…Keep out of the kitchen

It appears that Ian Wishart is back on the climate beat, with a couple of posts in the last week attacking Hot Topic. One goes so far as to accuse me of incompetence and dishonesty, which is a bit rich coming from someone who was threatening to sue me for libel a few months ago… Anyway, his latest offering attempts to chastise me for stating in a comment that global temperatures were not falling. That gives me a welcome opportunity to post on the subject and introduce a nifty little gadget programmed by a Hot Topic reader. Here’s Wishart:

Virtually all the major datasets are now acknowledging atmospheric warming has slowed to a crawl or stopped over the past ten years, and even some leading climate alarmists scientists are publicly suggesting we’ve entered a climate shift and may not see warming return for a further decade or more. The data clearly shows temperature anomalies trending down despite CO2 emissions rising:

He appends a graph of UAH monthly temperature anomalies from 2002 to some point earlier this year, with a descending trend line. Lo and behold, “cooling”!

Over seven years, this data set suggests that global temperatures are falling. The problem, however, is that climate is not measured over seven year periods, and there’s a very good reason why. The climate system is ‘noisy’ — natural variations in the ocean/atmosphere system such as the El Niño Southern Oscillation or volcanic eruptions mean that global temperatures go up and down a fair bit, so if you want to know about any underlying trends you have to look at a period of time long enough for the ‘ups’ and ‘downs’ to cancel out. That’s usually taken to be 30 years — the World Meteorological Association’s standard period for defining climate statistics.

Now for the nifty gadget. Hot Topic reader Colin Sharples (aka CTG) is a whizz with Java programming. Prompted by a discussion on climate trends at ReaClimate, he took NASA’s GISS global temperature dataset (to be precise, it’s the GISTEMP series for the climatological year (Dec-Nov) and he’s estimated a figure for 2009 by completing the year by calculating the average anomalies for the last few months of the year over the last five years) and the Hadley Centre’s HadCRUTv3 series and produced an interactive graphic that shows how changing the length of the period you select for trend calculations affects the trends you see. Here it is:

The slider at the bottom starts at 30 years — the standard period for climate stats. Choose between data series with the button at the top. Blue lines show negative trends, red ones positive trends, calculated for each successive 30 year period. In the GISTEMP series you can see some falling trends in the 1880s and 90s, and again from the 1940s to 70s. The rest of the time, temperatures are rising. No sign of cooling in the 21st century.

Now try moving the slider to 20 years. There’s a bit more blue in the early years, but things look pretty similar to the 30 year trends. At 15 years, a couple of brief ‘warmings’ appear in the previously cooling sections, but the most notable feature is that some of the trend lines become a lot steeper — there is faster warming and cooling appearing in the graph. With the slider at 10 years, not only do the trend slopes become even steeper (look at the ‘warming’ in the 1890s!), but bits of spurious warming and cooling appear. There are a couple of blue lines in the late 1980s to mid-90s, the first episodes of ‘cooling’ to show up over the last 40 years, but still no cooling to be seen in the last ten years. You have to wind the slider back to a seven year period before you get a cooling trend line in the 21st century. Just the one. And there’s still only one if you stick the slider at the minimum period of five years.

If you look at the big picture, using such a short period means that the trends oscillate up and down as global temperatures move and up and down. They’re reflecting the noise in the system, not the underlying trend — and when we’re discussing global warming we’re interested in the long term trend, not the ups and downs. Woodfortrees also provides a clear demonstration of the dangers of playing with short term trends here, using the UAH satellite temperature data.

That’s the central fallacy of Wishart’s assertion that warming has “stopped or slowed to a crawl” despite CO2 continuing to rise. It’s a claim you can only make by choosing very short timescales, and ignores the fact that the change we’re interested in emerges over periods of decades, not year to year.

The rest of Wishart’s long post is tortuous and unclear. He appears to be arguing that because one paper has found that aerosols and dust have an impact on the rate of ocean warming in the North Atlantic that this somehow downplays the effect of greenhouse gas forced warming. He says, for instance, that ocean warming is “mainly solar driven depending on atmospheric clarity”. But all warming is “solar driven” — that’s where the heat’s coming from. Dust, aerosols and greenhouse gases change the rate at which it’s absorbed by the system. And by the way, the last time I looked at a map, the North Atlantic was only a small part of the global ocean, and can’t be said to be typical of the whole.

Even his conclusion is muddled:

Get real, Truffle. The atmospheric temperature anomaly is trending down, the oceans are not displaying significant signs of heating, and some of your cheerleaders are admitting it’s not so hot right now. I’m sure warming will return, but this is good evidence of strong natural cycles at play.

So warming’s going to return because it will overcome those strong natural cycles? Sounds reasonable. Perhaps Wishart’s been following the monthly temperature figures at NOAA, which has August 2009 as the warmest in the record, and September as the second warmest. Looks like the warming’s already back. Because, of course, it never went away.

My thanks to Colin for allowing me to embed his GISTEMP Java applet. It may also appear in other places and in enhanced form in due course, but remember where you saw it first… 😉

95 thoughts on “…Keep out of the kitchen”

  1. You attack a straw-man Gareth. IW never said we have had a cooling trend, he said warming had stopped, there is an important difference,

    “Virtually all the major datasets are now acknowledging atmospheric warming has slowed to a crawl or stopped over the past ten years”

    While you are right that we can not say the climate is in a cooling phase after 8 years, we can not say we are defiantly still in a warming phase either. The direction of the climate is currently unclear.

    1. You just don’t get it, do you?

      We most certainly can say that we are still in a warming phase. The shortest trend which expresses only long-term variance is 20 years (following Bob Grumbine’s analysis).

      Put the slider at 20 years. All of the most recent 20-year trends are strongly positive, therefore we are still warming.

      1. Does your toy allow for ‘flat’ phases? i.e. the climate from 1000AD-1850AD in Mann’s Hockey Stick? (the climate before ‘climate change’)

        Jokes aside, what I am saying is that, although the temperatures warmed in the 90’s, given that temperatures have been flat to declining for 8 years, we may be entering a period of cooling, or flat temperature. This is not what is predicted by AGW so I understand it is impossible for a religious fanatic like yourself to accept. I accept it is too early too say this for certain yet because climate trends naturally have noise. But it becomes increasingly more likely with every year of non-warming. Wait and see I guess.

        Anyway this is what IW was saying, not that we are defiantly in a long cooling phase.

        1. All of the climate models predict inter-annual variability, and periods of 10 or more years of cooling trends within an overall warming trend are absolutely predicted by AGW theory.

          The point of my toy is to show that it is meaningless to pick two points on the graph, draw a line between them and say “there is a cooling trend”.

          An 8 year trend – warming or cooling – just has no meaning in the temperature data. The only trends you can draw conclusions from are 20 years or longer.

          By continuing to insist that “temperatures have been flat to declining for 8 years”, all you show is that you have absolutely no interest in or understanding of the science behind AGW.

            1. “So, if 8 out the 10 hottest years have happened this decade, the world is cooling?”

              By what measure? Hottest since when?

              Also: 6 of the coolest months of the year happened in the last 7 months, is New Zealand warming or cooling? What you have said has no relevance in looking at trends!

          1. It is meaningless? I accept it does not prove a climate shift but it is not meaningless.

            Look at stock market commentators at the moment. The stock market has been rising. Commentators say that it is unclear if it is a temporary recovery or the begening of a sustained recovery, but they do not say it is meaningless.

            I, and I think IW, are saying the same thing.

            The current 8 years of cooling, along with other factors, may be a blip or it may be that we are heading into a cooling phase. That is all he and I have said. The longer it goes the less likely it is a blip.

            While it does not dis-prove AGW, a balanced analysis would not claim 8 years of no global warming does anything to enhance the arguments of the IPCC and disprove the arguments of the NIPCC.

            I also point out that your toy does not allow for trends that do not have a statistically significant rising or falling trend.

            You will no doubt create another straw man from this comment, burn it, and claim some sort of victory.

            1. “I also point out that your toy does not allow for trends that do not have a statistically significant rising or falling trend.”

              The points in a time series are not independent. You cannot simply take, say 8 points from the time series, do a regression and decide whether that trend is or is not significant. Because that subset is part of the overall series, the start and end points depend on the points that come before and after them. Any one individual point on the series actually has a low probability of being exactly on the longer trend line – the “true” value for any one year is best represented by an average of that year plus several years either side of it.

              This is why short trends in these data are spurious – they are too sensitive to short term fluctuations about the long term trend. Take a year that is above the local average (e.g. 1998) as your start point, take a year that is below the local average (e.g 2008) as your end point, and voilà! You have a negative trend. This does not tell you anything about the long-term trend, which as you can see is still positive.

              This is basic statistics. Actually, it’s moderately complicated statistics, but the point is, there are rules in statistics that tell you how you can analyse things like time series, and you cannot decide to ignore those rules just because you want the data to show what you want. By claiming that there is a significant 8 year trend in the data, you are breaking the rules of time series analysis.

              I don’t know about you, but I think that whatever we do about climate change has to be based on science, and the science says that warming is still happening.

  2. Thanks for a great educational tool, Colin and Gareth.

    It comes as no surprise that the reality-challenged Wishart appears not to know the difference between weather and climate, or heat and temperature.

    Dorthe Dahl Jensen, the head of the Greenland ice core programme, spoke at At Te Papa a couple of weeks ago and gave the latest GRACE gravimetric results: 170 gigatonnes of ice lost from Greenland per year, 150 Gt/yr from Antartica.

    (Here’s a clue, Ian – heating ice at 0 C melts it to water at the same temperature).

  3. Very nice work CTG – far easier to use than woodfortrees.
    Adding the UAH lower trop temps would be good for completeness.
    Thanks for bringing this to us Gareth.

  4. …and even some leading climate alarmists scientists are publicly suggesting we’ve entered a climate shift and may not see warming return for a further decade or more.


    …and some of your cheerleaders are admitting it’s not so hot right now.

    I’m assuming he’s referring to Mojib Latif, who’s words on annual and decadel trends have been distorted a fair bit.

  5. I’m amazed that the politically-motivated idiot Wishart can get any traction on this. R2D2, time you demonstrated you are at least smarter than Dewhurst, otherwise you would be better off playing in his sandpit.

  6. R2D2 – if you think AGW is incompatible with recent temperature record, then please study this.
    Not a publication but I cant fault the stats. Can you?
    You could also actually LOOK at what AGW models predict instead of the strawman. No model EVER predicted monotonic warming. Every natural cycle is still working. Keelyside, Latif et al predict a decade of slow warming followed by very rapid warming, though in fairness other modellers dont agree. All would say that models have poor skill over short time frames. They are climate not weather models.

    1. You guys always attack things I didnt actually say. Its quite frustrating and time consuming to respond to.

      What I said was; “we may be entering a period of cooling, or flat temperature. This is not what is predicted by AGW ”

      To my knowledge global warming theory predicts warming. I understand 8 years of cooling does not prove it wrong (because nothing can prove AGW wrong). But I say that a prolonged cooling phase (ie acceleration of the last 8 years) is not predicted.

      1. But R2, there hasn’t been 8 years of cooling. Look at the frikking graph!

        The last 8 points on the graph are all warmer than every year before them – with the sole exception of 1998. On what planet can that possibly be called cooling?

        Yes, if there was a prolonged cooling phase – which in the context of the temperature record would need to be at least 15 years of temperatures actually getting cooler (rather than your kind of cooling where the temperatures keep getting warmer) – then that would be a problem for AGW theory.

        But as we haven’t seen anything remotely close to that, there is no problem with the theory.

        So why do you keep endlessly repeating that there has been “8 years of cooling” when there has in fact been no such thing?

  7. Wish I could see that widget! I’m using firefox via Ubuntu with javascript and java both enabled.

    However I have seen many graphs illustrating the same point and actually observed a denialist, who happened to post a 30 year graph with a line drawn across the top few years, end up acknowledging reluctantly that the same kind of ‘flat’ line could be drawn a couple of times earlier. Later he got in the gun for posting an animated graph intended to prove there was no global warming in the arctic since the late 50s. The data points were extracted from the graph and replotted to exhibit the global warming signature. There was a little more, but after years of battle he has vanished. I do hope he has been rethinking his beliefs but maybe he just gave us up as a bad job.


  8. Great device CTG, congratulations. It’s the sort of user friendly, interactive tool that you could easily (I confess to not being a programmer at this point) make predictive of issues the public may respond well (at least better than “temperature anomoly”) to (in an a-political manner no doubt), like sea-level, drought, tropical cyclones etc.
    The data’s presumably out there and there’s nothing like seeing your holiday home disappear under water at 412 ppm CO2 to focus the mind.

  9. BTW on the subject of the libel claim, Wishart blathers;

    SamV, you’ll have pleasure in knowing you form part of the evidence by which Hot Topic will be tested. Wouldn’t it be a terrible ignominy if something you said on his site formed part of the legal noose? To paraphrase Gareth, “Patience”.

    I’ve been quivering in my boots all week…

  10. “To my knowledge global warming theory predicts warming. I understand 8 years of cooling does not prove it wrong (because nothing can prove AGW wrong). But I say that a prolonged cooling phase (ie acceleration of the last 8 years) is not predicted.”

    Instead of saying “I say” why not look up the facts? That Tamino analysis for one thing gives idea of what kind pattern to expect from the internal variability. Take a look at Keelingside et al and see what the one of the models is predicting. All of it outputs from the physics with CO2 assumed to be increasing. This is not a matter of opinion.

  11. R2, you need statistics 101 to understand this stuff. It’s worth the time it takes. It changes how you see the world. People evolved to detect patterns (“… look at that …”). There is zero cost to detecting a tiger in the bushes when it’s just shadows and light — climb a tree needlessly, at worst. You have no ancestors who failed to detect a tiger in the bushes (those who failed just once got eaten). Your ancestors were _really_good_ at seeing tigers in the bushes. Often enough they were wrong. That didn’t hurt them.

    Now, look at a climate graph, or a market graph.
    You see patterns.

    You’re _bound_ to see patterns. You’re a pattern detection genius.

    Even when they aren’t there.

    This worked for us for a hundred thousand years or so.

    Now, it’s a problem. Statistics is the answer to knowing how likely it is that there’s really something there, or just shadows we imagine.

  12. Huh?
    “But I say that a prolonged cooling phase (ie acceleration of the last 8 years) is not predicted.”
    I read that as meaning that you claim that an 8 year “cooling” phase is not predicted. I respond by saying -wrong – look at what is predicted instead of what you think is predicted.

  13. Gareth, this is my first post here. Thank you for a well-designed and informative website. Thanks especially for hosting Colin Sharples’ graphic, which I think is terrific. As someone who analyses time-series data (ecology) for a living, might I offer one suggestion?

    Colour-coding the trend lines as passing or failing a test of statistical significance (e.g., regression lines as blue, red and grey at say, alpha=0.05) would really help to drive home your fundamental message that short time-series (i.e., small samples) can’t tell us much. That would require a lot of additional work I know…but this is a very important message that needs broader public dissemination.

    Best wishes from a Canadian who inhabits the same planet you do.
    — Andrew

  14. Colin, if you are choose to follow Wanderer2’s advice, remember that temperature data has a high degree of autocorrelation. You need take this into account when calculating significance.

    1. Yes, I know. I did consider doing that, but given that the whole point of the tool is to demonstrate that linear regression is a poor way to analyse the temperature data, I felt it would probably just muddy the waters.

      I changed it so that it would show red lines for r^2 > 0.50 and blue for < 0.50, just to get a feel for what would show up. Shorter trends (5-8yrs) tend to explain more variance than medium length (20-30yrs) trends. There are those who would misinterpret this as saying that shorter trends are therefore more valid than longer trends – to which you would then have to point out that the shorter trends are more prone to autocorrelation.

      Also, in the 20-30 yr range, it is the warming trends that tend to explain more variance than cooling trends, which no doubt would then lead to accusations that I had fudged it to only show warming.

      So in all, I felt it best to leave out any comment on the significance of the individual trends. It is more the overall pattern of trends that matters. If you get one negative trend in amongst 20 positive trends, then it doesn't mean that temperatures really are going down.

      If you really want to test statistical significance in the temperature data, there are other tests that would be more appropriate.

  15. R2D2 – also your comment that “nothing can prove AGW wrong”. Well I think that there are key predictions, any of which would cause me to reexamine the science if violated.
    1/ an upward trend in temperatures over 30 year period.
    2/ arctic (but not antarctic) amplification
    3/ stratospheric cooling and tropospheric warming. (whereas say solar influences would warm/cool both).

    The process is same as for all science. You feed your measurements from real world (TSI, aerosols, GHG, albedo, etc) into your physics model, read out predictions, compare to reality. But these are models of climate not weather.

  16. You warmists just don’t get it, do you? It is not enough just to point out the ~0.13 deg C/ decade rise we’ve seen since the ’50s. This is closer to zero than your catastrophist predictions which require +0.4 deg C/decade. More and more of the world’s eceonomically-hurting people are concluding that this moderate, not unprecedented and mainly beneficial warming is not a crisis that requires trillions to be taken out of there pockets (or even 5c for a plastic bag- GO PEOPLE POWER!!)
    Catastrophe cancelled.

  17. Steve – heard of feedback? Loss of artic ice = more black water and release of methane hydrates etc etc. You propose do nothing till things are so bad that you can achieve so little. The models are warning us about the future for our grandchildren if we dont take action now. And you get your “facts” on “beneficial warming” from where? Its the rate of change that we are worried about. Loss of land and disruption to hydrological cycle. To compare economic cost/benefit you need a realistic assessment of effects – something completely missing from analyses that favour doing nothing. Try Stern report instead of Lomborg.

    Oh and what have plastic bags got to do with it?? Environmentalists are down on plastic bags largely because the issues with plastic in the marine environment. Please dont confuse climate scientists with Greenpeace.

  18. #29. Scaddenp is absolutely correct about the need to consider autocorrelation when analyzing temperature (or any other time-series) data. Thank you. Another statistical no-no inherent in my initial comment (#28) would be the cumulative bias created by repeated linear regression tests using subsets of the same initial raw data.

    But I assume Colin Sharples’ intent was not to write a formal scientific paper — his point was to illustrate that short time-series in a noisy system can provide highly misleading results. Seldom have I seen an interactive graphic that so vividly shows this fact. Bravo.

    — Andrew

    1. Why thank you. Credit also goes to John Mashey, who suggested the slider, and Bob Grumbine, whose trend analysis prompted the discussion in the first place.

      My background is also in ecology – my M.Sc. thesis was a time series analysis of something you are probably familiar with – the 11-year cycle of the snowshoe hare and lynx :-) I used the wonderful Hudson’s Bay Company fur trapping records, which go back to about 1680. That’s what I call a data series!

      Sadly, despite what some people believe, I found that commerce pays better than science, so I’m now a Java programmer. I don’t think I’ll be submitting this as a formal paper any time soon :-(

      1. I am familiar with the lynx-hare cycles and the extensive Hudson’s Bay records. My specialty is endangered species and the demographics of same.

        I’m saddened to learn that that you have no plans to pursue scientific publication — that’s too bad because, in my opinion, you communicate the issues very well.

        — Andrew

  19. Scaddenp: “Steve – heard of feedback?”

    Yes, and 3.8 billion years of life support shows that Earth’s climate is dominated by negative feedback (like 99% of natural systems).

    “Loss of artic ice = more black water and release of methane hydrates”

    Your hypothesis fails the test: The noughties, the “hottest decade on record, has seen global methane concentrations statistically indistinguishable from flatlining.

    ” The models are warning us about the future for our grandchildren if we dont take action now. ”

    And they shake their little tush on the catwalk.

    “And you get your “facts” on “beneficial warming” from where? ”

    Longer growing seasons, CO2 fertilisation, and if warmer isn’t better for health, why are the oldies more likely to move from Milwaukee to Miami, or Timaru to Tauranga, rather than the reverse?

    “Oh and what have plastic bags got to do with it??”

    People are getting sick to the back teeth of green nannying. I’d be afraid if I were you guys. All moral panics have a shelf life. The warmist one probably won’t survive another 10 years of non-warming, despite Mojib Latif’s attempt at pre-emptive spin.

    1. Read Axford’s paper on 200,000 years’ worth of sediment cores from an Arctic Canadian lake – unprecedented warming since 1950, all in a timespan when the area should be cooling.

      Meanwhile, take your ignorant denialist views and shove them somewhere dark.

  20. Look more closely. Past rapid climate change goes with species extinctions. Geological processes fortunately remove CO2 from atmosphere – very slowly. Over those times spans the suns output has increased. Chucking millions of years of CO2 accumulation back into the atmosphere isnt a good idea.

    On methane. Notice it rising again? And notice that it is now that we getting methane release in the arctic. For a better perspective, try

    Again – its not whether warmer is better – it about the rate of change. Our civilization and agricultural patterns are based on different climate.

    You imply Latif fiddled his models to produce cooling for PR purposes? That would be libel. Science is an open process – you can check that this isnt true.

    I am worried that people confuse global warming with green nagging. If you base your assessment of science on attitudes like that then we really are doomed. I’ve looked what it costs to go fossil fuel free in NZ and frankly it doesnt seem too hard nor too expensive to me.

  21. RW, Nowhere does the University of Colorado press release mention unprecedented warming. They refer to biological and chemical changes which are proxies, but by definition smear out decadal changes over 200,000 years.

    Typical warmist modus operandi: Make alarmist claims that are not supported by the evidence you claim.

    1. Let’s not take Wrathall at his word, shall we..?

      From the press release:

      ‘The past few decades have been unique in the past 200,000 years in terms of the changes we see in the biology and chemistry recorded in the cores,’ said lead study author Yarrow Axford of CU-Boulder’s Institute of Arctic and Alpine Research. ‘We see clear evidence for warming in one of the most remote places on Earth at a time when the Arctic should be cooling because of natural processes.’

      The full quote is a little more illuminating than SW’s careful selection, is it not?

  22. Tonight’s chuckle: Wishart grandstanding on statistics in an update to his original post:

    This is the sort of slipperiness we’ve all come to expect from Hot Topic. We all know what the 30 year record shows, and the more informed of us know that the 80s and 90s marked a warming period on the back of an earlier cooler period. However, we also know, those of us with experience in statistics, that trends are built on raw data, and that the longer the current deceleration of warming lasts, the higher the warming will have to be in the latter years of the 30 year cycle in order to maintain the trend average.

    The truth is, warming has slowed dramatically over the past decade, despite rising CO2. The models did not predict this, and appealing to the 30 year trend does not disprove or “debunk” the reality of what is currently happening.

    Anyone care to count the number ways in which he is wrong? 😉

  23. Exactly. Exactly which 30 year period does he want to choose to show ‘cooling’?
    The ‘trend’ seems to be that when you’re in a corner you simply dismiss the data.

  24. So, Steve Wrathall, what’s your excuse?
    Did you, perhaps, not read the press release before citing it?

    Typical denialist modus operandi: make false claims and hope no-one bothers to check your “evidence”…

  25. RW claims “unprecedented warming since 1950, “. Your press release does not say that. You read it.

    In fact they cannot even claim the past 50 year’s chemical and biological features are “unprecedented” in the last 200 000 years. To do that would require several measurements within EACH 50 years period-for the past 200 millenia : over 10 000 measurements. Measurements apparently vary from every few centuries to every few millenia.

  26. So, Steve, you are now trying to create an argument over semantics – is that because you’ve run out of fake references?

    Q: Are you a smoker?

    If not, why not – could it be the weight of scientific evidence has convinced you that the likelihood of health problems is not worth the risk?

    Now, can you connect the dots?

  27. Congratulations on not smoking, Steve!
    Now, do you know the difference between heat and temperature?
    Clue: look in one of the student textbooks in your chemistry lab…

  28. I had an interesting exchange at Wishart’s site. He claimed my applet was pointless because it was using GISTEMP – “garbage in, garbage out” were his words. He claimed that only UAH and RSS are reliable – rather convenient for his cause, because he can then claim that the temperature record before 1979 is whatever he wants it to be.

    I responded with a graph showing that UAH and RSS both show warming of comparable magnitude to GISTEMP and HadCRUT over the satellite era.

    He replied by saying that the trends look similar, but the magnitude of the warming is different. I couldn’t work out what he meant at first. Looking at that graph, I calculate those trends as showing warming over the 30 years of:
    GISTEMP: 0.49°C
    HadCRUT: 0.47°C
    UAH: 0.39°C
    RSS: 0.47°C

    So UAH is a bit lower, but RSS is almost identical to the non-satellite series. What could he mean? Then it clicked – Wishart thinks that because GISTEMP and HadCRUT are higher up on the graph, they are talking about higher absolute temperatures. I pointed out that this is not the case because the different series use different baselines. His response shows that he clearly does not understand this concept:

    If you go back to your own gadget and compare the HadCRUT plot with the GISTEMP, you’ll see GISS plotting significantly above the average for most of the 20th century, while Hadley plots below it for the same period.

    What he means is this. Shock horror – this must mean that GISTEMP consistently overestimates temperatures, right?

    Well, no. The baseline for GISTEMP is the average from 1951 to 1980, whereas the HadCRUT baseline uses 1961-1990, so the baseline figure for HadCRUT is about 0.09°C warmer than GISTEMP’s baseline. So although HadCRUT spends a lot more time below its average than GISTEMP does, you have to realise – as Wishart apparently does not – that they are different averages.

    If you want to compare GISTEMP and HadCRUT on the same graph, you need to offset the GISTEMP figures so that they refer to the same baseline, like this. Now it is clear that although the two records are not identical (why would they be?), there is definitely no systematic over-estimation in the GISTEMP record as Wishart suggests.

    I didn’t apply the offsets in my original diagram of the trends, as I thought it was clearer without. Here is what it looks like with both GISTEMP and HadCRUT adjusted to the baseline used by the satellite records. In this case, GISTEMP is adjusted down by 0.24°C and HadCRUT by 0.15°C (how these numbers are derived is quite clearly explained in the Notes section of WoodForTrees).

    Finally, plotting the full series, rather than just the trends, for the four series shows that they are in quite remarkable agreement. If the satellite records are indeed reliable as Wishart claims, then GISTEMP and HadCRUT must be equally reliable, because they all show the same thing: rapid warming.

    It’s quite extraordinary that this has to be pointed out to Wishart.

  29. GISTEMP and Hadcrut use different method for estimating temperatures in areas of poor coverage (eg arctic). GISTEMP estimates from local stations; Hadcrut effectively fills gaps with global mean.

    Sat temperatures have their own special set of problems – eg the ongoing problems of reconciling differences in way corrections are made between RSS and UAH. Lots of users forget that its mid-troposphere not surface. Both have to deal with problem of looking through a cooling stratosphere. Lots of science on this of course but seldom looked at by deniers. Maybe they wonder why Christy (dissenter and at UAH) doesnt make the same claims they do.

  30. SW How many stations did you look at before you chose Clyde? Why not all the Baffin Island stations? Are you really trying to say that the arctic isnt warming or just looking for a snark?

  31. Scaddenp you and I are on the same page. Sadly to admit, as a professional conservation biologist I sadly remain an elderly cigarette addict to this day. After 25-plus years in the field at many mountain/arctic stations I visited since 1979…

    …my own personal addiction might make a small difference in terms of scientific understanding exhibited in the media. The sillyness is seldom understood until one smokes too muchBut it might help to save a species in close quarters.

  32. Fair enough Colin.

    “Creationists and climate change deniers have this in common: they don’t answer their critics. They make what they say are definitive refutations of the science. When these refutations are shown to be nonsense, they do not seek to defend them. They simply switch to another line of attack. They never retract, never apologise, never explain, just raise the volume, keep moving and hope that people won’t notice the trail of broken claims in their wake.

    This means that trying to debate with them is a frustrating and often futile exercise. It takes 30 seconds to make a misleading scientific statement and 30 minutes to refute it. By machine-gunning their opponents with falsehoods, the deniers put scientists in an impossible position: either you seek to answer their claims, which can’t be done in the time available, or you let them pass, in which case the points appear to stand. Many an eminent scientist has come unstuck in these situations. This is why science is conducted in writing, where claims can be tested and sources checked.”


    I also posted that not long ago in this thread (just one in a number of mind-numbing back-and-forths with a number of conservative Americans):

  33. Reading some of Ian Wishart’s debates with his critics, it occurs to me that perhaps he’s NOT just being ingenuous. Maybe his book was ghost-written for him, as he genuinely doesn’t appear to have a clue , e.g. this comment of his on Amazon:

    “Lest you be labouring under a misapprehension that there is bucketloads of evidence that CO2 definitely causes warming in the atmosphere, the nearest that RealClimate could get to endorsing this by way of proof was a “maybe”:

    >…at RealClimate:What does the lag of CO2 behind temperature in ice cores tell us about global warming? People forget the oceans in the CO2 annual flux – Greenpeace omits them. See above.

    “This is an issue that is often misunderstood in the public sphere and media, so it is worth spending some time to explain it and clarify it. At least three careful ice core studies have shown that CO2 starts to rise about 800 years (600-1000 years) after Antarctic temperature during glacial terminations. These terminations are pronounced warming periods that mark the ends of the ice ages that happen every 100,000 years or so. Does this prove that CO2 doesn’t cause global warming? The answer is no.

    “The reason has to do with the fact that the warmings take about 5000 years to be complete. The lag is only 800 years. All that the lag shows is that CO2 did not cause the first 800 years of warming, out of the 5000 year trend. The other 4200 years of warming could in fact have been caused by CO2, as far as we can tell from this ice core data… “<

    Like I said, hardly a ringing endorsement of the proposition that CO2 definitely causes warming in the wild."

    No, Ian, CO2 itself doesn't provide heat, it amplifies heating bought about by other forcings such as orbital cycles. Such heating causes oceans to warm and emit more CO2 in a vicious circle.

    You can easily check this yourself, with 2 warm bottles of soda water from the supermarket shelf and the aid of a fridge. Do take care not to leave a mess.

  34. Lets pretend for a sec IPCC models can predict the effects of CO2 increases on climate, do AGW believers also accept we are currently in an interglacial that is likely to one day end? And if so, should humanity be more worried about a possible 6C increase or a possible 6-9C decrease?

    1. If the natural ice-age cycles were still the dominant driver of the climate, the Arctic should currently be cooling. Instead, the Arctic is warming faster than the rest of the planet. Strangely, a warming Arctic is exactly what is predicted by the IPCC models under increasing CO2.

      Or do you think we should just ignore the evidence in front of our eyes and go on believing what we want to believe?

  35. R2, let’s pretend for a sec that you don’t know that this tired old denialist trope was debunked long ago and are just trying to muddy the waters.

    The unusually stable Holocene interglacial could have lasted another 10,000 years, but ended prematurely, with the Anthropocene.

    Don’t expect another Ice Age anytime soon…


    1. Anthropocene! haha more comedy, very funny indeed lol

      ‘The unusually stable Holocene” – do you see the doublethink? You say it is unusual in history for climate to be stable, yet you believe that the current warming is unusual and can not be explained by natural causes!

      I never said I knew when the current inter-glacial would end, only that it is likely to one day, as the previous ones have.

      (I’ll leave that to Stephen Schneider! http://www.climatedepot.com/a/3212/Inconvenient-Questions-Stanford-U-Bans-Climate-Film-from-Airing-Interview-with-Cooling-turned-Warming-Prof-Stephen-Schneider–You-are-prohibited )

  36. You do realise that Milankovitch cycles operate on geological time frames? So maybe it would be possible that in 6000 years humanity might like some hydrocarbons to burn to geoengineer out of cooling climate. Why dont you look at the Milkankovich insolation factors?
    Here http://tamino.files.wordpress.com/2009/09/annual90.jpg?w=500&h=325 for instance is the insolation at the pole over last 12000 years. So why arent we cooling? Because the atmospheric CO2 is too high. We heading for pliocene CO2 levels in the atmosphere – forget the ice age cycle in that environment. A BAU scenario could send us back to world where we didnt have icecaps at all.

  37. R2: you don’t need models to know that CO2 concentrations affect the planetary heat budget. That’s well understood physics. If we were in an “ordinary” interglacial with CO2 topping out at 280-300ppm, then (as scaddenp points out) orbital forcings would begin to tip us into a new ice age sometime in the next few thousand years. But CO2 is at 385 ppm, and that’s more than enough to offset any slow cooling from orbital factors (see comment on Arctic).

    If we do nothing, and we pass no serious positive feedback tipping points, then natural processes will reduce atmospheric CO2, but only on timescales of tens, perhaps hundreds of thousands of years. I recall reading a suggestion that current CO2 levels effectively mean that we have already “skipped” the next ice age.

    If, on the other hand, we manage to reduce CO2 (by active sequestration) to (say) 280 ppm in the next few hundred years, then we might need to worry about orbital forcings again – and think about a bit of a boost in atmospheric carbon to prevent it happening.

    Welcome to the anthropocene. Active planetary management now in progress. Personally, I think we need Slartibartfast.

    1. So Gareth, what you are saying is that:
      “If we were in an “ordinary” interglacial with CO2 topping out at 280-300ppm, then orbital forcings would begin to tip us into a new ice age sometime in the next few thousand years.”

      Which brings me back to my original comment, if this is true, should we be more worried about warming or cooling?

      Maybe (probably) a 2-4C warming is better than a 6-9C cooling?

      Let me guess, your answer is, “the temperature was good when I grew up, it must remain constant!”

          1. R2D2 – when someone points out that the science is something different from what you believe it says, with a reference, do you actually check? If not, then its pointless talking to you because you will believe your misconceptions no matter what evidence is presented to the contrary.

            So once more with feeling… A climate model is a PHYSICAL MODEL. It is not a forecast based on historical data. You run the inputs of the climate system through the equations of known physics. Source code is public; there are numerous articles for non-expert readers at likes of Realclimate explaining them and extensive published literature on them available at likes of GISS.

            As to relative forcing, (is 300 enough to stop an ice age etc), what you want is area of attribution studies. I am not aware of one single paper that can deal with this but the IPCC report summaries the science and the bibliography associated with this is a good start to the science.

            All this supposing you are actually interested in learning the truth and not just looking for things that correspond to you preconceived prejudices.

            As to “its all the sun”. Explain stratospheric cooling and arctic amplification with solar forcing then. Both key predictions from AGW.

            And once more with feeling…. You could look at what models actually predict. No model produces monotonic warming. The current pattern is completely consistent with the internal variability of the climate system. Are you going to suddenly change your tune when natural cycles go positive and then back to denier when go negative again?

    1. Amazing. He’s so fixated on the last ten years that he ignores the central point: you can’t say anything about long term trends (warming or cooling) over short time scales in a series with a lot of natural variation . You might as well argue that because today is colder than yesterday, summer’s cancelled this year.

    2. Don’t you just love the way he calmly uses the correct offsets I told him about without even acknowledging his mistake? Your Monbiot quote above seems quite timely!

      As for cherry-picking, I wonder why he didn’t look at the trends from 1997, 1999 or 2000?

      If there really was a significant cooling trend, then it wouldn’t matter what you chose as your start point, all of the recent trends would be negative.

      1. “If there really was a significant cooling trend, then it wouldn’t matter what you chose as your start point, all of the recent trends would be negative.”

        The same could be said about a warming trend. But Wisharts original statement didn’t claim a cooling trend, he claimed the absence of a warming trend (there is a difference),

        “Virtually all the major datasets are now acknowledging atmospheric warming has slowed to a crawl or stopped over the past ten years”

        I think it is accurate to say that no obvious temperature trend can be found in the last ten years.

        1. It’s not accurate. Set the slider (above) at 10 years, and there are no blue (ie “cooling”) trends. But it is also wrong to say there is no warming, or that it has slowed or stopped, because the presence/absence of global warming is not measured on such short time scales. That’s the central point, and you seem determined to miss it…

            1. Which part of “the presence/absence of global warming is not measured on such short time scales” do you not understand?

        2. “I think it is accurate to say that no obvious temperature trend can be found in the last ten years.”

          Ah, so we’re getting somewhere. Indeed, there is no obvious temperature trend, positive or negative in the last ten years, because ten years is not enough to cancel out the natural variability in the temperature record. That was the whole point of the original post. Glad to see you have finally recognised it.

          Looking at 20+ year trends, however, it’s all positive.

          And Wishart most certainly does claim that there is a recent cooling trend – see his latest post, where cherries are being picked all over the place. He is just as wrong about that as you are about saying there is an absence of a warming trend.

          By all indications, 2010 is highly likely to set a new temperature record. I predict that by the end of next year, you and the rest of the denialists will have forgotten all about cooling trends and predictions of ice ages, and will have found some other way to convince yourselves that nothing is happening and we can go on burning coal and oil to our hearts content.

  38. Gareth – that’s pretty much what I’ve posted under his piece

    “….when I got up this morning it was colder than it is now. That’s unarguable. So we’re obviously in a clear warming mode, and mine is a more recent data set than yours. There’s been a clear ‘climate shift’ (your words) since this morning. ”

    What is more astonishing is that he’s already been calling this blatant cherry-picking over and over again in a number of places but he persists anyway. From what I can tell he’s chosen a second data point (2002) so he can’t be accused of cherry-picking 1998. But, as clearly shown on his first graph, it simply means that he’s chosen the two highest points within his ridiculously short timeframe.

    Somehow he’s also determined that my name is also Colin. Which suggests that when he ‘Investigates’ (which I’ve found he always does when someone challenges him – check out the exchanges at amazon.com), the results aren’t always particularly accurate.

  39. If folks here haven’t already read it, may I recommend ‘The Republican War on Science’ by Chris Mooney? It’s specifically about abuses of science by the previous US administration on a whole range of issues from stem cell research to climate change to the teaching of evolution in schools, but it applies equally well to Ian Wishart.

  40. Definitely a book I’m wanting to read. Yesterday at Auckland Public Library I got out Mooney’s subsequent book; ‘Storm world : hurricanes, politics, and the battle over global warming ‘ which published in 2007.

    Am also now interested in reading ‘Bad Science’ by Ben Goldacre, after reading this exchange between a reviewer of Air Con and Ian on amazon.com…..

  41. Gareth: “Physics, R2. As long as there’s more than 300 ppm CO2, no ice age will begin, because the global warming forcing will exceed the smaller orbital forcing.”

    Ahmm excuse me but it’s well known that there have been many times in earth’s geologic past where temperatures have been low while atmospheric CO2 has been high. Such a ‘disconnect’ between temperature and CO2 is not unusual, partly because temperature changes have invariably PRECEDED changes in atmospheric CO2, which tends to follow. This is why it is possible for temperatures to fall suddenly (geologically speaking) while CO2 remains relatively high, and then follows a millennium or so later. If atmospheric CO2 controlled temperature (ie., acted as a climate forcer), it would prevent temperatures ever falling once they are elevated. The fact that they DO fall, and always have done irrespective of what level CO2 is at, is proof CO2 is not the controlling influence. I mean take now for instance: temperatures have been trending downward for close to a decade while CO2 is (according to Mauna Loa!) trending upward. If the supposedly “dangerous” level of 385ppm CO2 were such a potent climate driver, this would not have occurred because the increased CO2 would force it the other way. But clearly it doesn’t so obviously something else is at work. Some other force FAR more powerful… like the SUN perhaps!

    1. Sorry old fellow, but you are comprehensively wrong. The radiation physics of CO2 is very well understood, and its role in keeping the planet warm undeniable. You need to appreciate that it can be both feedback and forcing, depending on the circumstances. Warming out of an ice age, it is initially a feedback – a response to the orbitally-initiated warming – but it then adds to the warming to complete the transition to an interglacial. Other processes then intervene (warming means more vegetation, which locks up carbon), and when the orbital forcing declines, the planet begins to cool. Albedo from increased ice then adds to the cooling, and colder oceans take up CO2, completing the descent into an ice age. That cycle has been going on for the last 3 million years.

      In deep time, there have been periods when CO2 has been higher than now (how much higher is a matter of study), but lots of CO2 is inevitably associated with a warmer planet.

      You clearly need to do a bit more reading…

    2. It’s the SUN, stupid.

      Except, of course, there has been no significant change in the sun’s activity over the last 50 years, during which time the earth has warmed significantly. Whereas there has been a significant change in atmospheric CO2,

      So you are saying, let’s ignore all the scientific evidence that points to CO2 being the cause of the recent warming, and pretend that there is some scientific evidence that it is the sun?

      Why stop there? Why not pretend that there is some scientific evidence that it is Godzilla that is causing the warming? That might actually be more credible than “it’s the Sun, stupid”.

  42. Colin – I’m a little surprised by your last paragraph. I certainly wouldnt have picked 2010 as being a record year from what I have read. What are you basing that guess on? Latest ESNO prediction appears to be a moderate event, between 1-2, so far only predicted to last through summer.

  43. It’s not science denial that’s a character flaw. It’s what Wishart does – hating science, attacking science, spitting on science, downplaying science – then saying as often as possible that actually, science is on your side and what you’re doing. The verdict of science and the current consensus are the same thing.

    He’s a fundamentalist Christian with deeply right-wing economic views. Anything inconvenient to those things gets hands over the ears and “Nya Nya, I can’t hear you!” All of which are his perfect right.

    But it’s lying to pretend you are doing or understanding science when you’re doing apologetics.

    1. Hi Hank,

      Colin’s working on a revised version, using up-to-date numbers for global and NZ temps. Not sure when it will arrive, but when it does, I plan to give it its own permanent page.

    1. Should get this finished today.

      Hm. Looking back at this thread, from Oct 2009, I see that I made a couple of predictions – that 2010 would set a new temperature record, and that this would cause the “skeptics” to shut up about cooling trends. Well, one out of two ain’t bad :-)

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