Not long ago, the Hadley Centre/Climate Research Unit in the U.K. released their new “HadCRUT4” global temperature data set. That prompted David Rose of the Daily Mail to claim that “Global warming stopped 16 years ago.”
Here, according to Rose, is “the chart to prove it”:
There are some minor technical problems here. For one thing, the graph doesn’t show the last 16 years, it shows the last 15 years. For another thing, it isn’t “tenths of a degree above and below 14C world average,” it’s degrees Celsius above the 1961-1990 world average. Also, even though the first point is labelled “1997” and the last “2012,” the axis is a bit off because the first point is September 1997 and the last is August 2012.
But those are minor technical problems.
The major problem is that David Rose has made one of the most common mistakes studying data. He looked at a graph and concluded that the long-term temperature trend had changed around mid-1997, then showed only the data since mid-1997 and claimed it was “the chart that proves it.”
His choice to start with mid-1997 was made because that gave him the result he wanted. That’s a practice called “cherry-picking.”
The U.K. Met office replied that his choice to start with mid-1997 was cherry-picking.
David Rose has answered
Q Did The Mail on Sunday ‘cherry-pick’ data to disguise an underlying warming trend?A Some critics claim this newspaper misled readers by choosing start and end dates that hide the continued warming.
In fact, we looked at the period since 1997 because that’s when the previous warming trend stopped, and our graph ended in August 2012 because that is the last month for which Hadcrut 4 figures were available.
Apparently David Rose isn’t aware of this, but he has actually admitted that yes, the choice was cherry-picking — it was made specifically because of the result it gave.
If he could prove, statistically, that the previous warming trend stopped (or even slowed) around that time, then choosing mid-1997 to start an analysis would be legitimate. But he can’t. Because it didn’t. And then of course there’s the pesky fact that he didn’t even try.
Let’s put the last 15 years (of HadCRUT4 data) into context. Here’s the data since 1975:
I chose 1975 because you can prove (statistically, and there’s no doubt) that the trend changed at that time.
Notice that in addition to its long-term trend, there are also a lot of wiggles up and down. If you want to claim “no warming” whether it’s true or not, then you’d only show part of the data and you’d start when one of those wiggles was well above the overall trend line. Here’s where David Rose chose to start:
That’s not just cherry-picking, it’s championship cherry-picking.
Did the previous warming trend change then? One way to investigate is to “do the math.” David Rose didn’t. I did. It turns out that the trend using just the data since mid-1997 does not disagree (statistically) with the trend prior to mid-1997. You do have to take autocorrelation into account, so it’s not the simplest procedure. But we’ve learned how to handle that. It’s called “statistics.”
Perhaps the most interesting part is that even if the “bare” trend since mid-1997 did disagree (statistically) with the trend prior to mid-1997, it still wouldn’t prove it. That’s because mid-1997 was chosen because of the result it gives. If you just analyze some data (all of it), you apply standard statistical procedures. But if you’re allowed to try a lot of different starting times then choose the one you want (if you’re allowed to cherry-pick), it alters the statistical behavior. Dramatically. Those who are interested in the details should read this. But in this case, the result is so clear-cut we don’t even have to take the cherry-picking correction into account.
We can even look directly at how temperature since mid-1997 compares to the previous warming trend. Here’s the previous warming trend estimated by linear regression:
What would have happened if that trend continued unabated? This:
What would have happened is pretty much what did happen. Imagine that.
Of course global temperature didn’t follow the trend line exactly. It never does. It shows those inexorable wiggles up and down. It so happens that the last couple of years have shown us one of the “down” wiggles. But it’s no more “down” than the 1997-1998 wiggle is “up.” They’re both well within what would be expected, given the degree of fluctuation which global temperature shows all the time.
David Rose is taking advantage of the fact that we’re in a “down” wiggle right now, exploiting the fact that most people (like readers of the Daily Mail) don’t really understand that fluctuations like that are entirely natural, in fact unavoidable, and happen all the time. You can’t take them as evidence of a change in the trend — unless you’re ignorant of statistics and you’re pushing an agenda.
David Rose is also taking advantage of the extreme “up” wiggle in 1997-1998. It too is entirely natural, and is not evidence of a change in the trend — or perhaps David Rose would like to publish a story with the headline “Global warming took off like a bat out of hell in 1997!”
What’s worse, the choice to start with mid-1997 was made specifically because of the result it gives. David Rose himself, said so explicitly. That’s called cherry-picking.
It’s entirely believable that someone could make this mistake quite naturally, for no other reason than looking at a graph and drawing the wrong conclusion. People do it all the time, that’s why we’ve had to work so hard for centuries to develop the science of statistics.
But in David Rose’s case, I don’t think that’s so. My opinion: David Rose came to that conclusion because he has a political agenda and he’s constantly showing “confirmation bias” — he’ll go out of his way to find something he thinks is evidence to support his agenda (whether it really is or not). Since one of the main tactics for this practice is cherry-picking, that’s one of David Rose’s main methods. And he has just shown us a textbook case.
Just my opinion.
Open Mind 
He wanted to take the data and go as far back as he could with an apparently flat trend. Since he already “knew” the warming must have stopped, it was just a matter of finding out for how long. In other words, he interpreted the data exactly as much as his preconceptions would allow.
I love one of your earlier examples, where created artificial data with a perfectly linear trend and then layered noise on top. It really drove home the point that there can be a strong trend despite the short-term variation, and in that case we knew there was a trend because it was put there at the start. That was a pretty powerful teaching tool for this non-statistician.
Rose used to be an outstanding investigative jurno (crime/terrorism/war) but seems to have decided there is a ‘climate plot’ needing to be exposed. He is out of his depth in terms of understanding the science.
David Rose only does what GWPF tells him to do.
Oh, BTW:
“fluctuations like that are entirely natural, in fact unavoidable, and happen all the time”
Somebody page Marc Morano, Tamino has just admitted that it’s all natural and thus not man-made. ;-)
“David Rose only does what GWPF tells him to do.”
Indeed. On 10 October David Whitehouse writing on HADCRU4 states:
“Perhaps the best way to deduce the length of the recent standstill (in warming) is to start at the latest data and go back, year-by-year, until the hypothesis of constant temperature is violated. This leads one to 1997.”
On 14 October Daivd Rose does exactly that.
I’m convinced now that Rose’s Mail articles are joint efforts with GWPF staff.
This is no mistake by Rose. He is a well-known serial misinformer and misrepresenter (I would use the L-word but I don’t know how you feel about that).
Not only is this deliberate; he’s done it before. Tim at Deltoid has also exposed Rose’s dishonesty many times. What can one say about someone this brazen?
I’ll say it for you TrueSceptic.
David Rose is either incompetent with data and statisitcs or he is lying with data and statistics.
There’s no other plausible alternative.
Thank you Tamino for demonstrating that all David Rose proved was that he could add another step to the denialist’s escalator and that there are still too many folks ready to jump on for the ride down the rabbit hole where logic and proportion have indeed fallen sloppy dead.
Carbon Brief pulled together the six Rose rebuttals so far. Yours becomes the seventh — and I’d say the most powerful — Tamino. http://www.carbonbrief.org/3088.aspx
Threw you another – based on an even older Tamino post
.
From 2 years ago,
He was also one of the ‘usual suspects’ in this article of mine:
http://doc-snow.hubpages.com/hub/When-Did-Global-Warming-Stop
Ron, the telling thing is that the signal is around 0.15 degree Celcius per decade, and the noise is around 0.23 degree Celcius.
Even a smart lay person should be able to do a rough-and-ready back-of-the-envelope approximation of the time required for the signal to emerge ‘statistically’ from the noise even when the underlying warming trend is continuing as physics dictates and as scientists have indicated.
My opinion: you’re too kind. David Rose knows what he’s doing is bunk because he’s been told again and again. Rose is a bullshitter – he (and by extension his publisher) quite literally cares not at all about the veracity of what he writes, only whether it’s useful to him and whether he can get gullible people to suck it up.
What would be the least-squares best fit for a linear trend until mid-1997, some nominal temperature at that point in time then a linear trend since? I.e., making the trends before and after mid-1997 join up without hiding some warming in a “bat-out-of-hell” jump between the two trend lines.
I could work it out iteratively but, no doubt, you could solve it more directly. More importantly, you could, I assume, determine the error ranges on the three resulting parameters which would be beyond me.
My guess would be that the post 1997 trend would be lower than the pre one but not statistically significantly so. It’d be interesting to know, though.
Another twist would be to find the join point, in the 1975 to the present period, which gives the smallest least-squares error. If it turned out to be prior to 1997 that’d be a further indication that there’s nothing of interest happening.
Ed,
Unless I’m missing your point you could do this with a spreadsheet or use Wood for Trees.
If so, I’d be interested to know how. I’ve just had a quick look at Wood for Trees and it’s not obvious to me.
Just to be clear, what I’m suggesting is finding the trends before and after mid-1997 (easy, as you say) but constrained to intersect at mid-1997 (not so easy).
I could do this in a fairly brute-force way (probably in Python) to get the mid-1997 anomaly, the trend before and the trend after which gives the smallest least-squares residuals. However, without some estimate of the likely error ranges that’s a bit of a partial story.
The latest 16-year warming trend is 0.12°C per decade according to GISTEMP. Here are some other recent 16-year trends in GISTEMP:
1982 to 1998: 0.15°C per decade
1983 to 1999: 0.18°C per decade
1984 to 2000: 0.19°C per decade
1985 to 2001: 0.17°C per decade
1986 to 2002: 0.16°C per decade
1987 to 2003: 0.17°C per decade
1988 to 2004: 0.20°C per decade
1989 to 2005: 0.21°C per decade
1990 to 2006: 0.23°C per decade
1991 to 2007: 0.26°C per decade
1992 to 2008: 0.28°C per decade
1993 to 2009: 0.21°C per decade
1994 to 2010: 0.17°C per decade
1995 to 2011: 0.14°C per decade
1996 to 2012: 0.12°C per decade
Over the whole period of 30 years, the warming trend is 0.17°C per decade, but 16-year trends range from 0.12 to 0.28°C per decade (average 0.19°C per decade) – there is simply too much short-term variability to claim that a 16-year trend of 0.12°C per decade represents a genuine reduction in global warming. In any case, over 97.5% of the climate system’s heat content resides in the oceans, and that has actually been accumulating faster over the last three decades, not slowing down (Levitus 2012). The lower troposphere temperature trends are a result of both the energy coming in from above (solar irradiance plus downwelling IR) and the energy being transferred into the oceans, so with the ocean heat accumulation accelerating, it’s not surprising that the current ‘wiggle’ in atmospheric temperature shows slower warming – it doesn’t mean the climate as a whole is absorbing energy at a slower rate. Quite the opposite.
Of course, the beginning point 1997 is cherry picking at it’s best! Anyway, what do you think about about the article of Bob Ward in response to the “Daily Mail” article? http://www2.lse.ac.uk/GranthamInstitute/Media/Commentary/2012/october/myth-that-global-warming-stopped-in-mid-1990s.aspx . He calculates a significant warming trend in the monthly HadCRUT4 -record 01/1997…08/2012:
“So, here is a plot of the monthly data from had HadCRUT4 for the period from January 1997 to August 2012, inclusive. Applying simple linear regression using ordinary least squares to the data shows that this trend is statistically significant at the 95 per cent level.”
Do you confirm this when you consider the fact of autocorrelation?
[Response: No. Taking autocorrelation into account the trend is not statistically significant.]
We measure solar energy incoming and outgoing from the planet don’t we? And these figures do not show any significant changes from the results before 1997, correct?
Which leaves deniers with the same basic problem they have always had – if global warming is false, where has all the heat generated by greenhouse gases actually gone? To cloud cuckooland, that’s where.
Crunching data to deny AGW temperature gains without proposing a mechanism to account for how the extra heat, which we know must be present because of the greenhouse effect, is lost is a hallmark of the dishonesty of deniers.
I think the answer is the skeptics (‘deniers’ is the wrong term) don’t argue that there has been no warming (over say the last 200 or so years). Nor do they have to find anyplace for the greenhouse warming to go, because they think that there is only a small amount of that.
They don’t doubt it has warmed, they don’t doubt that CO2 produces warming. What they doubt is that the warming effect is amplified by feedbacks. So they think that a doubling of CO2 will produce warming of at most 1 degree C. They then go on to doubt that this much warming will have many deleterious effects, and the policy conclusion they draw is that expensive measures to prevent it by reducing emissions on the scale required are neither necessary nor cost effective.
The argument may be quite mistaken, but its not as stupid or easy to refute as the one you are crediting them with.
The really interesting point about the data series in the Rose article is what it should lead us to ask. We will all admit that at some point in the future, if the series remains flat or falls, it will be clear that the GHG and CO2 hypotheses have failed. Take a wild example, say that in 2050 we put up the same chart, and it basically shows a flat or slightly declining trend since 1995. At that point it would be all over for the hypothesis.
OK, what if we put up the same chart with the same trend in 2030? In 2020? At what point do we have disconfirmation? Surely what we all need to do is seek for critical experiments like this, that everyone agrees will decisvely settle the matter?
The Mail by the way is amazing. This really is a very much read UK paper apparently. My goodness! What an eye opener!
[Response: “Denier” is an accurate description.
They only admit there’s warming and appeal to “it won’t be much or harmful” when they’re forced to by facts they can no longer deny. And some of them still do so anyway. Here are some examples:
Consider your statement “say that in 2050 we put up the same chart, and it basically shows a flat or slightly declining trend since 1995. At that point it would be all over for the hypothesis.” You don’t realize the irony of your statement.
If the data dictate that warming has stopped, with statistical significance, I (and mainstream climate scientists) will accept it and seek better understanding. But if the data say otherwise, if in 2050 the temperature data showed continued, even accelerated warming, the fake skeptics (just “skeptic” is the wrong term) still won’t admit it. Some will go on about how warming won’t exceed 1 deg.C even if it has already. Some will talk about how more droughts and heat waves will be beneficial. And some of them will still — still! literally deny the truth, claiming the temperature rise is just due to UHI or has been faked by scientists in a world-wide conspiracy.
Climate scientists face reality as indicated by the data. Fake “skeptics” do anything but. “Deniers” is quite correct.]
Michel, you are painting the most charitable picture of “skeptics”. In my experience many of them would deny their own parentage, if they thought it would help their “team”.
Michel,
The no-feedback argument is as absurd as the no-greenhouse argument. We know with 100% certainty that the greenhouse effect raises Earth’s temperature 33 degrees warmer than it would be in the absence of an atmosphere. You could not get anywhere near that temperature rise without positive feedback. And we are to believe that the feedback magically switches to negative or zero when CO2 reaches 282 ppmv exactly…why?
The lukewarmers may be more sophisticated clowns, but they are no less clowns than G&T.
Why should one take seriously these “skeptics” when they do everything in their power to deny the critical importance of looking at things other than the atmosphere and the dry-bulb temperature of the atmosphere?
They do everything in their power to try get away with denying the total heat budget of the planet by denying the data or the physics with respect to heat going into the oceans and into melting ice.
And they also try to do everything in their power to deny that the enthalpy of air (total heat energy in the air) is more relevant than merely a dry-bulb temperature. That is, for example, 95 degrees F in high humidity conditions presents more enthalpy than 95 degrees F in low-humidity conditions. And in general, it becomes increasingly hard to increase dry-bulb temperatures when there is a continuing increase in the amount of H2O in the air from increasing evaporation from increasing heat energy. And so looking at just the dry-bulb temperatures to measure total heat energy is just not smart or wise. I note that just in the last 40 years, the amount of H2O in the global atmosphere has increased by as much as 4 percent.
That is, these “skeptics” will do everything in their power to deny the importance of these above data and related facts of physics to try to “show” that if the global atmospheric dry-bulb temperature does not grow over the 30 years after 2000 as fast as it did the 30 years before 2000, then *total* greenhouse gas effects and activity is weaker than was thought by climate science. And the reason for this is that when we truly take into consideration all these above data and related facts of physics, then these “skeptics” cannot “show” any such thing.
See prior post in this thread of comments by myself, and by Aaron Lewis whom I quote here:
“We have a big weather machine driven by the total amount of collected heat and various temperature differentials. HadCRUT4 only indicates a tiny fraction of that heat, and that fraction of heat is not in full equilibrium with other heat reservoirs in the system. Thus, not only does Rose get the details and mechanics of the statistics wrong, he also misses the point that the rate if temperature change he is interested in is affected by how fast the heat in the atmosphere comes into equilibrium with the heat in the oceans and the heat in the cryosphere. This changes as the temperature of the atmosphere changes. For example air above freezing transfers heat to snow and ice much faster than air that is below freezing, and air with a dew point above freezing transfers heat to ice very rapidly. The rate of heat transfer from the atmosphere to ice affects the temperature of the atmosphere (HadCRUT4) and thus, the apparent rate of warming. Nor does Rose address the point that air with a higher relative humidity holds much more heat. Thus, air temperatures can remain the same while the heat in the atmosphere goes up as relative humidity goes up. And, global relative humidity has gone up in the last few years.”
I certainly meet quite a few deniers–sorry, Michel, the term is precisely correct for the folks I’m talking about–who quite explicitly deny warming, deny that CO2 could possibly have anything to do with it, and deny anything else vaguely connected with the notion of AGW–no matter how mutually inconsistent those denials and their implications may be.
Not to be pedantic, but by my count September 1997 through August 2011 is just one month shy of 14 years. So isn’t he two years off?
[Response: It’s monthly averages covering the period from Sept. 1, 1997 through Aug. 31, 2012, 15 years.]
Tamino, you say that you’ve done the maths, but disappointingly, you don’t report the maths for those who (like me) are unable to do it for themselves.
Using Woodfortrees, I am able to see that the 1975 to 1997 trend (0.159 C per decade) is less than that from 1975 to Aug 2012 ((0.17 C/decade). I can also see that the 1997- Aug 2012 trend is still positive (0.047 C/decade). Unfortunately I cannot calculate whether the 1997-2012 trend differs significantly from the 1975-2012 trend (I assume it doesn’t, but would like that confirmed). I assume you also have trend figures that more exactly match Rose’s cherry pick.
http://www.woodfortrees.org/plot/hadcrut4gl/from:1997/offset:0.05/plot/hadcrut4gl/from:1997/trend/plot/hadcrut4gl/from:1975/plot/hadcrut4gl/from:1975/trend/plot/hadcrut4gl/from:1975/to:1997/offset:.05/plot/hadcrut4gl/from:1975/to:1997/trend
[Response: I usually report “the math” in detail. But this post isn’t so much for the regular readers (who seem to be keen on that) it’s for a more general readership, who often balk at such complications. My usual readers didn’t believe him in the first place. As for testing whether the trend changed in mid-1997 or thereabout, you really need to compare the 1975-mid1997 trend to the mid1997-present trend, you must account for autocorrelation, and recognize that the random noise isn’t AR(1). And to be rigorous, you need to apply the “cherry-picking correction” referred to (see the “read this” link for more details), because mid-1997 really is chosen for its result. Perhaps I’ll get around to posting about that, but at the moment there are some other things I’d like to post about first.]
Sorry, done the test myself with the Skeptical Science Trend Calculator.
1975-2012.67: 0.17 +/- 0.037 C/decade
1997.75-2012.67: 0.034 +/- 0.139 C/decade
The later does not differ statistically from the former, and hence there is no statistical basis for a claim that the trend has changed.
[Response: As I said, you really should compare the mid1997-2012 trend to the trend 1975-mid1997, not 1975-2012. But either way it’s the same result. And when you apply a cherry-picking correction, it’s not even close.
It’s also *very* interesting that, as you pointed out, the 1975-Aug2012 trend is numerically higher than the 1975-Aug1997 trend. That should be a clue for those who were duped by David Rose.]
#2 Stephen: “Rose used to be an outstanding investigative jurno (crime/terrorism/war)”
David Rose was suckered into believing Saddam Hussein was responsible for terrorism on September 11. He wrote a number of articles describing how Saddam trained the hijackers in a secret facility south of Baghdad.
Ahmad Chalabi was a known disinformer. David Rose simply failed to test the credibility of his source.
The only thing more pathetic than a liar is a liar who also lies to himself because he cannot face the truth. Add to that his utter cluelessness when it comes to the simplest analyses, and it is difficult to conclude that Mr. Rose is anything more special than stupidity sent to college.
That comment deserves to be bronzed.
Is it just me, or is all this discussion about trendlines, cherry-picking, and auto-correlation being a mite too generous?
Look at the graph in the article. What stands out? The matching endpoints. Is Rose basing his claim on looking at just two single points in the time series? Sure seems that, not only did he cherry-pick the interval, but, he also had to discard the vast majority of data in the interval to reach his conclusion.
Why?
Even by eye, there is more of the line below the two end points.
If you need stats to ‘prove’ something that you can measure, then your methodology is wrong.
Lets just think, we measure temperature with temperature sensors, they have accuracy and resolution parameters.
How can we be arguing about temperature changes that appear to be greater than either the resolution or accuracy of modern sensors.
The accuracy of historic data and methods used to collect it are worth a discussion on their own.
[Response: Indeed. But more worthy of discussion is the failure to understand random fluctuations, the tendency of the ignorant to discredit statistics out of hand, and the folly of conclusions made “even by eye.”]
But are we not talking about “understanding radom fluctuations”.
In radio communications we can receive and use signals ‘below the noise threshold’ by using statistical techniques. however, we then build the radio and ‘prove’ in the real sense of the word, that the system works.
What has been ‘proven’ in climate technology? Anything?
Has any model output matched any real value measured with a sensor?
I have not seen a single model output that works as proposed.
Until I do, I can not accept the group think that surrounds the whole IPCC output which is ALL MODEL DRIVEN.
I am glad that real engineers, who use simulators to design systems, actually try the real system in the real world before that conclude that their model is accurate.
[Response: Your ignorance is showing. There are many model results that have been observed in the real world, you just don’t want to see them. And for your information, unless you count “physics” as a “model,” the conclusions of climate science are not “ALL MODEL DRIVEN.”
Repeating old tired canards, even shouting them, doesn’t make them true.
As for your failure to understand random fluctuations (your example only proves that you don’t know what I was talking about), your failure to admit the ignorance of your having dismissed statistics out of hand, and silence about your folly in drawing conclusions “by eye” …]
Steve Richards,
Temperature trends are well within predictions. Humidity has trended pretty consistently with the models. The models predicted stratospheric cooling and growth of Antarctic ice near the poles.
There are a lot of predictions the models have gotten right. Your ignorance of them says more about you than about climate science.
If I am not mistaken, HadCRUT4 does not cover a huge swath of the Arctic, Taken from their FAQ @
http://www.metoffice.gov.uk/hadobs/hadcrut4/faq.html
“Q: Was 2010 (or 1998 or 2005) the warmest year on record?
A: The short answer is, maybe. It is not possible to calculate the global average temperature anomaly with perfect accuracy because the underlying data contain measurement errors and because the measurements do not cover the whole globe. ”
From that nice uncertainty Mr Rose pruned a graph.
I looked up his image, expecting him to look like Withnall, from “Withnall & I”, but he didn’t, instead looking like a very downmarket Colin Firth. But he does look *serious*, as though he wants to be taken seriously. I prefer my rogues to look like rogues.
Judith Curry strikes again. Put away beverages before you proceed.
Italian flag, on the red (against “AGW”):
“i) No significant increase in surface temperature since 1997
v) Growth of glaciers and ice sheets
vii) Failure of climate models to provide a consistent and convincing attribution argument for the warming from 1910-1940 and the plateau from the 1940′s to the 1970′s
viii) No increase since 1997 in atmospheric heat content from UAH, RSS.”
With respect to that Judith Curry post referred to:
Why does Judith Curry keep discounting the overall thermodynamics of the situation, namely that when we have a massive heat sink called the oceans we will see what we have been seeing, which is that on average an ever-increasing percentage of ever-increasing heat will have the tendency to go where there is less of it, into the oceans? (She dumps on the ocean heat data using all sorts of attempted excuses.)
And, if she wishes to still discount the oceans and stick to only the atmosphere, then, while looking at the long-term trend line and while observing which months in the last several years are above and below this line, she needs to ask herself which of these months were when we had La Nina conditions and ask herself whether she sees any pattern at all.
Side note: To turn the denier “Why isn’t it getting hotter?” thing on its head, she needs to ask herself why isn’t the planet actually getting colder as they have been predicting for the last several years will happen from certain non-greenhouse forcings they point to.
Finally, this – and I’ve made this point at this blog before: Perhaps we need to start paying more attention to the enthalpy – the total heat content – of the atmosphere (like looking at wet-bulb temperatures or heat indexes) rather than just look at dry-bulb temperatures (the usual thermometer temperatures). When comparing high-humidity to low-humidity conditions, there can be equal enthalpy but different dry-bulb temperatures. (That is, for example, 90 degrees in high-humidity conditions in Florida does not present the same level of enthalpy as 90 degrees in low-humidity conditions in Arizona. The reason Florida rarely sees dry-bulb temperatures above 100 while it is common in Arizona is because of the different levels of H2O in the air.) I would think that with ever-increasing amounts of H2O in the atmosphere from more evaporation from ever-increasing heat, eventually it has to be that it becomes harder than before to increase the dry-bulb temperatures.
Here is an online heat index calculator:
“Meteorological Conversions and Calculations Heat Index Calculator”
http://www.hpc.ncep.noaa.gov/html/heatindex.shtml
Playing around with different combinations of dry thermometer temperatures and humidity can show that very high and even killing heat indexes can occur with dry thermometer temperatures that are already common. Entering 100 degrees F with 75% relative humidity yields a 150 degree F heat index.
It might be appropriate to recall that killing heat in the future will not necessarily be from very high dry thermometer temperatures but from very high wet-bulb temperatures or heat indexes. See again that National Academy of Sciences paper that warned about future killer – even extinction event – wet-bulb temperatures or heat indexes:
“The Health Effects of Hotter Days and Nights”
http://www.gaia-movement-usa.org/?q=node/46
“Researchers find future temperatures could exceed livable limits”
http://www.purdue.edu/newsroom/research/2010/100504HuberLimits.html
I can imagine that future deniers would day that the globe is not getting hotter and hotter because of their looking only at dry-bulb temperatures even though the ever-increasing heat indexes would be killing more and more people and land animals all over the world. (As far as I am concerned, the type of claims put forth by such as Judith Curry is the beginning of this sort of thing.)
I linked to this article on another blog that is discussing the Daily Mail article and got this reply which I thought was so funny I had to share it here.
Unfortunately for your Warmist propaganda site, the Met Office themselves, after much disingenuous wriggling, finally admit otherwise.
The Met Office now confirms on its climate blog that no significant warming has occurred recently: ‘We agree with Mr Rose that there has only been a very small amount of warming in the 21st Century.’
http://wattsupwiththat.com/2012/10/21/update-and-confirmation-of-global-warming-stopped-16-years-ago/
I expect the irony was missed by the original poster.
The “warming stopped in 1998” meme is a hard one to kill. The El Nino in 1998 was a phenomenal event, and the associated temperature anomaly was ~0.4 °C. Given that the forced trend due to anthropogenic emissions of greenhouse gasses is less than 0.2°C/decade, this nonsense story is going to be with us for some more years. It is looking worse all the time, and eventually it will go away, just as the “there is no warming” meme of the 1990s did. (You could argue that meme mutated into the one Rose is spreading now).
The fact that the trend hasn’t changed, and the warmest years since 1998 are at least as warm as 1998, – and that without the El Nino should be enough to convince anyone. Otherwise, here is an analogy that may be helpful:
Lets say a journalist has an annual salary of say 50.000 pounds in 1997. His salary increases on average by 10% per decade so in 2007 he can expect to make 55.000 pounds and ~58K in 2012. Now, he buys lottery tickets every week and in 1998 he won 10.000 pounds in the lottery, so that year his income was around 60.000 pounds.
So, would the journalist be right in saying in 2012 that his income had stagnated since 1998?
Essentially this is the crux of the “warming stopped in 1998” meme. It’s comparing apples and oranges, – “salary plus lottery” with “salary only”, just as with 1998 we are comparing AGW + El Nino with AGW only.
Tamino,
Do you ever have the feeling when you are writing these posts that it’s deja doo-doo all over again?
Deja doo-doo
Spread anew:
“Warming stopped,
But not CO2 !”
You said:
I chose 1975 because you can prove (statistically, and there’s no doubt) that the trend changed at that time.
How would you prove that? Have you done that on an earlier post?
[Response: Yes, but I don’t recall which one. Maybe I’ll do it again just for demonstration.]
Try Changes, from August 13, 2010.
Neil-san,
Do a bunch of Chow tests.
We have a big weather machine driven by the total amount of collected heat and various temperature differentials. HadCRUT4 only indicates a tiny fraction of that heat, and that fraction of heat is not in full equilibrium with other heat reservoirs in the system.
Thus, not only does Rose get the details and mechanics of the statistics wrong, he also misses the point that the rate if temperature change he is interested in is affected by how fast the heat in the atmosphere comes into equilibrium with the heat in the oceans and the heat in the cryosphere. This changes as the temperature of the atmosphere changes. For example air above freezing transfers heat to snow and ice much faster than air that is below freezing, and air with a dew point above freezing transfers heat to ice very rapidly. The rate of heat transfer from the atmosphere to ice affects the temperature of the atmosphere (HadCRUT4) and thus, the apparent rate of warming.
Nor does Rose address the point that air with a higher relative humidity holds much more heat. Thus, air temperatures can remain the same while the heat in the atmosphere goes up as relative humidity goes up.
And, global relative humidity has gone up in the last few years.
Aaron — Have a link for that last assertion?
“There are some minor technical problems here.”
to be fair to Rose, you can’t expect him to get complicated statistics right. you can’t even expect him to get basic statistics right. in fact, you should probably consider it a win if he doesn’t accidentally jam his biro into his eye while writing.
Thanks Tamino, for your tireless public stats lecturing; that is refreshing again and again. And somebody has to do it ;) Curious: What autocorrelation model did you use, and how can you prove that there was a change in trend in 1975?
Although encouraging to read the responses neither they or this post itself will ever reach even one percent of the audience that Rose’s article did. So, unfortunately, a lot of people in the UK, now are even more convinced that global warming is a political ploy to increases taxes.
I’ve never understood even the basic logic behind the lefty_government_after_my_hard_earned_taxes conspiracy theory. CO2 taxes are basically revenue neutral. And if they weren’t. How is it any more of a money grab than a consumption tax…. a speeding ticket, train ticket, etc…?
So, spread the word.
David Rose comes up way short. Going back to when the earth was part of the solar nebula to this evening when it is 34 degrees F outside, I find that we are in a 4.5 billion year cooling trend.
Obviously, YOU do not understand how to use linear regression. It is clear that there was a warming trend until around 1997. The whole point is that the warming trend since that time is nil. It’s not cherry picking, it is recognizing that there has been an irrefutable change in the trend. An odd name you choose for your blog, as your mind apparently is quite closed on this issue. You might study a bit on proper application of regression analysis as well.
[Response: The trend in HadCRUT4 data since January of this year is warming at a rate of 49 deg.C per century! It’s irrefutable! You can see it!!!]
I can pick em with the best, too: http://woodfortrees.org/plot/gistemp/from:1999/to:2007/trend
3.27C per century (I used GISS because everyone knows that Phil Jones is a fraud (snort!))
Oh, and then there’s this one:
http://woodfortrees.org/plot/hadcrut3vgl/from:1997/to:2006/trend/plot/hadcrut3vgl/from:2006/to:2011/trend
The real question, though, Tom, is why you’re focusing on 5% of Earth’s surface system thermal capacity when you say, “warming trend since that time is nil.” In other words, what exactly does a 16-year insignificant surface temp warming trend (using a analysis that doesn’t incorporate the poles very well) mean to you? What does it signify? What conclusions can you draw from it? What would you say to your friends who might ask these questions?
In your response to Tom you state “The trend in HadCRUT4 data since January of this year is warming at a rate of 49 deg.C per century! It’s irrefutable! You can see it!!!]. 49C seems a pretty impressive warming rate especially as according to your earlier comment we are in a “downward wriggle”
[Response: How perceptive you are.]
Tamino sometimes uses exclamation points as an indicator for sarcasm, Ian. (Hmm, should I have used one myself?)
In the “WUWT is stranger than fiction” department, I linked to the main figure in this post in a comment over on WUWT and one of the commenters there came back with the most bizarre example of arguing against a “strawman” that I have ever seen: http://wattsupwiththat.com/2012/10/28/manns-hockey-stick-disappears-and-crus-briffa-helps-make-the-mwp-live-again-by-pointing-out-bias-in-ther-data/#comment-1130165 And, it’s not like I didn’t explain the graph clearly in my post. (And, sorry for not linking to your whole post, but I’ve had such links snipped before with some snide remark about giving you free advertising, so I thought a link to the graph alone had a better chance of making it through moderation.)
I especially love how he thinks that the fact that a trendline through all the data from 1975 to present is STEEPER than a trendline through just the data up to early 1997 is going to somehow help the “global warming stopped 16 years ago” argument!