coastlines, river deltas, and alluvial plains. The land isn't fixed. It is close to the current sea level for a reason.

        With only a tiny fraction of our industrial capacity we renew housing stock on a ~50-year cycle anyway. How old is the average house in your neighbourhood?

        If you're talking about sea level rise as projected by the IPCC, I think you underestimate both natural land-forming processes and our engineering capabilities. If you're talking about acceleration to extraordinary multi-metre sea level rises, that's a different topic and we'd probably have to discuss ice sheet dynamics. Needless to say, I don't find those claims credible.

        It's not a question of being self-centred. It's a question of extraordinary claims contrary to common sense being made without visible evidence.

        "“Show us *that* data.” Here it is."

        I had a look, but it doesn't go back to 8000 BP, which was the question I was discussing. :-)

        "Nullius, are you by any chance just saying stuff to argue?"

        I'm saying stuff to encourage a discussion of the arguments supporting these common tropes. Just saying "seas will rise faster than we can build houses" doesn't convince anyone not already convinced. Many people who are not convinced will just write it off as obvious nonsense.

        So it gives you the opportunity to set out and refine your arguments, to make a more convincing case. It gives me the opportunity to learn new and interesting stuff about the way the world works, and to test my own ideas for flaws.

        The original topic of the conversation was whether Romm's graph made a convincing case for the current warming being unusual and concerning in the context of Holocene history. I was explaining why the argument doesn't convince, and what you would need to do to fix that. If you can fix it, we move the debate forward. If you recognise that you can't easily fix it and switch to a different approach, we move the debate forward. But it's unproductive to endlessly produce dodgy-looking graphs and complain about how everyone is ignoring you, or only arguing for the sake of having an argument. Of course we're going to argue! If you're trying to figure out ways and means to convince the unconvinced, how does not listening to their arguments help?

      • "So it gives you the opportunity to set out and refine your arguments, to make a more convincing case. It gives me the opportunity to learn new and interesting stuff about the way the world works, and to test my own ideas for flaws."

        There is merit to this stance. The situation is dire and some people have little patience for sophistry. Such impatience is understandable. But it is still the case that as long as there are serious people who are unconvinced, well-mannered critic is useful.

      • 1. Large areas will become hot and dry.
        2. This will render them unsuitable for agriculture.
        3. Sea level rise will displace coastal populations faster than new housing can be built.

        I believe these are consensus predictions.

        First, I thought the prediction was more usually that precipitation will increase, and that much of the strongest warming will be in the cooler parts of the world.

        The prediction is that total precipitation will increase and become more bursty. Also the circulation belts will expand poleward, causing the dry subtropics to expand. This means that many populated zones will receive less precipitation.

        Further, most or all zones will warm up on average, increasing evaporation. So subtropical drought-prone semi-arid zones (Texas, Italy, South Australia) will become much drier.

        It is technically feasible to import water into these zones but this appears politically problematic.

        Also, extreme temperature events will increase and this may cause crop mortality.

        You do not mention increased year-over-year and decade-over-decade variability as the climate system gets further from equilibrium. This is not considered a robust consensus prediction but I have trouble imagining how this would fail to occur. If I am right this will also interfere with agriculture.

        I do not believe that global food production will decline for quite a long time, if ever. But local landholders will find it increasingly difficult to stay in business. Geographic diversification may be the key to profitable agriculture, which favors corporate entities over traditional farmers.

        I realise that at the regional level it is more complicated than that, but it seems to me that the story people tell about the future isn’t consistent, except that it’s consistently always whatever sounds worse at that point in the conversation, or more of whatever bad weather has most recently happened. If it’s hot and dry it’s going to get hotter and dryer. If it’s cold and wet it’s going to get wetter. After a while the pattern becomes tedious and it starts to stick out.

        I understand this perception and it's not without some basis in the actual reality of how nonscientists argue. Not every unfortunate weather event is a harbinger of doom. But that is no reason to dismiss the actual evidence at hand.

        If you’re talking about acceleration to extraordinary multi-metre sea level rises, that’s a different topic and we’d probably have to discuss ice sheet dynamics. Needless to say, I don’t find those claims credible.

        Why not?

      • "There is merit to this stance. The situation is dire and some people have little patience for sophistry. Such impatience is understandable."

        Indeed. The same impatience exists on both sides of the aisle. But while emotionally satisfying, it has so far proved unproductive.

        "Also the circulation belts will expand poleward, causing the dry subtropics to expand."

        How does the physics of that work? Genuine question.

        "You do not mention increased year-over-year and decade-over-decade variability as the climate system gets further from equilibrium."

        What do you mean by "further from equilibrium"? Doesn't the equilibrium just shift to a new equilibrium position?

        "I understand this perception and it’s not without some basis in the actual reality of how nonscientists argue. Not every unfortunate weather event is a harbinger of doom. But that is no reason to dismiss the actual evidence at hand."

        I agree. As a rule, I prefer to argue for improving the *quality* of the evidence at hand, rather than dismissing it. (For or against. Both sides are guilty.) It's only when people refuse to do so, or refuse to admit any need, that I become dismissive. Although dismissiveness is a problem for both sides, too.

        And I appreciate the acknowledgment that some non-scientists have used the unfortunate weather-is-climate line. I'm more inclined to take their arguments seriously when people do.

        "Why not?"

        Because the claims are based on speculations about ice sheet collapse, which as far as I know are based on unrealistic 2D models of ice flow (length + depth -- intended for glaciers rather than ice sheets, I think).

        In outline, the model supposes that the rate of change of ice extent has two terms - accumulation proportional to its length, and loss at the grounding line which is proportional to the cross-section area there, which because a constant width is assumed is proportional to the depth of the ice. This gives rise to a stability criterion that depends only on the rate of change of sea bed depth along the length of the glacier. If shortening the glacier increases the depth at the grounding line, increasing the rate of loss, the situation is unstable, and the loss accelerates.

        However, with an ice sheet as opposed to a glacier, the cross section at the grounding line depends not only on the height of the grounding line but also its length. If you have a central ice sheet flowing radially outwards, then the circumference changes with extent. (Like sediment from a river delta, an ice flow reaching the sea tends to fan out.) Also, when the ice is extending the ice flow is irregular and the boundary gets rougher; when the ice is contracting erosion is concentrated at the bits sticking out so the boundary gets smoother. (Think of frost forming, or an ice sculpture melting. It's asymmetric on time reversal.) If the boundary is a fractal it means its length increases faster than linearly as it spreads. These effects have a stabilising tendency.

        It's not the only issue I have with the models I've seen, but is perhaps the quickest to explain.

        In short, I don't think the studies make a convincing case that the 2D models are relevant to the real-world physics. And I think it's an extraordinary claim requiring extraordinarily good evidence before making expensive decisions on the basis of it. I don't believe it's been shown *not* to be true, either, and it's important to study further just in case, but I don't find the way it's been done, or the way it's been hyped, to be credible as yet.

      • But while emotionally satisfying, it [impatience] has so far proved unproductive.

        That depends on what you are trying to produce. There are many who advise the likes of me not to engage with the likes of you over details. They call doing so "the deficit model fallacy"; i.e., the prospect that you present, that if I am broadly correct I must convey the knowledge and information that I know to you, and then you would believe differently, is considered to be vanishingly unlikely (presuming the person in my role is correct and the other is incorrect).

        I don't believe this for a minute. I think that you may well be stubborn and unconvinceable, but that doesn't mean the conversation is fruitless. However, whatever the fruits of the conversation, "the deficit model fallacy" posits that such conversation will not be politically dispositive, much as you and I might agree that in fact it ought to be.

        How does the physics of [poleward shifting zone boundaries] work? Genuine question.

        And a good one. I don't actually know the answer though I believe that it exists and that I could investigate it. Maybe Isaac Held has something on his site, which I've been remiss in not following.

        I am confident, though, that it is a uniform feature of CGCM prognoses, and that this result in particular is a robust use of those tools. I could defend that point at least without bothering the top notch scientists.

        And I appreciate the acknowledgment that some non-scientists have used the unfortunate weather-is-climate line.

        Please read carefully if we are going to engage substantively. I said "Not every unfortunate weather event is a harbinger of doom." I did not say, and do not believe, that "no weather event can on its own be taken as a an indicator of climate change", and in particular hold that hurricane Sandy, mere category 1 that it was, was in fact in its details an event that would be quite implausible in the baseline climate.

        Because the claims are based on speculations about ice sheet collapse, which as far as I know are based on unrealistic 2D models of ice flow (length + depth — intended for glaciers rather than ice sheets, I think).

        This is hubris of the usual naysayer sort. Do you not think specialists would have thought of this? Actually if you look at ice velocity you will see that outflow through glaciers dominates the outflow of ice sheets.

        In any case, your point is belied by the data

      • Nullius, you should watch more news. Some alarmist predictions are already happening. Where have you been 2009/10/11/12? Start with news from Pakistan 2009 and 2010 to get a grip at the water cycle thing. Old news from Autralia gives you a picture of expanding tropical belt and shifting subtropics. News old and new from U.S.A. (e.g. Sandy) exemplify effects on human welfare.

        News today, March 19 2013: Cracks in Arctic sea ice have now reached Svalbard. That is, Arctic summer sea ice declared dead. Kangerlussuaq, Greenland, above freezing. Please don't talk about ice sheets and sea level. Just forget about it.

        Enjoy the weather and the last days of the Holocene.

      • "There are many who advise the likes of me not to engage with the likes of you over details."

        I know. I think it's a pity.

        "They call doing so “the deficit model fallacy”; i.e., the prospect that you present, that if I am broadly correct I must convey the knowledge and information that I know to you, and then you would believe differently, is considered to be vanishingly unlikely (presuming the person in my role is correct and the other is incorrect)."

        They're probably correct about that part. I've been reading Dan Kahan on the same topic. It's clearly not about information deficit - there's no significant difference in the information people on each side know. All the correlations are with cultural categories.

        --

        "I don’t believe this for a minute. I think that you may well be stubborn and unconvinceable, but that doesn’t mean the conversation is fruitless."

        Agreed. There are more reasons to talk to other people than to try to persuade them to our own point of view. I doubt you're very convincable, either! :-)

        I think there is value in exposing myself to a diversity of other points of view. It broadens the mind, teaches flexibility of thought, the ability to shift paradigms, to see other points of view, and maybe get the occasional glimpse into my own blindspots.

        It's something the Enlightenment philosophers knew as well:

        "The loss of so important an aid to the intelligent and living apprehension of a truth, as is afforded by the necessity of explaining it to, or defending it against, opponents, though not sufficient to outweigh, is no trifling drawback from, the benefit of its universal recognition. Where this advantage can no longer be had, I confess I should like to see the teachers of mankind endeavouring to provide a substitute for it; some contrivance for making the difficulties of the question as present to the learner's consciousness, as if they were pressed upon him by a dissentient champion, eager for his conversion."

        "When there are persons to be found, who form an exception to the apparent unanimity of the world on any subject, even if the world is in the right, it is always probable that dissentients have something worth hearing to say for themselves, and that truth would lose something by their silence."

        --

        "And a good one. I don’t actually know the answer though I believe that it exists and that I could investigate it."

        Thanks. That in it's way is a very good answer. It's always the first step to learning something new.

        --

        "I did not say, and do not believe, that “no weather event can on its own be taken as a an indicator of climate change”"

        So how do you tell the difference? And more to the point, how do you enable other people to tell? Can you, for example, provide a list of weather events that will or won't ever happen, and that didn't/did in the past, so that the claim becomes falsifiable?

        Say we take a 'weather' feature like the absence of the tropical upper-troposphere hotspot. Is it a sign of climate change? Is it quite implausible in a warming scenario?

        --

        "This is hubris of the usual naysayer sort. Do you not think specialists would have thought of this?"

        I think they *ought* to have done, but I try not to assume. That's why I tried to find out, and that's where I got all the stuff about the 2D models from. I'm no believer in argument ad verecundiam. Science is the belief in the ignorance of experts, as Feynman said. But it would be hubris, therefore, to consider *myself* the expert.

        I'd certainly be prepared to believe that specialists *have* thought of it, and I'm interested to read about what they say, but I'm not prepared to simply *assume* they have done so, just because they are 'the experts' and it supports a desired conclusion. That's just me, though. Not everyone thinks so.

        That's also why I enjoy talking about it in places like this - there's a fair chance that in the effort to prove me wrong, you'll point me to where the specialists *did* think of this, and I'll learn something. Cheers.

      • “And a good one. I don’t actually know the answer though I believe that it exists and that I could investigate it.”

        Thanks. That in it’s way is a very good answer. It’s always the first step to learning something new.

        No, it's a very bad answer. The number of people in the world whose answer I would credit is small, and for me to try to get access to them to satisfy the curiosity of someone who acknowledges being too stubborn to change (their) mind itself is a losing proposition. I have better uses for my time with experts.

        What's more the answer is bound to be subtle. If my brain is still firing on all cylinders, I could probably get a good grasp on it in a few weeks. Determining how certain I am of the answer would be tantamount to a two year postdoc. Then the likelihood that a single person would be interested in my understanding enough to follow the argument is small unless I put the equivalent of a major review paper's work into it.

        So unless the review paper already exists (always a dicey proposition) I have no answer for you that could conceivably be worth the effort, particularly since there are ongoing active efforts to lie and misdirect about other matters.

        ===

        Say we take a ‘weather’ feature like the absence of the tropical upper-troposphere hotspot.

        That one for instance.

        As far as I understand it this is not a topic of first order importance either to science or poilicy. The idea that it presents a deep mystery shaking the foundations of climate science that a predicted third order effect is not emerging from noisy observations seems to me a willful misdirection. (Also, whether it exists or not is not a weather-like phenomenon at all, so your argumentation is not especially coherent.

        In short in my opinion it's a red herring and a tar-pit - a political trick masquerading as intellectual engagement. If you have a case that it deserves a tenth of the attention it's gotten to date please feel free to elaborate.

        ===

        Your question about how to model ice sheets is interesting.

        The short answer is that 2 D dynamics suffices because there is no significant vertical dynamics other than hydrostasis. Essentially 2 D dynamics (with complex top and bottom forcing and boundary conditions) captures the flow to any order currently computationally feasible. Does that mean anything to you?

        Does it mean anything to the other readers? Does such talk belong here?

        Have you asked an ice modeler to explain?

      • "Then the likelihood that a single person would be interested in my understanding enough to follow the argument is small unless I put the equivalent of a major review paper’s work into it."

        I was interested enough to try to find out in the first place. I ploughed through a fair amount of mathematics to figure out what they were doing; how it worked.

        Whether people are interested depends on their prior beliefs. If somebody hears something they want to believe, they won't go to a lot of effort to check it. If they hear something they don't want to believe, instead of asking "*Can* I believe this?" they ask "*Must* I believe this?" and do a much more thorough check.

        If they don't get answer to satisfy them, they'll reject the claim. The effort they'll go to before they give up depends on how important they think it is to get the answer right, versus how confident they are in their prior belief.

        This difference in expectations regarding quality of evidence is one of the major dividing lines. Believers are prepared to accept quite casual and anecedotal evidence, handwaving, arguments from authority. And they can't comprehend how other people could find it any less convincing. That causes a lot of misunderstanding.

        That applies to *both* sides, by the way.

        --

        "So unless the review paper already exists (always a dicey proposition) I have no answer for you that could conceivably be worth the effort"

        Fair enough. There's no reason for me to change my mind, then.

        I ask only because I expect that there's a better *chance* you would know the basis of your own beliefs, and that it is therefore worth asking. I'd not expect you to do any extra work on my account, unless you found it interesting yourself. Someday, I'll maybe find somebody who will.

        Incidentally, don't you find it odd that there isn't a review paper for this, and indeed for all the other claims of major climate science concern? Wouldn't it make sense to have all the evidence and the entire chain of argument all in one place, and openly/easily accessible?

        --

        "As far as I understand it this is not a topic of first order importance either to science or poilicy. The idea that it presents a deep mystery shaking the foundations of climate science that a predicted third order effect is not emerging from noisy observations seems to me a willful misdirection."

        That wasn't my intention. I was simply trying to forestall the initial answer I expected - that individual weather events were to be judged unlikely in a baseline scenario on the basis of whether they happened in climate models. It's a reasonable argument to say that if an event is likely under one hypothesis and unlikely under the other, and it happens, that's evidence for the first hypothesis. But this only works if you've got a valid means of determining their likelihood - if you applied this logic to the tropical hotspot you'd conclude that global warming wasn't happening.

        Since I knew that wasn't a conclusion you'd accept, I figured you'd have to come up with a different argument, and we'd save some time. Unfortunately, the conventions of the game led to you misinterpreting what I intended and further distraction.

        The question was: so how do you tell the difference? How can you say ahead of time which weather events will or won't occur under a baseline or warming scenario?

        --

        "The short answer is that 2 D dynamics suffices because there is no significant vertical dynamics other than hydrostasis. Essentially 2 D dynamics (with complex top and bottom forcing and boundary conditions) captures the flow to any order currently computationally feasible. Does that mean anything to you?"

        Yes. I know perfectly well what you mean - it's helpful because it gives me insight into your thinking, and where it differs from mine.

        The issue isn't whether there are any significant *vertical* dynamics, but whether there are significant *lateral* dynamics. They model the vertical/longitudinal, and neglect the lateral component. I am asking why you think they think that's valid, because I would have expected that it's not.

        And if a real answer is not computationally feasible, what business do we have drawing any conclusions?

        --

        "Does it mean anything to the other readers? Does such talk belong here?"

        That's up to you. Are they constructive comments that move the discussion on?

        If you recall, I initially was going to skip discussion of the point since I thought it was off-topic, but you did ask why, and you did continue the conversation. I do try to keep it at a higher and more constructive level than the usual inter-side sniping.

        I've enjoyed the conversation so far, though. So thanks for engaging.

        --

        "Have you asked an ice modeler to explain?"

        I don't know any to ask. And I understand that climate scientists regard sceptics asking endless questions about the science as some sort of personal attack. But I have asked people who believe it is true and who seem to want to persuade other people, in the hope that at least some of them would understand the evidential basis for their own beliefs.

        Do scientists *want* us to believe? Do they *care* if we believe? Do they think this is an important subject for me to know about? Bear in mind my natural inclination is to dismiss it - that's what I *want* to do. It is an effort not to. So why am I being made to jump through any more hoops than necessary to find out?

        As I said earlier, why wouldn't all of this science be collected in one place and made easily accessible to anyone who wanted to know? They've publicised the conclusions, why do they make the science supporting those conclusions so hard for the interested non-academic to access? Shouldn't it have been published and summarised already, anyway?

      • As I said earlier, why wouldn’t all of this science be collected in one place and made easily accessible to anyone who wanted to know? They’ve publicised the conclusions, why do they make the science supporting those conclusions so hard for the interested non-academic to access? Shouldn’t it have been published and summarised already, anyway?

        That is an interesting question.

      • Look, I'd love it if you would pick a topic and stick to it. We might both learn something. Preferably not the "hot spot" since I think it's a completely irrelevant topic. But you have to pick one. Asking questions is much cheaper than answering them.

      • "Look, I’d love it if you would pick a topic and stick to it. We might both learn something."

        OK. I tend to respond to what other people say, assume that if they ask about it then it's on-topic, and that any bits that are off-topic or uninteresting will be ignored.

        We were originally discussing Marcott, frequency resolution, and whether the uptick at the end was evidence of 'unprecedentedness'. Do you want to go back to that? If so, we could discuss McIntyre's observations on core top redating and low sample size robustness. (I have to confess I missed completely on this one myself.) Or we could talk some more about ice sheet stability. Or weather-is-climate claims.

        "Asking questions is much cheaper than answering them."

        True. But asking questions is more open-minded and constructive than contradicting. I don't believe there are any individual local weather events that can be ascribed to climate change - the baseline/changed distributions (model uncertainties included) at the scale of weather are broad and overlap, and we don't have a reliable way of estimating probabilities for local weather events. The models have not been verified/validated for that purpose.

        But I thought it was better to ask how you justified your claim than to make my claims. It would give me a better insight into your thinking, and we get to concentrate a bit more on your good science rather than my contrarianism. :-) I assumed that since you made the claim, you had some well-developed thoughts on it. I was interested to hear them.

        Any time I ask a question you don't want to answer, feel free to ignore it, or say you don't have the time/interest/whatever. I won't be offended, or read anything into it.

  3. Just to drive home the point, you could put a little arrowhead at the end of the scythe blade, just to press home the point that a graph shaped like this is unlikely to head off in a different direction the moment we hit 2100.

  4. In my various work with my students and others I always criticize graphs that don't start at zero because they amplify the signal. This one, ironically, makes things worse by starting at zero. What would it look like if you go back another couple of thousand of years to the beginning of deglaciation?

    Not that I'm trying to make it seem any less scary - I'm on the "it's too hot already" team and have been for years!

    • I am guessing that is how much mud they had. Perhaps there is less mud to work with during the glacial period.

      Yes, the temperature curve is steeper and bumpier prior to the time displayed. But there's nothing in the record as steep as what is reasonably to be expected, at least over the past 50 million years or so. Chixculub might give us a run for our money.

  5. You really should be ashamed for putting such complete and utter nonsensical lies.
    There are actually some people out there that are stupid enough to believe this bullshit and you are scaring them.

    You are disgusting.

    • That would depend on whether this is a realistic representation of the science or not, wouldn't it? Why don't you look further.

    • Huh? This is an unsolicited attack without basis that makes no effort to assimilate the information provided. "Gary" seems to blame others for his refusal of science and reality. Unfocused rage doesn't solve anything. Unfounded accusations and insults fail to convince.

      At the very least, Gary could provide something he would call evidence, but his anger seems to blind him to how fact-free his claims are.

      I know science is difficult, but there are multiple trains of evidence all pointing the same way, and not all of them are scientific.

    • People should be scared. That's the point. Get their heads out of their infotainment and act while there's still time. Stop letting advertisers and marketing set the terms of our lives.

    • It is rushing toward a new quasi-equilibrium that it is far from. It will not run away forever but actual behavior as it approaches equilibrium is complex and hard to predict. How big the spike is depends on 1) the sensitivity 2) the transient response and 3) the amount we actually emit. 1 is pretty well known and 3 is under our control. 2 is not well-known but it is expected to be very fast on the time scale shown.

    • There is no doubt the temperature will equilibrate. It has to, in order to match the Blackbody Law. What's interesting -- and disturbing -- is what changes will be wrought upon the convective systems below the stratosphere in order to do so.

      Hey, Venus is in equilibrium, too.

  6. As someone who labors to be honest in the face of dishonest attacks almost every day, I think this discussion opens a useful door. Instead of concentrating on what we can and can't measure and why what we can't measure doesn't allow us to measure what we can and make the best of it, it says we can look at it all. We can hold the inconsistencies in our heads, accept them, and then notice that in the present time something extreme is happening.

    Instead of using the ability to obfuscate to the maximum extent possible, we can say we are working to find any information we can and then focus on what we know.

    I guess the reason I just repeated myself is that I find the continuing campaign to prevent progress very disturbing, since all our futures seem in my amateur best opinion to be being thrown away in the service of a lot of political quibbles and violent passions that have nothing to do with reality.

    • Disturbing indeed. That's why I find the prospects doubly alarming. It's not only climate destabilization I find scary, it's also the mental response of much of mankind. Shooting the messengers, many engulf in a spiral of reality denial. Technocracy marrying superstition, birthing hitherto unseen monsters of sophisticated stupidity. Will they one day soon burn witches and scientists again?

      • They'll just come after those who disagree with them with their newly augmented armories. Later on, they'll need to loot and kill their "enemies", a la Senator Graham (who boasts of having a fancy rapid-shooter in case he's in something like Sandy or Katrina). “You could find yourself in this country in a lawless environment from a natural disaster or a riot”

        http://www.rawstory.com/rs/2013/01/30/sen-graham-brags-about-his-ar-15-and-frets-gun-packing-moms-may-run-out-of-bullets/

        Hell yes, I'm angry! Why shouldn't I be. But I don't need a gun, and have no desire to ever have another person's life on my conscience.

  7. Why does a temperature increase always need to be BAD?
    Why does added CO2 in the atmosphere always need to be BAD?
    These are routinely assumed...w/o reason?
    These are routinely assumed...with reason?
    I chose the first.
    Who, just who, knows a few degrees warmer is bad? Answer this!
    Photosynthesis has increased...so far much to the good.

    • Sigh. Who's linking to us now? (Update: sure enough - Morano)

      So. Look at the graph. It doesn't matter whether the wall goes up or down at all. We just don't want to rock the boat THAT hard. I don't care if we capsize to port or to starboard. I'd rather stay afloat.

      • You haven't answered the question.

        Why does a temperature increase always need to be BAD?

        Why does added CO2 in the atmosphere always need to be BAD?

      • I did answer the question. Let me try again.

        A temperature increase is NOT always bad. A large and rapid temperature change, such as we are beginning now, is a big problem no matter which direction.

        Added CO2 is NOT always bad. A large and rapid shift in CO2, such as we have now, is a big problem no matter in which direction.

    • The person making routine assumptions is you.

      I suggest doing a little homework. This has been asked and answered many times before. While there's a campaign on to discredit the best resource for this, I suggest you go to SkepticalScience and follow the trail (their articles are well researched with plenty of links) and come back when you have studied the answers to your questions. Floating a balloon of ignorance only persuades people who have heard these questions and assertions hundreds of times before that you are unwilling, unable, or too lazy to follow through. But on the off chance that this is an honest question, here is the beginning of the many answers to your question:
      http://www.skepticalscience.com/global-warming-positives-negatives.htm
      http://www.skepticalscience.com/co2-plant-food.htm
      http://www.skepticalscience.com/co2-pollutant.htm

      Since I think it's likely you've been subjected to the smear campaign on SkepticalScience, you should know that it is a volunteer "crowdsourced" effort to collect all the information readily available in other places to provide these answers with as complete references as is possible. The hate stuff is because it is effective - you will find that anywhere the facts are presented, there is a massive effort, not a million miles removed from gazillionaire fossil fuel industry funding, to discredit if possible if if not, distract from learning and action that is much needed.

      That action needed, even if all this were not true, would be a positive addition to our economy. It would involve researching, developing, and distributing and storing clean energy, often from local sources. Pollution is a fact, but it need not dominate our world the way it does. That's down to wealthy interests with short-term goals.

  8. I am afraid your data is baloney. We have been at least 2 degrees C warmer 2000 years ago.

    Above someone asked, "Why is warmer bad?". the dinosaurs lived in a world where at least arctic was ice free and global temps were 5 decrees C warmer. My God, life should have been extinguished. How could we be here now? Warm is good, it allows plant growth. CO2 increases Vegetation growth dramatically. 1400ppm is optimal.

    You don't grow crops in ice, see 17th century Europe and China. People starved to death.

    You warmists don't do science, you do wishful thinking. The data shows your models are wrong.

    As a scientist, I can say, we don't know whats going on other than than our climate fluctuates dramatically and sometimes very rapidly in either direction.

    But if we have a choice, WARMER IS BETTER.

    is

    http://wattsupwiththat.com/2013/03/08/marcott-et-al-claim-of-unprecedented-warming-compared-to-gisp-ice-core-data/

    • What do you mean "as a scientist"?

      Again, there is no claim that warm is bad. There is a claim that extremely rapid change is bad.

      "You warmists don’t do science, you do wishful thinking. The data shows your models are wrong."

      That's a very interesting adjacency. All models are "wrong" in some sense but some are useful for some purposes, as is well known. If you don't understand this you are no scientist. What's ironic is this. To the extent you believe that "the data shows your models are wrong" for current data and current models implies "no need to restrain carbon emissions" for current emissions is an exact match for "wishful thinking".

      "But if we have a choice, WARMER IS BETTER."

      How much warmer? Presumably you do not advocate boiling the oceans, as Venus did. Again, you are using very blunt language. You are not speaking in a way one would expect from someone who has been around scientists.

      Your link at Watts conflates Greenland ice core temperatures with global mean surface temperatures and is therefore misleading. It is known that northern North Atlantic temperature is highly variable compared to global temperature. Since this trick has been tried before and corrected before on various occasions, it's hard to even take this as an honest mistake.

    • This is the same Dan Alter who says that the world is going to end on July 16, 2024?

      Yes, important to show that one's models are supported by real worl data...

    • "As a scientist, I can say, we don’t know whats going on other than than our climate fluctuates dramatically and sometimes very rapidly in either direction."

      Really? That's all? Granted lots of areas of science don't touch on atmospheric physics, but still....

    • "I am afraid your data is baloney. We have been at least 2 degrees C warmer 2000 years ago."

      Huh? Whose data is what? Oh wait, you don't offer data. Well here's a comment:
      http://scienceblogs.com/deltoid/2010/05/14/tony-abbott-and-the-roman-warm/comment-page-1/#comments

    • @Dan Alter

      Take a look at that graph from the Watts link you provided. Take an especially hard look at the y-axis.

      According to the graph at Watt's the temperature of the MWP was a balmy -31 degrees. Perhaps that graph doesn't show what you think it does.

    • Looks to me like it's not you are "afraid" but you hope people will believe your flat assertion of arrant nonsense. Just flap your keyboard and make a few driveby characterizations, and tie respondents up in knots since there's no "there" there.

      The sad thing is that people have to bother to answer this garbage.

      • Naw, we don't have to respond. Sometimes we want to though. It's fun and easy, and we can deliver useful information in a lighthearted way to the third party reader if not to the perp.

        P3 could easily have flushed this silly comment to the borehole and been well within our stated policy. But I let it through because I wanted to have fun with it.

        Somebody asked Keith Olberman on Twitter why he bothered to respond to trolls.

        "Target practice" he answered.

  9. Pingback: Another Week of GW News, March 10. 2013 – A Few Things Ill Considered

  10. What climate sensitivities, and what projection of CO2 to 2100, are being used to create these graphs?

    (Personally I don't think we should be throwing graphs around without talking about how they were created. It legitimizes that sort of tactic: anyone can draw a graph that shows what they want.)

    • Good questions.

      I think this is a schematic more than a graph and justifiable as such. It assumes "business as usual", and a consensus sensitivity and perhaps a slightly fast transient response if we take the vertical line to represent 2100.

      That is, this is indeed our best picture of the Ghost of Christmas yet to come if we do not change our ways.

      See Dana's link in the first comment on this article for a more formal set of plots. I think it is a fair claim that this is one of the first broad brush pictures that the public ought to be looking at.

      • I agree that a graph like this is a good idea. But if the people spreading them around can't point to a clear and precise explanation of what data and assumptions they come from, it'll be easy to argue they're just propaganda. It doesn't take that much more work to do things right.

  11. I'm not a scientist. Problem is, I don't trust scientists. Just a recent anecdotal example, a team of medical experts just told a friend they have a terminal brain disease. 2 weeks later, other experts looking at same data said her brain looks perfect. Wha?! Oh yeah, and just last week every computer model (programmed by the 'scientists') said my area would get between 4-8 inches of snow or more and we got...wait for it...nothing.

    As for global warming advocates, we have been warned for decades that the arctic would be ice free and sea levels up astronomically and no snow by now et al. Even before that we were told there would be no food left for the world or we should be frozen to death by now.

    There is no accountability, no one gets fired or mocked or ostracized by these brazenly erroneous predictions. I see no humility, only hubris. So why should I believe any prediction from what is really a very small group of such folks? Could it be possible that a) there is an agenda for political reasons b) they are too invested to admit any mistakes c) peer pressure disallows disagreement d) money money money (= cooked books?) e) overconfidence in knowledge of ancient climate details f) all of the above

    What I see is the goal posts being moved. Predictions don't happen so new ones just keep being made. You can show me every graph you want, use all kinds of technical terms. The graphs I can easily understand show global ice increasing at the same time CO2 increases. We were told the opposite would surely happen, yet still I'm supposed to panic about it b/c I'm too stupid to understand. 'That's not the ice you're looking for. Carry on.' Sorry your scare tactics won't work on my anymore, fool me once...

    • " other experts looking at same data said her brain looks perfect. Wha?!"

      Are you sure it was the same data and techniques? Learn about type I and type II errors. If someone doesn't pass a first screening and passes a second, that quite likely shows a medical system working well.

      "Oh yeah, and just last week every computer model (programmed by the ‘scientists’) said my area would get between 4-8 inches of snow or more and we got…wait for it…nothing."

      This is silly. Weather predictions have been getting demonstrably better. They are not foolproof.

      Neither of these examples is really very similar to climate projection.

      "The graphs I can easily understand show global ice increasing at the same time CO2 increases."

      This is simply not happening. You have been misled. Some would say deliberately.

      "So why should I believe any prediction from what is really a very small group of such folks?"

      For any given question, some group of people are the experts. You should evaluate what they know and how they would know it. The earth is a physical system and the properties of its atmosphere is a problem in classical physics. Some people know a whole lot about that. It makes little sense to trust political operatives over experts. However, the political operatives have the luxury of telling you what you want to hear.

  12. BartR proposed this other reason not to care much about low sensitivity:

    > It has been argued recently that the combination of risk aversion and an uncertainty distribution of future temperature change with a heavy upper tail invalidates mainstream economic analyses of climate change policy. A simple model is used to explore the effect of imposing an upper bound on future temperature change. The analysis shows that imposing even a high bound reverses the earlier argument and that the optimal policy, as measured by the willingness to pay to avoid climate change, is relatively insensitive to this bound over a wide range.

    http://www.pnas.org/content/107/18/8108.full

    Source: http://judithcurry.com/2013/03/10/new-perspectives-on-climate-sensitivity/#comment-302474

  13. A co-blogger for my Dutch blog, Jos Hagelaars, made this graph based on Marcott, extending it both forwards (to 2100) and backwards (to LGM).

    Turns out to be a pretty powerful graphic I find:
    http://klimaatverandering.files.wordpress.com/2013/03/shakun_marcott_hadcrut4_a1b.png

    • Excellent! Puts it all in perspective - that hump is otherwise confusing, and the sharp uptick at the end all to easily dismissed by the credulous.

  14. Poleward movement of zone boundaries --- This must be the Hadley cells each side of the ITCZ (almost on the equator). At the ITCZ the warm moist air rises and so intense precipitation ensues. The dry air aloft moves poleward and, thoroughly rung out, descends over the deserts below. The air near the ground then moves back to the ITCZ. The process is endless.

    As this mass of air generally warms it holds more moisture, intensifying the precipitation equatorward of the deserts. The air will not descend until desiccated which now takes longer. Therefore the deserts migrate polewards.

    I think that is about right.

    • Thanks for attempting an answer. I appreciate it.

      Why does more intense precipitation ensue? Warmer air not only evaporates more water, it's less inclined to release it as precipitation. And since more moisture reduces the adiabatic lapse rate, the cooling with altitude would be lower, the upper troposphere would warm even faster than the surface, and one might therefore expect less intense precipitation at the equator, and more moisture carried polewards.

      Similarly, if there is an increase in the difference between land and ocean temperatures, the rising air over land draws in moist air from the ocean and lifts it, leading to monsoons. I understand there used to be monsoons over the Sahara about 8000 years ago, during that Holocene Optimum we were talking about earlier... The theory is that this is because it was warmer back then.

      I don't know. I can see arguments going both ways, and I haven't seen any decisive argument to make it clear which is right. Can climate models give us an explanation for what they predict?

      • A parcel of air containing water vapor is lighter than air without as much. It therefore rises until equilibrium is obtained. But it is colder up there. Thus it rains more.

        Indeed, that has been measured, rather carefully. Precipitation in the tropics has gone way up; at mid and high latitudes it has gone up as well but not as pronounced.

        It certainly rained more in the Sahara many millennia ago; I don't know whether or not that was monsoonal. One might care to check what the rainfall was at that time on the northern side of the Mediterranean; I suspect it was much drier then. There are certainly indications that it is returning to that drier state.

      • A parcel of moist air will rise if it is moister than the air surrounding it - but why would it be? If the air around it is all warmed by the same amount, wouldn't it all be more humid by the same amount?

        Precipitation has generally increased over land north of 30°N over the period 1900 to 2005 but downward trends dominate the tropics since the 1970s. From 10°N to 30°N, precipitation increased markedly from 1900 to the 1950s, but declined after about 1970. Downward trends are present in the deep tropics from 10°N to 10°S, especially after 1976/1977. Tropical values dominate the global mean. It has become significantly wetter in eastern parts of North and South America, northern Europe, and northern and central Asia, but drier in the Sahel, the Mediterranean, southern Africa and parts of southern Asia.

        (Note that this statement is based on datasets including Mitchell and Jones 2005, which is the published paper associated with CRU TS 2.1, which many know better as the 'Harry' database. Caveat lector.)

        Of course, the fact that something has changed doesn't tell you the cause. Correlation does not imply causation. Beware of 'confirming the consequent'.

        And please don't let my arguments discourage you - we can learn more from hypotheses tried and discarded than we ever can from a tidied-up summary. I find this discussion fascinating.

      • Nullius: "A parcel of moist air will rise if it is moister than the air surrounding it – but why would it be? If the air around it is all warmed by the same amount, wouldn’t it all be more humid by the same amount?"

        I think the answer to your question is "latent heat of condensation":

        http://en.wikipedia.org/wiki/Lapse_rate#Saturated_adiabatic_lapse_rate

      • I am sure I didn't state 'moist air rises' very well. Since water vapor is lighter than the main constituents of air, air containing water vapor is lighter and so rises above less humid air. The exposition in Ray Pierrehumbert's "Principles of Planetary Climate" is particularly clear although it assumes a background in meteorology (for which I have only a little).

        Long-Term Increase in Rainfall Seen in Tropics:
        http://www.nasa.gov/centers/goddard/news/topstory/2007/rainfall_increase.html

        Warming May Increase Tropical Rainfall, Study Shows:
        http://www.climatecentral.org/news/new-study-shows-warming-will-increase-tropical-rainfall-15011

      • Mal Adapted,

        Thanks, but I wasn't asking why a moist parcel of air would rise if it was surrounded by dry air. I was asking why a moist parcel of air would be surrounded by dry air.

        The actual answer is that water has a molecular mass of 18, while dry air has an average molecular mass of 29, so moist air is less dense at the same temperature and pressure.

        The latent heat of condensation is the reason for the lowering of the moist adiabatic lapse rate, which is the reason the models predict the upper troposphere in the tropics should warm significantly faster than the surface. It would result in a *reduced* rate of cooling with height and therefore, arguably, less precipitation. But that subject is off-limits, so I'll say no more about it. :-)

        David Benson,

        Thanks, but it was I that didn't express myself very well. I know that if moist air is surrounded by dry air, buoyancy will lift it. But if moist air is surrounded by equally moist air, there is no net buoyant force. I would expect a temperature rise that increased evaporation would, once equilibrium was reached, cause *all* the air to become more humid. The humidity (and hence density) *gradient* would be no steeper, and arguably less steep. Is this wrong? Why would the moist parcel be surrounded by dry air?

        Thanks for the precipitation links - I note that the numbers in the first article are 'adjusted' to removed the effects of El Nino and volcanos, and even then, the trend doesn't look significant to me if the potential for autocorrelation is taken into account. The second link seems to be a comparison of models.

        My second paragraph was a quote from the IPCC AR4 WGI Chapter 3 summary. Is the IPCC wrong? Or have I misunderstood?

      • This is a really peculiar line of questioning, which is why people have trouble answering.

        A moist particle is commonly surrounded by dry air because it is buoyant. The bouyancy is caused by its saturation. It is an instability. Not a rare one. Have you heard of a thunderstorm? That is how it works.

        What on earth does "The latent heat of condensation is the reason for the lowering of the moist adiabatic lapse rate" mean?

        Oh, wait, I think I can glean some meaning. What a peculiar way to put it. Perhaps you mean to say that moist convection enforces a shallower lapse rate than dry convection, because otherwise moist parcels become bouyant. Which seems to be what confuses you in the first place. You have sort of answered your own question!

        Look, it's like this. If saturated air has too steep of a lapse rate, symmetry is quickly broken. That's how the lapse rate is enforced. Right?

        My offer of the clue you may be missing is this: if you see the lapse rate moving toward the moist adiabat, it is because there is moist convection, which typically means rain. So you cannot suggest that the tendency toward the moist adiabat reduces the rain. The tendency you posit (which I don't think is especially robust) is BECAUSE it rains more.

        Whether the models have the hot spot right or the outcome will be different is unclear (neither the theory nor the data are robust on this question) and to my understanding not extremely important either scientifically or practically. But if the "hot" spot is a real aspect of climate change, it won't suppress the rain in any case. It would be a consequence of the rain.

      • But the wind is blowing and so the coriolis effect must be taken into account. The is a (small) vertical component. Then drier air blows in underneath. That is enough although the drier air begins to pick up the evaporation. I'm sure a decent text on atmospheric physics can do I better job of this than my amateur understanding.

        IPCC AR4 is becoming dated. And there are plenty of other papers from which my two-fold claim stems: (1) substantially increased precipitation in the tropics; (2) some increase at mid and high latitudes.

      • I don't know about you, but I'm finding this discussion really helpful in organising my thoughts. It requires more detail than I had thought to explain what I mean.

        "This is a really peculiar line of questioning, which is why people have trouble answering."

        I suspect it's because one or other of us has a partial picture of what is going on. What I'm trying to get at is the same issue I'd raise if somebody said that the rise in sea level would make all the waves bigger. If sea level is a foot higher, then the wave tops must be a foot higher too, right?

        What I'm trying to get at is that a global, as opposed to a local rise must lift both the peaks and the troughs. The warmer air evaporates more moisture, but it does so across the entire ocean, and this moist air mixes continually with the air above it, so *all* the air is moister. Given that it is all moister, the buoyancy argument - which is related to *differences/gradients* in moisture - loses its effect.

        "It is an instability. Not a rare one. Have you heard of a thunderstorm? That is how it works."

        Hmm. Really? I thought thunderstorms were due to *conditional instability* when the lapse rate is between the moist and dry adiabats, combined with a moist boundary layer and low level convergence or orographic lifting sufficient to release the instability. The air is actually stable, until pushed far enough from the local equilibrium.

        I'd be interested to know if you can find a meteorologist to back you up, but I'm not going to argue. It's a sideline.

        "What on earth does “The latent heat of condensation is the reason for the lowering of the moist adiabatic lapse rate” mean?"

        It means that the moist adiabatic lapse rate is lower than the dry adiabatic lapse rate, and the latent heat of condensation is the reason for this lowering.

        "Perhaps you mean to say that moist convection enforces a shallower lapse rate than dry convection, because otherwise moist parcels become buoyant."

        No, I'd say because it became unstable - the instability goes both ways. In such circumstances, if a parcel of air was to rise it would expand, cool, water would condense, release heat, and expand things some more. But if a parcel of air was to fall, it would compress, warm, water would evaporate, absorbing heat, and contract some more. The former sounds a bit like higher buoyancy, but the latter does not. The moist adiabat assumes that the atmosphere all has the same water content - it just changes phase.

        "My offer of the clue you may be missing is this: if you see the lapse rate moving toward the moist adiabat, it is because there is moist convection, which typically means rain."

        Does it? In my experience, clouds quite often stay up in the sky without it raining.

        The way I think it works is that when air is saturated, tiny droplets condense. But these fall only very slowly, and as they descend into less saturated air they quickly evaporate again. The air is filled with an increasing number of tiny descending droplets in rising air, that release heat at the top of their trajectory and absorb it at the bottom, resulting in a net transport of heat upwards. It also means that the water rises more slowly than the air.

        Without condensation nuclei it would take much higher supersaturation levels to push it over the Kohler curve peak. Moist convection doesn't always mean rain.

        Precipitation depends not only on absolute humidity but also temperature. Warmer air has higher absolute humidity, and therefore a higher dew point, but it's also *warmer*, so it tends to stay at a temperature above the dew point for longer. Warm moist air has to *cool* to precipitate, and because it's carrying more latent heat along with it, it tends to cool more slowly.

        The outcome of this competition is not obvious to me.

        Not all the moisture drops out. Even desert air has about 20% RH. If it's relatively warmer at altitude, does more remain?

      • Ah well you are starting to make identifiable mistakes. That's better, maybe we can make some progress.

        What I’m trying to get at is that a global, as opposed to a local rise must lift both the peaks and the troughs. The warmer air evaporates more moisture, but it does so across the entire ocean, and this moist air mixes continually with the air above it, so *all* the air is moister. Given that it is all moister, the buoyancy argument – which is related to *differences/gradients* in moisture – loses its effect.

        This is a wrong picture, but I see it now and it's not an incoherent one. Your error is in the mechanism of water mixing. It is not diffusive at all; the atmosphere is too large for diffusive mixing or even small eddy mixing to dominate. The mechanism by which the atmospheric moisture is replenished is neither of those. The mechanism by which the lapse rate is maintained is also the same mechanism. Vertical mixing in the atmosphere is dominated by energetic mixtures in cumulonimbus clouds of two basic provenances: local convective instability, or baroclinic instability with convective instability at the frontal boundary. In either case it's thunderheads that actually do the work.

        (Other clouds matter radiatively, but don't actually participate in moist or kinetic energy exchanges, nor mass transport except as part of the ambient air mass.)

        So I can see your other questions making sense on a planet where the atmosphere has three dimensional flow everywhere that mixes as well as or better than convective towers do. This is not such a planet. Outside of thunderstorms the atmospheric flow is laminar and moisture mixes very slowly.

        Am I on the right track here?

      • Diffusive? I was thinking more of turbulent convective mixing. If you release smoke into the air, it doesn't all stay together in one mass, but mixes and disperses. (And in most places, without thunderheads.) It's certainly a lot faster than diffusion.

        "Outside of thunderstorms the atmospheric flow is laminar and moisture mixes very slowly."

        Do you mean above the atmospheric boundary layer?

        I agree that moisture mixes slowly, but would you agree that it mixes *eventually*? At least compared to the global warming spatial and temporal scale?

        "Am I on the right track here?"

        I'm not sure. I'm concerned that we're confusing effects at different resolutions.

        On the scale of waves, the sea is not flat, and the waves take a long time to die away. But on the scale of sea level rise, increased differences between peaks and troughs cannot be sustained. In the same way, at a local scale moisture varies, but the contribution of global warming to moisture applies broadly, to both the peaks and the troughs.

        But if you're saying that the effect of global warming on moisture is as if sea level rise initially only affected the wave peaks, and it takes a very long time for the troughs to catch up, and therefore the waves *would* get bigger if the seas rose fast enough, then maybe.

        But I'm still not clear on the physics of how that would happen. Why would global warming affect the moist bits more than the dry bits?

      • Water vapor does not become anything close to well mixed. A parcel of air picking up water vapor at (near) the ITCZ moves poleward as well as rising. It stays high until the moisture precipitates and then descends over a desert, returning equatorward.

        Water vapor cannot condense without condensation nuclei. The small water drops are not heavy enough to fall; larger ones do but may evaporate rather than provide sensible precipitation.

      • Diffusive? I was thinking more of turbulent convective mixing. If you release smoke into the air, it doesn’t all stay together in one mass, but mixes and disperses. (And in most places, without thunderheads.) It’s certainly a lot faster than diffusion.

        Careful. In meteorological jargon we distinguish between convection and advection, specifically to distinguish motion in the laminar directions from vertical mixing. We would not call turbulence "convection". This is slightly nonstandard.

        Anyway, smoke cools and rises and sheds aerosols until it meets a layer where it is neutrally buoyant. While it rises to that level it is "convective" motion. Once it reaches neutral buoyancy, it spreads horizontally only. This is why dust clouds and smoke plumes travel so far, in fact, exactly contrary to what you posit.

        “Outside of thunderstorms the atmospheric flow is laminar and moisture mixes very slowly.”

        Do you mean above the atmospheric boundary layer?

        That's fair, yes.

        I agree that moisture mixes slowly, but would you agree that it mixes *eventually*? At least compared to the global warming spatial and temporal scale?

        If all else were equal besides the latent heat of fusion of water which were negligible, we would have a dramatically different planet and you would never see anything resembling a moist adiabatic lapse rate.

        On the scale of waves, the sea is not flat, and the waves take a long time to die away. But on the scale of sea level rise, increased differences between peaks and troughs cannot be sustained.

        In the same way, at a local scale moisture varies, but the contribution of global warming to moisture applies broadly, to both the peaks and the troughs.

        But if you’re saying that the effect of global warming on moisture is as if sea level rise initially only affected the wave peaks, and it takes a very long time for the troughs to catch up, and therefore the waves *would* get bigger if the seas rose fast enough, then maybe.

        I don't understand what you think I'm saying but I ain't saying it.

        But I’m still not clear on the physics of how that would happen. Why would global warming affect the moist bits more than the dry bits?

        Because the dryest bits are over dry land? Dry land that's getting even dryer? But that's totally beside the point. I am trying to correct your now identified confusion.

        I'm not really sure exactly point you are making but it makes no sense. I have identified that you don't understand the key role for convective cumulus clouds, and until you get a grip on that that any talk of lapse rates will make no sense.

        Why is the moist adiabat important in your world? If it appears in meteorologists' world it is because moist convection (almost always in the form of thunderstorms) occurred. But in your world I fail to see why it would have any importance at all.

        Why would the lapse rate not follow the dry adiabat if convective mixing were suppressed?

        Do you know what a Radiative-Convective Model illustrates?

      • "Careful. In meteorological jargon we distinguish between convection and advection, specifically to distinguish motion in the laminar directions from vertical mixing. We would not call turbulence “convection”. This is slightly nonstandard."

        Conventions and usages vary, and physicists owned the terms first. :-) Advection is the transport of some conserved quantity by bulk motion of a fluid. Convection is the collective concerted motion of a fluid, and included bulk motion and diffusion. Convection is commonly used for heat transport by fluid motion, and motions driven by thermal buoyancy. I don't think usage is entirely uniform, even in meteorology, although the sense I get is that convection is bulk motion driven by thermal buoyancy and advection is all other bulk motions that can't easily be classified as convection. Vertical and horizontal winds may fall roughly into those categories, but I don't think verticality is the distinguishing characteristic.

        However, I see no point in arguing over definitions, so I'll try to bear your usage in mind.

        --

        "Anyway, smoke cools and rises and sheds aerosols until it meets a layer where it is neutrally buoyant."

        Yes, if it's hot.

        --

        "Once it reaches neutral buoyancy, it spreads horizontally only."

        Not so far as I know. If there is a horizontal wind, it will move horizontally faster than it spreads. But if there is no such wind, it moves with the the air, which goes in all directions: up, down, and sideways.

        --

        "I don’t understand what you think I’m saying but I ain’t saying it."

        Good. That's what I hoped. But that means I don't understand why you think general warming would increase the differences.

        --

        "Because the dryest bits are over dry land?"

        Wouldn't that *decrease* the humidity differences? More extra evaporation would occur in the hottest parts which are currently the dryest?

        --

        "I’m not really sure exactly point you are making but it makes no sense."

        There are numerous points we are exploring.
        1. General warming is said to expand the equatorial Hadley cells, shrink the polar ones, and move the dry zones polewards - I was asking why.
        2. An offered explanation is that more humid air is buoyant, and stays aloft longer - but I don't understand why there would be greater humidity *differences*, which are what drives buoyancy, as opposed to uniformly greater humidity, which would not.
        3. Also part of the explanation is the claim that more humid air results in more precipitation, but again I'm unclear on why warmer air can cause more water to be evaporated, but warmer air does not by the same mechanism prevent the same water from condensing. Air has to cool to precipitate, and less cooling aloft has a tendency towards less rain. Which effect wins, if either, is not clear to me.
        4. On a tangent, the claim is made that tropical precipitation has increased, but the IPCC said in AR4 that it had decreased. I don't think we've determined yet the cause or resolution of the discrepancy.
        5. People are confused over whether I was questioning why moist air surounded by dry would rise, or why moist air would be surrounded by dry. There is additional confusion with the moist adiabatic lapse rate. I tried to clarify that the buoyancy of water vapour is a distinct effect, and how the two effects work. The question remains unanswered.
        6. I'm told that moist air is surrounded by dry air because it is buoyant, and that this instability is the cause of thunderstorms. I don't think it is. I try to say that thunderstorms occur when conditionally stable (with an intermediate lapse rate) moist air is disturbed by low level convergence and orographic lifting. The difference of opinion is unresolved, but considered to be another tangent.
        7. I'm told that a moist adiabat typically means rain, which I don't think is correct, and that the shallower lapse rate resulting from more humidity is *caused* by there being more rain. This seeks to address my criticisms of point 3. It might do, but I think the argument is incomplete. It has not been shown that a moist adiabat means rain, or that it means more rain rather than the same rain from a different altitude.
        8. You have figured out the problem that I think the vertical mixing of the atmosphere is diffusive, or accomplished by other means besides thunderstorms precipitating. I didn't think it was diffusive, I'm not yet convinced that thunderstorms are unique in this regard, and I still don't understand how it answers the question. But I am reading attentively to find out.

        --

        "Why is the moist adiabat important in your world? If it appears in meteorologists’ world it is because moist convection (almost always in the form of thunderstorms) occurred. But in your world I fail to see why it would have any importance at all."

        In my world, the atmosphere approximates a moist adiabat in most locations, not just around thunderstorms. The International Standard Atmosphere assumes a lapse rate of 6.5 C/km. Vertical mixing occurs slowly (especially above the ABL) but continuously, and latent heat can be released by suspended microscopic droplets without necessarily falling out as rain.

        --

        "Why would the lapse rate not follow the dry adiabat if convective mixing were suppressed?"

        If convection were suppressed, it wouldn't follow the dry adiabat either. It would follow the Manabe-Strickler type pure radiative profile that results in an average surface temperature of 60 C. I'm not sure if there's some way to have convection without convective mixing, but if condensation is still allowed I'd expect it to still follow a moist adiabat. I've no idea why you think it would follow a dry adiabat, unless you think it would also prohibit condensation?

        Incidentally, the mixing argument was related to the buoyancy claim in point 2, rather than the precipitation claim in point 3. If air mixes, moister air is no moister than its surroundings. This is unrelated to the precipitation issue.

        --

        "Do you know what a Radiative-Convective Model illustrates?"

        I know many things they illustrate, but I'm not sure which one you're referring to.

        --

        Are we making progress? The identification of points for which the explanations are insufficiently clear - on both side - is helpful. I'll certainly be thinking differently about how to explain some things as a result of this conversation, and there are some points I hadn't thought about sufficiently. But we seem to be getting further and further from a resolution. As you said about the original question, the physics is probably non-trivial and would take a lot of research to determine. I'd agree with that.

        Do you want to continue? I'd be happy to do so, if you do, particularly on the misunderstanding you think you've identified, but I don't want to overextend my welcome.

      • Well, you're still making a lot of mistakes. I am still giving you the benefit of the doubt but it's clear you overvalue the spotty understanding you already have.

        You'd do well to study an undergrad meteorology/general circulation text, I think. I gather you have the background to do so without too much trouble. My generation was raised on Wallace & Hobbs. There seems to be a "new" edition (relative to my own experience) from 2006. I also like the somewhat different and more grad-student suitable perspective of Peixoto and Oort.

        http://www.amazon.com/Atmospheric-Science-Second-Introductory-International/dp/012732951X

        http://www.amazon.com/Physics-Climate-Jose-P-Peixoto/dp/0883187124

        I'm not averse to continuing the discussion, but as long as your understanding is so spotty and so colored by naysayer obsessions it looks to be a slog. I'm not convinced you're irredeemable but I'm having trouble estimating your level of sophistication and pitching the conversation appropriately.

        For instance "Not so far as I know. If there is a horizontal wind, it will move horizontally faster than it spreads. But if there is no such wind, it moves with the the air, which goes in all directions: up, down, and sideways."

        This is a stunner. First of all, no, no, no to this claim you keep making. No, you are flatly wrong.

        Air moves along slightly deformed but essentially horizontal surfaces except in unstable moist convection and small-scale turbulence. Flow in incompressible stratified fluids is stratified on density surfaces. It's a little subtler given the variation in pressure and compression in a planetary atmosphere, but there is essentially a comparable layering that emerges. In practice, except in the vicinity of strong storms, air moves nearly horizontally and does not mix across energy densities (isentropes) which increase upwards.

        But "if there is no wind it moves with the air" pretty much is a jawdropper. "If there is no wind" it doesn't move. Is that not obvious to you? I didn't think it needed an advanced degree to understand that. I mean, how am I to discuss the relationship of moist and dry adiabats and lapse rates with someone who says "if there is no wind it moves with the air"? Please tell me you didn't mean that air moves (relative to the earth) in the absence of wind.

        What's your background? Especially with fluids?

      • Me (on differing evaporation rates near the surface): “Because the dryest bits are over dry land?”

        NiV: 'Wouldn’t that *decrease* the humidity differences? More extra evaporation would occur in the hottest parts which are currently the dryest?'"

        Dang! Yew rilly aint ferm 'roun' these parts, son, are you?

      • "Well, you’re still making a lot of mistakes. I am still giving you the benefit of the doubt but it’s clear you overvalue the spotty understanding you already have."

        You know, I was thinking exactly the same thing, but I didn't think it helpful to a constructive conversation to say so! :-)

        Your reply to the initial question indicated that you had limited knowledge on the point, which is admirable modesty and perfectly OK. I respect that. But now it looks like you're trying to do the "patronising the denier" routine to give the impression I'm an idiot who knows nothing. I'm used to it, but I would expect that when it's done on scientifically literate sceptics who might still have open minds, it's liable to turn them against your consensus point of view. Is that a useful thing to do?

        I'm not complaining, mind. Just trying to be constructive.

        --

        "You’d do well to study an undergrad meteorology/general circulation text, I think. I gather you have the background to do so without too much trouble. My generation was raised on Wallace & Hobbs."

        Yes. For example, the bit about thunderstorms I was talking about above is described on p345 section 8.3.1(a) of Wallace and Hobbs. I had thought that was the standard meteorological understanding, which is why I was so suprised that you said what you did about it.

        --

        "I’m not convinced you’re irredeemable but I’m having trouble estimating your level of sophistication and pitching the conversation appropriately."

        As I've said before, it makes for a frustrating conversation if the aim is to "redeem" or persuade the other to one's point of view. I'm likely no more persuadable than you are - the division is not due to any kind of 'information deficit'. It's best just to regard it as a conversation, the aim of which should be a better mutual understanding.
        (Or "target practice"! :-) )

        --

        "But “if there is no wind it moves with the air” pretty much is a jawdropper. “If there is no wind” it doesn’t move. Is that not obvious to you?"

        When I was young I used to enjoy watching cigarette smoke moving in the air in a brightly sunlit room. It fascinated me that all these incredibly intricate eddies and patterns were going on invisibly all around me all the time.

        These motions are the residual turbulence from convection and other forces, and occur at a wide range of scales, and I wouldn't regard them as fast or organised enough to be called "wind". Differential heating of patches of land gives rise to thermals and downdrafts, differential heating along the coast gives rise to sea breezes (OK, that one is a wind!), and the residual turbulence from these motions extends over most of the world to altitudes of a couple of kilometres - as described in Wallace and Hobbs on p16, and in more detail in chapter 9.

        In the atmospheric boundary layer motion is quite routinely up and down, as well as horizontal. Turbulent communication across the boundary layer is rapid, around 30 minutes. It has nothing to do with moisture buoyancy - a very small effect - and nothing to do with the deep convection of thunderstorms.

        Any observations of smoke in the air would naturally be within the ABL, so I can't imagine why you would think they were constrained to be horizontal.

        Above the ABL is the capping inversion and then the free atmosphere. There is a lot less turbulence and vertical mixing here, I did think for a bit that this was what you meant, but it isn't zero - the clearest evidence for which is the adiabatic lapse rate. Once you get up into the stratosphere, the air *does* move very close to horizontally, constrained by the temperature inversion. But in the free troposphere vertical motion does occur - sustained changes at the boundary layer propagate upwards, horizontal weather systems at the mesoscale generate their own turbulence, and at the largest scales the Hadley cells drive upward and downward motions. Thermals can rise to the top of the boundary layer within an hour, boundary layer mixing happens within a day, mixing of entrained air into the boundary layer happens within about a week, free atmosphere turbulence mixes the surface air up to the troposphere within about a month, and Hadley cell mixing operates on a roughly 3 month timescale.

        So effects that occur on shorter timescales could give rise to changes in variability. Changes on timescales longer than 3 months, which I assume global warming would be, act more like sea level rise in lifting both peaks and troughs together. Or so I would have thought.

        I don't claim to be an expert, or to know more than anyone else. I'm not interested in playing oneupmanship games. I don't claim to be right, or ask anyone to take my word for anything. And you don't have to answer me if you don't want to. But I've seen a variety of claims being made here that conflict with my own understanding, and I'm simply asking if anyone can explain the physics to me so I can see if/why I got it wrong. I am open-minded to the possibility, but I'm not going to accept that I *am* wrong until it has been shown. Is that unreasonable?

      • We define a vector velocity field over the atmosphere. We call it the wind field.

        If you think the wind field is something else feel free to be specific as to which component of the velocity field is "Nullius-wind" and which is turbulence. Then we can talk.

        Pending such a definition in a formal mathematical language, then, I refer to the "velocity field" and the "wind field" indistinguishably. If there is advection there is wind.

        Turbulence can and does create net mass transports across pressure gradients, yes. Mostly in cumulus clouds, though, which is why the moist adiabat is important.

      • Also, I note you have not defended your "enhanced evaporation in the desert will cause relatively moister air in the desert" point, which fascinates me. I think there's a small complication you missed there. Don't you?

      • "We define a vector velocity field over the atmosphere. We call it the wind field."

        That's a statistical approximation, assuming the motions are differentiable at the microscale. At the level of individual molecules, the wind speed everywhere is in excess of the speed of sound. Every time molecules collide the value changes.

        The "velocity" therefore has to be an average taken over some defined spatial region and interval of time, and to get a smooth function we can work with we have to blur the scale a little and obtain a statistical distribution. We consider the temporal variance to be the statistical variance of the values over intervals of time close to the defined interval, and the spatial covariance to be the covariance over regions close in location, shape, and size to the defined region.

        It's therefore a vector distribution defined over intervals of space-time volumes, not a vector field over points.

        When the spread is small compared to the mean (at a defined time and length scale), the parcel of air is moving fairly uniformly and can be approximated by a smooth flow represented by the mean of the distribution.

        I would describe a distribution including zero velocity within, say, a minimum-volume 95% percentile as statistically indistinguishable from "no wind", for the particular volumes of space and time it is assigned to. Velocities within the region are disordered and large compared to the overall bulk motion.

        --

        "Pending such a definition in a formal mathematical language,"

        I think the formal definition used by meteorologists of "calm" is speed less than 1 knot, and "light air" is between 1 and 3 knots. That will do for me!

        --

        "Also, I note you have not defended your “enhanced evaporation in the desert will cause relatively moister air in the desert” point, which fascinates me."

        I didn't defend it because I didn't regard it as particularly important. It was a throwaway line and I was careless in the way I expressed it. I'm guessing your argument is that the air over deserts can't moisten as it warms because there's no water there to evaporate.

        The question is, though, is the air dry because the land is dry, or is the land only dry because the air is dry? Why is the air so dry? Where is it warmed? Because air over the tropics has been lifted, cooled, and much of the water precipitated out. The amount of water left depends on the minimum temperature reached during the cycle.

        So if this minimum temperature rises, the amount of moisture left will rise. The desert air is likewise heated at altitude, by latent heat. So the moisture balance is defined by how much moisture evaporates *up here*, not down on the surface.

        Nevertheless, deserts are not completely dry. Moisture is in equilibrium between air and surface, and since the RH of the air is about 20%, there must be moisture in the surface too. It might not be enough to sustain life, but there has to be some. If there is more moisture in the air for the foregoing reasons, there must be more in the surface at equilibrium, and hence more evaporation happening as part of that balance. There will also be heavier dew and more frequent precipitation to maintain the other side.

        I agree, though, I was less than clear about my meaning! Many, many apologies!

      • I am concerned that you stake out a position and then cleverly defend it rather than trying to learn anything.

        You are marginally interesting, but this is not constructive engagement, so you are a marginal case given our existing moderation policy.

        "I was less than clear about my meaning" is all I can get from you being utterly off base and in an elementary fashion.

        Rather than a "mea culpa", as in "oops I was being silly never mind" you back-pedal and pretend to have been sensible, staking out a new, less obviously silly position, but still one utterly detached from the hard-won knowledge of science (in this case meteorology).

        That is the opposite of constructive engagement.

        You say you cannot be swayed by evidence. That shows, vocabulary aside, a flatly unscientific worldview. Yes, curing information deficits is not enough to win a difficult political battle. But to say you are immune to information, and then to demonstrate it, is the opposite of constructive engagement.

        You have demonstrated to my satisfaction that you do not understand meteorology. You may have the rhetorical skill to make it difficult for me to prove it to others.

        Fortunately I now have the evidence that you somehow thought hotter deserts would evaporate more, which is clueless at an elementary level. Your particular back-pedal here is rhetorically unconvincing and I will just let it stand as is.

        I love to argue and I encourage argument, but I am not trying to spin up Planet3.0 because I love to argue. To a scientific mentality, the purpose of argument is to make progress. People who think the purpose of argument is to prevent progress, lobster chess style, are not engaging constructively, and are neither friends of science nor of progress.

      • "I am concerned that you stake out a position and then cleverly defend it rather than trying to learn anything."

        It wasn't a position. It was a throwaway comment that I worded casually and carelessly. There would be more evaporation in a desert as there would be on any bit of land, and I knew it had to be so since I knew that no desert is 100% dry, but I hadn't thought carefully about the whole picture. The part of the picture I had in mind was true, but one also needs to think about how this moisture was supplied. When you asked the question, it took a few moment's thought to fill in the gaps.

        So I did learn and found the question useful. But it was more a case of completing my understanding than correcting it. You can believe that or not as you choose.

        --

        "Rather than a “mea culpa”, as in “oops I was being silly never mind”..."

        Can you point to any examples in this conversation where *you* have done so? I don't expect it or require it. But it seems inconsistent of you to require it of me without setting an example yourself.

        I don't regard such point scoring as constructive. If people put in mea culpas, I will try to make a point of doing so myself. If they skip past their own errors and omissions, so will I. It's a lot more interesting to discuss the technical details, anyway.

        --

        "You say you cannot be swayed by evidence."

        I've said several times that I *can* be swayed by evidence. For example: "But I’ve seen a variety of claims being made here that conflict with my own understanding, and I’m simply asking if anyone can explain the physics to me so I can see if/why I got it wrong. I am open-minded to the possibility, but I’m not going to accept that I *am* wrong until it has been shown."

        That last clause is the issue - it is *extremely difficult* to construct a watertight argument to make the case. Human reasoning is sloppy, and skims over bits that conform with expectations and therefore seem "obvious". Sometimes they're not, and it takes a challenge from a sceptic (in the general sense) to get us to realise it. It's *highly unlikely* that you'll be able to construct such a detailed argument leading me all the way to the final conclusions, but this is not because I'm immune to evidence and argument.

        We can make progress on details, though. I submit that persistant sceptical challenge, even of the "obvious" and widely-accepted, *is* a part of the scientific worldview.

        --

        "You have demonstrated to my satisfaction that you do not understand meteorology. You may have the rhetorical skill to make it difficult for me to prove it to others."

        I thought that was obvious to others the moment I turned up? After all, I disagree with the consensus. So you have nothing to prove - they all know it already.

        --

        "Fortunately I now have the evidence that you somehow thought hotter deserts would evaporate more, which is clueless at an elementary level."

        Yes, it's interesting, isn't it? Because counterintuitive as it might be, hotter deserts *do* evaporate more, the same as anywhere else on land. The reasons are not easily seen at an elementary level, though.

        You can make of that what you will.

        --

        "To a scientific mentality, the purpose of argument is to make progress."

        Progress on what? Does the removal of scientific error count as "progress"? Some would think of it as going backwards. Or do you mean progress towards a political goal? If so, is that scientific?

        --

        "People who think the purpose of argument is to prevent progress, lobster chess style, are not engaging constructively"

        Your lobster chess players are playing politics, and that's an entirely different game. From a political point of view, I don't *need* to do anything to stop progress, because there *is* no progress. The international negotiation was already dead when they passed Byrd-Hagel, and more local efforts have been killed by the economic downturn. Politically, it was never really about climate change anyway.

        So if you mean political progress, then I'm sorry to have to tell you that all this discussion on the internet is a complete waste of time. I'm not even *considering* that.

        Scientific progress is another matter. I think that there's still a lot to be done there, and that climate science is as yet a very young science. It will take a while to get the politics out of it, but in the process of being kicked around politically there have been some very interesting developments around the scientific process, openness, electronic access and discussion, and so forth. In the long run, the entire episode may not be entirely without benefit. That's progress.

        Nevertheless, this particular discussion has gone on long enough, so I think I'll finish here.

  15. Nullius, you might make a regular practice of looking at water vapor animations. After a few years, you will see that while daily fluctuations are beautiful and interesting, as well as informative in a general sense, trends are a bit harder to spot. I don't know what part of the world you are in, but here are a few links, and you can find more with a simple search.
    http://weather.unisys.com/satellite/sat_wv.php?image=vis&inv=0&t=l12&region=he

    You can fiddle with the menu options on the left. It might be worth your time to compare actual (infrared) with water vapor too; WV provides a visual synthesis:
    http://www.ssec.wisc.edu/data/geo/index.php?satellite=sa&channel=wv&coverage=fd&file=jpg&imgoranim=8&anim_method=flash

    Rutgers also has a neat collection: i like the one from the POV of the north pole, though I wish one could slow down the animation:
    http://synoptic.envsci.rutgers.edu/site/sat/sat.php?sat=nhem&url=../imgs/wv_nhem_anim.gif
    This will give you an immediate sense of the coriolis forces, and a simple search will provide some excellent short tutorials.

    This may be distressing to a tidy mind, but nature is untidy. It is, however, headed in a specific direction, the direction scientists have been trying to elucidate. More water vapor, more energy, more heat trapping, more extremes. Arctic melt causing circulatory disturbance, so it's hot up north and colder in the mid latitudes instead of being mostly tightly confined (this breakup is not good news).

    I am a lot more amateur than David Benson or Michael Tobis, which is one of the reasons I like the visual aids.

  16. Susan, the North Pole view via the Rutgers link is AMAZING.

    We're sitting in the UK with near-zero temps, arctic winds and apparently weeks of the same in store. The very few daffodils that opened have keeled over in the snow. More seriously of course it's badly messing with farming and even killing livestock. It's not so unusual to get snow at this point; the severity and duration of the cold, snow and winds is.

    A few media outlets are mentioning the growing evidence for a link to arctic changes but even as the freeze makes a triple-dip recession more likely few people are making the connection while they struggle to face the worst economic situation since the 30s.

    It's pretty scary.

  17. Sorry, another thought. How do events in the Northern Hemisphere affect arguments about sensitivity? The connection between any specific sensitivity and actual impacts - like changes in the Arctic Circle - is not direct. Would it also be fair to say that, until last year, (almost) no-one knew how rapidly the Arctic would change and what implications it would have for the jetstream?

    I'm just having a little trouble seeing how to link sensitivity via what have turned out to be unknown unknowns right through to social and economic impacts (which I'm saying those examples in my last comment may well be). Maybe we can't, not in a way that allows us to make one of those neat "x degrees = y set of problems" tables. That's obviously no comfort, but it does leave us with a communication problem.

    • Thanks for the question. I have been meaning to write about this; maybe I'll have you involved in the draft.

      But I need to add a caveat: the connection between Arctic melting and cold outbreaks may not be simple or reliable. Remember that in 2005 we thought we'd be having thirty Atlantic hurricanes a year from then on as a result fo climate change? That hasn'tt happened since.

      My own expectation is that we will have a great increase in year-over-year variability but that it will be difficult to say much else.

      While at some point it all starts to fall into a climate change global weirding bag, and I think we're likely at that point now, I don't think we can be sure of it yet. But that said and more to the point, I suggest being wary of extrapolating the prognosis of a particular region from a single weird year. That hasn't worked so far, and if anything that will probably become less useful as things (by things I mostly mean the oceans) get further and further out of thermodynamic equilibrium.

  18. "My own expectation is that we will have a great increase in year-over-year variability but that it will be difficult to say much else. While at some point it all starts to fall into a climate change global weirding bag."

    Absolutely - in my amateur fashion, whenever I talk to people about this I say that when you poke a complex system you'll make it wobble. The more we poke it, the wobblier it'll get, and it won't even begin to dewobble until the poking's stopped. At which point, to stretch the metaphor a bit, it might have fallen over.

    In the meantime, the wobbles are already having a deeply troubling effect on our food production systems; in 3-5 year's time we're going to have a very strong evidence base for this not being a freak occurrence. I think "risk is expensive" is a golden rule of adaptation so I can't imagine there are anything other than very expensive solutions (e.g. UK environment minister Owen Patterson today pointing out lack of maintenance of rural drainage and its role in UK farm flooding).


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  1. There was a mini-ice age between the 1300s and the 1800s... called the "Little Ice Age". This is reflected in the graph by the temperature dip before the year 2000.

    http://commons.wikimedia.org/wiki/File:Ice_Age_Temperature.png

    Now... anyone going to mention anything about how BOTH temperatures AND CO2 cycled even HIGHER than we see today? Nearly matching the exact patterns every 100,000 years or so? How is that possible if Humanity was having zero impact on anything "Earth" related 125,000 years ago?

    The Earth has been experiencing the Modern Maximum for the last 100 years.

    http://en.wikipedia.org/wiki/Modern_Maximum

    This is a period of increased solar activity... warming the Earth. The last time this occurred was during Medieval times (1,000 years ago)... when it was called the Medieval Maximum or Medieval Warm Period.

    http://en.wikipedia.org/wiki/Medieval_Warm_Period

    In between these Maximums (usually lasting around 1,000 years) there are returns to normalcy and even Minimums...

    http://en.wikipedia.org/wiki/Maunder_Minimum

    which are periods of very low Sun activity when cooling periods takes place. There are a few minimums in between each Maximum... these minimums are called ice-ages and mini-ice-ages depending on severity.

    People have been buying into Big-Money's heavily propagandized scheme for creating a new carbon-currency that Big-Money planned to manipulate just as they already have the financial markets. This carbon-currency would be traded and purchased by individuals and companies whose carbon footprint exceeds "a" set limit... and would be a taxable resource as well... and also generate commissions and penalties. This would generate self-serving revenue for our corrupt

    http://capitolcityproject.com/watchdog-lawmakers-oversee-government-surveillance-programs-receive-millions-intelligence-companies/

    government so obviously they are assisting their Big-Money overlords

    http://humanprogress.files.wordpress.com/2012/01/power-pyramid01.jpg

    in developing a "reason" (warming caused by man). Hence all the purchased $cience saying... squawk... global warming is man-made... squawk... well... it isn't. The vast majority of the warming is caused by the Sun's activity (aka transition from the last Minimum, called the Maunder-Minimum (aka mini-ice-age) in the 1700s to our ending Maximum which began 100 years ago). This is all proven science... but simply ignored by all the owned by Big-Money media because Big-Money would not pay for "non-carbon-currency-producing" results... and would not advertise this on Big-Money's media outlets either.

    Most of $ciene has lost it's way... becoming all about generating revenue for other research and their universities instead of the pursuit of PURE facts and knowledge... for the SAKE of knowledge. They have to get those government grants and income from Big-Money... if the paid-for studies produce no desirable results... scientists and universities get no more money.

    This carbon con is all about more profit... with a little side-serving of more control.

    http://green-agenda.com/carboncurrency.html

    http://www.canadafreepress.com/index.php/article/19380

    http://www.nytimes.com/2007/05/06/business/yourmoney/06emit2.html?_r=0

    http://www.bloomberg.com/apps/news?pid=newsarchive&sid=aXRBOxU5KT5M

    And... their pyramid scheme is steadily falling apart. I am simply glad the Earth is getting the last laugh now... and since the timing for the current Maximum to end is around now... it is going to get colder.

    What an inconvenient scientific truth.

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