When will it start cooling?

WUWT is still on my google reader list, even though I got banned from commenting for pointing out AW’s wiki-fantasies. So I get to see the rather plaintive When will it start cooling?, in which David Archibald, Solar Nut, wonders why his brilliant predictions don’t seem to match reality. But, I hear you ask, what are his brilliant predictions? [And to those who want to talk about sea ice, hang on a bit, and to those waiting with baited breath for my review of Watts, Muller et al.: have patience.]

My papers and those of Jan-Erik Solheim et al predict a significant cooling over Solar Cycle 24 relative to Solar Cycle 23. Solheim’s model predicts that Solar Cycle 24, for the northern hemisphere, will be 0.9º C cooler than Solar Cycle 23

so it sounds like DA can’t even make up his own fantasies, but is borrowing JES’s. Before you get to the “predictions” you have to wade through a pile of graphs which he waves around to hide the paucity of his thought. [[Solar cycle 23]] seems to have ended in 2008, so we’re already 3.5 years into cycle 24, and its not really looking cool yet. So for 24 to average cooler than 23, especially by as much as 0.9 oC, you need to start getting pretty creative. But fear not, because the wackos are nothing if not creative, so DA manages to convince himself that cycle 24 will be 17 years long, thereby requiring “only” that the decline from mid-2013 will be 1.2º C on average over the then remaining twelve and a half years of the cycle. This will of course not happen (anybody wanna bet?) but I’m sure they will come up with an excellent reason why not. Perhaps some mysterious atmospheric constituent will be found to have a confounding warming effect? Or they could just discover variability, but that kind of complexity seems to be beyond them.


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62 thoughts on “When will it start cooling?”

  1. Watts kills me. I grew up in Chico, CA, and that idiot couldn’t predict rain if he’d stuck his head out the window and gotten wet. And he sets himself up as the ultimate arbiter of anything to do with climate change?

    Words do not suffice.


  2. Somebody archive these various predictions from these guys that it will be cooling, any day now, because of solar this or PDO that. Archive all that, before Watts disappears the evidence.

    Come to think of it, we haven’t heard much from the PDO cranks lately – I guess we’re due.

    [Good point, I should learn to webcite these things; I’ve done that now -W]


  3. David Archibald doesn’t just borrow from other papers. he has a real go at creating a fantasy world. Here is where he has been caught out in misrepresenting his importantance. His audience of Liberal nobodies morphed into the Australian Senate and his plea to get on the Liberal ticket morphed into testimony before the Australian Senate.

    Here are the relevant links




  4. I was going to say that Archibald is one of my favourite loonies and link back to my blog but someone has already done that. Thanks “Good grief”. William, I too have been banned from WUWT butprobably because I’m a little bit too……honest in my appraisal of Anthony. He has become a favourite of mine, only because I like the sensation of facepalming.

    On Archibald, 17 years will see him at retirement age or close to it.


  5. I just understood (or so I think) how they obtained their 17 year long solar cycle.
    Cycle 22 was 8.9 year long
    Cycle 23 was 12.8 year long
    So cycle 24 will be 12.8+(12.8-8.9)=16.7 year long, since the data *clearly* shows that there is a linear increase, right ?

    This is the only explanation I could get by moving numbers around. And trying to think like a Watts poster. If I am wrong, feel free to correct me …


  6. ” before Watts disappears the evidence”

    Oddly, he rarely does that. All his posts showing how confused he was about anomalies still exist (of course, there is some evidence that he is STILL confused about anomalies, as he seems to think that comparing absolute temperatures from the CRN to the HCN makes sense).. The only time I’ve seen him disappear evidence was the box highlight in the glossy publication he and D’Aleo put together where he accused NOAA of systematically deleted stations under the auspices of the WMO that disappeared in a an updated version of the SPPI glossy.


  7. Marco : I should be the first to be worried.

    Well, as a matter of fact my brain indeed scares me if it’s able to go that slope. Too much exposure I bet.


  8. I would appreciate it if you could spell out what the acronyms mean. I’m sure they are all blindingly obvious for people following this issue blow-by-blow but it presents a significant barrier to understanding what and who you are talking about to the uninitiated.

    [Sorry. There is a glossary (https://wmconnolley.wordpress.com/2010/07/14/common-abbreviations-and-uncom/) which used to be visible from the top level. I’ll try to re-add it -W [I succeeded, but its under “blogroll” for some odd reason -W]]


  9. My admiration for Leif Svalgaard and his line in concise dry sarc in that thread is unbounded.

    I suspect he is cut more slack as one of the few ‘real’ scientists to openly engage there….

    [I think he got some credit for pointing out some errors in one of the conventional solar sunspot number series, unless I’m thinking of someone else. That made him a “heretic” for a bit, and therefore immune. But it won’t last -W]


  10. Re Leif, I have a different impression. His recent work has succeeded (AFAICT) in pretty much reducing solar influence on climate (other than the short-term cycle) to negligible. That plus his sharp response to all of the solar crazy stuff Watts posts (which BTW appears to have succeeded in cutting the post volume way down) should have made him persona non grata there by now, but he makes a point of staying in their good graces by tossing in the occasional vague snipe against the IPCC, Hansen, etc. I wasn’t sure at first, but after a while it seemed clear that the latter stuff is just a tactic to maintain his status. Why that in turn is important is a good question, and I suppose the obvious answer is that he thinks WUWT is a key nexus for propagation of solar fantasies and that his presence tamps things down.


  11. Here’s a Leif comment of the sort I referred to, noting the use of “hype.”

    Just to add I have the impression from over the years that much of Watts’ assessment of his own worth is tied up in his knowledge of computers, a field in which Leif played a key role ~40 years ago.


  12. MMM, Watts was happy to disappear the entirety of RP Sr.’s comment threads. Lots of embarrassment down the memory hole there, as William will recall.


  13. @ Steve Bloom, you’d be surprised (or maybe not) how many climate scientists make “vague snipes against the IPCC, Hansen, etc.” Usually privately, and usually in moderate language. For example there’s a fair number of folks who wonder whether IPCC may have outlived its usefulness, and even more who believe it places too many demands on those involved in it.

    Being part of the consensus doesn’t mean lockstep agreement.

    [I’ve sniped at Hansen and the IPCC -W]


  14. FWIW, I’ve found where the 17 years long solar cycle comes from : Archibald made a quick note in the comments.

    True words, no cherry picking, I’ve only taken out the mention about his new titles
    “In his announcement last year, Altrock said that the progress of the green corona emissions was 40% slower than the previous two cycles. All things being equal, that means that Solar Cycle 24 would be 40% longer than the previous two cycles, which makes it 17 years long. For all things not to be equal, it would have to either speed up or stop short of 10 degrees. Hell’s bells, from that 17 year figure, we even know the year of Solar Cycle 25 maximum, which is 2032. There is a 17 year period in the numbered solar cycles, from the maximum of Solar Cycle 4 to the maximum of Solar Cycle 5. ”

    So I was wrong. But this calculation does not look very correct, either – even though my field of knowledge does not cover the Sun …

    [You’d have thought that this allows his to “predict” the cycle 25 max would be a hint that its all wrong -W]


  15. Oh sure, AI, but my point is that Leif is doing it strategically at WUWT (and of course by no means just in regard to the IPCC).

    bratisla, in a subsequent comment Leif points out that Altrock no longer holds that view. Things change fast in solar physics, which makes it tough on people like Archibald who love clinging to memes well beyond their sell-by date.


  16. It’s amazing that they miss the irony that a whooping 1,2 ºC decline in less than 20 years would mean that climate sensitivity must be higher than a giraffe in high hells.


  17. Ah, Tony just doesn’t like being shown as wrong. In this post he cited Drudge and Infowars as reliable sources. If he had bothered reading the link to the RFP in his post, he would have seen something different. He was most displeased when I pointed this out (NB: I wrote this comment before he made the update, he put it up afterwards for some reason…)


    Watts, always a prince.


  18. To change the subject a bit, I noticed from WUWT that Benny Peiser neglected to renew his domain name so the GWPF website is suspended. Lord Lawson will not be happy. And right before Steve McIntyre speaks to that hallowed group of climate science deniers, too.

    Things have been falling apart for them all a bit lately (she writes with some glee).

    [That is rather careless of them. Are they short of money as well as sanity? -W]


  19. This so-called solar consensus is just a cover up for what the scientific MSM seeks to keep out of the home school astrophysics curriculum- the unstioppable cycle of Lunar Compton Mudulation of Galactic Higgs Bosons. reported in Volume III ( in the press) of the Report of the Non-Governmental International Panel on Climate Conferences ( NIPCC)

    Half the time , the moon, not the sun, is the brightest object in the sky, yet lunar radiative forcing is conspicuosly absent from

    […from anyone sane’s model of temperature. For the obvious reason: it isn’t important. That is bleedin’ obvious, because there is no lunar cycle in temperatures -W]

    the ‘garbage in , gospel out ‘ models subsidized by the bureaucrats of Brussells. The paypal reviewed papers they subsidize at taxpayer expense fail even to mention the role of the Higgs field in moonbeam Compton scattering of electrons in the solar wind , although the tidal modulation of the lunar light flux and solar core fractionation has been statistically apparent in intercomarison of tide guage and well-sited thermometer readings in the Bay of Fundy since the Medieval Warm period.

    Instead of looking for the possibility of escape from the reality that is revealed by observations and measurements – no matter how unexpected – the basic precepts of science require us to follow the advice Ralph Waldo Emerson would have given Willis Eschenbach::

    “Place yourself in the middle of the stream of power and wisdom which animates all whom it floats, and without effort you will find yourself impaled on your kayak paddle if you are an eskimo being pursued by a polar bear.”


  20. “from anyone sane’s model of temperature. For the obvious reason: it isn’t important. That is bleedin’ obvious, because there is no lunar cycle in temperatures”

    Err, actually there is. It’s rather tiny, as you expect. The Moon radiates more slightly after the full moon and less slightly after at the new moon.
    The temperature cycle found was somewhat larger than can be directly explained by the heating, however tidal and other effects might matter.

    [Yeah, fair enough, I knew someone would jump on that. That comes into the “but you know what I mean” category. But thanks for the link; 0.02 K seems plausible -W]


  21. I don’t like reading WUWT on principle but it was worth it in this case for Svalgaard’s comments. It’s a joy to see him correct the arrogant ignorance of some there, especially that of the insufferable tallbloke.

    I asked Svalgaard some questions at McFraudit a few years ago and found him most helpful, but there’s something that still puzzles me: he’s happy to comment at WUWT and CA despite being repeatedly shown how DK-afflicted many of the denizens are, yet he found Open Mind generated more heat than light and thought that Eli Rabett was rabid. Odd.

    [I’m sure Eli wouldn’t object to being called rabid on occasion -W]


  22. 0.9C of cooling: New Haven, New Hampshire, the contiguous US, Northern Hemisphere or global?

    I can’t figure out which. His original work referred to New Haven, with predictions for the wheat belt of the northern US/Southern central Canada. A 0.9C drop there would be about a 0.3 or 0.4C drop globally.

    I think that 0.4C is the number we are supposed to look for.

    Perhaps Archibald is wrong. But what he has done is give a solid prediction with a time frame.

    [Errm, I thought you said just above that you couldn’t figure out exactly what he was predicting? Archibald is wrong. When the time comes and obs prove him wrong, he’ll just switch over to the next wacky theory, or he’ll just be quietly ignored. In either case, he’ll have contributed nothing but noise and, perhaps, a little bit of comedy -W]

    By 2015, only 2 1/2 years from now, he is saying that we will see a significant temperature drop in the world based on his solar cycle work. He’s put his cards on the table.

    Observations trump theory. I’m still not sure what Hansen says the global temperature will be in 2015 to demonstrate the warming of CAGW.

    [CAGW tends to be a strawman phrase only used by the Watties. I can’t recall Hansen ever using it. But Hansen, certainly, isn’t dumb enough to make predictions for an individual year -W]

    So far it looks as though Scenario “C” is going to be most likely the pattern observation shows in 2015, i.e. the one in which there has been no additional CO2 since 2000. If Scenario A or B are to be the tracking Scenarios, we will have to see a considerable increase in temperatures and soon.

    50% of the climate change fans will be disappointed in 2015, by my estimate. Considering all the money and intellectual ego on the line, the next months are going to be nail-biters for a lot of people.

    [Don’t understand you. I, and I think most people, expect an IPCC-type scenario to play out -W]


  23. So, in asking “when will it start cooling”, can we point out the cooling trend since 2001 in multiple global data sets?

    [I don’t think you can, but you’re welcome to try. Don’t forget to explain why you’ve picked the meaningless “since 2001” – W]


  24. “The Moon radiates more slightly after the full moon and less slightly after at the new moon.”

    And just to wag on, the fact that the moon is positioned to REFLECT visible radiation more onto earth when its phase is full is what imparts most of the lunar cycle, though it probably radiates more in the infrared as well.


  25. Yes, I have to say that this:

    “Place yourself in the middle of the stream of power and wisdom which animates all whom it floats, and without effort you will find yourself impaled on your kayak paddle if you are an eskimo being pursued by a polar bear.”

    Was pretty damn funny!


  26. Norvegicus can rest assured that Eli, Ralph Waldo Emerson , and Miguel’s pet rat have had their rabies shots,.

    I’m not so sure about Curry & Watta, commenters, for some , as with Jack Chick tracts , approach national treasure status alongside the rhetoric of Joe Romm or the oratory of Warren Harding , that drove Menken to write :

    “It reminds me of a string of wet sponges; it reminds me of tattered washing on the line; it reminds me of stale bean soup, of college yells, of dogs barking idiotically through endless nights. It is so bad that a sort of grandeur creeps into it. It drags itself out of the dark abysm of pish, and crawls insanely up to the topmost pinnacle of posh.


  27. TrueSceptic: what sometimes scares me is that I have met similarly utterly incompetent scientists (as in actual scientists, who publish papers on a regular basis). They really are completely incapable what is wrong with their methodology.That means that those who wish to create doubt don’t even need to “buy” people or be deceiving: there will always be a few cranks.


  28. One has a duty to thoroughly survey the world’s Worser Journals before making nominations for Worst Paper Ever.

    This is no small undertaking , as some serious university library systems have upwards of 30.000 subscription journals on their shelves .

    I’m sure I’m underreporting, but the finest example I have yet espied came over the transomes circa 1980 . It was entitled as I recall ” Theory of Plate Tectonic and the Mahabarata “, and appeared in the History Journal of a certain Himalayan university .

    The author’s thesis was simple : the inability of archaeologists to locate the battlefields described in the great Sanskrit epic stems from the ( to the author) “new theory of plate tectonic”. In the learned author’s historical opinion, India is being shoved under Tibet at a rate not of millimeters , but kilometers a year , and those seeking the arrows of Krishna should evote themselves to digging holes in the high plains north of Lhasa.


  29. Russell, that’s a good one. But if we can venture into the gray lit, my all-time favorite publication is Chonosuke Okamura’s “report of the Okamura fossil laboratory”. There was a copy in the geology library of the university where I was in grad school. It’s truly hilarious (or pathetic….)


  30. I’ll explain: I am unsure of which 0.9C Archibald refers to, but it IS a prediction.

    [No, still don’t understand you. How can we verify this “prediction” if we don’t know which temperature he is referring to? -W]

    Any Scenario IS a prediction – Hansen IS making a prediction even though the endpoint is 2100. Somehow we have to get from here to there for any Scenario, including Archibald’s, to be checked.

    Regardless of your ideology, so far the temperature and sea-levels have not risen to dangerous levels as proposed for 2100.

    [Yeees. You’re saying that, as of the present day, T and SLR have not reached 2100 levels? That seems a bit bleedin’ obvious -W]

    The IPCC science says that they must rise at a minimum, sustained rate because the dominant warming factor, CO2, is an easily observed, growing component of the atmosphere. In order to get to dangerous or very damaging levels by 2100, the temperatures and sea levels MUST begin serious acceleration: even a 1 meter increase in the next 82 years is a 3 to 4 X the current rate on average. Now that – even 4.5 mm/yr is noticeable.

    [Have you read the IPCC predictions? I don’t see a 1m SLR by 2100 in there. Could you say where you’re getting your figures from? I do you the favour of presuming you’re getting them from the IPCC rather than some second-hand reporting -W]

    As for CAGW: you are right. Hansen never uses it. But let’s be serious: the alarm is all about CATASTROPHIC temperature rise. Not just the 1900 to 1975 rate. The IPCC Scenarios are all about planetary changes that are injurious to the biosphere. If there is no actual serious danger to the biosphere, then there is no problem to be dealt with. So it is disingenuous to point out that CAGW is not the term in favour. It is certainly what Al Gore talks about.

    [Al Gore doesn’t speak for me. See posts here. I would say the science is more subtle than you seem to think. Predictions are for – what? – 2-3 oC by 2100, say. Is that “catastrophic”? It depends on what effects you’re thinking about. In terms of direct SLR,its hard to see it as catastrophic. In terms of ecology – well, who can tell? I’m certainly not an expert on ecology -W]

    The rate of temperature increase from 1995 to present is not that of either Scenario A or B. I’ll grant that it could be a minor hesitation. But for CO2 to be a driver per IPCC theory, there will have to be a speed-up as as backlog of CO2 is now in the atmosphere. Rates will HAVE to increase.

    I see 2015 as a breaking year. By 2015, if the rate hasn’t changed since 2000, anyway, 15 years is a significant length of time. Jones and Trenberth thought 17 years was required. 15 is close.

    The point is that CO2 is not impeded by any significant factor according to IPCC science. The temperatures have to go up or the IPCC settled and certain science is inadequate, a contradiction in terms of settled and certain. Archibald has put his career on the line and said the temperatures will not only not go up, but go down. One up, one down. Someone is going to be wrong.

    [Does Archibald have a career? He has no reputation to lose with anyone I know -W]

    There is a huge financial and political-social load on the line. Hansen, Gore and Connelly: will you be prophets, Cassandras of the 21st? Or goats?

    [I’ll be a stoat, thanks -W]

    “Global warming” is not about global warming, it is about changing our lifestyle and industrialization style of civilization because there is some evidence that fossil-fuel derived CO2 will kill millions of people, wipe-out the coral reefs and decimate the world’s oceans.

    As I said, there is a lot riding on what the temperatures will do in the next 2 or so years. Both sides have good reason to be anxious.


  31. -cooling trend since 2001 in multiple global data sets?

    > [I don’t think you can, but you’re welcome to try. Don’t forget to explain why you’ve picked the meaningless “since 2001” – W]

    Hmmm – I guess it would only be as meaningless as the question posed in the post title

    [You’ve been challenged on your referenceless assertion. If you can’t put up – in the form of references – then your options are (a, dishonourable) to shut up, or (b, honourable) to apologise for trying to mislead people. As for calling Archibald’s question meaningless – well, you can if you like, though I thought “plaintive” more accurate -W]


  32. The IPCC science says that they [temperature and sea-levels] must rise at a minimum, sustained rate [. . .]

    Are you sure about the ‘sustained’? I don’t think you’ll find it in the IPCC reports.

    But for CO2 to be a driver per IPCC theory, there will have to be a speed-up as as backlog of CO2 is now in the atmosphere.

    And the last 50+ years of climatology will have to be seriously wrong. Where do you think they have made the errors in their physics?


  33. Doug Proctor said

    Archibald has put his career on the line and said the temperatures will not only not go up, but go down.

    This is hilarious. Nuts like Archibald have made ridiculous claims for years and have never been called on them by the pseudosceptics. How would his career be affected in the slightest either way? From http://www.auscsc.org.au/about_us.html

    David Archibald is a Perth, Australia-based scientist operating in the fields of cancer research, oil exploration and climate science. After graduating in science at Queensland University in 1979, Mr Archibald worked in oil exploration in Sydney and then joined the financial industry as a stock analyst. Mr Archibald has been CEO of multiple oil and mineral exploration companies operating in Australia.


  34. “-cooling trend since 2001 in multiple global data sets”

    “You’ve been challenged on your referenceless assertion. ”

    I’m sorry, I thought you looked at data and knew these things already.

    [Why would I know about the short-term variability in all these series? I was just guessing; the long-term trends are all positive, as we all know -W]

    The data are all online.

    Linear fits of MSU-MT, RSS-LT, NCDC, NCDC sea surface, are all negative since 2001.

    You can see them here:


    Or use that wood for bonfires thingy.

    Or even do it yourself.

    [Much better, thank you. I didn’t bother look at them all (your link doesn’t work for me, and woodfortrees doesn’t provide NCDC or MSU-MT (I’m not sure what you mean by that one anyway)) . HadCRU4 is positive from 2001, as is GISTEMP, as is BEST; according to woodfortrees. Also I notice that the only one of yours I can easily check, RSS lower trop, is positive from 2000 (http://woodfortrees.org/plot/rss/from:2000/plot/rss/from:2000/trend). So even there you’re back to your original problem: trying to explain why 2001 is such an interesting year for you. Lots of people – Tamino most obviously – have pointed out why cherry-picking a year makes no scientific sense. So why are you doing it? -W]


  35. I think MT is middle-troposphere, known to still have a significant stratopheric influence. On WFT UAH LT gives a positive trend. In fact, only RSS is negative from 2001 onwards.

    [I guessed Middle Trop. But I didn’t understand why it was called “MSU-MT”. Given that UAH and RSS usually disagree (but perhaps only over the LT?), I’d expect it to be called either RSS-MT or UAH-MT. I think you’re right about the strat signal, though -W]

    I also looked at the NCDC data, and found a positive slope, but it did not include the 2012 data. But chosing 2001 is obvious: El Nino year, without getting accused of using the super El Nino of 1998.


  36. The title of the post – when will it start cooling? – can be answered by 2001.

    Such a time period is not a thirty year trend but has persisted to date during a period in which the IPCC proclaimed a .2C per decade warming.

    It is also coincident with the solar slowdown.

    This is the past of course and what happens is of keen interest.

    But an answer to when will it start cooling, based on observation, is 2001.

    [Its a very silly answer; essentially trolling. But if you’re happy with it, I don’t think there is anything I can do to help you -W]


  37. Jan: Why did you not say that cooling obviously started in 1980? After all, the temperature drop from 1980 to 1988 was greater than that from 2001 to 2011. Short periods of apparent decline are normal with noisy data, even when there is a general rising trend. That is why it is important to both understand and use basic statistics, and why you will never see a denialist attempt to determine if recent years deviate significantly from the long-term trend.


  38. Richard, the trend since 2001 is the current one. It’s nearly twelve years old now. I do understand that it could easily change. I also understand the variance of the temperature record. But the twelve years is the twelve years.


  39. Richard, the trend since 2001 is the current one. It’s nearly twelve years old now. I do understand that it could easily change. I also understand the variance of the temperature record. But the twelve years is the twelve years.

    People like Jan Morten keep slot machine manufacturers in business …


  40. “Richard, the trend since 2001 is the current one.”

    Why? Why isn’t the one from 2000 better? It is after all longer. Why not from the beginning of 2006? From then we’ve had over a .1C of warming according to UAH, and all of the indices are positive. The only justification for having your trend start in 2001 is you like the results. There’s no statistically valid reason for calling it “the current” trend.

    Just to clarify, *none* of the above trends is long enough to make the claim that the warming has stopped, let alone that cooling has started. It simply can’t be done. We are of course also leaving out the warming that has continued in the oceans, the melting ice around the world, and other signs that the Earth is still in an energy imbalance where it is taking in more energy than it is emitting back out into space.


  41. “From then [2006] … all of the indices are positive”

    You will find cooling trends since 2006 as well.

    Look – I’m not discounting AGW theory – the 30+ year trend is warming. And it’s likely to resume. But it’s also silly to discount the cooling simply because ‘you gotta believe’. When the cooling trend was only five years, this very blog said – ‘Look at all the five year cooling trends one can find through out.’ And that’s right.

    Then the trend grew to ten years.

    Now it is at twelve years. One must go a lot further back in the record to find another twelve year cooling trend.

    A better question to ask may be ‘When will it STOP cooling?’


  42. “Jan Morten, the nearly 12 years starts in an El Nino and ends with two La Nina’s”

    Yes, I’m aware of that, and examining the records, 2001 starts from above long term trends and ends below long term trends.

    So when are you predicting the cooling trend will end?


  43. “Look – I’m not discounting AGW theory – the 30+ year trend is warming. And it’s likely to resume.”

    You haven’t shown it ended, let alone that cooling has started. Your cherry-picked time frame is not long enough to say that lower tropospheric temps are not still warming.

    ” But it’s also silly to discount the cooling simply because ‘you gotta believe’.”

    We aren’t; we’re discounting it because we understand basic statistics.

    “Then the trend grew to ten years.

    Now it is at twelve years.”

    UAH, GISS, and HADCRUT4 show a positive trend from 2001 to the present. Which data sets are you talking about?

    “A better question to ask may be ‘When will it STOP cooling?’”

    Moot since it hasn’t started.


  44. Jan Morten

    The WMO recommend 30 years as the ‘classic period’ from which to infer climate trends from continuous temperature data.

    The linear trend over a rolling 30 year period in every major global temperature data set we have is +0.16 C/decade (+/- 0.01C): http://www.woodfortrees.org/plot/wti/from:1982.58/plot/wti/from:1982.58/trend

    This also fits well with the 0.14 – 0.18 C/decade value arrived at by Foster & Rahmstorf (2011): http://iopscience.iop.org/1748-9326/6/4/044022

    Incidentally, if you calculate a rolling 30 year temperature *average* (use any global data set, but the longer the better) and graph the results, you get a pretty startling image. It is an image in which 2001 “cooling” is not apparent.

    Trends are not always the best indicator of real world temperatures.


  45. Jan Morten is a hoot: “The current trend is the one starting in 2001”.

    It used to be 1998 with these [incivility deleted. Yes, I know I’m inconsistent -W].


  46. The key point to know if a calculated trend is actually a “trend” is to look at the error on the calculation. Look at how robust the result is when you vary the start and end dates. Tamino has done good posts about this. I’ll leave the google-fu to others. But a hint — if starting at 2001 gives you a negative slope, and starting at 2000 gives you a positive slope — that is not a robust result.


  47. This (hat tip to Metafilter) is a good read:


    (click past the adults-only blogger warning page)

    “… It is more interesting to reporters to cover climate-change deniers calling their opponents socialist traitors who want everyone to freeze in the dark as part of an elitist conspiracy, and green activists declaring that the skeptics are, every single one of them, stooges of the oil companies – more interesting because the reporter gets livelier quotes and more screams of outrage (while expending less effort on understanding what anyone is saying). Certainly it is easier and more entertaining than covering the complicated problem that if we are to detect serious climate change in time to do anything effective and affordable about it, we have to process some really cruddy just-barely-significant data, that the cruddiness and borderline detectability of the data

    [No, this is nonsense. That covering a good fight is more exciting -well, more immeadiate, at least – than trying to understand science is true enough. That the signal is borderline detectable is rubbish. You could with some justification write taht 10 years ago; not now -W]

    is probably intrinsic to the problem, and that it can be solved but not easily, and is apt to lead to harder choices than most people have thought about. There’s a really interesting intersection of science, statistics, politics, and economics here, in which scattered people of good will are trying to figure out what’s going on and sizable numbers of people have pre-committed to answers with inadequate evidence rather than asking how much we can know how soon and whether it will be enough. But interesting though the real argument is, it makes shitty television next to people accusing each other.

    Now, you may recall that I started off with snark, and here we are at comparative enthymemics, and you may be wondering if I’ll ever end, and indeed I am wondering that myself, but here goes at a conclusion:

    Snark is a dishonest reduction expressed with knowningness.

    In real, true snark, the teeth-gritting irritating behavior that its practitioners so pride themselves on , the accusation of self-interest, psychological acting out, sock-puppetry, or justifying one’s vices is made by adopting a knowing pose and not speaking it. Whatever the target is, whether it’s awe-inspiring or charming, insightful and difficult or light and merry, the snarkist simply poses as the person who always already knows that it is “really” an evil scam, a symptom of mental illness, or a mark of being duped or intimidated, and need not explain how.

    Snark is the universal solvent of cultural conversation….”


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