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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 74001 to 74050:

  1. Lessons from Past Climate Predictions: IPCC AR4 (update)
    #58 PaulK -- a minor quibble with your comment, and a further explanation of why the baseline adjustment method chosen by Dana1981 is incorrect ...... You use the abbreviation GMST. I assume this is Global Mean Surface TEMPERATURE. The datasets are not temperature, they are anomalies, or changes in temperature. We can monitor CHANGES in global average surface (actually 2 meter air) temperature much more accurately than we can monitor the actual absolute temperature. 0 degees Celsius (or Kelvin) on an AR4 model projection does not mean the temperature at which water freezes. It means "same same temperature as the average temperature from 1980-1999". Similarly, the GISS dataset is NOT temperature. It is the change, in degrees Kelvin, from the average temperature from 1951-1980. Fortunately, the GISS dataset can be converted to the same "degrees Kelvin change from the 1980-1999 average" that is used for the AR4 model anomalies. Contrary to what Dana1981 says, the choice of baseline is not arbitrary. On both this thread and the earlier thread of the same title, I have had a very limited specific goal. The desire to understand and replicate what Figure 3 purports to show. In the first thread, I was confused by Dana's claims that the 2000-2010 model mean trend was 0.12C/decade, followed by a model mean trend of 0.28C/decade. Those numbers have been corrected to the 0.18C/decade and 0.19C/decade numbers. What has not yet been resolved, at least in the main article, is the proper adjustment of two sets of temperature anomaly data series so that they have the same reference zero point.
    Moderator Response: [Dikran Marsupial] Trends are independent of the baseline, f(x) = 2x + 4 has exactly the same slope/gradient/derivative/trend (whatever you want to call it) as g(x) = 2x + 2. If the interest is in trends the baseline is irrelevant.
  2. Dikran Marsupial at 20:00 PM on 24 September 2011
    Lessons from Past Climate Predictions: IPCC AR4 (update)
    PaulK You mention "acceptable tolerance levels"; please specify what acceptable tolerance levels would be in this particular case. Note that even if the models were perfect, the observtions can only be reasonably expected to lie within the spread of the model runs, nothing more than that.
  3. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Model validation requires the demonstration that for a set of input vectors varying within credible uncertainty levels, the set of key output vectors vary within acceptable tolerance levels. Matching to a single dataset, such as GMST is a necessary but not a sufficient condition for model validity, whereas demonstrating that there is no match to a key data time series can be a sufficient condition to demonstrate the lack of validity of a model. The comparison of GMST here is disingenuous, to say the least, but suppose that Dana1981 could indeed credibly show a reasonable match of GMST between models and observations, should that convince us of the validity of the model(s)? AR4 WG1 reveals a very large shortwave heating deficit in all of the CMIP GCMs, which is compensated for by LW impedance. Until this is resolved, a comparison of GMST is like showing one face of a Rubik’s cube and claiming that the problem is solved. Model developers of CCSM have already reported on their latest model update, with focus on trying to solve the SW mismatch. The result is interesting:
    “The CCSM4 sea ice component uses much more realistic albedos than CCSM3, and for several reasons the Arctic sea ice concentration is improved in CCSM4. An ensemble of 20th century simulations produces a pretty good match to the observed September Arctic sea ice extent from 1979 to 2005. The CCSM4 ensemble mean increase in globally-averaged surface temperature between 1850 and 2005 is larger than the observed increase by about 0.4◦C.”
    Journal of Climate 2011 ; e-View doi: 10.1175/2011JCLI4083.1 http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI4083.1 What price the current comparisons of GMST?
    Moderator Response: [grypo] Thank you for that link. Fixed it too.
  4. Dikran Marsupial at 18:54 PM on 24 September 2011
    Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    John Russell, I live in the UK and am a keen cricketer and I can tell you that cool wet summers are not the "new normal". We (the team I play for) isn't loosing any more games to the weather than it used to. Summers in the UK are notoriously variable and they are little different to how they have been for the last 20 years or so. The difference is that more fuss is made of it than there used to be. Cold spells in the winter are also nothing new. IIRC the U.K. is a rather bad place to look for evidence of climate change or extremes; we are buffered to a large extent by the Atlantic ocean and our weather is changable because it depends so strongly on regional atmospheric circulation. If from the west it is wet an cool in the summer, wet an mild in the winter; if from the east it is dry and hot in the summer, dry and cold in the winter. The only new thing is there being a possible increase in weather from the north in winter, due to blocking, but the evidence for that is fairly weak AFAICS. All just IMHO of course.
  5. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    @muoncounter #15 writes: "There are new normals; get used to them." No need to be aggressive. Is that how you talk to your students (assuming that Norman is right about your profession)? That there are 'new normals' is exactly the point I was making. It's just that in some places, like the UK, our 'new normal' seems to be cool, wet summers and really cold spells in winter (-15C) -- which makes it difficult for me to convince the 'general audience' (that you say the book is aimed at) that global warming is real. You don't have to explain it to me, mate -- I get it. I know several people who I call 'on the sceptic side of don't know' who have been to SkS on my suggestion and asked a few innocent questions. Some of them (admittedly those with a tendency to the devil's advocate approach) have come away with a negative opinion about the site and therefore have been pushed further towards denial. Which makes my job harder as a climate communicator. That does not mean they've all had this experience, some have suddenly 'got it'. All questions should be answered in ways that does not belittle the genuine student. Your last line was a put down and was unnecessary.
  6. Ocean Heat Content And The Importance Of The Deep Ocean
    Lars - had a re-read of Palmer (2011). Now fixed. Thanks for the correction. A post on Meehl (2011) is forthcoming. And a more detailed breakdown of the deep ocean warming is provided in Kouketsu (2011). I'll get around to that one too - eventually.
  7. Galactic cosmic rays: Backing the wrong horse
    My reading of the first sentence implies that the SkS rebuttal contradicted Kirkbys own words. I'm assuming Kirkbys words contradicted the popular press??
  8. Ocean Heat Content And The Importance Of The Deep Ocean
    Rob: These are not climate change simulations. Palmer et al. describe control runs, with all forcings kept constant at pre-industrial values. The TOA imbalances are not specified, they are inherent in the models. They study the models internal variations on decadal time scales, and find that, as you say, heat is distributed to all depths of the ocean. There is another, even newer, study by Meehl et al. in Nature Climate Change (”Model-based evidence of deep-ocean heat uptake during surface-temperature hiatus periods”) which has the same sort of analysis, but for future-climate simulations. Meehl et al. get essentially the same result as Palmer et al., which is very interesting: Both papers shows, by different simulations, that Treberths missing heat probably is in the deep ocean (Trenberth is a coauthor of the Meehl et al. piece). One should also note that there are a number of measurements showing that the deep waters actually are warming. Purky and Johnson has a nice review (”Warming of Global Abyssal and Deep Southern Ocean Waters Between the 1990s and 2000s”).
  9. Ocean Heat Content And The Importance Of The Deep Ocean
    Dave123 @ 1 - "Isn't increased heat movement into deeper ocean layers an arrow pointing towards lower short term climate sensitivity?" IIRC Roy Spencer, and a few other skeptics, argue the opposite - because his simple model soaks up heat very quickly he claims climate sensitivity is low - the oceans having a limited capacity. Remember the oceans are the Earth's main heat sink, so that makes sense, if it were true. Spencer's model, however, is nothing like the real ocean. Bodhod @ 2 - warming of the deep ocean from volcanic activity is a natural contributor to the Thermohaline Circulation. As cold, dense, and salty water sinks around the poles and travels across the ocean floor heading towards the equator, it picks up a small amount of heat from volcanic venting. That, combined with mixing, makes the bottom water warmer and less salty and therefore more buoyant. This contributes to the rising portion of the circulation, so it a key component of the ocean's natural cycling.
  10. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    muoncounter @14 From other places you have posted I believe you are a teacher or college professor who lives in Texas. Here is an interesting link to Texas climate. Historical and Current Texas Weather Patterns. Some interesting points is that droughts have been less intense, on average after 1960. Last year and this year have been very bad for Texas but not unusual. Also in this document they have an interesting page with Texas Hurricane History. In the first graph they have hurricanes from 1950 to 2000. This is a 50 year period and the trend is up. Many may conclude that hurricanes are increasing and then link it to global warming. Then the next graph is Texas hurricanes from 1850 to 2000. Now the trend line is down. Maybe the author is trying to point out that weather trends are not that meaningful in trying to determine the future. This sample shows that 50 years has one trend, 150 years has the opposite trend. Who knows maybe 500 years and you have another postive trend and then go back 1000 and it is negative again. Also look at the rain and temperature graphs at the start of the document.
  11. Ocean Heat Content And The Importance Of The Deep Ocean
    I'd expect the Ice Sheet values and the Arctic Sea Ice to switch in order in the near future, correct?
  12. Ocean Heat Content And The Importance Of The Deep Ocean
    I didn't see it there, but no matter. It answers Bodhod's question quite neatly. A quantum of insignificance? Might use that some time.
  13. Lessons from Past Climate Predictions: IPCC AR4 (update)
    radar @53 - the UAH trend isn't zero over the past decade. Moreover, it's odd that you're willing to acknowledge the short-term cooling effects of volcanic aerosols, but don't seem to recognize the cooling effects of anthropogenic aerosol effects over the past decade.
  14. Ocean Heat Content And The Importance Of The Deep Ocean
    Adelady#3, Here's something on the question; don't know if its what you are referring to. Global (magma and lava) production rates are estimated at 3km^3 per year for mid-ocean ridge systems and 1km^3 per year for continental volcanic systems. For global impact, (mid-ocean ridge (MOR) ~80,000km long; average water depth of 2,500m) there’s enough energy in the volume of lava produced by MOR annually to raise the temperature of 8,000 km^3 of seawater by just over 0.5°C – that’s a drop in the ocean (1.3 billion cubic kilometres). New unit: 8000 / 1.3 billion = a drop in the ocean; perhaps this is a quantum of insignificance?
  15. Lessons from Past Climate Predictions: IPCC AR4 (update)
    I don't disagree that 10 years does not a model falsify, but it's not too short to raise an eyebrow. [snip] I reiterate, the point of the post is to say that the models are 'reasonably accurate'. Look at Lucia's graphs above and realize that plenty of folks understandably disagree.
    If you want to raise an eyebrow and impute falsification, one first needs to demonstrate that certain assumed model inputs have actually behaved as was assumed at the time of modelling. As others have noted, solar output has been much lower than was expected at the time of modelling for AR4. Such a result does not falsify the models. Unless, of course, one revisits the models and repeats them with the inclusion of the real-world parameters obtained subsequent to the original runnings, and gets a result that then invalidates the predictions. If there is work that shows this, I'd be most interested to see it.
  16. Lessons from Past Climate Predictions: IPCC AR4 (update)
    radar#53: Do you accept charlie's graph here? If so, how do you not agree that model is 'reasonably accurate'? I don't know what field you are in, but it doesn't get much better a fit over a short period than that.
  17. Ocean Heat Content And The Importance Of The Deep Ocean
    Dave123. Depends what you call short term. I'd wait to see what the next couple of El Ninos do in terms of heat release/ reorganisation before thinking along these lines. And the previously unpredicted speed of loss of Arctic ice might be an indicator of where some of that heat is going. BodHod. I know I saw something only a few days ago on this - and didn't save it. Presumably someone more careful than I am did save it. We just have to hope they show up soon. (Though considering how trivial the CO2 emissions are from all volcanoes compared to ghg emissions, it's pretty well a given that the heating contribution will be similarly tiny.)
  18. Lessons from Past Climate Predictions: IPCC AR4 (update)
    radar "... the point of the post is to say that the models are 'reasonably accurate'." The 'models' - plural - are demonstrably 'reasonably accurate'. The only IPCC model on which we need to withhold judgment for the time being is the most recent one. Judging on past performance, i.e. demonstrated accord with reality, most people are willing to say we'll wait for the decade or so needed before calling yay or nay on this one. (Perhaps if the previous ones had been wildly off the mark, a lot of people might say, "Uh oh. Looks like we're doing it again." But that didn't happen so there's no need to venture down a similar path.)
  19. Lessons from Past Climate Predictions: IPCC AR4 (update)
    I appreciate the feedback. What is the point of this post, if not to 'bust the myth' that the models are forecasting more temperature rise than is being observed and to state that they are 'reasonably accurate' ? I don't disagree that 10 years does not a model falsify, but it's not too short to raise an eyebrow. UAH and RSS may have problems, but we are looking at trends. How many 10 year periods of dead flat temperatures have the models shown that did not immediately follow a volcanic eruption? One might think that this would peak the curiosity of a website named "Skepticalscience". NYJ "The IPCC AR4 was only published a few years ago, and thus it's difficult to evaluate the accuracy of its projections at this point." As Dana said the models supposedly started in 2000 regardless of the publishing date of AR4 so not only a "few years", 10 in this post, 11.58 in reality. I reiterate, the point of the post is to say that the models are 'reasonably accurate'. Look at Lucia's graphs above and realize that plenty of folks understandably disagree.
  20. Lessons from Past Climate Predictions: IPCC AR4 (update)
    #49 Dana says "Charlie, thanks for your (totally subjective) opinion on what's "proper". It looks strikingly similar to Figure 3. " Ummm. I don't know why you call it "totally subjective". The model means are referenced to a 1980-1999 baseline (see the caption you posted in Figure 2, which I assume is a true copy of the IPCC figure). Doesn't it make sense to use the same baseline for both the observations and the model projection? Do you consider using the same baseline to be "totally subjective"?
  21. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Willis - the IPCC does use HadCRUT data [Albatross acknowledged the error in comment #44]. I don't think it really matters what observational data set the IPCC chose. We're not examining their observational data, we're examining their model projections.
  22. Ocean Heat Content And The Importance Of The Deep Ocean
    When considering deep ocean warming, do studies/models consider the effects of submarine volcanoes? Do we know enough about the effects of submarine volcanoes to draw meaningful conclusions about how they affect deep ocean temperature?
  23. Willis Eschenbach at 11:01 AM on 24 September 2011
    Lessons from Past Climate Predictions: IPCC AR4 (update)
    Craig Allen at 15:12 PM on 23 September, 2011 Craig claims that the reason for not doing a sensitivity test is that the IPCC used GISS data, viz:
    Lucia, The post is about the IPCC AR4 projections (as described in chapter 10.3 or the AR4 report) and their accuracy. Figure 2 is the second figure in that report. It presents GISS data up to the year 2000 and model projections from there until 2100. Had the IPCC plot used one of the other instrumental records or a different cut-off between the observational and modelled data then it would make sense for Dana to have used those. But that isn’t the case.
    Albatross agrees that the IPCC used GISS data, viz: Albatross at 15:50 PM on 23 September, 2011
    Hello Lucia,
    ..."a) Included other observational data sets like HadCrut and NOAA. (If s/he thinks they are inferior GISTemp, s/he should say why he thinks so.)"
    What Craig said @12. I think that you know as well as we do that each of the datasets has its limitations. What do you think is the best GAT analysis and why? Dana was simply being true to the original graphic that was shown.
    I find this line of argument curious. Sensitivity analyses don't depend on what the original graph does. It is an attempt to find out if the original graph is correct. In any case, I just followed the link to Chapter 10.3 of the AR4 report. I don't find Figure 2 there, as claimed above. It is located in the SPM ... but there, it says nothing about using GISS data. Nor is this helped by Figure 1, which says nothing about the data source either, only that it is based on Stott 2006b. But Stott 2006b doesn't use GISS either, it uses HadCRUT2 data ... so I fear I can't find a scrap of backup for the claim that the IPCC used GISS for either Figure 1 or Figure 2. Cite? I'm not saying they didn't use GISS, I just can't find any evidence they did use GISS ... and generally, they use HadCRUT. w.
  24. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Charlie, thanks for your (totally subjective) opinion on what's "proper". It looks strikingly similar to Figure 3.
  25. Lessons from Past Climate Predictions: IPCC AR4 (update)
    @Charlie A #46 I completely agree with Dana that for the trend-conclusion the value of the baseline is "diddly squat". It seems you ran into the same problems as I did, trying to reconstruct the Figure 3 graph. When everything is baselined to 1981-1999 you get the your graph, using some average around 2000 you get the graph from this post. When I use all the model data you can download from the IPCC site, I get the same graphs. I tried the opposite of what you did and baselined the IPCC average data or an average of all model data to 1951-1980, this results in a graph where the IPCC A2 model data are a bit lower than in your graph, e.g. the 2005 Giss value will be just a bit lower than the A2-model value. I am still figuring out why. Of course, muoncounter is right and the whole discussion is about some small insignificant value, but it will only take a little time and I will encounter an image on a Dutch denier site with a graph using a certain baseline with real T-data and where they try to convince every Dutchman that the IPCC models are completely wrong and therefore all CO2 related theories can be added to the household garbage. I want to have my answer prepared when that happens. An image like a good explanatory graph is hard to set aside. For example, the famous hockey stick graph immediately tells you what is happening, even when you didn't finish high school. In my opinion that's why there is so much resistance from the deniers regarding this hockey stick graph.
  26. SkS Responses to Pielke Sr. Questions
    @ alan_marshall #190: Excellent post. I sincerely hpoe that people will still drop by this comment thread and read it. Would you be interested in transforming it into an article for guest-posting on SkS?
  27. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Charlie A#46: "the proper apple-to-apple comparison" Nice job. It looks like the projections are less than 0.05 deg from the actual. Given the short time period represented, that's hardly a significant difference.
  28. SkS Responses to Pielke Sr. Questions
    Spin Doctor? In his second question to Sks, Dr Pielke offered two different framings of the climate change debate offered by Mike Hulme. Neither of these framings necessarily reflects Hulme’s own position. He is providing them as examples. Hulme has prepared climate scenarios and reports for the UK Government (including the UKCIP98 and UKCIP02 scenarios), the European Commission, UNEP, UNDP, WWF-International and the IPCC. He therefore knows a lot about communicating climate change science and about accommodating genuine differences of opinion between scientists. He is also aware how the message can be slanted by anyone, with or without the relevant expertise, who has a particular agenda. It will be instructive for those reading this thread to hear Mike Hulme’s own explanation of what “framing” is all about. The material which follows borrows much the profile of Hulme at ABC Carbon. Hulme defines framing as, “The deliberate way of structuring complex issues which lend greater importance to certain considerations and solutions over others”. He offers a sample of six different ways of framing climate change: 1) A market failure In this view, business emits carbon dioxide to the atmosphere for free, but there are ultimately costs associated with that waste disposal. So to ensure the market is operating efficiently, carbon dioxide emissions should be priced. 2) A technological hazard Like asbestos or nuclear waste, carbon dioxide emissions are a potentially toxic side effect of our modern technologies. This view advocates improved energy technologies to allow us to continue our modern life, but without the hazardous side-effects. 3) A global injustice Climate change when viewed through this framework is seen as a problem where the West dominates and controls the global agenda, leaving the developing world out of the picture. A solution to climate change for this world view would involve what Aubrey Meyer describes as ‘contraction and convergence’, or an equal sharing of the carbon dioxide budget between all countries, regardless of their wealth. 4) Overconsumption If our environmental impact is a function of our consumption, our population, and the technologies we use, then solving climate change through this framework would involve finding a path to a prosperous but non-growing economy, or improving contraception. 5) Mostly natural If climate change is mostly natural, then the solution in this framework is to spend money on adaptation to the new environment. 6) A planetary tipping point And finally, if climate change is viewed as leading to a planetary tipping point at which life on Earth becomes untenable, then no holds must be barred, and solutions would include massive geoengineering projects. According to Hulme, our pre-existing values, beliefs, upbringing and maybe even genes cause us to frame climate change in a certain manner. Even before the scientists have whipped out the first graph, people are already disposed to interpret the data in a particular way. In my earlier post (The Games People Play @ 43), I was perhaps a little unfair to Dr Pielke in suggesting his questions on framing were an attempt at entrapment. What I am convinced though, as Hulme so eloquently demonstrates, is that “framing” can be as much about spin as communication. The climate skeptics who have testified before the US Congress appear to be masters of spin. The purpose of spin is sometimes to give emphasis to an aspect of an issue that one believes is important, but all too often its purpose is to confuse and obfuscate. We see this endlessly in what passes for political debate in Australia. Rightly or wrongly, I get the impression that Dr Pielke is more comfortable playing with words that discussing the real implications of numbers. In Australia, there is confusion among the general public, fanned by conservative politicians and radio commentators, over man’s contribution to the CO2 in the atmosphere. Words can confuse, but accurate numbers don’t lie. For example, since the dawn of the industrial revolution, CO2 has increased from 278 to 393 ppm, numbers I expect Pielke would accept. Such numbers can’t easily be spun, and given that climate sensitivity, including short-term feedbacks, is around 3 degrees C, the implications for our future are frightening.
  29. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Dana1981 at #43 says "it's true, baselines can be manipulated for dishonest purposes, but that's not something we would permit on this site, of course. " As shown in the caption to your figure 2, the baseline for the AR4 projections is 1980-1999. You choose to compare the projections to the GISS global temperate time series. The proper thing to do is to use 1980-1999 as the baseline for both GISS and AR4 projections. It is trivial to adjust the GISS to that baseline. This is the plot of the annual data, properly baselined. When using the proper apple-to-apple comparison (and using the GISS temp series preferred by Dana) the only years where the observation exceeds the projection are 2002, 2003, and 2006. Note the difference between this and Figure 3 of this post.
  30. Ocean Heat Content And The Importance Of The Deep Ocean
    Isn't increased heat movement into deeper ocean layers an arrow pointing towards lower short term climate sensitivity?
  31. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    John R#13: "climate shift diagram is a little simplistic" Of course it is; this is a book for a general audience. But this story is entirely consistent with what some are calling 'rolling 13s' - a pair of normal dice gives 2-12; we're seeing that nature has new and different dice. Here's a cogent summary statement from Michael Tobis' analysis of the Texas drought report by John N-G: Climate characterizes the statistics of weather and the statistical bounds of weather. If we start seeing weather patterns change, that can indicate a change in climate. The question is all about how likely it is that this weather would occur if the statistical parameters of the climate were held fixed as it has been since instrumental records began, say. If weather like this is sufficiently unlikely under our previous understanding of regional climate, it may be (a piece of) evidence that the climate is itself experiencing a dislocation. There are new normals; get used to them.
  32. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Hi again Lucia, One more thing. I noticed that you neglected to answer my question: "What do you think is the best GAT analysis and why?" Just to be clear in case it was not already clear from the context, I was specifically referring to the surface temperature record. Thoughts? Thanks.
  33. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    The climate shift diagram is a little simplistic, as it shows globally-averaged temperatures. In the case of the UK, for instance, global warming is tending to change air patterns so that we've been experiencing record cold spells in the winter. This is because the change in climate, certainly over the last few years, has been tending to push Arctic air further south than historically has been the norm. I only mention this because anyone reading the book might think that increases in extreme weather will always tend to be at the warmer end of the scale and -- if they are so minded -- therefore claim that an increase in extreme cold events experienced locally proves climate change to be a hoax. So there's a danger in over simplification. We need to be careful what predictions we make.
  34. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Hello Lucia, Re my comment that "Dana was simply being true to the original graphic that was shown. You are correct. Thanks for pointing that out. The caption does indeed state that they were using HadCRUT3. But that was my mistake, not Dana's. You see, it is quite easy to admit error :) As for your lengthy defence (and obfuscation) of your other demonstrably wrong assertions, it is very unfortunate that you are not willing to concede that you erred. A double standard is evident on your part when it comes to admitting error. You demand it of others, and even go so far as to insinuate intent to mislead, but when it comes to you admitting error the hand waving starts. So be it then. Fortunately, reasonable and sensible people will see right though that. Have a lovely weekend.
  35. Galactic cosmic rays: Backing the wrong horse
    Dave123#10: "rate of formation of droplets of a given size becomes the rate limiting step, NOT the rate of nucleation..." Kirkby's language is qualified on this point: Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. --emphasis added This point was buried deep within the Nature News press release: Lockwood says that the small particles may not grow fast enough or large enough to be important in comparison with other cloud-forming processes in the atmosphere. The press release ranks as a low point in science journalism, complete with this factually incorrect description: ... bombard the chamber with protons from the same accelerator that feeds the Large Hadron Collider, the world's most powerful particle smasher. As the synthetic cosmic rays stream in, the group carefully samples the artificial atmosphere to see what effect the rays are having. CLOUD uses pions, not protons; small detail to some, but then again, this is science and we're supposed to get small details right. But all of that is entirely ignored by the pro-GCR crowd because the headlines give them what they want.
  36. Lessons from Past Climate Predictions: IPCC AR4 (update)
    John H @35 - no, I believe the conclusions remain valid and don't require any change. I think michael sweet @37 and adelady @40 did a good job illustrating why. NewYorkJ @39 also provides a very revealing quote from lucia's relevant to the discussion here. Jos - it's true, baselines can be manipulated for dishonest purposes, but that's not something we would permit on this site, of course. Thanks for the Dutch translation :-)
  37. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Another serendipity moment. CSIRO has just released results showing that wind speeds across Australia have increased by 14%. Media release And for the Antarctic, this item is on deep ocean heating but there's a lot of Antarctic info in the second half of the article.
  38. Galactic cosmic rays: Backing the wrong horse
    Coming from a chemistry perspective, I find certain concepts missing from the discussion (not yours muoncounter). There is a simplification we use called "the rate limiting step". In multi-step reactions, the slowest reaction governs the rate of the ensemble. Thus a chemist naturally asks what the rate limiting step in a droplet nucleation process is. It may not be the initial nucleus formation. Depending on conditions a droplet may form only to rapidly evaporate again, and only if a critical size is reached will the droplet be stable under the conditions. Thus the rate of formation of droplets of a given size becomes the rate limiting step, NOT the rate of nucleation by contact with aerosol particle or ionization by cosmic rays. The degree of supersaturation is important here. The next consideration is auto-catalysis. Given droplets, they can split, regrow and split again. This process can dominate ab initio droplet formation (and in crystallization processes usually does). Thus only a very low threshold rate of droplet formation is required and other process dominate after that. This kind of process could make cosmic ray triggers irrelevent. I haven't seen any summaries of cosmic ray nucleation discussing these kinds of issues, and it could be there. Is it?
  39. Lessons from Past Climate Predictions: IPCC AR4 (update)
    @dana1981 #34 I completely agree with your conclusions and this comparison which I liked very much. It's just that I wanted to reproduce your Figure 3, which took me a couple of hours to figure out the numbers. Reading your answer, my guess was approximately correct about your baseline. The baselines are not important, that's true of course, but when I visit a deniers site I regularly encounter graphs where they moved baselines just to trick people. An example is Bob Tisdale with his ocean heat content regression line as described in: http://tamino.wordpress.com/2011/05/09/favorite-denier-tricks-or-how-to-hide-the-incline/ I construct and reconstruct graphs just to learn about the relations that exists in data, besides that a strong visual image, like a explanatory graph, is a very powerful tool. Thanks for your time and regards, Jos. PS, I had to look up the meaning of "diddly squat", in Dutch this means "helemaal niks".
  40. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Radar, There are reasons to believe that both HadCRUT and UAH have issues giving enough reason for exclusion. Regarding HadCRUT I have discussed the reasons above. Regarding UAH they are discussed over at Tamino's and it isn't even measuring the same thing as the models would be predicting really and the datasets from the TLT have a strong dependency on El Nino and Volcanism... Also you shouldn't compute trends on monthly data (See RomanM's blog for this). It results in a stepwise trend change from month to month. (maybe stepwise isn't the right word). Finally Dana didn't cherry pick, based upon advice given on the options and on work he's seen he selected the dataset he felt was the most accurate at this time. Perhaps he should have been explicit about his reasoning but ultimately I could not call this a cherry-pick.
  41. Lessons from Past Climate Predictions: IPCC AR4 (update)
    radar, "What does this tell us" ...it's difficult to evaluate the accuracy of its projections at this point. We will have to wait another decade or so to determine whether the models in the AR4 projected the ensuing global warming as accurately as those in the FAR, SAR, and TAR." is the conclusion of the post. That's a very long way from "saying they are accurate". It does say that the IPCC has a good track record from earlier projections. But it does not claim that the latest projections are accurate. Yet. A decade of further observations are required for that (or its opposite).
  42. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Dana accurately says "The IPCC AR4 was only published a few years ago, and thus it's difficult to evaluate the accuracy of its projections at this point." That didn't stop Lucia. In 2008, she stated: "The current status of the falsification of the IPCC AR4 projection of 2 C/century is: Falsified." Now I don't know of she's changed her argument since then, but it's this sort of silly stuff that reduced my time spent reading her blog since then. Related to this, model mean doesn't really tell us much at the decadal level, as trends in individual model runs ("real-world" scenarios) vary wildly at that level. RC had a post on this topic some time back, showing trend distribution of 8-year and 20-year trends of model runs. On a different note, I don't quite understand why trends in temperature data products like HadCrut are compared to modeled trends of the global average as if they are a 100% apples to apples comparisons, expected to match very closely over the long run. As has been mentioned here, HadCrut neglects the Arctic. So if projections were accurate and precise, wouldn't HadCrut be expected to diverge on the cool side, with the divergence becoming larger over time?
  43. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Per Dana “Evaluating all the data is by definition not cherrypicking.” Agreed, so use multiple data sets and up to date data. Decadal Trends: 2000-Current GISS: +.121 HadCrut +.0024 UAH +.143 RSS +.004 Most Recent 10 years (to 2011.58) GISS +.0022 HadCrut -.0075 UAH +.0036 RSS -.006 Sorry I don’t have NCDC on my computer…) Models highlighted in AR4 are not performing well. The data set is too short to say ‘the models are falsified’, but to write a post saying they are accurate is gilding the lily in the extreme.
  44. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Lucia, You have made a very long post. What is your point? You seem to be raising questions about Dana's motivation for the way he graphed the data. When I look at the various graphs presented it is clear to me that not enough time has passed to make any kind of conclusion. Dana pointed this out in the post. You are splitting hairs about a graph of data that is not definative in any case. When the other data sets were added the conclusion is the same, why do you continue to complain? Minor baseline shifts do not matter to the conclusion. Dana claims the data is consistent with the IPCC conclusions, but it is a little low, the changes you recommend would lead to the same conclusion. Do you have a graph that shows that conclusion is not true? If you cannot challenge the conclusion why are you going on and on? Dana did not even point out that the solar radience is at its lowest point in 50 years which affects the data significantly. I have seen you make similar posts on other sites. Please stop whinging and add to the conversation.
  45. Lessons from Past Climate Predictions: IPCC AR4 (update)
    @All commentors: At this juncture in the comment thread, do you have any reason to believe that the conclusions stated in the final paragraph of Dana's article are incorrect? If so, why?
  46. Lessons from Past Climate Predictions: IPCC AR4 (update)
    @dana1981: At this juncture in the comment thread, do you have any reason to revise the conclusions stated in the final paragraph of your aticle?
  47. Lessons from Past Climate Predictions: IPCC AR4 (update)
    JosHag @31 - the point of this exercise was to compare the model projections to the data. The model projections began in 2000, so I adjusted the baselines accordingly. I looked at the 5-year running average for the model projections and GISTEMP, and offset the models such that they matched in 2000. I'm interested in trends, in which case as Zeke noted, baselines mean diddly squat. Charlie A - of course the post-slope adjustments made the models match the data. That was the entire point of the adjustments - to see what slope (sensitivity) would make the models match the data. I haven't done that here because as I noted in the post, there's insufficient data for a meaningful comparison. However, there has obviously been more time elapsed since the SAR, so it was a useful exercise.
  48. Galactic cosmic rays: Backing the wrong horse
    silence(7): Good point.
  49. Galactic cosmic rays: Backing the wrong horse
    silence#7: "the smaller more recent variations would have no discernible impact." Agreed. However, the basis of the GCR experiment rests on proxies for increased GCR flux during past cold events (see any of Kirkby's papers, especially Fig 2 in Cosmic rays and climate 2008). The popularizers and non-science media fixate on this unsupported mechanism with such insightful remarks as, 'Its the sun, stupid'.
  50. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Perhaps Dana used the same baseline adjustment technique he used for the FAR model comparison: "All I did was offset the SAR projection in 1990 to match the GISTEMP 5-year running average value in 1990 (approximately 0.25°C)." Lessons from Past Climate Predictions: IPCC SAR In other words, he matched the start of projections with the 5 year running average in the start year. In that comparison, he also adjusted the slope or scale factor of the projections. Not surprisingly, with after-the-fact adjustments of both slope and offset, the projections were a good match for observations.

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