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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 72251 to 72300:

  1. Dikran Marsupial at 19:47 PM on 16 October 2011
    Continued Lower Atmosphere Warming
    Ger The models are dynamical systems, forcings can be applied to them to simulate both the transient and equilibrium responses. For example of analysis of transient response, IIRC there were several papers on modelling the transient response to the Pinatubo eruption. However discussions of the workings of the models are clearly off-topic for this thread, as they are not involved in assessing whether there has been a statistically significant change in the observed trends. So please take the discussion to a more appropriate thread, such as "the models are unreliable".
  2. Continued Lower Atmosphere Warming
    #57, Spaerica, did glance over the document, and yes most if not all are equilibrium models on which perturbation is applied to find out how well behaved those are. Equilibrium sensitivity etcetera. But is cloud forming, mainly shape etc. governed by a equilibrium model? Is the change of coastal areas and changing flow patterns governed by an equilibrium model? Are volcano eruptions, earthquakes etc governed by some equilibrium model? One can consider all those as governing conditions to be input to an equilibrium model, but those boundary conditions are rather unpredictable. Clouds, coastal lines etc can be modelled into by chaotic models perhaps. No idea if that will obey normal statistics. Volcanoes etc. are related with radio-active decay so one can assume those will follow a Poison distribution.So to say: any one can pick a starting date, before or after a large change in one of these parameters and "proof" or "disprove" a statement based on the statistics of an equilibrium model. One can have endless debates on the time period to chose whether not to include, exclude those singularities.
  3. Ocean Heat Poised To Come Back And Haunt Us?
    Muon - "No one suggests warming is monotonic" Except for a great many skeptics you mean. Statistical significance is a whole lot less intuitive to a public audience, than is examining why we have these hiatus periods. No matter, let's just say we disagree and leave it at that. There are a whole bunch of climate scientists who have looked at this hiatus period, and have papers awaiting publication. So I'll be writing more about it in the future.
  4. Ocean Heat Poised To Come Back And Haunt Us?
    Rob P, No one suggests warming is monotonic without making gross oversimplifications. But as many have said, its a noisy dataset; analysis of short period variation is a messy business at best.
  5. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    You are absolutely kidding me, Norman. You're saying that one city does not show a trend, therefore we can't be sure there's a trend. Peterson08 analysed thousands of stations across North America, the overall trend in temperature and precipitation extremes is very clear, as shown by their conclusions. That you continue to try and dismiss a published quantitative analysis of extremes at thousands of stations by discussing a single station is utterly ridiculous.
  6. Ocean Heat Poised To Come Back And Haunt Us?
    Muon - I see little point in pretending a short-term hiatus doesn't exist, just because the long-term (and statistically significant) trend is one of warming. Why pretend warming is monotonic?
  7. keithpickering at 15:01 PM on 16 October 2011
    Correction to the True Cost of Coal Power - MMN11
    The important point is that even using the most conservative estimates, the price of coal is artificially low by a factor of ~2. Correcting this imbalance via a pigovian tax would put renewables on a level playing field.
  8. Ocean Heat Poised To Come Back And Haunt Us?
    Rob P#14: "why the climate varies on short timescales, the up-and-down wiggles" Didn't we just finish wrangling over how those wiggles weren't statistically significant? And take a well-known researcher to task for statements such as "The lower tropospheric global annual average temperature trend (TLT) from 2002 until now cannot distinguished from a zero trend." ...and the trends during this time period are different than the trends earlier in the time period."? Why now are we making very similar sounding statements? "we may currently be in one of these decade-long hiatus periods."
  9. Ocean Heat Poised To Come Back And Haunt Us?
    Barry @10 - I'm working my way through a few papers. This one mght be of interest to you, given your questions: The passive and active nature of ocean heat uptake in idealized climate change experiments - Xie & Vallis (2011) Jsquared @11 - Yes. Plot the data and let us know what you find. Also see Sutton & Roemmich (2011). From the abstract: "Key Points: -The southern ocean dominates decadal global heat content change -Steric contributions below 1500 m are significant and increase towards the south -Simple spatial averaging of WOCE data does not resolve decadal signals" I have copy of the full paper, but I can't remember where I got it from - so can't provide a link. From Peru @13 - you're not the first "warmist" to get hung up on that. I am not referring to long-term trends - yes, we know the Earth is warming, but short-term periods of little or no warming are clearly evident in the observational record. We are looking at why the climate varies on short timescales, the up-and-down wiggles, rather than following a monotonic (straight line) trend. Interesting that the NINO 3.4 index, that you link to, shows a La Nina-like trend since about 2005 (not that this wasn't obvious).
  10. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Normna, this has now been going on since comment 15. We're up to 225. 85 of those are yours... more than 30%. They all say the exact same thing, over and over. "Look, look, I found another extreme weather event. Here's another anecdote! Another headline! Another thingy." You have littered this thread with 85 comments pointing out that there has been extreme weather in the past, and so without any other metric than squinting one eye and saying "looks the same to me" you are trying to argue that nothing is wrong, nothing to see, everyone please move along. After 85 of 225 comments it has become very tiresome.
  11. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Norman, is that seriously the best you can come up with? That there were some prior events considered 'extreme' is not news to you, me, James Powell or anyone else. Additionally, cherry-picked news articles can hardly be considered credible enough to faithfully place weather events into their proper climatological context (usually kinda turns the readers off...). I'm sure the newspapers from Russia, Pakistan or other places would have been suitably apocalyptic in their prognosis of the relevant extreme events! What is more interesting is when data is placed into a climatological context, such as Peterson et al, or many other papers including Rosenzweig (outdated with regard to recent extremes by virtue of being published in 2001, but hardly supporting your case anyway). By the way, in Peterson et al fig 16, the smoothed line is most likely a moving average or other smoothing function so that you can see the trend over the noise. Is that the worst criticism you have of that paper, seriously? I'll echo michael sweet's request at #223.
  12. Visual depictions of Sea Level Rise
    adelady, thank you ... I'll have to think about the explanation.
  13. Ocean Heat Poised To Come Back And Haunt Us?
    Ummm, this paper shows how a hiatus in global warming can be totally consistent to climate models... ...but I seriously doubt that the 2000s were a hiatus decade, because: 1)Temperatures do not flattened: 2) As is evident in this NINO 3.4 timeseries, ENSO was either neutral or moderate El Niño for most of past decade. The only significant La Niñas were in 2007-2008 and 2010-2011. This is consistent with the previous graph, that shows continuing warming except for a small hiatus in 2008-2009. Certainly a 2-year cooling or flattening is not a warming hiatus decade, is just a minor yearly fluctuaction. The warming pattern is different that the pattern of figure 4: Showing strong warming in the Arctic, unlike figure 4, that shows strong cooling. So is an interesting article, but it could explain some possible warming hiatus decade in the future, not in the present.
  14. Ocean Heat Poised To Come Back And Haunt Us?
    Re #1. Roughly decadal or perhaps roughly 11 years? http://www.woodfortrees.org/plot/sidc-ssn/from:1960 It is perhaps coincidence that the period where this whole haitus thingy starts (~2002) happens to be around the maximum of solar cycle 23, since which we've seen a significant drop to the solar minimum of 2009.
  15. Correction to the True Cost of Coal Power - MMN11
    Not. all. economists, Michael.
  16. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Norman, Your list includes many newspaper headlines. I recall last fall when deniers trumpeted a headline stating England was having the coldest winter in 350 years. It did not pan out that way. Dr. Masters has researched his list and when he says it was the worst flood in Pakistan in 500 years that is believable. The newspaper headlines you quote are not vetted and not believable. Please provide a peer reviewed list of disasters. I will note that last year there were 19 countries with all time highest temperatures and none with all time lows. How does that list count for extreme weather? Top that, if you can.
  17. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Norman#219: Nice article you've cited: Human activities are causing the augmentation of the natural atmospheric greenhouse effect. Future climate models (which should not be accepted uncritically) predict that anthropogenic forcing will bring about changes in the magnitude and frequency of all key components and natural cycles of the climate system. Climate change will gradually (and, at some point, maybe even abruptly) affect regional and global food production. Warming temperatures and a greater incidence and intensity of extreme weather events may lead to significant reductions in crop yields. --emphasis added Given that this was in 2001, perhaps those projections are coming home to roost. Oops, that was a short compilation of news events.
  18. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Daniel Bailey @220 I am not actually allied to the c3 website and I do not agree with their thoughts on Skeptical Science. I like this web site and it contains a vast amount of useful information. I like the strict moderation to keep things on topic. I just saw the list of items on this page and clicked on several to see they were newpaper items. I do not know how else one can determine extreme weather events since they do not always leave evidence that can be analyzed later. I do not want to disappoint and will steer clear of c3 or other type blogs for gathering evidence of the point I am trying to make. That weather may not be getting more extreme as the globe warms.
  19. Ocean Heat Poised To Come Back And Haunt Us?
    Rob Painting @#6 The NODC datasets for ocean heat content to 700m and to 2000m are divided up into contributions for the northern and southern hemispheres. They are at ftp://ftp.nodc.noaa.gov/pub/data.nodc/woa/DATA_ANALYSIS/3M_HEAT_CONTENT/DATA/basin/yearly/h22-w0-2000m.dat and h22-w0-700m.dat. Shouldn't they also show that the heating of the deep ocean is more pronounced in the southern hemisphere? I haven't plotted those data, and I don't have any feeling for what the coverage of the measurement grid is in the lower southern ocean.
  20. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    To tack onto muoncounter's able comment above: I would not trust any information from a site such as c3 (given its history) in any fashion, to the point of even checking what the time of day was compared to that shown on the website. No compilation of news events, no matter how lengthy, should be relied upon with any form of scientific accuracy. There is simply no context to base any kind of assessment. It is simply a cacophony of anecdotal events in tabular form, listed with the presumption by the reader that it is not only complete but accurate as well. At best, one may consider it interesting in the same sense that one finds supermarket tabloids interesting. Honestly, it is difficult to even know how to respond to you Norman, without it sounding cross. You continually cherry-pick, use anecdotal references interchangeably with scientific ones and preferentially cite denialist websites preferentially over scientific ones. This latest site you ally yourself with has this post:
    "SkepticalScience.com: The 'SS' Global Warming Propaganda & Lie Machine Exposed - Fundamentally Evil"
    Seriously? Since you, by extension/virtue of your reliance upon c3, maintain that Skeptical Science is "Fundamentally Evil", then why are you here? I, for one, no longer believe your protestations of 'just looking for the truth' (paraphrased). It can no longer be construed as innocent mistake your predilection for frequenting & citing such websites as c3. Indeed, I am personally quite offended by this most recent tack you have taken. It was a mis-step; you have over-played your hand. And I am very disappointed.
  21. Correction to the True Cost of Coal Power - MMN11
    It is amazing how economists wil devalue the lives of our children (and ourselves if you are less that 60).
  22. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Daniel Bailey, Here is a link to a peer-reviewed article that shows similar patterns to the c3 website. Look at Table 1 of the link. Severe droughts and severe floods from 1977 to 1998. Many samples of such events taking place. It does not seem to be as alarming as James Powell feels it is. Peer Reviewed article with list of weather extremes.
  23. Ocean Heat Poised To Come Back And Haunt Us?
    I am still curious about the physical systems that draw warmth down to the depths. As per my question a couple of weeks ago, how, when the physical processes are so little known, are we able to ascertain mixing rates in order to determine, for example, that oceanic thermal lag takes about 30 - 40 years to reach equilibrium with changes in forcing (Equilibrium Climate Sensitivity)? Also, I read about the 30 - 40 year lag, but also that ocean turnover takes 100s of years - and that these are not to be confused. But it is confusing. Why is the centennial turnover rate not a factor in ECS, and how does one make these distinctions when the physical processes of vertical mixing are so little understood? (At least, I have not found much in the literature or elsewhere that suggests we know more than a little about where and how vertical mixing takes place. I have enquired before, but no luck with recommendations so far)
  24. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Okay, so in spite of my better judgement, I clicked a few of these - and there was good old Steve G, Prince of CherryPickerville. Including the infamous picture of USS Skate, supposedly at the 'ice-free' North Pole. That's the problem with a 'source' like C3: there is no vetting of the material cited, which leaves those gullible enough to take it on face value thinking, 'wow, that's a lot of information - must mean something.' We've had another player - friend PT - who operated the same way. It's also a Faux News tactic - 'people are saying that global warming is ... ', when the 'people' saying those things are the Faux News on-air talking heads. Repeat it often enough and it must be true, no? In addition, Norman: please note that many of these headlines are reports of disaster - bridge collapse, 400 dead, etc. You've specifically disputed the use of disaster counts as meaningful - yet here they are being used by you.
  25. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    [ response to deleted snipped ] The topic of this Thread is "Extreme weather and Climate Change". Finding a large sample of past extreme weather events that compare to those in James Powell's ebook should not be considered off-topic or extraneous. It is what the topic is about. The topic is Global Warming causing climate to shift in such a way that more extreme weather will be the result. If it can be clearly demonstrated that extreme weather events are not exceptional for these last few years (by showing large lists of past extreme weather events that are very similar to the ones brought up today), then that would seem a valid position to consider.
  26. Models are unreliable
    DB, I appreciate your response. In fact, I have already pointed out the fact that anomalies rather than absolute temperatures are used for the reasons stated by NOAA. My problem was that I was not sufficiently confident of my facts regarding the models to say for certain that the raw data output does not appear in the form of absolute temperature. It certainly wouldn't make sense for it to do so given that the global temperature datasets are presented as anomalies, but I wanted to check up first. Thanks, Paul
    Response:

    [DB] Apologies; I didn't mean to imply that you hadn't.  My intent was to provide you with a sourced, concise reference.  Sphaerica gives some good links to resources on models here.

  27. Ocean Heat Poised To Come Back And Haunt Us?
    Karamanski - without going into technical detail - think of how heat is lost by the human body when you sweat, the evaporation of moisture takes heat with it, cooling the skin. In much the same way, the same thing occurs over the surface of the Earth. Consider how much cooler local temperatures are in tropical forests (with lots of moisture) compared to dry regions of the world at similar latitudes. I'll track down some papers for you - if you're genuinely interested (I do remember a very recent one about forests and water recycling cooling the Earth surface). As for the PDO, AFAIK I don't think an actual mechanism has been discovered. So whether it can be responsible for anything is moot.
  28. Ocean Heat Poised To Come Back And Haunt Us?
    Karamanski, I assumed (anyone can correct me if I'm wrong) that it is a result of increased evapotranspiration/Latent heat. The added water on land gets less energy put into heat/temperature, because it goes instead into evaporating at least some of the additional water (which requires a substantial amount of energy -- 600 times more to evaporate water than to raise it 1˚C).
  29. Ocean Heat Poised To Come Back And Haunt Us?
    It doesn't make any sense how more rain over land would cool global surface temperatures during La Nina and how less rainfall over land would warm global surface temperatures during El Nino. I was also wondering what cycle governs when hiatus periods occur. Is it the Pacific Decadal Oscillation, or increased frequency of La Ninas?
  30. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Daniel Bailey @214, I would hope that linking this sight does not undermine my credibility. Someone took the time (which would be a daunting task to compile) and gathered newpaper clippings of extreme weather events in the past. If one ignores the opinion of the author of the sight and concentrates only on the actual data (Newpaper clippings from around the world on extreme weather events) you get a historical perspective on severe weather events in number, intensity, and time frame. If you would insert Jeff Masters 2010-2011 weather compilation into this long list would it still stand out as something not seen since 1816? When looking at the whole globe, it would appear that somewhere they are experiencing extreme weather quite often. Look at some of the headlines in the long list of extreme event. Here is a sample: "1976: Worst Drought In England And Wales For 500 Years" "1951: Mississippi River Reaches Highest Level For 107 Years" "1951: 100 Degree Heatwave Lasts For 7 Weeks In Texas" "1952: Scientist Says Both Polar Ice Caps Melting At Alarming Rate" "1977: Worst Drought In California History - Year 2" "1977: Antarctica Iceberg Is 45 Miles Long & 25 Miles Wide"
  31. Models are unreliable
    With reference to my post above, I've now been given a link to the article it is apparently based on. It's from lucia at The Blackboard Has anyone come across this before?
  32. Ocean Heat Poised To Come Back And Haunt Us?
    Critical Mass - See Sutton & Roemmich (2011). Based on the observations, they indicate that most of the ocean warming is occurring below about 35°S. Not so co-incidentally the model used by Meehl (2011) indicates that is where most of the heat uptake to the deep oceans is occurring too, although I don't mention that in the post.
  33. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    213, Norman, Wow. That's just amazing. You (and your source) have proven that there have been extreme weather events prior to the advent of AGW, therefore AGW must not be affecting extreme weather events. Well done! Fantastic! Well, I'll certainly sleep easier tonight.
  34. Ocean Heat Poised To Come Back And Haunt Us?
    FundME - For the warm-coloured regions (in figure 4) - think of what happens when you pull the plug from the bathtub - you get this rotating mass of water as it disappears down the plughole. Those warm-coloured regions are gyres - rotating masses of water, and these are affected by wind speed. Increase wind speed and more heat is driven down into the deep. It's whole lot more complex than that of course, but that's the broad picture. Remember too, that the cool water brought to the surface during La Nina or La Nina-like periods, allows it to be warmed by the sun (that's how the ocean are warmed). So that surface layer, even though it is causing cooler global surface temperatures, is steadily gaining heat. These two processes are operating at the same time. Is that any clearer?
  35. Ocean Heat Poised To Come Back And Haunt Us?
    Joshag - Nice work there. I've not seen any observation-based studies which look at this issue, so I'll see if I can get a reply from some of the experts working on this. It does seem to support the decadal trends seen in the climate model though.
  36. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Norman, why is it in your desire to prosecute your agenda (and it is patently obvious you have one) you first frequent the denialist and dissembling websites for ammunition rather than relying upon the science and the scientific method themselves? A hint: The words "Gore 'Lie-A-Thon' " on the top of your linked source should have been a tipoff of bias. And a very typical page at c3. Reliance upon this type of "source" undermines your credibility severely.
  37. Models are unreliable
    A blogger has just posted an objection to climate models that I haven't come across before. Hopefully someone here knows more about it than me. The claim is that: "By concentrating on anomalies they (scientists) hide the fact that the models get the absolute global temperatures wrong by as much as 2C." I was under the impression that temperature anomalies are used because they correlate well over large distances, whereas absolute temperature doesn't. This sounds like the type of argument that McKitrick and Essex might have used. Any ideas, anyone? Thanks, Paul
    Response:

    [DB] "By concentrating on anomalies they (scientists) hide the fact that the models get the absolute global temperatures wrong by as much as 2C."

    The key word in your quote is "hide".  Your blogger is operating under the premise that there is a conspiracy, therefore ____________ is true.  This is a blatant obfuscation, easily proven wrong.

    From the NOAA page:

    1. Why use temperature anomalies (departure from average) and not absolute temperature measurements?

      Absolute estimates of global average surface temperature are difficult to compile for several reasons. Some regions have few temperature measurement stations (e.g., the Sahara Desert) and interpolation must be made over large, data-sparse regions. In mountainous areas, most observations come from the inhabited valleys, so the effect of elevation on a region’s average temperature must be considered as well. For example, a summer month over an area may be cooler than average, both at a mountain top and in a nearby valley, but the absolute temperatures will be quite different at the two locations. The use of anomalies in this case will show that temperatures for both locations were below average.

      Using reference values computed on smaller [more local] scales over the same time period establishes a baseline from which anomalies are calculated. This effectively normalizes the data so they can be compared and combined to more accurately represent temperature patterns with respect to what is normal for different places within a region.

      For these reasons, large-area summaries incorporate anomalies, not the temperature itself. Anomalies more accurately describe climate variability over larger areas than absolute temperatures do, and they give a frame of reference that allows more meaningful comparisons between locations and more accurate calculations of temperature trends.

    NASA has a nice synopsis on models, here.

  38. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    michael sweet @212 It appears someone has already compiled a list of what I have been looking for. This person took extreme weather events from the 1950's, 60's and 70's and put them on a list. I will link you to this webpage and you can see what you make of it. List of some extreme weather events.
  39. Philippe Chantreau at 06:38 AM on 16 October 2011
    Continued Lower Atmosphere Warming
    Of course muon, that's the way it will inevitably be represented by some. There is nothing anyone can do about that. The attentive reader who wants to know will notice that Dr P in fact showed nothing. Sure he showed that there is no warming "trend" since 2002 but also readily acknowledged this was meaningless because no trend, or lack thereof, can be establish over that time period. Then when asked by why he would devote so much attention to a meaningless trend, he was rather evasive. I must say I found that whole exchange rather surprising considering Dr P's background. We had countless occurrences on this site of people arguing about meaningless short term "trends", I recall there were threads devoted to the explanations of why short term says really nothing. I do not remember any respectable scientist with a deep understanding of noisy time series making that same argument.
  40. Visual depictions of Sea Level Rise
    shibui Try this one.
  41. Visual depictions of Sea Level Rise
    According to Steven Goddard at Real Science, the Envisat data is showing a drop in sea levels.Does anybody have any information on this?
  42. Continued Lower Atmosphere Warming
    DM#60: "it is not unreasonable to expect the same from the skeptics" There are 'skeptic' circles with a far shallower understanding of the foundations of this bridge. I'll go out on a limb and make a devil's advocate speculation: In those circles, this exchange will be played as 'Dr. P showed that warming really did stop and they couldn't show that to be false.' Of course, the other hypothesis could be that there will be universal acceptance within the 'skeptic' world that it cannot be proven that warming stopped. Anyone care to give odds on which hypothesis will win out?
  43. Continued Lower Atmosphere Warming
    Dikran, that was a great explanation of power!
  44. Ocean Heat Poised To Come Back And Haunt Us?
    Rob Painting might care to comment on this quotation by Berenyi Peter on a prior thread. It poses an interesting theory about how the overturning is mechanicaly driven: Quote: (-Very long quotation snipped-). unquote I believe the forties and fifties south latitudes are not well measured and therefore the extnt of heat sequestration or loss to space is largely unknown.
    Response:

    [DB] Please provide a link plus an explanation of why it is relevant to this thread.  Long quotations are considered poor etiquette and are frowned upon.  Thanks!

  45. Dikran Marsupial at 01:47 AM on 16 October 2011
    Continued Lower Atmosphere Warming
    Here is another way in which Prof. Pielke could demonstrate that the post-2002 trend is interesting, rather than just a likely artifact from looking at a noisy time series over too short a timespan. Rather than basing the argument on the failure to reject a null hypothesis, he could instead reframe it so that he was arguing for an alternative hypothesis, for instance H1: The rate of warming has diminished since 2002 And then see if he could reject the null hypothesis H0: The rate of warming has remained constant throughout He is then back in the normal statistical hypothesis testing setting, where he has to show that the observed trend is inconsistent with H0. This is straightforward, if you detrend the data, assumung a constant linear trend over the entire time series, H0 can be rejected if the residual trend from 2002-present is statistically negative. Now if we are going to talk about bridge-building, then I would say that I have built my side well over half way. I have listened to Prof. Pielkes argument, but I have seen what I consider to be a fatal flaw. I have pointed out this flaw, and remained patient and civil when my criticism has been repeatedly ignored (which is a rather disprepectful thing to do). I have now explained why the criticism in some detail to show why it is important, and even suggested two ways in which Prof. Pielke could strengthen his argument to the point where I would accept it. The latter certainly goes well beyond duty; the onus was always on Prof. Pielke to test his hypothesis before publicising it, as he himself said. I am deinitely in favour of building bridges with the skeptics, but if the the foundations of the bridge have to be built on the tacit acceptance of scientific arguments that are clearly fundamentally flawed, then the bridge is unlikely to stand for long, even if it can be completed. I doubt any of us here at SkS expect skeptics to accept any argument just because we think it is obvious, and it is not unreasonable to expect the same from the skeptics (a term I view as high praise rather than perjorative).
  46. Eric (skeptic) at 00:21 AM on 16 October 2011
    Continued Lower Atmosphere Warming
    It seems to me that a good way to determine the significance of a trend in a particular portion of a time series is to perform an analysis on the entire length of the series based on an assumed model. The model will prescribe the length of the series needed. The model is based on theories of various phenomena in the physical system being studied, in this case the atmospheric temperatures and their strong dependence on ocean-atmosphere heat exchange in quasi-cycles, in particular ENSO. When the entire time series is analyzed based on the model, the analysis produces an explanation of the variance in the series which can then be used to determine the statistical significance of a trend in a portion of the series. Here's an example: http://www.atmos.berkeley.edu/~jchiang/Class/Fall08/Geog249/Week13/gv91.pdf
  47. Ocean Heat Poised To Come Back And Haunt Us?
    # Heat buried in the deep ocean remains there for hundreds to thousands of years. It is not involved in the heat exchange occurring in shallower layers. # The ocean, as a whole, is still steadily building up heat, so the next warm phase of this natural cycle may drive global temperatures to new record highs (the ocean heat coming back to haunt us). I am having difficulty reconciling the two statements litsted above. Also when you say # The deep ocean warms during these hiatus decades because heat builds up in mid-latitude regions and is quickly funneled downwards. Do you mean the mechanism can be imagined as a giant funnel whereby the warm water is gathered over a large area at the mouth of the funnel and is somehow compressed downward towards the spigot by which it is transported to depth? I see it as some sort of giant hypodermic syringe by which the warm water is injected to depth. Am I right in these assumptions or is there some other mechanism at play.
  48. Dikran Marsupial at 23:41 PM on 15 October 2011
    Continued Lower Atmosphere Warming
    So how could Prof. Pielke estimate the statistical power of the test? There are many ways you could go about this, but this would be my recipe: According to Tamino, temperature time series are well approximated by a linear trend with ARMA(1,1) noise process. The first step would be to detrend the data and estimate the parameters of the ARMA(1,1) noise process (see this article by Tamino and this one). I can then simulate as many synthetic temperature times series as I like, with the expected effect size under the alternative hypothesis (warming has continued at a constant rate throughout the UAH dataset), by adding ARMA(1,1) noise to a linear trend of (IIRC) 0.138 degrees per decade. Next I generate a large number of these, where we know by construction that the null hypothesis is false, and see how often we get a statistically significant trend from 2002-2011. The proportion of trials where we can reject the (false) null hypothesis (zero trend) is an estimate of the statistical power of the test. I very much doubt it will be 0.8 or above, which is the traditional threshold for useful statistical power. Note we should test the significance of the trend assuming ARMA noise, not white noise. We know the data are correlated, so the confidence interval for the OLS trend will be optimistically narrow, which biases the test. This would be my approach, and if Prof. Pielke could demonstrate useful power by an estimate of that nature, then I would be convinced that the "flat trend since 2002" was of genuine scientific interest, rather than just the a random artifact from looking at a noisy signal over too short a period. Unlike me, Tamino is a genuine expert in time series analysis, so he may have a better test, or be able to pick holes in my recipe, I would of course take any critcisim seriously. The ball is in Prof. Pielke's court; if he wants to convince us that the post-2002 trend is interesting, I have set out what he needs to do. If he wants to concede the point and move on, then that also is fine.
  49. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Joe Romm reports on extreme flooding in Thailand this month and last. It is by far the most expensive flood in Thai history and has resulted in 10% of their rice farms destruction. They are (were?) the largest rice exporter in the world. They often get heavy rain during La Nina, but the current Nina is fairly weak. Joe links to Jeff Masters blog about this flood. Do you eat much rice? The price will rise this year. Maybe this is just another coincidence and the weather has not responded to AGW, or maybe we are looking at the future.
  50. Every Picture Tells A Story
    Since we're talking about pictures telling a story, watch this on the BBC homepage (and apologies if someone already posted it): http://www.bbc.co.uk/news/world-south-asia-15216875 Melting in the Himalayas captured in photographs.

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