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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 74201 to 74250:

  1. Ocean Heat Content And The Importance Of The Deep Ocean
    Please clarify whether the total energy in the graphs of figure 2 are observed total energy or the total energy as simulated by a model. My understanding is that what is shown is the correlation between two outputs of the model and that none of the data in Figure 2 is measured, observed data. Correct?
  2. Galactic cosmic rays: Backing the wrong horse
    12, Paul D, The first sentence says the rebuttal features his own words, not contradicts. Here are those specific words:
    "At the moment, it actually says nothing about a possible cosmic-ray effect on clouds and climate, but it's a very important first step" -- Dr. Kirkby
  3. Ocean Heat Content And The Importance Of The Deep Ocean
    Actually, average depth of the oceans is 3.8 km, not 4.3. Otherwise, a good post. In terms of the short term climate sensitivity, yes, putting heat into the ocean slows down warming but in turn means that the eventual cooling will not be fast.
    Moderator Response: [John Hartz] Source please.
  4. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Charlie A at 12:29 PM on 24 September, 2011 What's the difference between the trends in your graph, and the trend in Dana's graph?
  5. Dikran Marsupial at 23:01 PM on 24 September 2011
    Lessons from Past Climate Predictions: IPCC AR4 (update)
    Jonathon "reasonably accurate" is not a "strong conclusion" and hence is supportable by the evidence. To my eyes "reasonably accurate" means "as accurate as there is reason to suggest it should be". As I have said before, even if the model is perfect, there is no reason to expect anything more than for the observations to lie within the spread of the model runs. If the observations (considering their uncertainty) lie within the bulk of the model runs, rather than right out in the tails, then "reasonably accurate" would be an excellent summary. In order to work out whether the models are accurate, you first need an estimate of the variance that can be caused by internal climate variability. We can't get a good estimate of that as we have only one realisation of the observed climate. So the best estimate we have of climate variability is given by the spread of the model runs. If you have a better estimate, lets hear it, the models mean cannot be expected to be any closer to the observations that that.
  6. Lessons from Past Climate Predictions: IPCC AR4 (update)
    John Hartz asked: John Hartz (at 06:42 AM on 24 September, 2011) asked:
    @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?"
    The last section is very problematic to me, and seems to contain logical incompatibilities. In the space of a few sentences it states (concerning IPCC AR4 projections), that "it's difficult to evaluate the accuracy of its projections" and that the projections are "reasonably accurate thus far"..... ....and that it will take another decade before we know what the projections will say about climate sensitivity, but that their "reasonable accuracy thus far" indicates that this will provide evidence that climate sensitivity is near 3 oC. This seems a semantic and logical mess. I don't see how one can say at the same time that it's difficult to evaluate the accuracy of projections, and that they're reasonably accurate! Nor can we say at the same time that we consider that the accuracy of the projections so far (which is supposed to be difficult to evaluate) will indicate that climate sensitivity is around 3 oC, and that we won't know what the projections will say about climate sensitivity for another decade. I don't think I'm being overly obtuse (if I am I'm sure you'll say so!). I would have thought that the justifiable conclusions are that the AR4 simulations are not inconsistent with the surface temperature progression since 2000, and that they are not inconsistent with the broad consensus of evidence that the climate sensitivity is near 3 oC (plus/minus a bit). However so far comparison of the AR4 models with the surface temperature progression of the last decade doesn't really tell us anything very much at all about climate sensitivity at all. One the other hand if one were to consider the comparison of climate model projections since the late 1980's, for example, with the subsequent temperature progression, then those models and the empirical data would give us confidence that our understanding of atmospheric and ocean physics and climate sensitivity are quite well supported. Overall I have a few concerns about the perception and use of model data in an out-of-science context. In my experience models are very useful for systematising large amounts of independent physical understanding into a useable predictor (through parameterization), for testing the reliability of our parameterizations through comparison of model output with empirical data, for suggesting possible interpretations and experiments (not quite so useful in the case of climate models) and providing a focus for independent study (for example, by identifying arenas where models and empirical observations are seemingly incompatible; good examples are model success with respect to MSU tropospheric temperatures; tropospheric water vapour uncertainty). There's no question that climate models are important for projecting multi-decadal consequences of specific emission scenarios. However we should be very careful in considering the value of decadal model-empirical comparisons, when it's very well understood that we don't have any expectation that models will necessarily do a good job of this (at least with respect to tropospheric or surface temperature progression).
  7. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Michael, I agree that the data set is too short for strong conclusions. It appears that there are two beefs with Dana's conclusion that the AR4 models are reasonably accurate. First, that the time frame is too short to draw an accurate conclusion. Second, that the trend for the observational temperatures does not reflect the most recent data. Either way, the statement that the AR4 projections are reasonably accurate is not supported (nor falsified) by the recent temperatures.
  8. Lessons from Past Climate Predictions: IPCC AR4 (update)
    Paulk The next line abstract for JoC paper is important
    This is consistent with the fact that CCSM4 does not include a representation of the indirect effects of aerosols, although other factors may come into play. The CCSM4 still has significant biases, such as the mean precipitation distribution in the tropical Pacific Ocean, too much low cloud in the Arctic, and the latitudinal distributions of short-wave and long-wave cloud forcings.
    The models inability to model the cooling effects will mean the models will overestimate warming. If they didn't, it would be more worrisome for the modellers.
  9. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Dikran/John I also live in the UK. I agree that one might not perceive much in the way of temperature change in relation to our notoriously variable summers (the one just past being pretty pathetic warmth/sunshine-wise, 'though we did have a fantastic summer in March-April!). However the earlier onset of Spring is quite noticable on a personal level, and I believe that what I perceive to be an increase in extreme rainfall events is a reflection of real changes in rainfall (increased during Autumn and Winter) that are consistent with expected global changes in precipitation regimes in a warming world. Likewise at a personal level I am aware of the problems in Scotlands skiing industry over the last 25 years with Glencoe shutting down, Glenshee being put up for sale and Cairngorm being taken into public ownership and skier days plummeting in the last 20 years ('though again 2008-2009/10 were very good years snow-wise in Scotland!), and am concerned about global warming related effects on the ecology of some unique habitats e.g. the Cairngorms, etc. Obviously some of these problems are exacerbated by non-climatic factors (continued paving/cementing over of urban centres reducing soil absorption of rainwater; tendency for skiers to head for more glamerous locales). But global-warming related impacts are already occurring and will undeniably bite deeper. Whether that's going to have much of an impact on our unreliable summers is a moot point!
  10. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    @Dikran Here in the SW of the UK, we've not had a good summer for the last four years. Instead we've had a lot of rain and it's been very difficult to find a slot for bringing in the hay. Because I grow trees on a large scale, the state of the ground is very high on my radar and it's been on the whole much wetter that it was a few years ago. I accept that in some areas of the UK, say the SE, that's not been the case and certainly a farming colleague in East Anglia has been moaning about drought. As far as the winters go, since the cold spells of my childhood in the 50s and 60s, as you know, winters have on the whole been very mild. Until 2 years ago most people under, say, 40 had not experienced snow drifts that come up to your waist. Most snowfalls in the south of the country seemed to melt within a day or so. The last two winters however have shown us how cold it can get and have caught many people out as they didn't consider it normal (ask your plumber!). You'll be aware that denialist writers like Delingpole and Booker have been making hay with this in the popular press, and will probably do so again this winter. Note that overall I'm talking about perception rather than the facts. I'm well aware that, considered annually, our average temperatures have been slowly rising: but that's not what people notice -- they don't experience weather through a thermometer. In this situation convincing some people that global warming is real, based on their experiences, can be difficult in the UK -- that's why the concept of climate change, with its redistribution of weather patterns, is the idea to push in the UK. I'm sure a shift towards higher temperatures (as illustrated by the temperature 'shift' bell curve) is probably a lot easier to sell in the US and Oz.
  11. Lessons from Past Climate Predictions: IPCC AR4 (update)
    There are several posters on this thread who are making nit-picks about how data has been presented. The lead post clearly states that the data set is too short for strong conclusions. These posters are making arcane arguments that there is some problem with the graphs in the post. Can they please post a proper graph that shows the conclusions are not correct? So far the "corrected" graphs argee with the lead post's conclusions. If the changes do not affect the conclusions, why bother? If you think that you are proving doubt by questioning the baseline of a short term graph you are wrong (0.05C!! who cares). Read a book about analyizing data with a lot of noise. There is always more than one way of properly presenting data of this type. If the conclusion is not affected by the change, it is not important. Please post data that shows the conclusion is not correct.
  12. Ocean Heat Content And The Importance Of The Deep Ocean
    Rob, [indirect ad-hominem deleted] I've been trying to build in my mind a geography of climate change thought, wondering about the boarderlands of denial vs legitimate skeptcism. The business with both Lucia and Dr. Pielke Sr. sounding 'lukewarmist' was a bit of a trigger. So I see a distinction in this mental geography betweeen the statements- "We have a climate sensitivity of 3 C nearterm and this results in the rapid ice loss at the poles and greenland" and "We have a X w/m2 energy excess that will result in a Y degree GMS temperature rise and a Z rate of ice melting". I know this isn't the topic of this thread...I'm not even sure there is a thread for this...but I'm starting to wonder about the use of GMST as a singular objective function for GCMs and whether Dana is going in the right direction with his historical series on that account. I do not buy into Dr. Pielke's (apparent) view that GC models are not useful if they don't forecast nearterm regional climate change accurately, but at the same time I think ice melt, extent, precipitation, and GMST with appropriate weightings as an objective function might be more useful.
    Moderator Response: [Dikran Marsupial] Please restrict the criticism to the argument, not the source, even if the ciriticm is indirect.
  13. 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.
  14. 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.
  15. 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.
  16. 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.
  17. 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.
  18. 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.
  19. 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??
  20. 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”).
  21. 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.
  22. 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.
  23. 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?
  24. 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.
  25. 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.
  26. 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?
  27. 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.
  28. 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.
  29. 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.)
  30. 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.)
  31. 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.
  32. 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"?
  33. 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.
  34. 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?
  35. 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.
  36. 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.
  37. 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.
  38. 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?
  39. 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.
  40. 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.
  41. 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.
  42. 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?
  43. 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.
  44. 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.
  45. 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.
  46. 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.
  47. 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.
  48. 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 :-)
  49. 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.
  50. 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?

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