Update on Climate Temperature Sensitivity (Good News, the Numbers are Falling)

I have not had the time to write much about climate of late, but after several years of arguing over emails (an activity with which I quickly grew bored), the field is heating up again, as it were.

As I have said many times, the key missing science in the whole climate debate centers around climate sensitivity, or the expected temperature increase from a doubling of CO2 concentrations in the atmosphere  (as reference, CO2 in the industrial age has increased from about 270 ppm to close to 400 ppm, or about half a doubling).

In my many speeches and this video (soon to be updated, if I can just find the time to finish it), I have argued that climate computer models have exaggerated climate sensitivity.  This Wikipedia page is a pretty good rehash of the alarmist position on climate sensitivity.  According to this standard alarmist position, here is the distribution of studies which represent the potential values for sensitivity - note that virtually none are below 2°C.


The problem is that these are all made with computer models.  They are not based on observational data.  Yes, all these models nominally backcast history reasonably correctly (look at that chart above and think about that statement for a minute, see if you can spot the problem).  But many an investor has been bankrupted by models that correctly backcast history.  The guys putting together tranches of mortgages for securities all had models.   What has been missing is any validation of these numbers with actual, you know, observations of nature.

Way back 6 or 7 years ago I began taking these numbers and projecting them backwards.  In other words, if climate sensitivity is really, say, at 4°C, then what should that imply about historical temperature increases since the pre-industrial age?  Let's do a back of the envelope with the 4°C example.  We are at just about half of a doubling of CO2 concentrations, but since sensitivity is a logarithmic curve, this implies we should have seen about 57% of the temperature increase that we would expect from a full doubling of CO2.  Applied to the 4°C sensitivity figure, this means that if sensitivity really is 4°C, we should have seen a 2.3°C global temperature increase over the last 150 years or so.  Which we certainly have not -- instead we have seen 0.8°C from all causes, only one of which is CO2.

So these high sensitivity models are over-predicting history.  Even a 2°C sensitivity over-predicts the amount of warming we have seen historically.  So how do they make the numbers fit?  The models are tuned and tweaked with a number of assumptions.  Time delays are one -- the oceans act as a huge flywheel on world temperatures and tend to add large lags to getting to the ultimate sensitivity figure.  But even this was not enough for high sensitivity models to back-cast accurately.  To make their models accurately predict history, their authors have had to ignore every other source of warming (which is why they have been so vociferous in downplaying the sun and ocean cycles, at least until they needed these to explain the lack of warming over the last decade).  Further, they have added man-made cooling factors, particularly from sulfate aerosols, that offset some of the man-made warming with man-made cooling.

Which brings us back to the problem I hinted at with the chart above and its distribution of sensitivities.  Did you spot the problem?  All these models claim to accurately back-cast history, but how can a model with a 2°C sensitivity and an 11°C sensitivity both accurately model the last 100 years?  One way they do it is by using a plug variable, and many models use aerosol cooling as the plug.  Why?   Well, unlike natural cooling factors, it is anthropogenic, so they can still claim catastrophe once we clean up the aerosols.  Also, for years the values of aerosol cooling were really uncertain, so ironically the lack of good science on them allowed scientists to assume a wide range of values.  Below is from a selection of climate models, and shows that the higher the climate sensitivity in the model, the higher the negative forcing (cooling) effect assumed from aerosols.  This has to be, or the models would not back-cast.aerosols2

The reasons that these models had such high sensitivities is that they assumed the climate was dominated by net positive feedback, meaning there were processes in the climate system that would take small amounts of initial warming from CO2 and multiply them many times.  The generally accepted value for sensitivity without these feedbacks is 1.2°C or 1.3°C (via work by Michael Mann over a decade ago).  So all the rest of the warming, in fact the entire catastrophe that is predicted, comes not from CO2 but from this positive feedback that multiplies this modest 1.2°C many times.

I have argued, as have many other skeptics, that this assumption of net positive feedback is not based on good science, and in fact most long-term stable natural systems are dominated by negative feedback (note that you can certainly identify individual processes, like ice albedo, that are certainly a positive feedback, but we are talking about the net effect of all such processes combined).  Based on a skepticism about strong positive feedback, and the magnitude of past warming in relation to CO2 increases, I have always argued that the climate sensitivity is perhaps 1.2°C and maybe less, but that we should not expect more than a degree of warming from CO2 in the next century, hardly catastrophic.

One of the interesting things you might notice from the Wikipedia page is that they do not reference any sensitivity study more recent than 2007 (except for a literature review in 2008).  One reason might be that over the last 5 years there have been a series of studies that have begun to lower the expected value of the sensitivity number.   What many of these studies have in common is that they are based on actual observational data over the last 100 years, rather than computer models  (by the way, for those of you who like to fool with Wikipedia, don't bother on climate pages -- the editors of these pages will reverse any change attempting to bring balance to their articles in a matter of minutes).  These studies include a wide range of natural effects, such as ocean cycles, left out of the earlier models.  And, as real numbers have been put on aerosol concentrations and their effects, much lower values have been assigned to aerosol cooling, thus reducing the amount of warming that could be coming from CO2.

Recent studies based on observational approaches are coming up with much lower numbers.   ECS, or equilibrium climate sensitivity numbers (what we would expect in temperature increases if we waited hundreds or thousands of years for all time delays to be overcome) has been coming in between 1.6°C and 2.0°C.  Values for TCS, or transient climate sensitivity, or what we might expect to see in our lifetimes, has been coming in around 1.3°C per doubling of CO2 concentrations.

Matt Ridley has the layman's explanation

Yesterday saw the publication of a paper in a prestigious journal,Nature Geoscience, from a high-profile international team led by Oxford scientists. The contributors include 14 lead authors of the forthcoming Intergovernmental Panel on Climate Change scientific report; two are lead authors of the crucial chapter 10: professors Myles Allen and Gabriele Hegerl.

So this study is about as authoritative as you can get. It uses the most robust method, of analysing the Earth’s heat budget over the past hundred years or so, to estimate a “transient climate response” — the amount of warming that, with rising emissions, the world is likely to experience by the time carbon dioxide levels have doubled since pre-industrial times.

The most likely estimate is 1.3C. Even if we reach doubled carbon dioxide in just 50 years, we can expect the world to be about two-thirds of a degree warmer than it is now, maybe a bit more if other greenhouse gases increase too….

Judith Currey discusses these new findings

Discussion of Otto, one of the recent studies

Nic Lewis discusses several of these results

This is still tough work, likely with a lot of necessary improvement, because it is really hard to dis-aggregate multiple drivers in such a complex system.  There may, for example, be causative variables we don't even know about so by definition were not included in the study.  However, it is nice to see that folks are out there trying to solve the problem with real observations of Nature, and not via computer auto-eroticism.

Postscript:  Alarmists have certainly not quit the field.  The current emerging hypothesis to defend high sensitivities is to say that the heat is going directly into the deep oceans.  At some level this is sensible -- the vast majority of the heat carrying capacity (80-90%) of the Earth's surface is in the oceans, not in the atmosphere, and so they are the best place to measure warming.  Skeptics have said this for years.  But in the top 700 meters or so of the ocean, as measured by ARGO floats, ocean heating over the last 10 years (since these more advanced measuring devices were launched) has been only about 15% of what we might predict with high sensitivity models.  So when alarmists say today that the heat is going into the oceans, they say the deep oceans -- ie that the heat from global warming is not going into the air or the first 700 meters of ocean but directly into ocean layers beneath that.  Again, this is marginally possible by some funky dynamics, but just like the aerosol defense that has fallen apart of late, this defense of high sensitivity forecasts is completely unproven.  But the science is settled, of course.


  1. Joe_Da:

    What is to stop the positive from spiraling out of control and overheating the planet to no end. Why haven't those positive feedbacks kicked in during any of the prior warming periods and spiraling out of control - The climate science explanation - Those positive feedbacks know to only kick in if the warming is due to man made co2.

  2. NormD:

    CO2 has been much higher in the past, well into the 1000's ppm

  3. NormD:

    Corrected image with axis

  4. LarryGross:

    the first thing is that weather is not climate and looking at weather conditions will not inform you as to climate.

    the second thing if your formal knowledge is not hard science and your actual experience is not working in the field - why do you think you know as much as those who do have a formal education and a couple decades of work?

    the third thing is that whether you are talking about a Trident Missile or a Tomahawk Cruise Missile or a Hubble Telescope or a NOAA Hurricane satellite -they are ALL models - ALL subject to errors but ALL relied on because they are the best method we have.

    Now do you think you know how to build a computer model for these things much less figure out the errors?

    It's like the training and experience that scientists have is worthless.

    I wonder if we believe doctors are the same?

    would you, for instance, presume to tell your doctor that he is wrong about telling you that smoking can cause serious health issues because you read on the internet that doctors are biased against cigarettes?

    Worse that that - ALL scientists - no matter their formal training and actual work - are engaging in a worldwide conspiracy to defraud people of the truth about climate..


    isn't that the basic premise?

  5. gobluejays:

    Here's a question I would like to pose to alarmists: if aerosols have such tremendous cooling effects - wouldn't that be the solution to AGW? Shouldn't we just spew as much of them as we can into the atmosphere? Sure they might exacerbate asthma and cause a rise in cancer, but surely that is better than the end-of-civilization-as-we-know-it doom and gloom they predict, no?

  6. Russ R.:

    Wow... of all the kneejerk arguments you've presented here, this one absolutely takes the cake.

    You've just argued that climate models are better than observations for understanding climate. Which is especially ironic considering that climate models have reliably failed to align with observations. (Show me a model that projected flatlined temperatures since the late 90's).

    Take a step back, leave your confirmation bias at the door, and try looking at the data again.

  7. LarryGross:

    what else happens ? who would you ask about ALL the potential effects - a guy on the internet who has read all the right wing anti-climate blogs?

    so we have this contest - guys that have 4 or more years of formal schooling in a hard science then a couple or 3 decades of work in the field including peer-reviewed works - verses someone who has no degree in hard science and has not worked in the field one day - but he knows how to "analyze" scientific data.... AND he ...has determined ... that .. there is a worldwide conspiracy of scientists... all seeking to defraud the public of the "truth".

    sorry -if 90% of scientists agree on something - it does not mean it's the truth - but I'll take it any day over an armchair scientist.

  8. Dale:

    I’m confused, doesn’t heat go up and cold go
    down. Why would the heat be going that far down in the water,
    and how is the heat getting down there?
    And if it somehow did get down there wouldn’t it just start right back
    up again?

  9. LarryGross:

    nope. did not. said that understanding them - observations vs models and the whole ball of wax was something for people who have formal training in the hard sciences and experience in the field and not folks who "read" the internet and spend time at right-wing echo chamber sites.

  10. LarryGross:

    who are these folks: http://geocraft.com ?

  11. Russ R.:

    Show me one climate model projection that accurately predicted a scenario with 15 years of rising GHG concentrations yet no increase in temperature. Show me just one (link, please).

    And I'll show you every climate model projection from the world's leading climate science authorities that have all significantly overestimated warming, every single time...

    Hansen et al. (1988):
    Projected warming trend from 1984-2012 (deg C / decade): Scenario A 0.337 ; Scenario B 0.287 ; Scenario C 0.206 (http://www.realclimate.org/data/scen_ABC_temp.data)
    Observed warming from 1984 - 2012 (deg C / decade): 0.176 (http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.txt)

    IPCC (1990):
    Projected warming from 1990 - 2030 (deg C / decade): 0.175 to 0.375 with a best estimate of 0.275 (http://www.ipcc.ch/ipccreports/far/wg_I/ipcc_far_wg_I_chapter_06.pdf)
    Observed warming from 1990 - 2012 (deg C / decade): 0.156 (http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.txt)

    IPCC (1995):
    Projected warming from 1990 - 2100 (deg C / decade): 0.182 (http://www.ipcc.ch/pdf/climate-changes-1995/ipcc-2nd-assessment/2nd-assessment-en.pdf)

    Observed warming from 1990 - 2012 (deg C / decade): 0.156 (http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.txt)

    IPCC (2001):
    Projected warming from 1990 - 2025 (deg C / decade): 0.114 to 0.314 (http://www.ipcc.ch/pdf/climate-changes-2001/synthesis-spm/synthesis-spm-en.pdf)
    Observed warming from 1990 - 2012 (deg C / decade): 0.156 (http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.txt)

    IPCC (2007):
    Projected warming from 2007 - 2027 (deg C / decade): 0.200 (http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html)
    Observed warming from 1990 - 2012 (deg C / decade): -0.014 (http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.txt)

    So, exactly how much faith should I put in climate models that project catastrophic warming in the future?

  12. Russ R.:

    Sorry, i just noticed that the reference links above include a closing parenthesis in the URL... you'll have to click on the link, and then manually delete the ending parenthesis from the address bar in order to follow the link.

  13. Russ R.:

    No idea... never heard of them before.

  14. rxc:

    I used to do thermal-hydraulic modeling (akin to climate modeling, but with MUCH smaller systems) for a living. And I can tell you that it is really difficult to predict, to the nearest degree, much less 0.1 degree, the temperature distribution inside a nuclear reactor containment building during a very well specified accident scenario. When these models are verified against actual data, from real experiments in real buildings with real, well metered heat sources and well-measured heat sinks, for period of time on the order of a few days, it gets just about impossible. So the engineers bias the models to produce the worst possible outcomes, and design in a LOT of margin to account for the uncertainly, and add lots of systems and capability to deal with those uncertainties.

    Based on my experience with those models, I have no confidence whatsoever that anyone on this planet can really predict changes to the temperature of the planet(whatever that means) in 100 years, with only a change to the CO2 concentration. The models that the climate people deal with have lots of what we used to call "dials". They adjust internal parameters of the model to deal with situations they have seen in the past, but these parameters are rarely physically based. Sometimes they can be empirical, but that can be hazardous, too. If the data is limited, it can lead to what we used to call 6-pack correlations - internal models that were derived after consuming a 6-pack of beer, and which looked right at the time.

    The climate people have no way to model clouds, other than to just make a wild-ass guess. Clouds have all sorts of impacts on the results, from reflecting sunlight back to space to reflecting it back to earth to changing rainfall patterns. If you can't model clouds from first principles, all those calculations are just garbage. And now we have evidence that the sun is not quite a constant as they have assumed it is. It may have effects that we don't understand (on clouds, interestingly enough). So, it has been just one big scan to gain control over the populace.

    All with good intentions, of course.

  15. rxc:

    The heat in the deep ocean is "smart heat", like the "smart grid". It knows that it should go hide somewhere that no one can detect it.

    They don't know what else to say, except "we were wrong", and they CAN"T say that.

  16. AnInquirer:

    With a couple of decades of computer modeling of complex systems, perhaps I could be considered more than an armchair scientist. There are many reactions I could give you, but I will limit my post to one observation and one question. First, I have spent years reviewing and analyzing the GCC models to which Mr. Meyers refers. He is absolutely correct in pointing out the key role that aerosol assumptions play in getting backcasts to fit. As we say in modeling, give me enough dummy variables, and I will get any model to fit history.
    Second, while conspiracy is too strong of a word, don't you have any concern about the process or the selection of the these "90% of scientists" who agree? I stopped paying attention to the 90% figure when AP polled its selection of scientists following the release of Al Gore's AIT. How could 90% of them agree that AIT had no scientific weakness when the errors are so blatant and so easy to identify? Something is amiss with the process in polling scientists on climate, and perhaps it will take decades to figure out what it is.

  17. LarryGross:

    I've worked with models also and there are two things you can say:

    1. they are not 100% accurate and the tweaking to make them better is never ending

    2. they are vital

    you take, for instance, a ballistic or cruise missile. They use models. The models predict performance and accuracy that are then used as inputs to guide the missiles.

    when you see a cruise missile or a drone hitting a target - it's using models to do it.

    hurricanes are predicted with models - a dozen or more - and none of them are 100% accurate and in different scenarios some are in error but they are used extensively with hurricane forecasting and entire cities and regions are evacuated based on what a model says - and sometimes the model is wrong but would you then subsequently ignore the models?

    No, of course not. better safe than sorry - just for one town - right? but not that way for the entire planet - nope... no safe but sorry approach for the planet.

    people do not understand the purpose and value of models. this comes from their sound-bite armchair science approach to understanding them rather than actually getting a degree in a hard science and then actually working with models for a decade or two.

  18. rxc:

    Mr. Gross,

    Yes, models can be useful. I have also worked with useful models. For models to be useful, they have to be tested. This means that they have to make some sort of prediction that can be validated. Hind-casting can be useful in developing a model, but you can only validate a model by making a prediction. If you make a good prediction for a scenario in a system where you know the system very well, but don't know the results (blind prediction) that is good. When you use a model to make a good prediction where you have never seen the system perform before (double blind), that is very good.

    Climate models do not make good predictions. They predict a large amount of tropospheric heating in the tropics which has not been observed (probably hiding in the deep oceans). They don't predict this 18-year long "pause" in the heatup of the atmosphere. The modelers average together runs from different models to arrive at a consensus (this is truly bizarre to me). And the people who hold the data that are used for so-called verification continually "adjust" it. In my business, "adjusting" the experimental data that is used for model validation would get you thrown in jail.

    The problem is that the climate modelers are trying to emulate real scientists and engineers. They think that they can just say scientific-sounding stuff and present graphs and charts, and get away with hand-waving. Engineers who use models to build stuff have to show that the models really work, or else the building collapse or the airplanes fall out of the sky. Climate modelers don't really test their models, and when they don't agree with the data, they say that the data is wrong and they fiddle with it.

    We used to joke that no one accepts the results of the models, except the guy who developed the model, but everyone accepts the data from the experiments except the guy who ran the experiments.

    I think the latest results from CERN about the Svensmark event are going to be very important. Those guys are working in a place where they do real science, and they got slapped quite hard the last time they said something premature that caused the "settled science" religion some pain, so they are going to make sure it is all nailed down before they go public again.

    Mr. Gross - you say you have used models - are you a practicing engineer?

  19. LarryGross:

    they have to be validated which is not the same as saying they cannot be useful unless they are infallible. No model meets that standard.

    Climate models are like many other models. They are no worse or no better. They are not perfect by a long shot and they end up with contradictory results but the same thing is true of other models. Weeks can and are spent on why a ballistic missile missed by a mile instead of feet... weeks, months and years can be spent on why a Hurricane model got a dead on accurate prediction OR was totally wrong.

    How many times have the folks that do hurricane models been accused of a global conspiracy because they have some level of consensus?

    Climate models are among the hardest to calibrate even with ballistic missiles because what historical data tells you may on any given day - not at all be what you actually encounter on a missile shot.

    models are what they are. As I said before, when a "model" predicts the path of a hurricane, we do not accuse the scientists are nefarious conduct in the creation and use of the model to produce the prediction. We take the prediction and we know it may not be dead on - but we also evacuate entire cities and regions based on what the model and science tells us.

    we take this safe but sorry approach in that context but in another similar context we say that the models are wrong and not to be believed and the science behind them is bogus - and bad-faith collaboration about climate scientists.

    this is wrong on many levels but it basically shows just how ignorant society has become on things they know little about other than what they read on the internet.

  20. marque2:

    Actually most missiles and drones and whatnot are tested live at some point so you can have feedback into the model. Only nuke missiles aren't tested.

  21. marque2:

    The waters in the North pacific and North Atlantic follow a counter clockwise flow. As they flow due to the Coriolis effect, the water pulls away from the shoreline and this brings up colder water from the deep areas. The warmer water then has to drop to take the place of the displaced colder water.

    I some smartass is going to get all over me over technicalities of this statement (yes water flow is a bit more complicated than a circle in the Northern Hemisphere and Southern hemisphere) but thems basically the facts, and how heat can end up deep below.

    I think this only works to a certain depth however.

  22. marque2:

    It is not a joke, your hypothesis has been supported by several alarmists, Of course they would be put in the upper atmosphere. Along with this solution there are also plans for cloud generators, and launching pebbles into space.

  23. marque2:

    Yeah, that is a problem, if our atmosphere were governed by strong positive feedback, it would have been blown off the planet eons ago, and we would be left with little or no air, much like Mars.

  24. LarryGross:

    nuke missiles are tested guy - sans the actual nukes but with dummies. And you'll find that models are used to predict damage from nukes these days - in part based on previous nuke tests but also - just additional data and science.

    Models are widely used in a wide variety of fields and not a one is dead-on accurate usually and there can be multiple models - that generate conflicting info.

    For instance for a missile, you can have 5-10 different models and run them all on a particular scenario and come up with conflicting results.

    that sends people back to further investigate - 2 steps forward, 1 step back, etc.

    but no one accuses scientists that do models for missiles, or hubble or space stations, or hurricanes or even Tsunamis and volcanoes or ozone holes of being corrupt and engaging in a nefarious worldwide conspiracy to defraud people - only the climate guys - and it's coming from people who largely lack education and work experience with models...

    it's totally bizarre and ignorant IMHO of course.

    when one (or more) hurricane model(s) says a hurricane is going to hit Charleston, SC, imagine what would happen if the right wing blogs erupted into their blather about how the folks who do the hurricane models are colluding to "alarm" people so they can get more grant funding... and it's wrong to evacuate... cuz it will be just spending money for no good purpose... it's bizarre.

  25. LarryGross:

    unless you are formally trained and actually work in the field - all you are doing is reciting what you have read... somewhere.

  26. marque2:

    Maybe not with smoking cigarettes, but with diet, that seems to change every 20 years, so your doctor is probably just as confused as anyone else about diet. Yes I could tell my doctor he is full of it. It is also why folks who have kids with rare diseases search on the Internet until they find a doctor that understands the issue. No doctor is familiar with every disease. Many a kid has been saved by parents telling the doctor he is full of it, and finding another one who knows what to do.

  27. marque2:

    You really don't have to be such an ass. Of course the missiles are tested. It is just the payload is not. On a conventional missile the payload is tested as well.

    The point was that for missile data they eventually get hard data with which to test the models and verify them. For weather they don't and the models are forced to use CO2 as the primary driver of temperature increase. Notice how there aren't any divergences in ideology in that regard. You would think one model at least would consider solar activity.

  28. marque2:

    If you are formally trained to be a doctor, all you are doing is reciting what you have read somewhere - unless you are doing medical research. Is your family doctor a medical researcher?

  29. LarryGross:

    the payloads if nukes are "tested" in different ways that do not require an atmospheric burst, data collected, - and put in models.

    they get "hard" data but not air burst data.

    with weather and climate - it's more complex and bigger scale but it's the same basic approach. You do get hard data that you can with current and historical observations and other things like ice cores, fossils, even geology...

    but it's not dishonest science conducted by a bunch of colluding scientists who are engaging in a worldwide conspiracy - that is their "consensus". No more or less than scientists around the world agree or disagree about tsunamis, or volcanoes, or ocean currents, or tornados, etc...

    science evolves.. and it reaches consensus and even then can back up as you point out with diet and other issues.

    there ARE SOME corrupt scientists...just like there are corrupt people in all walks of life but when a solid majority of scientists around the world reach some level of consensus about something - they are not engaging in a worldwide conspiracy.

    the bigger point is - if they think there are some potential serious problems - but not 100% sure and there is even some disagreement - you don't dismiss it as a conspiracy and do nothing.

    that's dumb.

    it's like saying that because no hurricane model has a perfect record that we should never evacuate a city because the model says so...

    we take precautions ... we should do that.. we should never dismiss out of hand anything that has hundreds or thousands of people in the field agreeing on....

    sorry to be such an ass... truly.

  30. LarryGross:

    no. you have several years of medical training, and then real world practice, then you read not one but several/a bunch of publications that are written by other people with formal training and actual work in the field - and those publications are peer reviewed by similarly qualified people with CREDIBLE qualifications and boni fides.

    then if ALL or most of them agree on something - you can be forgiven for buying into it.. at least tentatively.

    doctors do not go out onto the internet to be "educated" by people who have no formal training, and work in the field who themselves have "read" things posted by others whose main credentials are as armchair scientists.

    you don't get "real good science" from realgoodscience.com

  31. marque2:

    Seems like you have completely forgotten climate gate. And lead alarmists not being able to produce their source data. Or Michael Mann basing his entire hockey stick theory on one tree in Siberia using a tree species that is known not to be a good indicator.

    It is actually scientific fraud. And if "right wingers" are the only ones willing to stand truth to power the way liberals used to in the 1960's against these government sponsored scientists trying to proof a government agenda - well god bless them.

  32. David:

    Not all models are of the same quality - I can model the solar system with a beach ball and some marbles, but I won't get accurate or useful predictions. The quality of a model is determined by validating (testing) the predictions it makes.

    Hurricane models make predictions which are tested quite often, and are
    tweaked as new information is learned. Do the climate change models
    make predictions which are testable?

  33. HenryBowman419:

    Warren, you might be interested in a very recent paper that essentially places the blames for AGW of halogenated molecules, and predicts a return to 1950s-era temperatures in the next 5-7 decades:

    An interesting paper on a possible cause for observed planetary temperature variations over the past 50 years or so: Cosmic-Ray-Driven Reaction And Greenhouse Effect Of Halogenated Molecules: Culprits For Atmospheric Ozone Depletion And Global Climate Change, by Q.B. Lu (Int. J. Mod. Phys. B DOI: 10.1142/S0217979213500732). The paper's thesis is supported by an extremely high correlation between observed temperatures and the total amount of stratospheric halogenated gases during 1970–2012. The paper notes, as others have, the near-zero correlation of carbon dioxide concentrations and observed temperatures. The physical explanation also provides a very plausible explanation for how the effect of solar activity on atmospheric temperatures is amplified: such explanations, proposed previously, have typically shown insufficient amplification to account for observations.

    From the abstract: "These results provide solid evidence that recent global warming was indeed caused by the greenhouse effect of anthropogenic halogenated gases. Thus, a slow reversal of global temperature to the 1950 value is predicted for coming 5~7 decades. It is also expected that the global sea level will continue to rise in coming 1~2 decades until the effect of the global temperature recovery dominates over that of the polar O3 hole recovery; after that, both will drop concurrently."

    All-in-all, one of the more interesting contributions to the field that I have seen for a while.

    Abstract: http://www.worldscientific.com/doi/abs/10.1142/S0217979213500732

    PDF article (from ArXiV): http://arxiv.org/ftp/arxiv/papers/1210/1210.6844.pdf

    Commentary (WUWT): http://wattsupwiththat.com/2013/05/30/study-says-global-warming-caused-by-cfcs-not-carbon-dioxide/

  34. dale:

    Larry, so how do you account for all the experts
    in any field of study, throughout history, being proven so totally wrong? No Larry, we get to use our common sense. Besides what’s wrong with learning by reading,
    and then using that knowledge to understand the world around us?

  35. dale:

    RXC, I like that, it made me laugh.

  36. LarryGross:

    it's right wing idiocy... pure and simple. let's agree that one or two or a half dozen messed with the data.. how does that translate into a worldwide conspiracy?

  37. LarryGross:

    if you know the field then you know the issues with modelling... and you know that it's not only not an exact science but it's complex - but in the end yields important useful info that moves the ball forward - if others with background and experience concur and themselves add to the body of knowledge.

    how would you look at ANY science where there is a 90% consensus and deduce from that - that something is amiss? when 90% of doctors tell you that smoking cigarettes is likely to end badly - do you suspect something amiss because 90% tell you that?

  38. Russ R.:


    we're still waiting for your response to the inconvenient problem that ALL of the climate models used to date by those "educated people with formal training" at the IPCC, have overestimated warming.

    I gave you a long list of model projections dating back to 1988, complete with references, and physical observations to date.

    You've given us nothing but blather.

  39. LarryGross:

    totally true.... and there really are more than "one" climate model. there are model models that show some agreement in some areas and some contradictions in others - as ALL models do in many fields INCLUDINg hurricane models.

    Climate models are testable to the extent you could go back and get the original data and see if it predicts what we have now - with caveats - as you might have - for instance, if you went back with the conditions prior to some famous past hurricane - put it in the current models then see which ones predict what actually happened.

    this is a valid question and I agree with it in terms of how you go about validating a model but you can bet that if you DID go back to conditions prior to some past hurricane or tornado and put in the variable into todays models - that it's ain't going to be nirvana either.

    the point is if you use an imperfect model to actually take some action - like evacuate a city why would you not use a similar approach to climate when multiple models and 90% of scientists are reach some level of consensus?

    why bet the farm that all of them are wrong - and nothing should be done - period?

    if we did that with the Ozone holes, what would have happened? Did we waste money and hurt the economy unnecessarily when we switched CFS?

  40. LarryGross:

    you're telling me what the right wing echo chamber has concluded - not science, guy. remember, you do not believe the scientists - because when 90% of them reach a consensus, it signifies a conspiracy.

    there are contradictions in some of the data. That's not abnormal with models but the preponderance of ALL of the outputs have convinced 90% of the scientists that there IS a problem.

    and the right wing idiotically cherry-picks some of it (that their understanding is based not on their own scientific credentials but their armchair assessments) to claim that there is a world wide conspiracy of scientists trying to defraud people.

    I can accept the arguments about the inconsistencies and contradictions of SOME of the data but when a majority of scientists agree overall what the totality of the data means - are then accused of colluding on a worldwide basis to lie - that goes over the edge.

    it becomes luddite ...

  41. Russ R.:

    You obviously didn't follow the links... I referenced (in order):

    Hansen et al. (1988), IPCC FAR (1990), IPCC SAR (1995), IPCC TAR (2001), IPCC AR4 (2007) and NASA GISTEMP data (produced by James Hansen himself).

    Last I checked, the above group are all supposed to be world's top climate scientists... And their own observational data refutes their model predictions.

    Keep on blathering pal.

    We're still waiting for you to show us ONE climate model that predicted 15 years of steeply climbing GHGs and no significant warming.

  42. LarryGross:

    re: " And their own observational data refutes their model predictions."

    who says that? you? do climate scientists say that? what do climate scientists say?

    sorry I don't take your word nor anyone else whose primary credentials is "armchair" and reading other un-credentialed anti-climate web sites.

    If you tell me that a majority of climate scientists say the data is wrong then it might convince me but when you tell me that you checked it out... sorry... there's more to the story that one thing you picked out of a bunch of things and you, without credentials "has decided".

    if the worlds "top climate scientists" ... AGREE with YOUR assessment then I do apologize.


    but I suspect not, right? and the reason they don't is why? because they are engaged in a worldwide conspiracy, right?

  43. Russ R.:

    "what do climate scientists say?" Exactly what I said... that observations don't match the models.

    In their own words:

    "The best estimate of TCR [transient climate response] based on observations of the most recent decade is 1.3 °C (0.9–2.0 °C). Our results match those of other observation-based studies and suggest that the TCRs of some of the models in the CMIP5 ensemble with the strongest climate response to increases in atmospheric CO2 levels may be inconsistent with recent observations."

    Alexander Otto, Friederike E. L. Otto, Olivier Boucher, John Church, Gabi Hegerl, Piers M. Forster, Nathan P. Gillett, Jonathan Gregory, Gregory C. Johnson, Reto Knutti, Nicholas Lewis, Ulrike Lohmann, Jochem Marotzke, Gunnar Myhre, Drew Shindell, Bjorn Stevens & Myles R. Allen http://www.nature.com/ngeo/journal/v6/n6/pdf/ngeo1836.pdf

    I'll await your apology.

  44. LarryGross:

    no... what do these same guys say about the WHOLE of climate - not individual things. what is the overall assessment of GW even after they have taken into account the inconsistencies?

    that was my intended question - but looking back - I do owe you an apology so I do.

    but it's not one thing - it's the totality of the body of knowledge - that really is at issue.

    you seem to think that because some things are inconsistent that it invalidates the rest whereas science is looking at the preponderance of all the factors.

    this is why I say some are "armchair". Science is not about one thing. it's about the body of knowledge - as agreed to by other scientists (or not agreed to) but when 90% agree despite some parts that are not consistent - it means they agree and when you disagree what is your response to their agreement - that they are conspiring globally to foster a lie?

  45. LarryGross:

    " This new work by Otto and colleagues refines our estimates of the climate sensitivity, but the overall picture remains unchanged. Even medium-range climate scenarios suggest that the atmospheric carbon dioxide concentration will have doubled, relative to pre-industrial levels, well before the end of the current century. If our emissions of greenhouse gases continue unabated, we still face an uncomfortable future."

    entitled: "

    Long-term warming,short-term variability: why climate change is still an issue


    this is why I asked what climate scientists are saying - overall - what is the context of this particular finding?

    you choose to interpret it differently than climate scientists do. what does that mean?

    are you qualified to differ with their assessments?

  46. marque2:

    You greatly edited the post I was responding to.

  47. LarryGross:

    my bad... repeat it please.

  48. AnInquirer:

    Yes, I know it is complex, and I also know the avenues that are often used to get around sticky points in modeling. In fact, it was Dr. Hansen's evasivenss to my inquiries on his model that first alerted me that something was amiss. I certainly do not know everything that can go wrong with the GCC models, but the amount that I do know leads me not to trust them. I do not consider it a conspiracy, but the climate scientists who get the most attention from media and political circles have an incredible amount of GroupThink and confirmation bias.

    There are huge big difference between 90% of doctors saying smoking is bad and what goes on in the name of climate science. First of all, you have the very people who make forecasts are the same people who -- through complex and obscure algorithms -- develop the observations by which the forecasts are judged. In any other field, I believe that would raise red flags in the science community and in the media. For some reason, climate science gets a pass. Second, in other science fields, results are verifiable and reproducible. That has often not been the case in climate science. You may remember that the study author's successfully hid the Yamal data for ten years. When others got a hold of data after ten years, the study's conclusions were destroyed in three days. Third, if scientists studying smoking had conducted themselves the way that we know the leaders do in Climate Science (Climategate being only one example), the campaign against smoking would have suffered severe setbacks. Those are some of the differences that the 90% figure doesn't mean much in Climate Science.

  49. LarryGross:

    I don't consider 90% agreement as "group think" guy. and I still question how you are more qualified to question others assessments... and suspect you are not.

    why is climate science more vulnerable than other science to your concerns?

    why do you select it ?

    that's my problem. I don't see you going after the hurricane modellers - who have many of the same failings that you name here.

    Science is a mess. It's done by humans with all the human foibles from corrupt to genius.

    but the body of knowledge - the areas of science that are accepted by most scientists has some merit - usually - and usually is not referred to as "group think" or "confirmation bias".

    only for Climate Science do these particular issues seem to be in play.


  50. David:

    You didn't actually answer my question. Do the climate change models make predictions which are testable? An example of a prediction which is testable is "an increase of atmospheric CO2 by X percentage should cause an increase in temperature of Y degrees with Z precision over T years." Then, after T years, see what happened.

    I know there have been predictions made; are those predictions bearing out reality?