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GWPF throws out centuries of physics, climate scientists laugh, conservative media fawns

Posted on 29 February 2016 by dana1981

Climate models, and the predictions they make, are based on physics. We know how much more energy is trapped on Earth when we increase the greenhouse effect, and we have a good idea how much this trapped heat will warm the planet. We’ve understood these physical scientific concepts for over 150 years.

When climate contrarians make their own predictions, they tend to throw physics out the window. For example, as documented in my book and a paper I recently published with Rasmus Benestad and colleagues, contrarians have made climate predictions based on things like the orbital cycles of Jupiter and Saturnocean cycles and sunspots, and “natural fluctuations,” but they often completely disregard the basic, long-understood physics of the increasing greenhouse effect.

And so we have the latest such unphysical climate prediction, made in a report by Loughborough University statistics professor Terence Mills, on behalf of the anti-climate policy advocacy group, the Global Warming Policy Foundation (GWPF). The report essentially fits a statistical model to past global and local surface temperature changes, and then uses that statistical model to forecast future temperature changes. It’s an approach that’s been used to predict financial market changes, for example.

The obvious flaw in this application is that the Earth’s climate is a physical system, and the statistical model includes no physics whatsoever. You simply cannot accurately predict how a physical system will change if you ignore physics, like the increasing greenhouse effect. As DeSmogUK put it, the GWPF report predicts no global warming by ignoring the main cause of global warming. And as climate scientist James Annan wrote,

The basic premise is that if you fit a nonsense model with no trend or drift, you generate a forecast with no trend or drift (though with huge uncertainty intervals, necessary to allow for the historical warming we’ve already seen). Amusingly, even with those huge uncertainty intervals, the temperature is already outside them

Indeed, as NASA Goddard Institute for Space Studies Director Gavin Schmidt noted, temperatures have already risen outside of the GWPF forecasted range.

forecast fail

A number of other climate scientists immediately had a good laugh at the report’s and media’s expense.

Unfortunately, the seemingly juicy story nevertheless made the rounds in the conservative media, including the Timesthe Australian (both Murdoch-owned),the ExpressCanada Free Press, and the Daily Mail. At least the Mail called the report “controversial” and noted the mockery from climate experts, who called the GWPF report “silly” and “daft.” Climate scientists Emily Shuckburgh and Ed Hawkins even took the time to write a letter to the Times to correct the story.

James Annan used the opportunity to propose a modest wager based Professor Mills’ forecast. As Annan describes it,

There followed a fruitless exchange in which [Mills] declined to comment on whether he thought the forecast was credible and refused to even discuss any possible bet. I’m still baffled as to what might motivate a statistics professor to put their name to such obvious drivel, it’s hardly something that will enhance his reputation in the academic community, or that he can feel proud to have written.

As Mann et al. (2016) most recently showed, physics-based climate models are doing a very good job at predicting global warming and climate change. As expected based on our understanding of the greenhouse effect, if we keep pumping vast amounts of carbon pollution into the atmosphere, the planet will continue to warm dangerously rapidly.

mann et al 2016

Global mean temperature series (red) along with five different Monte Carlo surrogates based on forced signal + ARMA noise realizations (gray) using CMIP5 all-forcing experiments. Illustration: Mann et al. (2016)


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Comments 1 to 12:

  1. Note also that the Global Warming Policy Forum is attempting to pull the same stunt with a porky pie production line of Arctic sea ice misinformation. For all the gory details of this long running saga please see:

    The Great Global Warming Policy Forum Con

    Dear Benny,

    I note that the GWPF webmaster has still not taken on board any of the helpful [Arctic sea ice] advice I have proffered over the last few weeks, and has now posted some inaccurate information about “global warming”. Will he or she never learn?

    Apparently not!

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  2. It's like saying that the burner on my stove isn't going to heat up based on past patterns, and ignoring the fact that I just lit the gas.

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  3. The technical basis of this GWPF Technical Paper No1 actually rests on a method that is well known here at SkS. The result rests wholly on the method employed to identify the break-points in the HadCRUT4 & RSS TLT data series. This method is not without its critics so GWPF Technical Paper No1 presents the reasons for employing this method in Note 9. And these reasons are that the 'author' (posh word for kid with crayon) Terence C. Mills of Loughborough University (likely attached to the university's kindergarden) feels he can argue that (firstly) alternative methods are less well developed that his chosen approach and (secondly) break-points can be identified over the full length of the data series when using his chosen method.

    This chosen method thus allows him a level of flexibility unavailable with any of the alternatives.

    The method utilises a very powerful piece of equipment call a Mk1 Eyeball. Yes, you have it right. The kid with the crayon is cherry-picking his breakpoints visually. Note 9 does make plain that other break-points can still be considered but the kid with the crayon is happy to ignore any of that and go with his prediction for temperatures out to 2020. And I note there is some press coverage showing that the kid with the crayon has got his hands on a longer ruler than the one used in GWPF Technical Paper No1. He is reported  predicting global tempertatures out to 2100(And they are talking years not hours!!) based solely on the data 2002-2014. The kid may well know that short sets of noisy data (less than 18 years or so) give statistically unsound results but he probably hasn't learnt to count up to eighteen yet.

    9. The break-points were determined ‘exogenously’, in other words by visual examination of a plot of the series. This was done for two related reasons. First, methods for determining breaks endogenously remain in a relatively early stage of development (see Bai, 1997; Bai and Perron, 1998, 2003,McKitrick and Vogelsang 2014) and their properties in dynamic regression models have not been completely established. Second, these methods require observations to be ‘trimmed’ from the beginning and end of the sample to ensure that the tests have reasonable properties: any trimming at the end of the sample will make it almost impossible to find a break that occurs near the end of the sample, as may well have happened in this series, this being the well documented ‘pause’ or ‘hiatus’ in temperatures. Consequently, other researchers may wish to explore alternative break points: certainly bringing the last break point forwards from December 2001 will begin to produce a significant positive trend for the fifth regime.

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  4. Mills' paper starts with the assumption that climate temperature changes are a non-stationary process, which is to say a random walk.

    Unfortunately for his hypotheses, a physical system cannot exhibit a random walk without violating the Conservation of Energy - it must be trend-stationary to forcings, potentially varying around that trend but with an ever-increasing returning tendency when it does. A random walk, on the other hand, can accumulate variations either + or - from the forcing levels, leading to a situation where the climate would either gain or lose energy forever; that is just physically absurd. 

    Note that trend-stationary behavior is clearly demonstrated from a proper application of test for random-walk behavior (which the climate doesn't exhibit), see here and here for some very clear analysis by Tamino. 

    Given that bit of nonsense as a starting point, nothing else in Mills paper physically follows, including his 'eyecrometer' picks of breakpoints. If someone ever tells you that climate exhibits 'non-stationary' behavior or is a random walk, you can assume that they don't know physics, and you can ignore the rest of their spiel. 

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  5. MA Rodger @3, your are correct about crudeness and inappropriateness of using cherry picked break points in this sort of study, although the references to 'kindergarden' are uncalled for.  Also uncalled for are suggestions elsewhere that Mills is only publishing a report of this nature because of the fee he recieved from the GWPF.  He has taken a similar line in the (dubious) Journal of Cosmology, although at least avoiding the fraudulent practise of cherry picking in that paper.

    What is interesting is that in 2009 in Climactic Change, Mills performed an analysis showing that:

    "Using an updated data set of global temperature and radiative forcings, it has been shown that temperature and total radiative forcing cointegrate and that this relationship is stable across the period from 1850 to 2000. A robust estimate of the temperature sensitivity to a doubling of radiative forcing is calculated to be in the range of 1–3C, with a point estimate of just over 2C. Since we cannot reject the hypothesis that the different radiative forcings have an identical impact on temperature, this result can also be interpreted as providing the temperature sensitivity to a doubling of atmospheric CO2 concentration."

    (Note that the "temperature sensitivity" discussed is the Transient Climate Response.)

    Thus, Mills has shown that total radiative forcing is a robust predictor of meant global temperature.

    Mills also analysed NH trends in 2006 using a variety of methods, concluding that:

    "In summary, then, although the techniques investigated here display certain idiosyncrasies, they share the common feature of a ‘long wave’ in trend NH temperatures with a pronounced warming trend since 1970.  The range of trend functions provided by these techniques should, however, temper the enthusiasm of anyone tempted to use them for extrapolating trend temperatures far into the future."

    That last caution is wise given the limitations of purely statistical techniques.  Had Mills taken it at face value, he would never have published his latest excrescence for the GWPF.  Needless to say, if purely statistical trend prediction are dubious for predicting the future, purely statistical trend prediction based on cherry picked break points is not worth the paper it is printed on. 


    Further, in a peer reviewed trend analysis in 2009, he wrote:

    "As can also be seen from Figure 2, the trend slopes are all approximately constant, at around 0.03oC per annum. This implies that, at this current rate of trend increase, Northern Hemisphere temperatures will be some 3oC higher by this time next century. Being parametric, the stochastic trend model provides a standard error for both the current trend level and slope: these are 0.05 and 0.01 respectively. Forecasted trends will also have standard errors. Although the forecasted trend in 2105 will be around 3.6oC (above the 1961-1990 mean), it will have a standard error of 2.3oC attached to it, indicating the imprecision with which such long run forecasts are necessarily accompanied by: a 70% prediction interval runs approximately from 1.3 to 5.9oC. This long-range trend forecast is very much in line with the projections made by the Met Office’s Hadley Centre coupled atmospheric-ocean general circulation models, HadCM2 and HadCM3, using a ’business as usual’ scenario that assumes mid-range economic growth but no measures to reduce greenhouse-gas emissions."

    That paper also analysed the Central England Temperature series (CET), in which he found two short term trends of similar magnitude to the late twentieth century trend, but that is to be expected when that series represents temperatures over a small region.  Hemispheric and global series, in contrast, will show the average over many regional trends and consequently be far less variable.  Consequently, we need not expect temperatures of 14.08 C by 2005 (as predicted from the CET trend), and contrary to Mills assertion, that temperature is not inline with model predictions.

    Taking the three papers together, Mills own work has shown that radiative forcings are a robust predictor of temperature, while statistical patterns in temperature patterns alone are not a robust predictor of gobal temperature.  Further, purely statistical predictions are downgraded by cherry picking trend periods.  Therefore, to treat projected trends based on cherry picked data as refuting climate models, whose results are consistent with the robust predictions of temperature from radiative forcing directly contradicts Mills' own work.  In short, not only does he know that is work in the GWPF report is of poor quality - not only does he know that it is not robust - but Mills knows the conclusions drawn for him by McKittrick in the introduction are directly contradicted by Mills actually peer reviewed work.

    It is no wonder that he refuses to confirm that he considers his result to be credible.

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  6. Tom Curtis @5.

    The ridicule I present @3 is indeed unscientific but when a paper is as you say "not worth the paper it's written on," that paper hangs on to the very edge of science by its fingertips. Add to that the comments by McKitrick in the GWPF's forward (saying how important this paper is for policy makers) and Mills' no-temperature-increase-this century prediction reported in the press: given such a situation, for an academic to remain silent and not set out where he stands - that is unforgivable in science. The paper could just as as well be written in crayon in the kindergarden.

    And do note that this particular set of GWPF are the Global Warming Policy Foundation. This part of the GWPF is a registered charity (an educational charity no less, so that'll learn you!!) and being a charity that £3,000 paid to Mills was part funded by the UK taxpayer. Yet again the Gentlemen Who Prefer Fantasy bring legitimate UK charities into disrepute.

    Resorting to ridicule may not be entirely appropriate within an SkS comment thread where scientific analysis should not be drowned out by laddish invective but on the interweb generally I do consider ridicule an effective response to these GWPF jokers.

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  7. I think it may be a problem for the GWPF when their scientist-for-hire produces the required drivel at such a level of detail that it is instantly falsifiable.

    My climate prediction:  Expect GWPF to hire someone less verbose, and more opaque, in the future.

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  8. Isn't this sort of like driving your car by looking only at your rear view mirror? I mean they used temperature data from the past, so they have a view of where the climate has been, but I don't see how that predicts what's in the future.

    Seems a bit like a turkey scientist, on the eve before Thanksgiving, performing a statistical anaysis of the previous 364 days and concluding with confidence that tomorrow will be just like every other day.

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  9. BBHY @8, you are too generous.  

    Mills not only looks in the rear view mirror - he cherry picks break points to ensure a low trend for the final term for the segmented trends; and simply omits the trend term from his analysis to ensure a zero trend for the full autoregressive model.  That is, for figure 5 above, his analysis finds a trend of 0.6 C per century, which he then simply omits in order to make a projection.  For figure 6, his analysis finds a reduced trend in the final segment due to a cherry pick of 0.8 C per century (it would have been closer to 2 C per century with objectively determined breakpoints), which he then simply omits to get a zero C per century trend for his prediction. (Details from Nick Stokes at Moyhu)

    On top of that, he has performed a statistical analysis showing that total radiative forcing is a robust predictor of temperature, with a Transient Climate Response of 2.1 +/-1 C per doubling of CO2 (significantly greater than IPCC estimates).  Therefore he knows that the temperature history of the 20th century is a result of radiative forcings, not of a random walk.

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  10. > that statistical model to forecast future temperature changes.

    > It’s an approach that’s been used to predict financial market

    > changes, for example.

    You omitted the word "unsuccessfully" there.

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  11. Water vapor is a global warming gas, yet I see no discussion of its effect on global warming.  All the attention is given to CO2, yet there is more then 80 times (by volume) H2O versus CO2.  You would think that H2O would play some role in atmospheric temperature rises.

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    Moderator Response:

    [TD] See the post "Explaining How the Water Vapor Greenhouse Effect Works." First read the Basic tabbed pane, then the Intermediate one. In future, to find discussion of a topic, enter search terms in the Search field that is at the top left of every page. Or peruse the list of myths/arguments below that Search field.

  12. I have responded to richpender on the moderator suggested thread.  I'll note here that the very existence of that thread, not to mention papers like this one, and the host of papers on the water vapour feedback effect falsify richpender's claim that "All the attention is given to CO2".  It may well be true that he "...see[s] no discussion of [the effect of water vapour] on global warming", but that is not because it is not copiously discussed by the scientific community.

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