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Mind the Gap!

Filed under: — rasmus @ 18 November 2008

Mean temperature difference between the periods  2004-2008 and 1999-2003
Confusion has continued regarding trends in global temperatures. The misconception ‘the global warming has stopped’ still lives on in some minds. We have already discussed why this argument is flawed. So why have we failed to convince ;-) ?

Una traduzione in italiano è disponibile qui.

The confused argument hinges on one data set – the HadCRUT 3V – which is only one of several estimates, and it is the global temperature record that exhibits the least change over the last decade. Other temperature analyses suggest greater change (warming). Thus, one could argue that the HadCRUT 3V represents the lower estimate, if a warming could be defined for such a short interval.

Global mean temperature estimates: CRU, NASA-GISS data and the NCEP and ERA40 re-analyses
A comparison with other temperature analyses, such as the NASA/GISS (pink in the figure on the left), reveals differences. We can also compare with model-generated data (re-analyses), keeping in mind that one must be very careful with these data since they are not appropriate for studying long-term climate change (they give a misrepresentation of trends – at least on a local scale). Nevertheless, information from independent data suggest an increase in global mean temperatures even over the last decade.

All scientific questions involve some degree of uncertainties (error bars), and these can only be reduced if one can prove that they are influenced by an external factor (‘contamination’) or if some of the data are not representative for the study. Hence, if some of the data are incorrect, then it’s fair to exclude these to reduce the error bars. But this requires solid and convincing evidence of misrepresentation, and one cannot just pick the low values and claim that these describe the upper limit without proving that all the data with higher values are wrong. In other words, arguing that a lower limit is the upper bound is utter nonsense (even some who claim they are ‘statisticians’ have made this mistake!).

Another issue is that some of the data – i.e. the data from the Climate Research Unit (CRU) – have incomplete coverage, with large gaps in the Arctic where other data suggest the greatest increases in temperature. The figure below reveals the holes in the data knowledge. The figure compares the HadCRUT 3V data with the NCEP re-analysis.

Temperature measurements over the Arctic: CRU data and the NCEP re-analysis
Figure caption: The difference between Oct. 2007 – Sep. 2008 temperature average and the 1961-1990 mean temperature for HadCRUT 3V (upper left) and NCEP re-analysis (upper right). Below is a comparison between the 12-month 60N-90N mean temperature evolution (red=NCEP, black = HadCRUT 3v)). (click on figures for PDF-version)

Re-analysis data are results from atmospheric models where observed data have been fed into the models and used to correct the simulation in order to try to get a best possible description of the real atmosphere. But it’s important to note that the NCEP re-analysis and other re-analyses (e.g. ERA40) are not regarded as being appropriate for trend studies due to changes in observational systems (new satellites coming in etc). Nevertheless, a comparison between the re-analyses and observations can highlight differences, which may suggest where to look for problems.

Mean temperature difference between the periods  2004-2008 and 1999-2003
The animated figure shows the temperature difference between the two 5-year periods 1999-2003 and 2004-2008. Such results do not show the long-term trends, but it’s a fact that there have been high temperatures in the Arctic during the recent years.

The recent Arctic warming is visible in the animated plot on the right showing the NCEP re-analysis mean temperature difference between the periods 2004-2008 and 1999-2003.

The NOAA report card on the Arctic was based on the CRUTEM 3v data set (see figure below) which excludes temperatures over the ocean – thus showing an even less complete picture of the Arctic temperatures. The numbers I get suggest that more than 80% of the grid-boxes north of 60N contain missing values over the most recent decade.

Temperature measurements over the Arctic: CRU data and the NCEP re-analysis
Figure caption: The difference between Nov. 2007 – Oct. 2008 temperature average and the 1961-1990 mean temperature for CRUTEM 3v (upper left) and NCEP re-analysis (upper right). Below is a comparison between the 12-month 60N-90N mean temperature evolution. (click on figures for PDF-version)

The funny thing, however, is that the last decade of the Arctic CRUTEM 3v temperatures are closer to the corresponding estimates from NCEP re-analysis than the more complete HadCRUT 3v data. This may be a coincidence. The re-analyses use additional data to fill in the voids – e.g. satellite measurements and predictions based on the laws of physics. Thus, the temperature in areas with no observations is in principle physically consistent with surrounding temperatures and the state of the atmosphere (circulation).

Below is a figure showing a similar comparison between HadCRUT 3v and GISTEMP (from NASA/GISS). The latter provides a more complete representation of the Arctic by taking spatial correlation into account through an extrapolating/interpolating in space. But GISTEMP does not really have a better empirical basis in the Arctic, but the effect from the extrapolation (the filling in of values where there is missing data) gives the recent high Arctic temperatures more weight.

GISS-CRU warming difference over 1996-2004
Figure caption: The 2007 mean temperature anomaly wrt to 1961-90: (upper left) HadCRUT 3V, (upper right) GISTEMP, and (lower) temperature evolution for the Arctic (red=GISTEMP, black = HadCRUT 3v).

A comparison between temperatures over the most recent available 30-year period (1978-2007) shows high temperatures over parts of Russia (Figure below – upper left panel), and the difference between the GISTEMP and HadCRUT 3v shows a good agreement apart from around the Arctic rim and in some maritime sectors (upper right panel). The time evolution of the Northern Hemisphere mean for the two data sets is shown in the lower panel, showing a good agreement over most of the record, but with slightly higher GISTEMP estimates over the last 10 years (the global mean was not shown because my computer didn’t have sufficient memory for the complete analysis, but the two data sets also show similar evolution in e.g. the IPCC AR4).

GISS-CRU mean difference over 1976-2005
Figure caption: (upper left) HadCRUT 3V mean T(2m) anomaly over 1976-2005 (wrt to 1950-1980) ; (upper right) The GISS – HadCRUT 3V difference in mean T(2m) over 1976-2005; and (lower) the Northern Hemisphere mean temperature variations (red=GISTEMP, black=HadCRUT 3v).

Note, the low Arctic sea-ice extent over the last summers are independent evidence of high Arctic temperatures.

The insufficient observational coverage has also been noted by the IPCC AR4 and by Gillett et al. (Nature Geoscience, 2008), who argue that the observed warming in the Arctic and Antarctic are not consistent with internal climate variability and natural forcings alone, but are directly attributable to increased GHG levels.

They also suggested that the polar warming is likely to have discernable impacts on ecology and society (e.g.).

In their study, there are at least 15 grid boxes with valid data (usually representing one measurement) over 1900-2008 period. Furthermore, the only valid observations they used from the Northern Hemisphere were from the Arctic rim, as opposed to in the high Arctic itself. The situation is slightly better for the Antarctic (with one observation near the South Pole). Nevertheless, the title ‘Attribution of polar warming to human influence’ [my emphasis] is a bit misleading. Parts of the high-latitudes yes, polar no.

The attribution study was based on series of 5-yr-mean temperatures and spatial averages of 90 degree sectors (i.e. to four different sectors), where sectors and periods with no valid data were excluded.

There are some caveats with their study: The global climate models (GCMs) do not reproduce the 1930-1940 Arctic warm event very well, and the geographical differences in a limited number of grid-boxes in the observations and the GCMs may have been erased through taking the average value over the 90-degree sectors.

The 1930-1940 Arctic warming was probably not externally forced, but one could also argue that the models do not capture all of the internal variations because few reproduce similar features. Furthermore, the present GCMs have problems reproducing the Arctic sea-ice characteristics (which tends to be too extensive), ocean heat content, and fail to capture the ongoing decrease in Arctic sea-ice area. Most of these problems are seen in the gap with no CRUTEM 3v data, but there are also some uncertainties associated with the lack of data in the Polar regions.

The optimal fingerprint analysis hinges on the assumption that control simulations with the GCMs realistically reproduce the climate noise. I think that the GCMs do a good job for most of the planet, but independent work suggest local problems in the Arctic associated with a misrepresentation of the sea-ice extent. This may not have affected the analysis much, if the problem is limited to the high Arctic. Furthermore, the results suggested a one-to-one correspondence in trends between simulations and observations, but the analysis also gave a regression coefficient of 2-4 for natural forcings. The latter suggests to me that there may be some problems with the analysis or the GCMs.

Thus, this is probably not the final word on the matter. At least, I’m not convinced about the attribution yet. The whole boils down to insufficient amounts of empirical data (i.e. observations), GCM limitations at the high-latitudes, and too large data gaps. But the pronounced changes in the Arctic are consistent with AGW. The irony seems to be that the real world shows signs of more dramatic changes than the GCMs project, especially if you look at the sea-ice extent.

The lack of data in the polar region is a problem, and the ongoing International Polar Year (IPY) campaign is a huge concerted international effort to improve the data. Data is irreplaceable, regardless of the modelling capability, as science requires the theory to be tested against independent empirical data. The re-analyses provide a physically consistent description of the atmosphere – suggesting high temperatures in the Arctic – but we can only be sure about this when we actually have been there and made the real measurements (some can be done by satellites too)

A glimpse into the technical details
More technically, the complicated analysis involved a technique called ‘optimal fingerprinting‘ or ‘optimal detection’, looking for best signal in the noisy data and puts emphasis on regions where the GCMs give most realistic description of the climate variations. Basically, the optimal fingerprint techniques involved linear least-squares regression, which is familiar to many analysts.

The analysis of Gillett et al. involved ‘time-space’ orthogonal empirical functions (EOF) with truncation of 28 (and up to 78 modes for the Arctic, where the maximum truncation was the number of sectors multiplied with the number of 5-yr means – see supplementary material Fig. S3). These come into the equation through the estimation of the noise (covariance matrix), i.e. the internal variations and their magnitude. The clever thing is that they let each EOFs describe a set of 20 maps of 5-year-mean temperatures, thus representing both the spatial features as well as their chronology.

For the mathematically inclined, EOFs are similar to eigenvectors, and are mainly used to prepare data before further analysis. The purpose of using EOFs is often either to (i) compress the information or (ii) to make the data more ‘well-behaved’ (in mathematical terms: orthogonal). While one typically only use a few of the first EOFs, Gillett et al. experimented with just one up to the whole set because they took advantage of their orthogonal properties to allow the calculation of the inverse of the noise co-variance matrix. This is a neat mathematical trick. But this doesn’t help if the GCMs do not provide a good description of the internal variations.

419 Responses to “Mind the Gap!”

  1. 101
    Jim Eager says:

    Re Andrew @93: “Jim; I can appreciate that there is a lot more fresh water flowing into the arctic ocean. But as far as I know, that does not explain how there could be the large region of cooling temperatures in the arctic.”

    Not saying it does, just that there could be a link. I can think of one: fresher sea water near Arctic river mouths will freeze earlier, thus cutting off evaporation in local areas, and also changing albedo locally, both would lead to more cooling locally, no?

    Captcha is getting specific: 79.45 points

  2. 102
    John Lang says:

    Re #93: “Did you compare the numbers in the two studies? I very much doubt that there’s a conflict.
    Comment by Steve Bloom”

    I would like to able to compare the data in the studies but one needs a subscription to the AGU. Google searching produced one chart from the study which only indicated an average 1.0 w/m2 impact (versus 2.0). Does anyone have link to a public copy of the study or the data?

  3. 103
    Eli Rabett says:

    That was Werner Aeschbach-Hertig who now has his own blog, Reality Check. Eli blogged on the Aeschbach-Hertig vs Chillingar.

  4. 104
    Steve Reynolds says:

    >Both papers show positive water vapour feedbacks.- gavin]

    Do these measured feedbacks agree quantitatively with your models?

    The factor of two they quote seems too small to even reach 2.5C climate sensitivity without other major effects.

  5. 105
    Rod B says:

    Hank (91), the acid rain problem in Central-Eastern Europe came from high stacks to get the stuff out of the source city, and destruction was wide spread, but not by very much — barely into the neighboring country.

  6. 106
    Rod B says:

    Ike (75), the big bad oil companies direct NASA, direct DOE, own Congress (the same folks, including Dingell, who publicly pillory oil CEOs, before they try to stick ’em up every time gas prices hiccup higher), pretty much own the press, and can turn scientists into charlatans with the wave a some bucks. Is that right?? Boy! You credit them with way more competence than I would. And did I hear you right? — they also corrupted the 1880 sea merchants into taking bad temp readings??

  7. 107
    steven mosher says:

    RE 72. Interesting. You can see the coverage here

    Now, whether this amount of coverage is enough to find a “reliable” mean, that is another question. And it poses the question “reliable for what?”

    You’ll note of course a heavy reliance on coastal areas for land temps.

    With the grey areas representing areas of no coverage.

  8. 108
    Hank Roberts says:

    > destruction was wide spread, but not by very much

    Yep; I wasn’t saying it was a _good_ idea. Nor did Eastern Europe adopt either the tall stack-high velocity or the late 1970s sulfate scrubber. I’m just saying those three Alaska stations are cherries.

  9. 109
    Pierre Allemand says:

    What about SSTs ?
    It seems, according to the site of the NOAA ( that weekly SST have stayed stable and even have slightly decreased since 1998.
    SSTs are probably the most reliable indicator of températures evolution. Can you comment ?

  10. 110

    Gavin and CO.

    Your article deals with the issue if the global warming has stopped.
    Or “Has temperatures stopped rising?”

    Your firs graph:
    1) It contain data that is – as you know – wrongly showing 2005 as warmer than 1998, which is wrong.
    There is no excuse for not correcting this when the whole issue is exactly the temperatures of the very last years.
    Question, please answer honestly: Why have you not showed a true temperature curve?
    This is “real climate”, not?

    [Response: It depends on which data source you look at. If you look at HadCRUT 3v then 1998 is warmest because of the strong El Nino. These data are for real. -rasmus]

    2) You know of course that GISS/NOAA graphs lately has a much higher temperature-rising-trend that the sattelite data.
    If you want to present “Real climate” why is there no mention of the sattelite data what so ever?

    [Response:Have a look at our old posts (here , here & here) . Please do your home work before you accuse RealClimate for not discussing sattellite data. -rasmus]

    Then antother graph of yours, the temperatures of the arctic.
    Do you want to show people the real temperatures of the arctic?
    If so, why do you print a graph with lattitudes down to 60 degrees N??
    60 degress, well thats like Stockholm, and many other big scandinavian towns, All Finland, and near Sct Petersburg..

    [Response: The Arctic is often defined as being north of 60degN.]

    You know as well as i that if you take range like 90N – 70N or 90N – 66N or even 90N – 64N will show much less warming compaired to the 1940´ies, dont you?

    [Response: Not true – see the ACIA report (Fig 2.6 in Chapter 2). Please do your home work before making claims. -rasmus]

    These are the only graphs i took a look at. A dare not see the rest.

    [Response: Yes – the graphs can be quite scary. -rasmus]

    K.R. Frank lansner

  11. 111

    Here is the true simple facts:

    If you go back to jan 2001 with GISS data, you will get a flat trend curve.
    If you go back to feb 1997 with RSS data, you will get a flat trend curve.
    In average you then have 9 years and 9 months of flat trend.

    As you know, Hansen needed less than 10 years trend after the 1978 low temperature point to claim catastrophical warming trend.

    But now when trend is stopping, 10 years is not enough?

    How many more yeats should go by with no temperature raise before you accept that temperatures are nor raising?

    And its not just ten years. Oh no, its ten LAST years, and there is nothing substantial what so ever to claim that a temperature raise is arouns the corner. On the contrary, AMSU daily says Down for now, Sun is sleeping and PDO is wild in cold mode.

    NOAA is even predicting a mild La Nina into at least mid 2009..

    [Response: (i) Have a look at the following YouTube animation. A decade is too short for trend analysis in the presence of decadal internal variations. The important thing is what the future developments will look like. (ii) Have a second look at the graphics: GISSTEMP & NCEP re-analysis. -rasmus]

  12. 112
    Jonathan Bagley says:

    Re: speculation as to why there are a large number of climate change deniers.
    I think you are being a little patronising. Two years ago I had little interest in global warming, as it then was. I had been looking into “passive smoking”, following the announcement of the English smoking ban and discovered the junk statistics and propaganda used to justify it. I teach statistics and probability so I was amazed by my own naivety. I then decided, in an idle moment, to see if I could find a climate change “denier” (what an offensive term) who wasn’t regarded as a crank. I’d heard of Lindzen so I looked him up in wpedia, where much was made of his views on smoking and passive smoking, which seemed like an attempt to discredit him. The usual row went on on the discussion page. Here is a quote:

    “There’s a common pattern of global warming skeptics having also denied or played down the risks of smoking, for example Steven Milloy, Fred Singer, Frederick Seitz, Alexis de Tocqueville Institute and so on. Obviously, as you say, this tends to discredit their views in general, suggesting either poor judgement or conflicts of interest. The general point is more relevant to global warming controversy, so I’ll add it there. JQ 06:40, 18 April 2007 (UTC)”

    Well this was enough for me. Judge a man by his friends and enemies. I started looking into the subject became a man-made global warming sceptic. Why did you change its name? It didn’t work for Windscale. I am not a denier and I don’t care what happens to the planet. I now just take an interest in the subject out of intellectual curiosity. I know it is not your fault, but your supporters do your cause no favours.

  13. 113
    MrPete says:

    Edward (#65), that’s simply ridiculous.

    The entire value proposition of Google is that you can’t “game” the system. There’s no way to purchase a high ranking. And there’s a constant battle to ensure only “honest” references add to the priority of a site.

  14. 114
    simon abingdon says:

    #92 Kevin The “underlying trend” does not exist. It is an artificial concept: a construct used by statisticians in a futile attempt to predict the future when their knowledge of the relative importance and consequent interplay of all the actual forces causing change is insufficient. Hence the continuing arguments over when an imagined “trend” becomes significant.

  15. 115
    MacDoc says:

    #79 Rod B Says:
    19 November 2008 at 10:20 AM

    MacDoc (59) seriously puts forth arguments that I throw out cynically and derisively. One of us has to be wrong. I contend the 20 trees replacing the shrubs along the crick (or any other local phenomena) is no indication of global warming, let alone anything near a proof.


    The crick bit was seriously tongue in cheek but when the phenomena covers the entire northern hemisphere it is NOT local at all.

    Biota have well established ranges of warmth requirements. When you have a massive migration towards regions previously too cold for species that’s a superb analogue signal with very little noise given the breadth of the signal.

    If anything gathering a group of ubiquitous species that have strictly defined temperature requirements to use as monitors anywhere would seem most sensible practice.
    This takes away the criticism that there are too few monitoring stations.

    Derive a metric from biota change – we’ve certainly enough data both migration north and also vertical for temperature tolerance.
    Then the sampling frequency issue is gone.

    Would it give us month by month readings? – no – would it establish trend direction?…..undeniably, and that’s my point.
    There is no need to “convince” in situ biologicals that it’s getting warmer –
    They just move north or up as the warmth allows.

    It’s for the benefit of one mistakenly skeptical species. ;-)

    Biota changes are simply a broad based clear analogue signal that “Yes Victoria it IS getting warmer.”

    Leave it then to the science wonks to measure how fast and what the drivers are. The plants and animals and ocean species changes are purely the observable test on a broad scale.
    They tell us a direction of change – not the cause.

    If there are new trees around one crick it’s local, if there are new trees on 1,000,000 cricks across a continent – it’s climate change.

  16. 116
    MrPete says:


    I know there’s a lot of concern about pH, and don’t want to discount that. However, it pays to be skeptical about attribution-piling-on.

    Example: there’s a lot of assumptions being made about the impact of pH on coral reefs. A powerful alternative explanation is quickly gaining traction. Are you aware of the recent and growing body of research showing that coral reef impact has not been due to pH but rather to sunscreen?!! Amazingly, it takes only a tiny amount of sunscreen in the water to cause a tremendous amount of damage.

    This is an area of some interest to me, and even more to my wife (she studied at Hopkins, one of the leaders in marine research…)

  17. 117
    Anna Loftin says:

    Hi all – I’ve been following your conversation and think the bottom line is that changes in global temperatures are happening and in order to make an impact, we need to influence decision-makers.

    On the 11th December 2008, European political leaders will decide what their response to global warming is going to be. Last year, they agreed to a 30% cut in greenhouse gas emissions by 2020 to keep the earth’s temperature below 2 degrees. Now, with the downturn in the economy, they are promising only 20%.

    As a result, Friends of the Earth, Greenpeace and World Wildlife Fund through the coordination of the Climate Action Network (CAN) formed the campaign Time to Lead (which I am currently working on). Time to Lead is a movement that urges European citizens and organisations to act by contacting local government leaders and issuing support of the 30 percent reduction in Europe’s own carbon emissions by 2020. Citizens act by joining the ‘call to action’ at The site also offers interesting statistics on this argument. Have a look and pass it on.

  18. 118
    Mike Tabony says:

    Mr. Bagley (#109),

    No need to read all these words to decide if AGW is occurring. Ask a local farmer, gardener, or even bird-watcher if they noticed warmer or cooler temperatures in their outdoor activities over the past decade or two. (Here in Virginia, USA, winters are almost non-existent compared to a mere 25 years ago and the old-timers talk about real cold when a horse and loaded wagon could cross the James River on the ice, when blocks of river ice were cut to be used in underground icehouses before electric refrigeration.) Ask around your neighborhood and don’t forget to observe nature for yourself.

    Consider that every gallon of petroleum product burned adds roughly 20 pounds of fossilized carbon dioxide to the atmosphere and we humans burn over 3 billion gallons a day. Every kilowatt-hour of coal-generated electricity adds almost 2 pounds of fossilized carbon dioxide to the atmosphere.

    I hate AGW as much as the next guy as it demands from me “an inconvenient responsibility”, a responsibility to the future of my species, my biosphere, my planet. This responsibility has changed my life. Significantly reducing your fossilized carbon footprint is not an easy task and, in my opinion, that is the main reason there are so many who choose not to believe.

  19. 119

    A short answer to the sophmoric “hasn’t risen for ten years” would be to enumerate all of the past periods when the same statement might be made.

  20. 120
    Lawrence Coleman says:

    Re:83 Geoff Beacon. I also do not believe the methane issue is factored into the principal climate models used by the IPCC. Methane is 20x more potent a greenhouse gas than CO2 is. The length of time methane is in the atmosphere is only a small fraction of what CO2 is. However there are billions of tonnes of the stuff tied up a methane hydrates under the arctic ocean and now begining to be released as the ocean floor warms. The same is true for the tundra of siberia, scandinavia, canada and alaska. I dont know if methane contributes directly to ocean acidification- I dont think it does. Water vapour is the prime mover of climate. An imbalance of CO2 and CH4 and N2O (nitrous oxide) changes the hydrologic cycle. We should indeed be very concerned about methane. Even a 1-2C increase in the arctic floor raises the temp above 0C and massive amounts of CH4 are then released.

  21. 121
    Ray Ladbury says:

    Jonathan Bagley, Lindzen ceased to be a scientist for me when he claimed that there was a common warming mechanism throughout the solar system–implying a solar mechanism. The thing is, in the outer solar system, the Sun doesn’t even provide the majority of the energy budget of the gas giant planets! Lindzen is too intelligent not to know this, so I can only assume that when he brings up points like this in front of a lay audience, he is intentionally trying to mislead them.

    I hope your students canget their money back.

  22. 122
    Rod B says:

    Hank, well enough. Whether the Alaska stations are cherries or not is a valid debate. But that’s a (proper) retraction from the professed argument (implied by you — at least what I inferred, and explicitly stated by Ray) that the low Alaskan temperatures were a direct result of the sulfate pollution/aerosols from CONUS, and mostly eastern CONUS.

  23. 123
    Lawrence Coleman says:

    Re:83 read that article in the guardian. Why it has not yet been used in climate models is because there is not enough consistant data to make an accurate calculation. The permafrost lid may well be perforating as a result of CC but not uniformly or it could be an increase of land slides on the ocean bed or volcanic activity etc. Some CH4 as small gas bubbles which are absorbed again by seawater or used by micro-organisms on the way up..only the visable gas bubbles make it to the surface and because of the vast areas involved and the harsh climate in those locales getting reliable data is difficult. All the IPCC can do is hypothesize and say OK..if this relative amount or that amount is released over a predetermined time frame what climate forcing will that produce. Then it’s up to the researchers on the ground to go out and collect as much data as possible to slot into their equations. Not easy!

  24. 124
    Rod B says:

    Jonathan (111), Junk science, made-up statistics, and ad hominems are perfectly acceptable by some (not all by any means) in the pursuit of what is deemed a good cause, especially second hand smoke, and also a bit of AGW.

    You’re likely to catch hell.

  25. 125
    Hank Roberts says:

    > Judge a man by his friends and enemies

    Judge a corporation by its lawyers, and an industry by its lobbyists and PR firms. You fell for a PR program, J. Bagley.

    I’ll bet you know the phrase “sound science” — have you ever wondered where it came from? Look it up. Here, this will help:

    Constructing “Sound Science” and “Good Epidemiology”: Tobacco, Lawyers, and Public Relations Firms – ► [HTML]
    EK Ong, SA Glantz – American Journal of Public Health, 2001 – Am Public Health Assoc …
    Cited by 120

    Turning Science Into Junk: The Tobacco Industry and Passive Smoking – ► [HTML]
    JM Samet, TA Burke – American Journal of Public Health, 2001 – Am Public Health Assoc
    … The goal of “sound science” seems an admirable one; it should not, however, be used to dismiss available but uncertain evidence in order to delay action. …
    Cited by 33

    Attacks on Science: The Risks to Evidence-Based Policy – ► [HTML]
    L Rosenstock, LJ Lee – American Journal of Public Health, 2002 – Am Public Health Assoc
    … TACTICS USED TO UNDERMINE SOUND SCIENCE. … Economic Manipulation. First and foremost, vested interests may use money to inhibit or stall sound science. …
    Cited by 68

  26. 126

    #111 (Jonathan Bagley):

    “Well this was enough for me. Judge a man by his friends and enemies.”
    Wouldn’t it be more appropriate to judge him by the substance of his arguments?

    “I started looking into the subject became a man-made global warming sceptic.”
    Well, I do hope you continue looking, as there are mountains of evidence in favor of the AGW hypothesis.

    “Why did you change its name? It didn’t work for Windscale.”

    Huh? Who is the “you” in your statement? RealClimate? I know of no reason to suspect this site of any great responsibility for shifting terminology.

    “I am not a denier and I don’t care what happens to the planet. I now just take an interest in the subject out of intellectual curiosity.”

    You are boggling my mind here. How can you not care what happens to the planet, and why would you think that that is somehow persuasive? Do you not plan to live on this planet?

    “I know it is not your fault, but your supporters do your cause no favours.”

    I regret it if you are offended by the comments of some AGW proponents, but there are lots of over-the-top comments on the other side, so I don’t think this factor should determine your opinion of the reality of AGW. (Just this morning on another site, for instance, one denialist accused James Hansen of lying repeatedly. This, based on an newspaper opinion piece which said no such thing–biased and one-sided though the piece was. Offensive and unfair, but as you point out, it’s not the responsibility of everyone who disagrees with me on the subject–say, you, or RC resident skeptic Rod B!)

    My perception is that by and large, denialist sites–and I use the term intentionally to denote those who systematically refuse to consider evidence for AGW; sorry if it offends you, but to me it is accurate and differentiates from the merely skeptical–denialist sites in general are quite rife with illogical or even paranoid arguments; with the ad hominem argumentation they object to so strenuously when used against them; with unsupported assertions; with an unbecoming eagerness to seize at flimsy ideas (Svensmark comes to mind) as if proven while rejecting ideas long since proven quite robust by the scientific process of ongoing criticism and validation; and with a generally low quality of discourse. Of course there are exceptions–people who put forward arguments that have at least some substance and who challenge one’s understanding of the science. The latter do us all a favor; the former, not so much.

  27. 127

    I don’t care what happens to the planet.

    They why are you posting here?

  28. 128
    Arch Stanton says:

    Jonathan Bagley (111),

    A single post by a non-professional is enough for you, and you choose to post about it rather than the data and statistics (your area) presented in the topic…

    Also, who is “you?” in “Why did you change its name?” The IPCC has been such since its formation in the late 1980’s and I suspect that the term “climate change” predated that. The reason for the change should be obvious; it more accurately reflects the scope of the issue. Perhaps it should once again be changed to “environment change” to more accurately encompass the issues of ocean acidification…? Naw, that would likely be “enough” for someone else.

  29. 129
    gerda says:

    111 Jonathan Bagley

    if you are a statistician you might find this site interesting;

  30. 130
    William Jones says:

    Why would anyone try and argue that the near surface tropospheric anomaly trend has stopped rising? It obviously hasn’t.

  31. 131
    David B. Benson says:

    gerda (127) — Second your recommendation.

  32. 132
    Stuart Harmon says:

    I thought this link would assist the debate regarding Arctic temperatures.

    No sea ice in 1922? Flora and Fauna changing?

    Interestingly the lack of sea ice and warmer temperatures were perceived to be a good thing.

    Please draw you own conclusions one of the few good things about statistics is they cannot disprove factual evidence.

    Finally it is about time that all the name calling stopped? Alarmists Denialist etc whats that got to do with proper scientific debate.

    [Response: What does cut and pasting anecdotes from old newspapers have to do with scientific debate either? Look at the sea ice for 2007 or pretty much any recent year and see where the summer ice line was compared to the exceptional 1922 summer. It might have been exceptional then, but it would be a cold year compared to any of the last decade. – gavin]

  33. 133
    Alexandre says:


    On your response to Frank Lansner

    [Not true – see the ACIA report (Fig 2.6 in Chapter 2)]

    Didn´t you mean Fig. 2.7?

  34. 134
    Geoff Beacon says:

    Re:118 Thank you Lawrence. I wish I could get an “official” reaction to this danger. I’m getting responses like “We can’t estimate it properly so we’ll ignore it.” That’s not good enough.

    Btw isn’t 70x CO2 more realistic for methane? 20x is the impact measured over 100 years. I doubt we have that long.

    I’ve just noticed your other post (#121). I did read the Guardian article and much more. I’ve a quote from last year “The CH4 (and CO2) permafrost feedback isn’t included in current
    EarthSystemModels and it is potentially large but no-one really knows.”

    Have we time to wait for definitive research. Or will the Earth beat the researchers to it?

  35. 135
    Steve Bloom says:

    Re #102 (John Lang): Both papers are available on Andrew Dessler’s site. Note also Gavin’s reply to your #89.

  36. 136
    Hank Roberts says:

    I suspect Mr. Bagley was doing instant messaging, maybe about other things, or about RC, and typed a reply into the response by mistake. Stuff happens.

    Statistics — any publications? Writing up a problem with the tobacco epidemiology will find ample opportunity to publish, as you can see if you look.

  37. 137
    tom says:

    Which portions of the globe weren’t covered? In 1880, the sun never set on the British Empire, the American frontier was on the verge of being closed, and Latin America, Africa, and Asia all had their temperature stations. I’m sure the coverage wasn’t as comprehensive as now, but that doesn’t mean they didn’t have enough to find a fairly reliable mean.”

    There are major data coverage and integrity issues with the global and US databases. I’m talking now, not just the 1880’s either.

  38. 138
    Michael Mullendore says:

    The reason there are so many \deniers\ is that the science is a lot more ambiguous than the \alarmists\ will concede. It is not difficult to come to the conclusion that the AGW believers are the \deniers\ when they fail to acknowledge the many issues which are not consistent with the IPCC beliefs. The lack of the hot spot, the considerable disparity of the 4 main global temperature measurements, the ardent denial of any solar impact on global temperature, etc. are vehemently dismissed as relevant issues by the AGW believers. Any reasonable scientist understands this is hogwash and until the AGW proponents calm down and legitimately address these issues, the \denialists\ are quite likely to increase in number.

    [Response: Frankly, I have no idea what you are reading. IPCC is almost by definition the mainstream position – tell me in which section you find that the ambiguities are not discussed, or that there is a failure to acknowledge uncertainties. On the contrary, the report is chock full of such things. But instead of reading what is actually being siad (as opposed to some imagined paraphrase gleaned from god knows where), you come back with a bunch of straightforward rubbish: the ‘hot spot’ is seen in many of the analyses of the radiosonde data (and why aren’t you acknowledging the ambiguity in those data eh?), the 4 temperature sets are just not that different; I have written half a dozen papers on the solar impact on climate (odd for a ‘denier’) – and so, yes, your statements are dismissed as hogwash, because they are. Why not try actually focusing on the real uncertainties instead of made up ones? – gavin ]

  39. 139
    Stuart Harmon says:

    Post 132

    Please come of it Gavin, your response is disingenous. We are told that Arctic Sea Ice extent is the lowest since records began, without the proviso that the satellite record is 30 years old. As to cutting and pasting I gave a link to a record which provided evidence of a reduction of sea ice in 1922 and a commentary regarding a warm period in the arctic. The article was in the Monthly Weather Review and posted by the American Consul at Bergen.

    The observer interviewed in the article was a sea captain who had sailed in the area for fifty years and commented that he had observed a period of warming. So it was not just one year of warming?

    Maybe I am an old fashioned guy but I thought observation was a part of science. Just as measuring the width of tree rings is observation.

    Anyway Take care.

    [Response: But you don’t seem to realise that previous observations are in fact built in to the statements about sea ice. Old ice charts from the Danes, UK, Norway etc. go into the HadISST product for instance. The ice was more extensive in the past, and in fact there are plenty of old observations of extensive land fast ice back in the 18th Century that simply doesn’t exist any more. That is not being disengenuous. What is disengenuous is quoting a 1922 report without putting it context to imply that nothing is different now – you could not be more wrong. – gavin]

  40. 140
    Jared says:

    One interesting thing to note is that GISS and satellite-measured lower tropospheric temperatures have seen a rather large divergence this year. Since 1999, GISS has been between .008C and .055C warmer than UAH, with most years around .045C to .050C (when you put them both on the same baseline). So far in 2008, however, GISS is running .142C warmer than UAH…and since March, that number is +.199C.

    While it is understood that surface data and satellite data do not measure the same exact thing, it is kind of strange that there is a much larger differnce this year compared to recent years. Any ideas about what could be causing the larger divergence this year?

    [Response: The satellite records clearly have more sensitivity to ENSO than the surface (look at 1998), therefore it’s unsurprising that they would cool more associated with the La Nina earlier this year. – gavin]

  41. 141
    Lawrence Brown says:

    “On the 11th December 2008, European political leaders will decide what their response to global warming is going to be.”

    On the 21st of January,the U.S. will be able to join the other western leaders to help mitiagate change, and reverse the shameful record of obstruction, censorship,delay,lip service, and other odious ways of being counter-productive,by the present administration, in regard to energy,environmental, and climate change policy.

    In the main post Rasmus states:”Furthermore the,the present
    GCM’s have problems reproducing the Arctic sea-ice characteristics, …………. and fail to capture the outgoing decrease in Arctic sea-ice area.
    Anyone looking at time lapse photos of the sea ice,in this area,over the past few decades, can’t fail to recognize that it is dramatically shrinking,-not to mention the appearance of the fabled Northwest passage ,recently, as a reality, at least for parts of the year.Including this phenomenon in the models,while desirable,is in some ways extraneous, since one can almost predict the disappearance of Arctic sea ice in the not too distant future.

  42. 142
    Marcus says:

    I don’t suppose RealClimate has a carbon cycle expert who might want to weigh in on the potential overstating of the recent Australian soil carbon results? Sadly, neither of the two institutions through which I can get journal articles has a Nature Geoscience subscription, so I’ll have to wait until I can swing by the Library of Congress to actually dig into the details. But what I can gather from the internet is that they discovered that soils release significantly less carbon into the atmosphere than had been previously expected due to stable “black carbon” forms of char from old fires. Of course, the implication that I would take from this result is one of a few possibilities: first, given that the soil system has to be approximately in balance, then the soils must either be taking up less carbon than expected, or there must be another soil respiration mechanism. Second, the result is not actually applicable outside Australia. Third, the result is just wrong (remember the big “live plants generate methane” result that seems to have disappeared into the ether from a few years back?).

    But the authors seem to be pushing the “global warming predictions are overestimated” angle instead, which just seems weird. I know that AR4 models average about 60 ppm increase out to 2100 from land carbon cycle feedbacks, presumably in part due to increased soil respiration from higher temperatures. But I can’t imagine that the black carbon stability would reduce this feedback by more than half, and 30 ppm, while a nice benefit, is still small peanuts compared to 700+ ppm BAU scenarios. Any thoughts?

  43. 143

    Do we know why, from 1900 to 1940, there was a strong warming ? As for the latest respite in global warming, this is not surprising because of La Nina (and associated Indian Ocean cooling)or decadal variability. The IPCC should not have filtered the data, these took out of the picture the swing in temperature due to El Nino and La Nina. I guess they did not want to confuse the policy makers. Cheers

    [Response: The difference between the 1900-1940 warming to the present warming was that the former mainly involved the high northern latitudes whereas the latter has been more uniform accross all latitudes. -rasmus]

  44. 144
    PHE says:

    Re gavin’s response to 138 and 139. gavin, your response and belittling of the commentators says it all. Your faith has completely overtaken your scientific judgement. Your attitude only serves to demonstrate to those who have retained their scientific judgement that your arguments are weak.

    [Response: Actually it isn’t. It’s just a sign that my patience is finite for people who repeat half digested talking points without doing any thinking and then accusing me of being rigid. There is nothing wrong with talking about real uncertainty (aerosol microphysics and the indirect effect, tropical convection, the impacts of ocean eddies) and I’d be happy to. But this continued elevation of nonsense over thought is tiresome. – gavin]

  45. 145
    Vince says:

    [Response: The satellite records clearly have more sensitivity to ENSO than the surface (look at 1998), therefore it’s unsurprising that they would cool more associated with the La Nina earlier this year. – gavin]

    Hello. I’m wondering why, if the above is correct, would the divergence between GISS and UAH increase towards the middle of the year as La Nina conditions returned to neutral? Is there a delayed reaction to ENSO in satellite readings that doesn’t apply to land station data?

  46. 146
    Lawrence Coleman says:

    Re:134 Geoff Beacon. I wouldn’t say they are ignoring the methane issue (nearly all environmental groups I have read articles from understand the potential consequences of methane) but because the data out there is so sketchy and the mechanics of the interactions are still not that well understood re: CH4 vs CO2/N20 O2 CFC’s etc at different layers of the troposphere etc, different temps. Oh yeah! Small methane bubbles on the way up from the ocean floor join also with O2 molecules and form CO2..(presumably releasing hydrogen in the process) so yes methane does contribute to ocean acidification after all. I sincerely hope with the turmoil of the Global financial crisis that funding of important climate and environmental research is not reduced or thought be be less important that propping up the likes of GM, Ford or Crysler who after all are partly responsible for this dire predicament we all find our selves in. (I drive a Honda Civic for the record!)
    At a time when climate science funding should be greatly increased globally the GFC could not have happened at a worse time.

  47. 147
    MacDoc says:

    139 Stuart Harmon says

    “The observer interviewed in the article was a sea captain who had sailed in the area for fifty years and commented that he had observed a period of warming. So it was not just one year of warming?

    Maybe I am an old fashioned guy but I thought observation was a part of science. Just as measuring the width of tree rings is observation.”

    The Arctic ice is just ONE indicator out of many and there are massive amounts of data, observations of fauna arrival, nesting, plant blossoming going back far earlier, some more than a century or even multiple centuries all of which support accelerating warming.

    Treeline changes and tundra lines moving are broadbased so if you accept the need for observation, as I do – then the ice aspect is just MORE support for the trend and those trend lines in many cases are decades and in a few, centuries long.

    Long trendlines across diverse species and diverse locations – robust signal. Our satellites only now give dramatic images to what the biota have been responding to.

    Now certainly some long cycle decadal plus cycles may be in play for the oceans but the trend line across environments and species is far too consistent to in anyway deny that it IS warming and has been for a long while – consistent with GHG changes.

    In my view the nitpicking about manmade sensor readings and coverages too often ignores the broad based signal already provided by temperature sensitive species.

    Plants are far slower but more consistent responder than said fisherman’s recollections.

    Again this is aimed at those that deny the warming trend exists at all.

    Quantifying the trend rate over time and assigning cause….different gordian knot.

  48. 148
    Paul says:

    But this is about the Northern hemisphere is it not? Don’t we need to address this question of global trends with reference to global data and analysis?

    Even those nifty spinning globes fail to show a large chunk of the southern hemisphere.

  49. 149

    Re: #25

    Dear Dr. Pelto,

    Your site has a photo (2nd from top on far right column) with this legend:

    “Lyman Glacier taken from same location in 1988 and 2008.”

    but the photos seem not to have been taken from the same location.

    Dr. Pelto, if you believe that Mark Fiore is correct, what should we be doing?

  50. 150

    Well … I’ve said for a number of years now that we’ll learn how much influence the sunspot cycle has on climate when Solar Cycle 24 gets underway.

    Perhaps instead of saying “10 years isn’t long enough” the pro-AGW crowd will start to recognize that the giant ball of fire has an influence? If SC24 continues as it is now, the next 11 years (or more — mild cycles last longer)) will see a steady decline in global average temperature and an increase in skepticism. In addition to the present handed us by the Asian Brown Cloud, we’re also being handed a present in the form of SC24. We need to act very aggressively to reduce CO2 emissions.

    In response to a comment up-thread about reducing CO2 levels — it can be done. Just make the right choice every time you can.

    (reCaptcha says — “motorman shoes”. I wear boots when I ride my electric motorcycle — shoes wear out to easily ;) ) (Oh, yeah, I bought an electric motorcycle — a Vectrix — to help cut my gasoline consumption.)