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apiratelooksat50 at 01:50 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
J Bob @ 68 "Getting all the info from one source does not seem like an objective approach." Exactly! And, to take it a step further, even if the source is a compilation of articles/papers/data more than one site should be used. -
Charlie A at 01:47 AM on 1 June 2011Can we trust climate models?
Eric the Red @75: "I agree that given accurate forcings, we can make accurate temperature predictions. Therein lies the main question: How accurate are our predictions of the forcings?" A main point of Hansen's recent whitepaper is that we don't know current forcings very well. The GISS-E model runs of 1880-2003 for AR4 and Hansen's 2007 paper used aerosol forcing data that was arbitrarily flatlined for the entire 13 year period of 1990-2003. In his recent whitepaper the model runs replaced that flatlined data with an approximation that set the sum of (aerosol + black carbon + indirect aerosol + snow albedo) forcings = -1/2 of (CO2 + O3 + strat. H20) forcing. I find this surprising, although it doesn't seem to have attracted much attention. People refer to tuning of model parameters, but it appears that a lot of the fitting, whether consciously or via observer bias, has been done with adjustments of the forcings. -
RyanStarr at 01:28 AM on 1 June 2011Ljungqvist broke the hockey stick
The rules forbid me from saying what I would like to say. The Hadcrut overlay is... not right. The abstract of the paper itself only suggests the late 20th century is likely the warmist. How does the author here then manage to show recent years as being > 0.5 C above the highest Ljungqvist peak. I've googled and found other overlays too, they don't even come close to this result. Decadal mean temperatures seem to have reached or exceeded the 1961-1990 mean temperature level during substantial parts of the Roman Warm Period and the Medieval Warm Period. The temperature of the last two decades, however, is possibly higher than during any previous time in the past two millennia, although this is only seen in the instrumental temperature data and not in the multi-proxy reconstruction itself.Response:[dana1981] The figure in the post is correct. Ljungqvist terminates the data in his paper at 2000, so that's probably where the overlays you found on Google terminate as well. However, NH land temps did not stop warming in 2000. Our figure is up-to-date and uses the correct data, as other commenters have noted.
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seeker25801 at 01:27 AM on 1 June 2011Video on why record-breaking snow doesn't mean global warming has stopped
Global warming: maybe. Man-made global warming: nah. I just wish both sides would tell the full story. Our climate is "dynamic". Ever-changing. We're coming OUT of a global cooling period so of course it's going to get warmer. And weather is NOT climate. -
barry1487 at 01:24 AM on 1 June 2011Database of peer-reviewed papers: classification problematics
Hey Ari, nice to see you posting here. ------------------------------------------------------------- I'd like to see papers centred around a value, like climate sensitivity, sea level trends or temperature trends. Eg, label a y-axis -2 to 12* (for climate sensitivity), and a vertical bar for each paper per the range each gives. So when a skeptic cites Lindzen climate sensitivity estimates, I can point to the graph that shows not only what outliers his estimate are and where the studies cluster, but how much work has been done. Skeptics pounce on a paper as if it's the final revelation, instead of one of dozens. That's the visual that I think will make the most impact. Seems like a lot of work, though. * I don't know what the range for climate sensitivity should be. I just made it up, like Eric did (I got you, ETR). -
J. Bob at 01:13 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
actually thoughtfull(?), says “information you could have found by searching this very site - not even requiring a Google search”. Getting all the info from one source does not seem like an objective approach. You also say, “Good thing you didn't base your job on your post above - you would be unemployed!”. Actually, before retirement, I was Dir. of R&D for an international Co. But getting back to the discussion, what points do you disagree with me? -
DaneelOlivaw at 01:08 AM on 1 June 2011Database of peer-reviewed papers: classification problematics
It's a mess. One thing I would suggest is identifying those arguments that are most relevant to the global picture and only taking those into account. So, for example, any paper addressing the "polar bears" argument is not pro, against or neutral... it's simply irrelevant. Of course, there are some studies whose relevance may be disputed. Is a paleoclimatic study investigating the climate 10 million years ago relevant to current warming? Some could say that it is since it may tell us a lot about climate sensitivity, but how much is difficult to say. I think that, in the end, we need to proceed as a scientist and look at the issue from multiple perspectives. Use different classifications schemes, filters and inclusion criteria and see what they tell us. A more compelling case can be made if the same conclusion (most papers agree with AGW) arises from multiple lines of evidence. -
Tom Curtis at 00:58 AM on 1 June 2011Can we trust climate models?
Eric the Red @75: 1) The climate response to doubling CO2 is well constrained independently of the models, so the GHG component of the forcings are unlikely to be significantly in error; 2) This means the four degree plus predictions for BAU are fairly reliable; 3) Natural variability (short of catastrophic meteor impact or vulcanism) is constrained to be less than 2 degrees by the fact that mean global temperatures have remained in a 2 degree range (more probably a 1 degree range) through out the Holocene; 4) As 2 degrees is considered the upper limit for "safe" temperature increases, natural variability will not save us from the consequences of BAU (and are as likely to worsen them as to mitigate them); 5) Therefore for practical purposes, the models are reliable enough. Having said that, there is a slight possibility that increasing temperatures will reach a tripping point that will generate a significant negative feedback, thus saving our collective bacon. It is significantly less likely that it will reach a tipping point (or several of those thought to exist) which will greatly accelerate global warming. These possibilities are beyond the models (and our) capabilities to predict at the moment. For policy purposes they are irrelevant. Relying on these possibilities is like taunting Mike Tyson in the confidence he will have a heart attack before the blow drives your nose out of the back of your skull. -
CBDunkerson at 00:57 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
apiratelooksat50 wrote: "6. Therefore, humans are partially responsible for the increase in global surface temperature." Too vague. Only the complete lunatic fringe argue that humans aren't responsible for any of the increase. The mainstream scientific position is that we are responsible for most of it. Your 'partially' could fall anywhere in between. -
Albatross at 00:47 AM on 1 June 2011The Critical Decade - Part 1: The Science
Ken First, you do not deny that Camburn misrepresented Hansen. Good, but then you go and say this: "It Camburn and I are cherry picking on short timescales - then we seem to be in the company of Jim Hansen." Not true-- and your accusation of cherry picking against Hansen is ridiculous and unfounded, or are you simply musing about scientific misconduct by one of the world's leading climate scientists? Hansen, as always, looks at the big picture and context, even when he might be looking at shorter periods of time to solve a problem (i.e., it is not cherry picking to look at ENSO, but don't try and use ENSO to claim that the the long-term warming in global SATs is because of ENSO like contrarians McLean et al. infamously tried to do). Also, as I explained above to your friend @97 above, and which fell on deaf ears, "Tamino has shown otherwise, but regardless Hansen and Sato are wisely most definitely are not using noise in the data record as a reason to claim that we are not facing a whole lot of trouble down the road if we continue along those path. So you have misrepresented Hansen's position." To do so, focus on the noise and then make grandiose claims about the big picture, would be foolhardy. This game of focussing on the noise in the climate system to claim that 'warming has stopped or slowed so there is nothing to worry about', or that the 'theory of AGW has been overturned' etc, is very old, and I for one am sick of "skeptics" playing that game. We can be playing that game circa 2100-- "Ooh global SATs slowed somewhat the last 5 years", meanwhile the planet will have warmed significantly between now and then. "The UCAR SLR chart which you seem loathe to discuss and is often quoted in these threads, covers the period 1993-2010 - all of 18 years inclusively." A strawman, and not true. I posted an image of the satellite altimeter data above @52. Now I do not know if advancing strawmen and demonstrably false statements is a valid form of debating...oh wait it is, it is called baiting and gish gallop, and techniques which are used liberally by self proclaimed 'skeptics' and deniers of AGW. The Australian Climate Commission's report was right on the mark. How inconvenient for the 'skeptics', yet more evidence that runs counter their ideas. No wonder they are scrambling to obfuscate and fabricate debate. -
CBDunkerson at 00:46 AM on 1 June 2011Can we trust climate models?
Eric the Red wrote: "Other forcings must also be included, although some will average out in the long term (i.e. ENSO)." ENSO is not a climate forcing. It is a redistribution of energy within the climate. The confusion likely arises in that climate sensitivity is often estimated as a 'surface temperature anomaly'. Since ENSO involves movement of energy between the oceans and the atmosphere it can impact surface temperature anomalies on a short-term scale. This differs from a climate forcing in that it is not actually increasing the total energy in the climate system... just temporarily adjusting the proportion of that energy in one part of the climate which we commonly use as an indicator since it is (relatively) easy to measure. -
apiratelooksat50 at 00:35 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
AT at 50 What mitigation efforts do you propose? -
Tom Curtis at 00:34 AM on 1 June 2011Ljungqvist broke the hockey stick
1) Science moves on. This is a fact hated by deniers because it robs them of talking points. (Talking points, of course, because they lack valid arguments.) Thus in 1998, Mann, Bradley and Hughes pioneered an innovative technique to reconstruct past temperatures. It was innovative, so they had nobodies mistakes to learn from except their own, so they made a few minor errors. Further, they had limited data to work with, which also created problems. As a result they produced a reconstruction with insufficient multi-decadal variability. The scientists picked up on the mistakes (the scientists, not McIntyre and McKittrick whose criticisms where mostly either trivial, or wrong), and have produce better recent reconstruction, such as Mann 2008 shown above. Clearly the denier talking point that RyanStarr wants to ressurect doesn't fit well with that graph, so he goes on about it because talking points is all he has. 2) The original MBH 98 graph did not even cover the medieval warm period. Their follow on MBH 99 did, and shows medieval temperatures approximately equal to those shown by Lungqvist. It then followed a more or less straight line, with decadal but not multidecadal variation to approximately the temperaure shown by Lungqvist in 1850. Consequently it was not the MWP that was supressed by the limitations in MBH's first time efforts, it was the Little Ice Age. That, of course does not fit the denier narrative, so RyanStarr ignores it and goes on about the MWP. 3) As noted above, and by Lungqvist in his paper, Mann et al 2008 shows a very similar curve to Lungqvist. Indeed, Mann 2008 shows a slightly warmer MWP (0.32 vs 0.29 11th century mean) and a very slightly colder LIA (-0.18 vs -0.17 in the 17th century), thus showing greater variability than Lungqvist, and two years before him. Therefore if Lungqvist "slaughters" MBH 99 (the hockeystick), he arrives late on the scene and only manages to slay a corpse. The real action came two years before, when Mann "slaughtered" MBH 99. Again, that doesn't fit the denier narrative, so only Lungqvist gets credit in the denier rant. This of course beautifully illustrates my first point. Scientists, because they pursue truth, move on. Deniers because they are only using talking points to sow confusion, cling to those talking points regardless, leaving them not only wrong, but ten years out of date to boot. Cue more empty denier talking points from RyannStarr ... -
apiratelooksat50 at 00:34 AM on 1 June 2011Are you a genuine skeptic or a climate denier?
AT @ 50 [inflamatory stuff deleted] It did leave me uncertain as to where your confusion on my stance comes from. Let me state it again. 1. Global warming is real and happening now. 2. Global climate change is a naturally occurring phenomenon. 3. CO2 is one of the greenhouse gases and is partially responsible for causing the Earth's surface to be warmer than if it were not present. 4. Human activities have led to changes of the Earth that have resulted in alterations of the climate. 5. Some of those activities include the burning of fossil fuels that have resulted in the increase of CO2 in the atmosphere. 6. Therefore, humans are partially responsible for the increase in global surface temperature. 7. As good stewards of the environment we should: take reasonable and rational methods to reduce our dependence on natural resources (both renewable and non-renewable), develop and utilize alternative energy (wind, solar, geothermal, nuclear, hydroelectric, etc...) where econmically feasible to reduce dependence on fossil fuels, and practice conservation. That should be fairly clear to most readers.Moderator Response: [Dikran Marsupial] Inflamatory material snipped. Whatever the perceived provocation, please try to stay within boundaries set out in the comments policy. -
Eric the Red at 00:33 AM on 1 June 2011Can we trust climate models?
Tom, I agree that given accurate forcings, we can make accurate temperature predictions. Therein lies the main question: How accurate are our predictions of the forcings? Yes, we can control CO2. We can also control many other manmade factors. But, what is the normal range of natural variability? More importantly, what will be the natural response to an increase in CO2? Actually, the errors will compound. Given a climate sensitivity of 3 +/- 1.5 C/doubling, the uncertainy will increase as CO2 concentrations increase. Other forcings must also be included, although some will average out in the long term (i.e. ENSO). -
CBDunkerson at 00:18 AM on 1 June 2011Ljungqvist broke the hockey stick
So what you are saying is that you didn't actually read the article. If you had you'd likely have seen the part about Ljungqvist conceding that current temperatures being higher than any other point in the last 2000 years. The reason that Ljungqvist's reconstruction doesn't show the "line flying off into blue sky" late in the 20th century is that... his reconstruction doesn't include the late 20th century. It stops before 1950. Figure 2 above shows the late 20th century warming from the instrumental record added on to the end of Ljungqvist's results in red. -
The Skeptical Chymist at 00:06 AM on 1 June 2011Database of peer-reviewed papers: classification problematics
Some thoughts 1) It would be good to be able to suggest deletion of articles or movement of articles between categories. eg; checking the 2010 skeptic articles, I found that one is from Americanthinker "Climatism: Redoubling Misguided Efforts". Which doesn't belong in a list of peer-reviewed papers. eg: A paper listed in the 2010 skeptic articles is "Marine Reserves Enhance the Recovery of Corals on Caribbean Reefs", which is also listed under the myth "Corals are resilient to bleaching". Having had a quick look at the abstract and introduction it seems this paper is not skeptical about AWG or the threat of coral reef bleaching, but has identified a mechanism which can help reefs recovering faster from bleaching events. IMHO this paper belongs in the neutral section. 2) Naomi Oreskes' classification method is quite good in that it help to get a the guts of whether a paper accepts the basic consensus around climate changes, which is: are humans warming the planet? Perhaps papers could be classified by both methods? 3) Many papers are not shown to be wrong by specific rebuttal but simply become irrelevant over time. ie: a skeptic paper written in the 80's suggesting the climate was not warming or papers claiming the climate was not warming based upon the faulty UAH data. It would be useful if these could be marked in some way. -
Tom Curtis at 00:04 AM on 1 June 2011Database of peer-reviewed papers: classification problematics
Eric the Red @5, in addition to CBDunkerson's well made points, I would add that the percentages you give are undefined because you provide no time period to your hypothetical. In the real world case, changes to CO2 forcing have a very small influence relative to ENSO on a year to year basis, but on a multidecadal basis they swamp the ENSO effects. So unless you specify whether you are considering annual, decadal, centenial, or (make your choice) variability, there can be no rational answer to your question. -
Tim Curtin at 00:03 AM on 1 June 2011Of Averages and Anomalies - Part 1B. How the Surface Temperature records are built
In reply to skywatcher at 15:53 PM on 31 May, 2011 who said: "That's a large accusation to make without evidence there Tim Curtin, and yes you are cherry-picking, be it individual stations or individual records. The glaciers are 'cooked' as well, explains why nearly all of them are retreating". I do NOT cherry pick, Hansen and BoM do, that is why they prefer to use Wagga rather than Canberra, and Heathrow rather than Oxford. As for the glaciers, they have been receding since the end of the Little Ice Age, and thank goodness for that. A retreating glacier does NOT imply reduced rainfall, especially as ( -Snip- ).Moderator Response: (DB) All-caps usage is a Comments Policy violation; please refrain from their use. -
Tom Curtis at 23:46 PM on 31 May 2011Can we trust climate models?
Eric the Red @70, the statistical test was for the accuracy at predicting the temperature for each given year given that you have initial conditions determined for that year by the model, and that you have known forcings. The test was carried out for over a century of time. Therefore, we can be confident that with known forcings, the models make accurate predictions. They make accurate predictions even a century out, given an accurate prediction of the forcings. Now of course we cannot accurately predict the forcings a century out. But that is a little irrelevant. It is irrelevant because the predicted dominant forcing under BAU is under our control. We can continue with BAU, in which case the GHG forcings will be high enough to completely dominate the normal range of natural variability and the temperature rise will be sufficiently large that the error in the models will be of no consequence relative to that rise. Or we can keep GHG forcings at or below current levels, in which case temperatures will rise by not so much that natural variability is inconsequential, or that the error is irrelevant. The Logic is very simple. Given forcings, the model makes accurate predictions. We can't predict forcings, but we can significantly control them. Therefore the models cannot tell us what will happen, but they can tell us what will happen if we continue at BAU. Finally, with regard to your specific point, the errors introduced from year to year in the retrodictions did not compound over the century and more of the model run. That was because the results were constrained by the forcings. Hence your point is irrelevant to my point. -
RyanStarr at 23:45 PM on 31 May 2011Ljungqvist broke the hockey stick
Why no comments? This slaughters the hockey stick, without nitpicking the 20th century rise is on par with the MWP. And look at Mann's line flying off into blue sky late 20th century, Ljungqvist's does nothing of the sort. Originally Mann's HS didn't even recognize the MWP and him and others attempted to downplay it in other ways. A truely skeptical science site would hold that up as a discussion point. -
CBDunkerson at 23:27 PM on 31 May 2011Database of peer-reviewed papers: classification problematics
Eric the Red wrote: "For instance, where would you classifiy a paper which concluded that global temperatures were influenced by the following factors in the given percentages? CO2:30%, solar: 25%, UHI: 20%, ENSO: 15:, albedo: 10%." Most likely classification: 'Fiction' If we are really talking about "global temperatures", rather than temperature anomalies, then the solar value is ridiculously low. If you meant to ask about anomalies then the solar, UHI, and ENSO values are ridiculously high. Obviously, it isn't really possible to classify such a hypothetical paper because we have no knowledge of the evidence shown for these conclusions. Based on known evidence they are beyond absurd, but the 'unknown evidence' of the hypothetical could be anything. -
Kevin C at 23:22 PM on 31 May 2011Can we trust climate models?
Model accuracy and Cross Validation I've taken my empirical lag model a little further, and I'll show some results here. But at the same time I'd like to introduce a method which scientists and statisticians in many fields use to answer the question 'can we trust our model?'. The problem here is that you can make a model which gives an arbitrarily good fit to any set of data. How? Simply add more parameters. In the extreme case, you could just tell the model the answers, giving a perfect fit. But then your model only works for the data you already have. It's also possible to do this more subtly and fool yourself into thinking you have a meaningful model when you don't. So, in the case of calculating an empirical climate response function in order to get the temperatures from the forcings, we could simply assign a value for each year in a 120 year response function. If we refine those values to get the best fit against a 120 temperature series using 120 years of forcings, we can get a perfect fit: R2=1. But the result is meaningless. R2 is not a good indicator of model reliability. A simple approach is to prescribe a minimum data/parameter ratio. For example, if we want a data/parameter ratio of at least 10, then for a 120 year time series we can use no more than 12 parameters. But this approach is limited in a number of ways, for example a noisy datum is worth rather less than an exact value. So, how do we evaluate models? For one approach to this problem, we can go back to the scientific method. We start by forming some sort of hypothesis based on the information we have. There may be multiple competing hypotheses. These hypotheses are tested when we try and use them to predict the outcome of a new observation (in Popper's terminology, we subject the hypothesis to a test which is capable of falsifying the hypothesis). Or in other words, we test the predictive power of the hypothesis. So, in the case of a climate model, we could test the model by using it to predict climate for some period in the future, and then compare it with what actually happens. Unfortunately that takes a long time. Ideally we'd like something more immediate. This is where cross-validation comes in. The idea behind cross-validation is that we hide some of our data away - often referred to as a holdout or test set, and develop our model using the rest of the data. We then use the model to predict the values of the holdout set. The quality of the model is given by the match to the holdout set, sometimes referred to as the 'skill' of the model. We can do this multiple times with multiple holdout sets if required. We could, for example, hold out one year of data, and fit a model to the rest of the data. However, there is a problem: the year-on-year temperatures are highly correlated, as Charlie and others have noted. So the prediction doesn't require much skill. So let's go to the other extreme, and set the empirical lag model a very tough challenge. We've got 124 years of data. Let's hold out 62 years, and predict the other 62. We can hold out either the first or last 62 years (or any other set) - I'll do both. The correlations only run over a few years, so this is a real test of the model. Fitting the response function with only 62 years of data is a tough challenge, I had to make some improvements. Firstly, I produced an ENSO-removed temperature series by subtracting a weighted combination of the last 9 months of SOI data from the monthly temperature data, with the weights chosen to give the best fit between the temperature data and a 61-month moving average. Then I modified the model to use a response function constructed from 5 quadratic B splines, centered at integer positions 0,1,2,3,4 on a logarithmic time axis t' where t'=ln(t+1)/ln(2.5) (i.e. at t=0,2.5,6.3,15.6,39.1), constrained such that the spline coefficients must be positive. The b-spline is a bell curve like a Gaussian, but has compact support (i.e. no long tail to infinity which we can't fit against our limited dataset). The resulting model is very marginally better than the two-box model with both time constants refined (at the cost of an extra parameter), but much more stable. Unlike the two-box model, the parameters can be fit roughly against only 62 years of data (although an 80 year training set / 40 year test would be better). Here's the results of training 3 empirical models, with the models being trained against the whole time series, the first 62 years, and the last 62 years respectively.
Clearly there is some sort of predictive power here - from the early period we can make a reasonable prediction of the late period climate, and vice-versa. How can we parameterise this?
Here are the R2 statistics on the whole period and the two sub-periods for each of the three models:
The two numbers in bold are the holdout statistics. These are the real indicators of the predictive power of the model. Note that fitting a model on only part of the data improves the fit to the included data, at the cost of making the fit to the other period (the holdout set) worse. Throwing away data makes the model worse, and the holdout statistic tells us that. Note the numbers for the early period are systematically smaller because there is less signal in that period, not because the model is necessarily worse! The values here are not absolute - rather they can be used to compare different models. So at this point we could go back and do a real test of the two-box model (if it were stable) to see whether it is a better or worse model than the b-spline model, by doing the same calculation and looking at the holdout statistics. For completeness here are the response functions for the three models:R2 on 1880-2003 R2 on 1880-1941 R2 on 1942-2003 Fit on 1880-2003 0.865 0.500 0.817 Fit on 1880-1941 0.831 0.525 0.774 Fit on 1942-2003 0.859 0.482 0.820 
We can see the benefit of compact support in the basis functions here: The response functions reach a plateau quickly for the short-period models, and have almost plateaued in the long run model. The climate sensitivities over the limited periods are 0.58 C/(W/m2) for the full-period model and 0.41 and 0.56 C/(W/m2) for the short period models. The lower number comes from fitting the early period, where there is less climate variation to fit the model parameters. These estimates should be considered lower bounds because the model explicitly excludes any long term response beyond about a century.
Question
To what extent do climate modellers make use of cross-validation in the evaluation of climate models?
I don't know the answer to that question. Hence my queries at #16.
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les at 23:22 PM on 31 May 2011Can we trust climate models?
70/71: sorry, re-reading, I misunderstood... scrub 71. -
kdkd at 23:04 PM on 31 May 2011Database of peer-reviewed papers: classification problematics
I think the point is not so much the classification of the paper itself (as due to the way science is conducted most papers will be neutral), but the potential for the conclusions to be misused or taken out of context by deniers. Or by alarmists for that matter, but that seems a rarer occurance. -
les at 22:58 PM on 31 May 2011Can we trust climate models?
70 - "Statiscally, when you multiple a value by ten, you multiple the uncertainty by ten also." you quite sure about that? -
Eric the Red at 22:52 PM on 31 May 2011Database of peer-reviewed papers: classification problematics
I tend to dismiss these types of surveys as they are largely subjective. For instance, where would you classifiy a paper which concluded that global temperatures were influenced by the following factors in the given percentages? CO2:30%, solar: 25%, UHI: 20%, ENSO: 15:, albedo: 10%. (These numbers were completely made up and have no real bearing except to provide a basis for my hypothetical question.) -
Eric the Red at 22:46 PM on 31 May 2011Are you a genuine skeptic or a climate denier?
AT, I think you are a little over the top there. I am glad you are so clear in your thinking. However, there are many of us in the field who understand that there are many things which we do not understand. The recent acknowledge by Hansen regarding aerosol forcings is one of them. To say there is no middle implies that there are two distinct "sides." Let us assume there is one "side" that says there has been and will not be warmer. My question is what is the other side? Is it 1C of warming? 2C? 4C? More? There exists today a wide range of model predictions and forecasts based on different inputs and forcings. Is the climate sensitivity 3C per doubling of CO2? Higher? Lower? Actually, 3C is just an average of several calculated values, with a rather wide range. It is neither black nor white, but very grey. I hope you were not referring to Doran's survey with your numbers, because that is woefully misleading, and could be classified as cherry-picked extraordinair. There are several credentialed scientists who would disagree with you or me on our positions, not that science proceeds by majority anyway. The logic statement is that an increase in CO2 will lead to an increase in temperature. If temperatures increase, we can make no inference about CO2. Conversely, if CO2 does not change, we can no make no temperature inference also. These so-called natural variabilites (and other man-made attrributes) must be removed from the logic equation in order to achieve the conditional statement. I believe this is the origin of the "muddled middle." -
Eric the Red at 22:20 PM on 31 May 2011Can we trust climate models?
Tom, Your uncertainty is for one year, and cannot be applied uncorrected to a century worth of data. Statiscally, when you multiple a value by ten, you multiple the uncertainty by ten also. This is slightly different in that the uncertainties are compounded, and must be treated as such. In reality, the models that predict a 4C rise by the end of the century have a much higher uncertainty than 0.2. The actual uncertainties are an order of magnitude higher; different for different models. The models are accurate based on recent temperature measurements because they have calibrated based on past observations and been fined tuned to recent values. The models are being adjusted constantly, such that by the end of century, it is entirely possible, that the models will barely resemeble those today. We can make predictions based on current knowledge of forcings, but as Hansen pointed out recently, some of that knowledge has a rather high uncertainty. This will become irrelevant if those forcings change very little, but if they change appreciably, then the unctertainties could become huge. In summary, models cannot predict short-term changes accurately due to natural variability. In the long-term, we cannot say that the models are any more accurate, as seemingly small errors today could become large errors tomorrow.Moderator Response: [Dikran Marsupial] The uncertainty of a ten year trend is actually less than the uncertainty of a one year trend. The inter-annual variabilility does not apply multiplicatively to long term trends, but additively, and so the errors from year to year tend to average out to zero. That is why climatologists are interested in long term (e.g. 30 year) trends, not annual weather. Also asserting that the models are accurate because they have been fine tuned from recent observations doesn't make it true (reference required). If you look at Hansens 1988 projections, then they were actually remarkably good, and there can be no accusation of fine-tuning there (unless Hansen has a time machine). -
Bern at 22:12 PM on 31 May 2011Are you a genuine skeptic or a climate denier?
Glenn, yes, I think you may have something there... I gave a (repeat) presentation at work today, about global warming. Depressing turnout - between two sessions, and only 10 people out of 40 came to see what it's about. That's in an environmental consultancy, too... My conclusion was a bad news / good news type thing. The Bad News: We're screwed. The Good News: We're not totally screwed. Yet. (speaking of which, I now have great admiration for people who can give a talk on global warming and keep the # of slides & the length down... I've got 75 slides in mine!) -
Ari Jokimäki at 21:42 PM on 31 May 2011Database of peer-reviewed papers: classification problematics
Paul: "Local results can have a global context. eg. if it can occur in one location, then logically it may occur in another location due to AGW given the right circumstances." Yes, but remember that we are classifying only a single paper, we are not making statistics of several papers of different locations. For that single local paper, it is impossible to say anything about the global situation. -
Paul D at 20:50 PM on 31 May 2011An Interactive History of Climate Science
Just found this NYT timeline which starts in the same year, although later it deviates from purely research papers: http://www.nytimes.com/interactive/2009/12/07/science/20091207_CLIMATE_TIMELINE.html However it has a similar groupings of events, with a greater density in modern times. -
Paul D at 20:12 PM on 31 May 2011Database of peer-reviewed papers: classification problematics
Local results can have a global context. eg. if it can occur in one location, then logically it may occur in another location due to AGW given the right circumstances. Are there examples that can be discussed?? Would be interesting. Maybe the neutral circles in the visualisation should just drop to the floor in a pile, rather than cluster in a group :-) -
adelady at 20:03 PM on 31 May 2011An Interactive History of Climate Science
Refutations. Might require a fair bit of faffing about. 1. Providing a link to a published paper which explicitly refutes the evidence/ conclusions after publication of the relevant item should be fairly straightforward. A little red dot, per paper rather than per refutation, in the relevant circle would be handy. 2. Some egregiously wrong papers which ignore or try to override others' well-accepted work could also have some indication (with a pale pink dot?) / link to a list of published works which contradicted the paper before it was ever written. 3. The thorny problem. Many truly dreadful papers are not refuted in formal papers by others after publication because the competent scientists just can't be bothered (again, and again, and again). But there are letters and similar critical responses where bad papers somehow made it into reputable journals. No idea how this might be incorporated. -
Glenn Tamblyn at 19:00 PM on 31 May 2011Of Averages and Anomalies - Part 1B. How the Surface Temperature records are built
Wow, I am of the net for a day due to 'technology problems' and my post is already into specific stations and ice sheets! The purpose of this series is to look at the broader issues and 'encourage debate' and consideration of how to think about this subject, in the mathematical sense. I would like to make a general point. The concept of Teleconnection is well established in Climatology/Meteorology. Things are connected together. Damorbel has suggested that things such as elevation need to be considered. However this can easily fall into the trap of looking at temperatures rather than temperature anomalies. The graph from Hansen & Lebedeff 87 shown in post 1a (sorry but with the declining health of my laptop, posting a link is too hard). Is a plot of the correlation of Temperature Variation (Anomaly) vs station separation for station pairs. And it is based on randomly selecting those station pairs. Including variation in elevation. This is the key point, which can easily distract us. Long term climatic conditions at differing locations out to 1000 km or so ARE correlated, based on the evidence. Not that they have the same climate. But that their climates are related. Damorbel makes a valid observation that this will start to breakdown at the land/ocean interface. Even more so, we can't project this correlation out into the ocean. But these analyses only apply to land data. Ocean temps are processed separately. And this aligns with the observation I make that the correlation between stations and how they decline with separation is clearest in those latitudes with the highest proportion of land. However, Damorbel suggests that a 1200 km link is in some way unreasonable without supporting data. Firstly, the analysis from HL97 provides the supporting data. As I mention, commonality of weather systems passing over 'adjacent' locations provides a mechanism by which adjacent locations can see comparable temperature variations (anomalies). And from the data the 1200 km range is most reasonable at latitudes where there are high proportions of land. This is where the difference between temperature and temperature anomaly, climate vs climate variability can be a bit of a head bender. The mathematically valid approach doesn't align with our unconscious, intuitive sense. The unconscious is strong, but in this context it is strong. I will discuss some of these issues further in the last 2 parts of the series. But with the tight publication schedule here at SkS, that won't be till the end of the week. -
Paul Barry at 18:55 PM on 31 May 2011An Interactive History of Climate Science
Well done. Nice presentation. Tor B's idea above to improve it is important. Some are likely to use the same graphic and say "Look! There is a substantial number of papers that argue against AGW. Hardly a consensus!" It would be very useful to be able to identify refuted and erroneous papers and even remove them from the graphic as well. This would also reflect the actual nature of scientific consensus: that it is not merely majoritarianism. -
adelady at 18:43 PM on 31 May 2011Are you a genuine skeptic or a climate denier?
RSVP "...(If on the other hand, it seems there is more "evidence" in support of the effects of AGHG's, it is only because this line of thinking gets more airtime.)" I can assure you that a good paper with good evidence contradicting our current understanding would get a very, very good reception from at least this reader. There are a couple I'd be deeply, truly, really, really happy to see. The first one would be a demonstration that CO2 in the atmosphere behaves differently (and better for us) from CO2 in a laser. The knowledge that the warming we've seen so far is not necessarily indicative of what's to come would be fantastic. The other one would be a convincing then-and-now demonstration that the climate sensitivity shown by e.g. the escape from the 'snowball earth' state, is inapplicable in current circumstances because .... several valid reasons. Another occasion for rejoicing. (My longer list of unlikely demands includes a paper showing that a sea ice free Arctic can be maintained as a seasonal phenomenon rather than as a transient condition on the way to year-round ice free conditions. And a baker's dozen of others.) I'm pretty certain that many regulars here would give more, plenty more, 'airtime' to worthwhile papers giving quality evidence of this kind. -
Glenn Tamblyn at 18:09 PM on 31 May 2011Are you a genuine skeptic or a climate denier?
John I have spent some time over the years discussing AGW on Unleashed. And I have never seen so many comments, so fast from so many DIFFERENT people. You really have dragged the lurkers out into the limelight. Do I get the sense that your somewhat more acerbic than usual tone has pressed a few peoples buttons. Quite a few people with tones of anger. It has been my experience of life that when you see anger, it is usually best to start looking for the fear that lives behind the anger. What fear could your post engender? The fear that the rather jerry-built edifice of 'Climate Denial Science' might be revealed for the house of cards that it is. And if the house falls down, well then they might have to deal with the reality that must be avoided at all costs. Confronting the reality that humanity is in D@@p S**t, and we have to do something about it. And treasured ideas of our sense of our place in the world may be one of the first and necessary casualties. This is the real denial. That their sense of how the world works, what is meaningful, may not actually match reality. And that they actually need to abandon that sense and replace it with one more grounded in reality. This is an existential burden that is hard on anyone. But there is one final arbiter of which 'view' of life is correct. Her view over-rules everyone else. Her name is Mother Nature. Her bat and ball, her back yard. So her rules. And if what we think doesn't match that, we loose. Thgis is hard for some people to handle, probably hard for their personality type to accept. The last vestiges of the Anthropocentric view of the Universe reside in the conservative, individualist personality type. -
Ari Jokimäki at 17:33 PM on 31 May 2011Database of peer-reviewed papers: classification problematics
Caroza: "Isn't your definition of "neutral" going to artificially inflate the neutral bucket? A paper which is local in scope but which accepts AGW as causative or even axiomatic is not neutral in viewpoint, yet that is how it will be counted." As long as we are classifying these papers per argument, we need to do it like that. If the argument is global, then paper on one location is irrelevant for the argument, because local results can be remarkably different from global results. -
Ken Lambert at 17:28 PM on 31 May 2011The Critical Decade - Part 1: The Science
DB at #99. KL: "Camburn has made several valid and reasonable points" DB: Which fail to stand up to scientific rigor and scrutiny. Well DB how about answering my #96, which goes back to your chart post at #58 and the issue of the validity or not of UCAR SLR chart. I see no scientific rigor in your posting conflicting chart evidence and then not explaining which is correct. -
caroza at 17:04 PM on 31 May 2011Database of peer-reviewed papers: classification problematics
"I also think this same logic should be applied to research dealing with the effects of AGW on certain species: studies that focus on one plant species and how it will respond to AGW, for instance, are classified as “neutral” as well, as generalizations among plant species (especially) are illogical to make." Isn't your definition of "neutral" going to artificially inflate the neutral bucket? A paper which is local in scope but which accepts AGW as causative or even axiomatic is not neutral in viewpoint, yet that is how it will be counted. I think you're right that you probably need to extend the database to cater for classification per argument rather than only per paper, but perhaps you also need more classification dimensions. -
Bern at 16:58 PM on 31 May 2011Are you a genuine skeptic or a climate denier?
philipm: oh, dear, not PDEs! (I really should have studied more during that subject at uni, it was the most interesting engineering maths subject I did. 20 years later, though, and I can barely even remember what a PDE looks like, let alone solve one!) -
Bern at 16:57 PM on 31 May 2011Are you a genuine skeptic or a climate denier?
Hah, 326 comments and counting... looks like that analysis might take a while there, John! Certainly plenty of material, though... [rolls eyes] -
philipm at 16:44 PM on 31 May 2011Are you a genuine skeptic or a climate denier?
The deniers are out in force at the Drum now. All repeating tired cliches. If there is indeed an argument against the mainstream science, I'm sure we would have heard it by now. Conspiracy theory is so passé. Science is supposed to be stuff like calculus. These people should get a grip and solve some PDEs, then report back on what they know about science. :( -
Bern at 16:43 PM on 31 May 2011Are you a genuine skeptic or a climate denier?
RSVP: Kindly point out some 'evidence' against AGW, that has not already been debunked on this site. Those of us who support the science know there are uncertainties. We also know roughly how big they are, where they are, and what impact they have on the overall conclusion as to the existence of AGW (the phrase that comes to mind is "two thirds of stuff all"). Anyone with half a brain knows there is uncertainty. The only people who think the uncertainty is all on the low side (i.e. it all runs counter-AGW) *only* have half a brain... Is there a slim chance that some fluke of natural climate variability just happens to have produced a warming signature that exactly matches that of increased GHGs, right at the time when humans are emitting billions of tons of the stuff? Yes, there is. Is there a slim chance that you can jump out of plane kilometres above the ground without a parachute, and survive? Yes, there is. It's probably not a good idea to try it, though. The odds are somewhat against you. -
Tsumetai at 16:19 PM on 31 May 2011Of Averages and Anomalies - Part 1B. How the Surface Temperature records are built
What Hansen is doing is looking to see if he can reconstruct temperature records where there aren't any which is creative, not scientific.
And yet this 'creative, not scientific' approach produces basically the same results as everything else. Apparently, Hansen is some sort of wizard. -
jacob l at 16:06 PM on 31 May 2011Of Averages and Anomalies - Part 1B. How the Surface Temperature records are built
it is worth noting that N.C.D.C. uses Empirical Orthogonal Teleconnections to fill in areas that are not well represented,so it's not just an average of stations in a 5 by 5 grid cell, I don't mean to take way from any other points being made thanks jacob l -
tallbloke at 15:55 PM on 31 May 2011Climate Change Denial book now available!
skywatcher@71 "It's rather hard to have ice ages with low sensitivity." In Defense of Milankovitch Gerard Roe GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L24703, doi:10.1029/2006GL027817, 200 Received 9 August 2006; accepted 3 November 2006; published 21 December 2006 http://courses.washington.edu/pcc589/2009/readings/Roe.pdf -
RSVP at 15:54 PM on 31 May 2011Are you a genuine skeptic or a climate denier?
"Deniers, on the other hand, refuse to accept any evidence that conflicts with their pre-determined views." ...as is the case of AGW GHG supporters. These however, deny their denial, making for "denial squared". (If on the other hand, it seems there is more "evidence" in support of the effects of AGHG's, it is only because this line of thinking gets more airtime.) -
skywatcher at 15:53 PM on 31 May 2011Of Averages and Anomalies - Part 1B. How the Surface Temperature records are built
That's a large accusation to make without evidence there Tim Curtain, and yes you are cherry-picking, be it individual stations or individual records. The glaciers are 'cooked' as well, explains why nearly all of them are retreating...
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