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Of buckets and blogs

Filed under: — gavin @ 1 June 2008

This last week has been an interesting one for observers of how climate change is covered in the media and online. On Wednesday an interesting paper (Thompson et al) was published in Nature, pointing to a clear artifact in the sea surface temperatures in 1945 and associating it with the changing mix of fleets and measurement techniques at the end of World War II. The mainstream media by and large got the story right – puzzling anomaly tracked down, corrections in progress after a little scientific detective work, consequences minor – even though a few headline writers got a little carried away in equating a specific dip in 1945 ocean temperatures with the more gentle 1940s-1970s cooling that is seen in the land measurements. However, some blog commentaries have gone completely overboard on the implications of this study in ways that are very revealing of their underlying biases.

The best commentary came from John Nielsen-Gammon’s new blog where he described very clearly how the uncertainties in data – both the known unknowns and unknown unknowns – get handled in practice (read that and then come back). Stoat, quite sensibly, suggested that it’s a bit early to be expressing an opinion on what it all means. But patience is not one of the blogosphere’s virtues and so there was no shortage of people extrapolating wildly to support their pet hobbyhorses. This in itself is not so unusual; despite much advice to the contrary, people (the media and bloggers) tend to weight new individual papers that make the news far more highly than the balance of evidence that really underlies assessments like the IPCC. But in this case, the addition of a little knowledge made the usual extravagances a little more scientific-looking and has given it some extra steam.

Like almost all historical climate data, ship-board sea surface temperatures (SST) were not collected with long term climate trends in mind. Thus practices varied enormously among ships and fleets and over time. In the 19th Century, simple wooden buckets would be thrown over the side to collect the water (a non-trivial exercise when a ship is moving, as many novice ocean-going researchers will painfully recall). Later on, special canvas buckets were used, and after WWII, insulated ‘buckets’ became more standard – though these aren’t really buckets in the colloquial sense of the word as the photo shows (pay attention to this because it comes up later).

The thermodynamic properties of each of these buckets are different and so when blending data sources together to get an estimate of the true anomaly, corrections for these biases are needed. For instance, the canvas buckets give a temperature up to 1ºC cooler in some circumstances (that depend on season and location – the biggest differences come over warm water in winter, global average is about 0.4ºC cooler) than the modern insulated buckets. Insulated buckets have a slight cool bias compared to temperature measurements that are taken at the inlet for water in the engine room which is the most used method at present. Automated buoys and drifters, which became more common in recent decades, tend to be cooler than the engine intake measures as well. The recent IPCC report had a thorough description of these issues (section 3.B.3) fully acknowledging that these corrections are a work in progress.

And that is indeed the case. The collection and digitisation of the ship logbooks is a huge undertaking and continues to add significant amounts of 20th Century and earlier data to the records. This dataset (ICOADS) is continually growing, and the impacts of the bias adjustments are continually being assessed. The biggest transitions in measurements occurred at the beginning of WWII between 1939 and 1941 when the sources of data switched from European fleets to almost exclusively US fleets (and who tended to use engine inlet temperatures rather than canvas buckets). This offset was large and dramatic and was identified more than ten years ago from comparisons of simultaneous measurements of night-time marine air temperatures (NMAT) which did not show such a shift. The experimentally-based adjustment to account for the canvas bucket cooling brought the sea surface temperatures much more into line with the NMAT series (Folland and Parker, 1995). (Note that this reduced the 20th Century trends in SST).

More recent work (for instance, at this workshop in 2005), has focussed on refining the estimates and incorporating new sources of data. For instance, the 1941 shift in the original corrections, was reduced and pushed back to 1939 with the addition of substantial and dominant amounts of US Merchant Marine data (which mostly used engine inlets temperatures).

The version of the data that is currently used in most temperature reconstructions is based on the work of Rayner and colleagues (reported in 2006). In their discussion of remaining issues they state:

Using metadata in the ICOADS it is possible to compare the contributions made by different countries to the marine component of the global temperature curve. Different countries give different advice to their observing fleets concerning how best to measure SST. Breaking the data up into separate countries’ contributions shows that the assumption made in deriving the original bucket corrections—that is, that the use of uninsulated buckets ended in January 1942—is incorrect. In particular, data gathered by ships recruited by Japan and the Netherlands (not shown) are biased in a way that suggests that these nations were still using uninsulated buckets to obtain SST measurements as late as the 1960s. By contrast, it appears that the United States started the switch to using engine room intake measurements as early as 1920.

They go on to mention the modern buoy problems and the continued need to work out bias corrections for changing engine inlet data as well as minor issues related to the modern insulated buckets. For example, the differences in co-located modern bucket and inlet temperatures are around 0.1 deg C:

(from John Kennedy, see also Kent and Kaplan, 2006).

However it is one thing to suspect that biases might remain in a dataset (a sentiment shared by everyone), it is quite another to show that they are really have an impact. The Thompson et al paper does the latter quite effectively by removing variability associated with some known climate modes (including ENSO) and seeing the 1945 anomaly pop out clearly. In doing this in fact, they show that the previous adjustments in the pre-war period were probably ok (though there is substantial additional evidence of that in any case – see the references in Rayner et al, 2006). The Thompson anomaly seems to coincide strongly with the post-war shift back to a mix of US and UK ships, implying that post-war bias corrections are indeed required and significant. This conclusion is not much of a surprise to any of the people working on this since they have been saying it in publications and meetings for years. The issue is of course quantifying and validating the corrections, for which the Thompson analysis might prove useful. The use of canvas buckets by the Dutch, Japanese and some UK ships is most likely to blame, and given the mix of national fleets shown above, this will make a noticeable difference in 1945 up to the early 1960s maybe – the details will depend on the seasonal and areal coverage of those sources compared to the dominant US information. The schematic in the Independent is probably a good first guess at what the change will look like (remember that the ocean changes are constrained by the NMAT record shown above):

Note that there was a big El Niño event in 1941 (independently documented in coral and other records).

So far, so good. The fun for the blog-watchers is what happened next. What could one do to get the story all wrong? First, you could incorrectly assume that scientists working on this must somehow be unaware of the problems (that is belied by the frequent mention of post WWII issues in workshops and papers since at least 2005, but never mind). Next, you could conflate the ‘buckets’ used in recent decades (as seen in the graphs in Kent et al 2007‘s discussion of the ICOADS meta-data) with the buckets in the pre-war period (see photo above) and exaggerate how prevalent they were. If you do make those mistakes however, you can extrapolate to get some rather dramatic (and erroneous) conclusions. For instance, that the effect of the ‘corrections’ would be to halve the SST trend from the 1970s. Gosh! (You should be careful not to mention the mismatch this would create with the independent NMAT data series). But there is more! You could take the (incorrect) prescription based on the bucket confusion, apply it to the full global temperatures (land included, hmm…) and think that this merits a discussion on whether the whole IPCC edifice had been completely undermined (Answer: no). And it goes on – once the bucket confusion was pointed out, the complaint switched to the scandal that it wasn’t properly explained and well, there must be something else…

All this shows wishful thinking overcoming logic. Every time there is a similar rush to judgment that is subsequently shown to be based on nothing, it still adds to the vast array of similar ‘evidence’ that keeps getting trotted out by the ill-informed. The excuse that these are just exploratory exercises in what-if thinking wears a little thin when the ‘what if’ always leads to the same (desired) conclusion. This week’s play-by-play was quite revealing on that score.

[Belated update: Interested in knowing how this worked out? Read this.]

267 Responses to “Of buckets and blogs”

  1. 1
    Pepe Larios says:

    good job
    Thank you

  2. 2
  3. 3
    Thom says:

    I would count Roger Pielke Jr. out. Take a look at his latest post.

    Thompson et al. do not provide a time series estimate on the effects of the bias on the global temperature record, but Steve McIntyre, who is building an impressive track record of analyses outside the peer-review system, discussed this topic on his weblog

    As you can see, Pielke Jr. is not afraid to bring in the heavy thinkers when it’s required.

  4. 4


    I would be careful if I was you. Citing Roger Pielke Jr. only gives him respectability, creates doubt, and results in complacency.

    The Arctic sea ice is rapidly disappearing with a time scale of years rather than decades, and it is becoming increasingly likely that the with the Greenland ice sheet will also collapse rapidly. Droughts are contributing to food shortages, and destructive cyclones and hurricanes seem to be increasing. Wild fires, a symptom of desertification are being reported from Alaska to California, and from the north Mediterranean coast of Europe to the main populated regions of Australia. We should be concentrating on the dangers happening now and in the future, not allowing ourselves to be distracted by minor inconsistencies in the past with no relevance to the future.

    Arguing about a 0.1C difference in SSTs during 1945 is totally irrelevant and only leads to a false optimism that the main problem of cutting fossil fuel use by 90% can be left for the next generation. The Arctic sea ice will have vanished long before then :-(

    Cheers, Alastair.

  5. 5
    pete best says:

    Re #4. although you are right Alastair you cannot keep optimists down and the world abounds with peope in positions of influence who are optimistic about everything. Realism aint their thing but optimism is, if the world aint as they want it to be then change it and make it that way.

  6. 6
    Geoffrey says:

    Sorry for being off-topic. I read a number of alternative financial sites. Along with being contrarian about economic issues, most posters reject AGW. One in particular is TickerForum. The site is owned by Karl Denninger, who posts as Genesis. In a thread from a couple weeks ago, he has posted what seem like softball questions. If my math were better I would debate him myself. If anyone has the energy to get into it with another denier I think it would be beneficial if you could change his mind as he is fairly influential with the people who read his site.

    A link to the thread below and his questions.
    You will need to register with the site to post.

    1. The percentage of contribution for each greenhouse gas out of the whole.

    2.The measurement for man’s contribution to CO2, expressed as a scientific measurement (pick your units but they must match the first answer), and that measurement must include an uncertainty.

    We’ll ask some tougher questions (which I suspect you won’t like) once you produce the first two answers.

    Again – how much of the CO2 generated in a given year is man-made?

    In scientific form please.

    Same for methane.

    [Response: It’s a set up since the questions are ill posed, but he thinks he’s knows the answer (but he will be wrong). For the current situation CO2 provides about 20% of the greenhouse effect (water vapour is about 50% and clouds about 25%, ozone and other minor gases make up the rest) (defined as the net reduction in the difference between longwave emitted from the surface and the longwave emitted to space, uncertainties are a few percent maybe). For CO2, the anthropogenic component is about 27%, methane it’s 60%, N2O it’s about 13%, CFCs it’s 100% (uncertainties of a couple of percent). His second set of questions are either irrelevant or make no sense. Last year, we emitted about 9 GtC, and increased concentrations by ~2ppm CO2. Your chap will most likely respond with a reference to a website run by mhieb (see here for more debunking). – gavin]

  7. 7
    Roger Pielke, Jr. says:

    I respond to this post here:

    [Response: Roger, when you’ve calmed down please do let us know when you: a) work out the difference between the ocean and the global temperature, and b) realise that there is difference between getting criticised for asking questions, and for getting the answer wrong (the latter being the central point here). Thanks! – gavin]

  8. 8
    Abbe Mac says:

    Re #5 Hi Pete,

    I felt I was being rebuked when you wrote:

    … if the world aint as they [optimists] want it to be then change it and make it that way.

    I am trying to change it, but no one listens. Besides it was Professor Martin Parry who wrote “A curious optimism …” not me.

    But I am no longer optimistic about the future. Only tonight I heard a Russian scientist say about global warming: “People claim that there is not enough evidence to act. I say there is not enough time.”

    Optimism is fine when things are going well. Now is the time for realism :-(

    Cheers, Alastair.

  9. 9
    Tom Gray says:

    Why is it when I read this posting I think of an episode of “Yes Minister”. The minister asks Sir. Humphrey what to since the figures used by the ministry have been shown to be clumsily and obviously incorrect. Sir Humphrey responds by noting that while the figures could be considered incorrect that they are incorrect in a very complicated and learned way. That while strictly speaking they are wrong’ tey are wrong in a very educated way

  10. 10
    Abbe Mac says:

    Re #7

    Just as I predicted. Roger Pielke is luring you into a slanging match with inviting remarks like “There is a lot of science and civil discussion there, with a healthy mix of assorted experts and a range of ordinary folks” but absolutely no science at all in his post at:


    Cheers, Alastair.

  11. 11
    Hank Roberts says:

    That’s like trolling, but with simulated rather than edible bait.

  12. 12
    Roger Pielke, Jr. says:

    Hi Gavin-

    I’d be happy to work from a proposed adjustment directly from you, rather than rely on the one proposed by Steve McIntyre or the one you point to from The Independent.

    Thompson et al. write: “The new adjustments are likely to have a substantial impact on the historical record of global-mean surface temperatures through the middle part of the twentieth century.”

    It is hard to see how temperatures around 1950 can change “substantially” with no effect on trends since 1950, but maybe you have a different view. Lets hear it. Give me some better numbers and I’ll use them.

    [Response: Nick Rayner, Liz Kent, Phil Jones etc. are perfectly capable of working it out and I’d suggest deferring to their experience in these matters. Whatever they come up with will be a considered and reasonable approach that will include the buoy and drifter issues as well as the post WW-II canvas bucket transition. Second guessing how that will work out in the absence of any actual knowledge would be foolish. – gavin]

  13. 13
    Craig says:

    One of the things I like about RealClimate is how easy the articles are to read and understand, compared to the slanted ramblings on the denialist-delayer blogs. I went and looked at that post of Roger’s – what a missmash! And of course he reaches into his bag of tricks and …

    A. Starts his plot halfway through the data record so that he can argue that there has been a reduction of 20th century warming by 30% – when if he had started the plot before the period in question he would not be able to make that assertion.

    B. Takes an adjustment to sea temperatures in a defined period and implies that it impacts the global mean temperatures trend estimates over the entire twentieth century.

    C. He attributes the plot to RealClimate!!!

    I’m fascinated that he is now accusing RealClimate authors of writing in a ‘passive’ manner, like it is some kind of devious technique.

    I suspect that people relying on such sources must think the science is not reliable because it appears to be confused. But it’s the denialist-delayers who are working hard to make it seem so.

    It would actually be really interesting to see a series of plots that show how the datasets of measured sea and land temperatures have evolved over time as they have been improved with adjustments such as this.

  14. 14
    cce says:

    Question as to how this might relate to GISTEMP.

    GISTEMP uses Smith et al (1996) and Reynolds & Smith (1994) for SST, but those papers document SST interpolation methods. Who performs the underlying corrections used for the in situ (pre 1982) data in the current GISTEMP analysis? The satellite sst measurements (1982+) are said to be calibrated using “quality controlled” buoy data, so I presume corrections are rarely necessary with them.


    [Response: GISTEMP uses HadISST up to 1982 and Reynolds thereafter – there may still be issues in melding the two approaches because small potential offsets between the buoys and other methods of determining SST. – gavin]

  15. 15

    Cautionary as Nature’s account of this tale of a tub may be,it is hopelessly outclassed by this week’s Culture Of Modeling news-

    La Scala has commissioned a full length opera based on
    An Inconvenient Truth.

    Stay tuned for the encore :

  16. 16
    Slioch says:

    re Response to #6

    “For CO2, the anthropogenic component is about 27%”

    Pre-industrial CO2 c.280ppmv
    Present CO2 c.385ppmv

    Shouldn’t your 2 be a 3 Gavin? ie

    “For CO2, the anthropogenic component is about 37%”

    Otherwise, great. Thanks.

    [Response: No. 105/385 = 27% of the current concentration is anthropogenic. 37% is the rise over pre-industrial levels, but that wasn’t what was asked for. – gavin]

  17. 17
    Nylo says:

    Modifying the adjustments will not change the overall 20 century trend. Modifying the adjustments will, however, change the perception of how much we warmed in the first half of the century, and how much in the second half, possibly invalidating claims that we are warming faster now. And of course any sea-surface temperatures history change will affect global temperature history change to a great extent. Most of the Earth’s surface is ocean.


  18. 18
    Ike Solem says:

    You know I was just looking through some old papers and came across a few records… worth reviewing now, I think:

    “In 1989, not long after James Hansen’s highly publicized testimony before Congress and shortly after the first meeting of the UN’s Intergovernmental Panel on Climate Change, the Burson Marsteller PR firm created the Global Climate Coalition (GCC). Chaired by William O’Keefe, an executive for the American Petroleum Institute, the GCC operated until 1997 out of the offices of the National Association of Manufacturers. . .

    “The GCC has also used “Junkman” Steven Milloy’s former employer, the EOP Group, as well as the E. Bruce Harrison company, a subsidiary of the giant Ruder Finn PR firm. Within the public relations industry, Harrison is an almost legendary figure who is ironically considered “the founder of green PR” because of his work for the pesticide industry in the 1960s, when he helped lead the attack on author Rachel Carlson and her environmental classic Silent Spring…”

    “Industry’s PR strategy with regard to global warming issue is also eminently practical, with limited, realistic goals. Opinion polls for the past decade have consistently shown that the public would like to see something done about the global warming problem, along with many other environmental issues. Industry’s PR strategy is not aimed at reversing the tide of public opinion, which may not in any case be impossible. Its goal is simply to stop people from mobilizing to do anything about the problem, to create sufficient doubt in their minds about the seriousness of global warming that they will remain locked in doubt and indecision…”

    “In 1991, a corporate coalition composed of the National Coal Association, the Western Fuels Association, and Edison Electrical Institute created a PR front group called the “Information Council for the Environment” (ICE) and launched a $500,000 advertising and public relations campaign to, in ICE’s own words, “reposition global warming as theory, (not fact)…”

    “To boost its credibility, ICE created a Scientific Advisory Panel that featured Patrick Michaels from the Dept of Environmental Services at the University of Virgina; Robert Balling of Arizona State University, and Sherwood Idso of the U.S. Water Conservation Laboratory. ICE’s plan called for placing these three scientists, along with fellow greenhouse skeptic S. Fred Singer, professor emeritus of environmental sciences at the University of Virgina, in broadcast appearances, op-ed pages, and newspaper interviews. Bracy Williams & Co., a Washington-based PR firm, did the advance publicity work for the interviews…”

    “…According to Peter Montague of the Environmental Research Foundation, “S. Fred Singer is now an ‘independent consultant’ for companies including ARCO, Exxon Corporation, Sheel Oil Company, Sun Oil Company, and Unocal Corporation. Rather than conducting research, Singer “spends his time writing letters to the editor and testifying before Congress….”

    “In April 1998…the New York Times reported on yet another propaganda scheme developed by the American Petroleum Institute. Joe Walker, a public relations representative of the API, had written an eight-page internal memorandum outlining the plan, which unfortunately for the plotters was leaked by a whistle-blower. Walker’s memorandum called for recruiting scientists “who do not have a long history of visibility and/or participation in the climate change debate.” Apparently, new faces were needed because the industry’s long-standing scientific front men – Balling, Michaels, Idso, and Singer – had used up their credibility with journalists.”

    -“Global Warming is Good For You”, Ch. 10, in “Trust Us, We’re Experts” by Rampton & Stauber (2001)

    Well- that’s interesting. I wonder who they decided to go with? I imagine it’s not too hard to find out – just look at the most widely promoted and quoted “climate science skeptics” in the leading press outlets over the past 8 years or so.

  19. 19
    ab says:

    RE_ #The Article says: The biggest transitions in measurements occurred at the beginning of WWII between 1939 and 1941 when the sources of data switched from European fleets to almost exclusively US fleets (and who tended to use engine inlet temperatures rather than canvas buckets).#
    In the Pacific the US shipping dominated since the ambush on Pearl Harbor, but in the North Atlantic most tonnage was under British, Norwegian and Neutral Flag. The specific war situation concerning SST is explained in paper from 1997 and 1998, ,

  20. 20
    Eric (skeptic) says:

    There is no hint in Rayner06 of a reversion to canvas buckets after WWII. There is a quantitative effect of this error, both on global average calculations up to the 1970’s and on the uncertainty of that number. Your post does not calculate that effect. It would appear that aerosols explaining cooling into the 1970’s has to be revisited, is there a quantative analysis of that (i.e. including actual aerosol measurements)? Another correlation to be investigated is solar since (nonquantitatively speaking) warming started more in the 40’s than in the 70’s as previously thought which is more in line with solar trends (modern maximum).

    [Response: Not so – the quoted section clearly refers to that. As for the 40s-70s cooling, this is still seen in the land data and is not tied to SST changes in 1945. The first cut at the revisions linked above has effectively the same match to the model trends as before (maybe a little better) and so no revisions to the models nor to attribution studies are likely. – gavin]

  21. 21
    anonymous says:

    In June 2008, Miami artist Xavier Cortada will travel to the North Pole, ninety degrees North (90N), to create site-specific installations exploring our connection to the natural world.

    The work addresses global climate change and will include the reinstallation of the “Longitudinal Installation” and “Endangered World” (originally created in the South Pole, 90S, during January 2007 as part of a National Science Foundation Antarctic Artist and Writers residency).

    The artist will also plant a green flag at at the Earth’s northernmost point to encourage the reforestation of native trees in the world below.
    At a time when melting polar sea ice is causing so many to focus on which political power will place its flag over the Arctic, controlling the Northwest Passage shipping lanes and the petroleum resources beneath the sea ice, Miami artist Xavier Cortada has developed a project that engages people across the world below to plant a green flag and native tree to help address global climate change. Reforestation helps prevent the polar regions from melting.

    Cortada will plant a green flag the North Pole when he arrives there on June 30, 2008. On that same day folks from around the world will be asked to also plant a green flag and native tree in their community.

    Miami artist Xavier Cortada created Native Flags as an urban reforestation project to help restore native habitats for plants and animals across South Florida. Launched last year at the Miami Science Museum, Native Flags now calls on individuals globally to join the effort.The conspicuous green flag serves as a catalyst for conversations with neighbors and a call to action to help rebuild our native tree canopy. Community leaders can model the behavior by planting a native tree and green flag at their science centers and city halls.

    To learn about this please visit the artist’s website at

  22. 22
    Eric (skeptic) says:

    Gavin, wouldn’t the difference between northern and southern hemisphere trends (e.g. indicate an potential SST sampling error, especially right after WWII?

    [Response: Why? Hemispheric trends can differ due to different forcings, different thermal inertia, different impacts of ocean circulation change etc. The sampling issue is much worse in the SH and so the uncertainty there is greater, but you can’t automatically associate a hemispheric difference with an artifact. – gavin]

  23. 23

    OK, this is a question only about the “blog” part of this topic.
    We need help over at Dot Earth, again.
    Please see this comment:

    #60. June 2nd, 2008, 7:28 am


    The graphs are of actual measurements, so it doesn’t matter what our opinions are of Dr. Spencer.

    Just exactly how has Dr. Spencer been discredited?

    The most important greenhouse gas, water vapor, overwhelms all the others combined, including methane. Apparently, the water vapor is self regulating, more than offsetting all the other greenhouse gases combined. Simple precipitation counterbalances the thermal forcing of much of the growth of CO2 and others.

    Why did the globe gradually warm then in the latter part of the 20th century? Increased solar activity.

    Why is the globe cooling now? Decreased solar activity, with the current 23rd solar cycle yet to end.

    It is only a matter of time before the thermal momentum of the latter part of the 20th century is reversed, and the northern polar cap begins to cool back down, reforming the ice. The southern polar region has already been cooling for several years, with an increasing ice cover.

    By the way, did you catch this story? 24.TRIPPING24/TPStory/

    The Northwest Passage is not quite as easy to navigate as we have been led to believe.

    Eppure, si rinfresca

    — Posted by Jack Simmons

    That comment was in response to my comment #56, a response to his comment #54.

    The link to the blog thread is this one:

    I would appreciate your help because you guys are so much better at this than I could ever think about being.

    Thank you.

    [Response: Your correspondent can’t possibly believe that climate sensitivity is zero (due to some magical stabilisation mechanism) and also claim that the sensitivity to solar is enough to explain the 20th C trend. Either water vapour is stabilising or it isn’t (and it isn’t by the way – as shown by the water vapor changes during ENSO, after Pinatubo, the long term trends etc. – see Soden et al, 2001;2003;2004). And why would anyone think that the NWP is navigable easily in May? Even in 2007, the opening was in the second half of August… more FUD. – gavin]

  24. 24
    Fred Moolten says:

    The most revealing item is Gavin’s “Colocated Anomalies” graph showing the relationship between corrected SST (HadSST2 in red) and marine air temperatures (NMAT in green). The air temperatures were not susceptible to bucket or engine inlet artefacts. The first thing that stands out is that the mid-century aberrations are not merely a “dip” after 1945, but also a peak that preceded it. Here, both curves coincide during the ascending and part of the descending limbs of the peak, and the upward and descending limbs may be attributable, at least in part, to El Nino years between 1939 and 1942, a transient downturn in the AMO (Atlantic Multidecadal Oscillation) warm phase and a more persistent shift from warm to cool in the Pacific Decadal Oscillation) in the mid-1940s, among other natural events.

    Strikingly, both curves show the post-1945 “dip”, with the main difference residing in the deeper decline of the SST curve, and its more sudden drop. (The differences are even better seen in IPCC AR4, WGI, Chapter 3, p.246, Fig. 3.4a).

    It seems plausible, therefore, to conclude that most of the peak and dip were not caused by SST measurement artefacts, and presumably reflected natural events, with the artefactual component mainly limited to the modest excess in depth of the SST curve between 1945 and about 1956, rather than the entire dip.

    If this interval is corrected, it appears that the 1945-1975 interval of the SST curve may become slighly flatter, consistent perhaps with a slightly greater aerosol masking of greenhouse gas forcing than previously estimated. Probably more important, most sections of the twentieth century warming curve will not be substantially affected, and should not require significant reinterpretation.

  25. 25

    Re: comment #23

    Dear Gavin,

    Thanks for your response. Of course he does not believe what he is writing — he is one of those industry-paid denialists that show up on Dot Earth to confuse the uninitiate. I have to use layman’s language to explain to other readers where he is fantastically incorrect, but as I am not a scientist, it is not so easy for me to do that.

  26. 26
    Ray Ladbury says:

    Tenney, Your correspondent not only does not believe what he is writing, he doesn’t understand it. It is pure gobbldygook. Water vapor as a stabilizing (negative) feedback–what happens to water content as temperature goes up? Moreover water vapor peters out at cloudtop level, while CO2 stays well mixed into the stratosphere. Then there is the relative lifetime of H2O and CO2–days to hundreds of years.
    This guy is just parroting back what he’s heard/read somewhere else, and he’s not even doing a particularly good job of parroting. Go back and read “A saturated Gassy Argument” and Gavin’s posting about greenhouse forcing in 6 easy steps. Understand those and you’ll blow this guy out of the water.

  27. 27

    #23, Terry, I would like to read that Globe and Mail story (link is a dud). Living next to the Northwest Passage, I must say, if it infers in anyway that it is just as hard to Navigate this passage as with any previous times during the shipping season, it is absolute hogwash. It necessarily might have omitted that it is also easier to snowmobile on the passage during winter, reason: no old ice, virtually none on sight near Arctic communities. RC press rebuttals should be syndicated in every news outlet out there, correct interpretations of climate science is regularly mangled, to the point where I get Arctic visitors, some journalists, who regularly quote bad science from misleading news sources, newspaper stories are considered like science journals, peer reviewed quoted news stories especially, namely that 10 year cooling German model forecast. Like Alastair says. no time to trivialize how serious the disappearance of old multi year ice, but it seems that this mega story gets less attention than a Mars landing. But a rapid response to immediately kill mischievous news stories is apparently, not quick enough, syndicate guys!

  28. 28
    Richard Ordway says:

    #23 re. Tenney Naumer “The Northwest Passage is not quite as easy to navigate as we have been led to believe.”

    Well according to a Science Journal article it was navigatable enough for two “huge dry docks” to be taken through to the Bahamas in 1999:

  29. 29
    Hank Roberts says:

    > navigatable

    All I can see is the Abstract, here:

    I’d speculate they used icebreakers.
    Anyone know for sure?

    “… In 1999, Russian companies sent two huge dry docks to the Bahamas through the usually unnavigable Northwest Passage ….”

    Science 19 January 2001:
    Vol. 291. no. 5503, pp. 424 – 425
    DOI: 10.1126/science.291.5503.424

    Prev | Table of Contents | Next
    News Focus
    Arctic Life, on Thin Ice
    Kevin Krajick

    Field observations from the Beaufort Sea to Hudson Bay are suggesting that the food web in the Arctic Ocean is ailing, causing many species to flounder as a result of the warming environment. Sea ice in the Arctic, on which arctic animals hunt, rest, and reproduce, now covers 15% less area than it did in 1978; it has thinned to an average of 1.8 meters, compared to 3.1 meters in the 1950s. If this trend continues, in 50 years the sea ice could disappear entirely during summers–possibly wiping out ice algae and most other organisms farther up the food chain.

  30. 30
    Martin J says:

    I’m sorry but I don’t think the contributors to this website fully appreciate how bad this “bucket” saga really is. As someone who was using a bucket to obtain water samples on a UK registered survey vessel during the years 1981/2, I can testify that the quality of data obtained was not high – be it a wooden, canvas or plastic bucket that was employed. Even if there was a standardised proceedure for measurement- and it’s my understanding there was no universal proceedure- I suspect those proceedures would not have been adhered to on shipboard conditions. It was bad enough slinging a bucket over the side in the North Sea; I would hate to have been the deckhand assigned the job in the South Atlantic. Working at sea, especially in “weather”, has to be experienced to be appreciated.

    Further, conscientiously done work could be undermined by slight positional changes by the ship; a vessel could move from a warm current area to a cold current within a few hundred yards and the temperature changes could be of the order of degrees. Off the Outer Banks where the Gulf Stream veers off into the Atlantic is an example. Frankly, when sea temperature measurements were being taken using buckets, few envisaged those measurements would be read as precision readings. I would suggest that much of data collected had errors margins of +/- 2C.

    This being the case, I believe the whole area of oceanic temperature measurements should be comprehensively re-examined.

  31. 31
    Martin Vermeer says:

    Tenney #25, what Ray said.

    What you should clearly understand here is that the water vapour doesn’t know what warms the air it is in. Your correspondent effectively claims that the water vapour produces a strong negative feedback (in whatever way; who cares) reducing total sensitivity. But this feedback is mediated through tropospheric temperature. If it happens for CO2 radiative forcing, it will also happen for Solar activity -related (or any other) forcing, which thus would be equally ineffective to explain late 20th century warming. This is Gavin’s argument in layman’s terms (I hope).

    …and there is a second impossibility compounding the first one: during the last few decades of accelerating global warming, the Sun has been very precisely monitored from space, and its brightness hasn’t shown any discernable trend. Same for solar activity (sunspots), interplanetary magnetic field, cosmic rays… so you would have to first explain away a known and understood forcing mechanism (CO2) and then replace it by one that cannot even work because it has the wrong time signature.

  32. 32
    John Lederer says:

    I confess to a little confusion from your post.

    Let’s put the details aside fro the moment.

    At some time in the past measurements were predominantly by bucket.

    At some time in the recent past (arbitraily, say 2000) readings were predominately by water intake.

    Buckets apparently read colder than inlets by some amount, possibly .3 degrees.

    So the change in the measurement, regardless of the intervening use of different mixes of buckets and other means, overall would be about .3 degrees between the “past” and the “recent past”..

    Is this currently factored out of the trends or not?

  33. 33
    Hank Roberts says:

    For Richard Ordway, re #28, Google is your friend, albeit not a wise advisor. Tell your friends they did use an icebreaker – and had trouble doing the job:

    Russian icebreaker M/V ADMIRAL MAKAROV (14,058 gt, built 1975), towing a dry dock to the Bahamas, had towline break on Oct 14 and the dry dock was adrift off eastern Canada in the Cabot Strait between Nova Scotia and Newfoundland. The dry dock, with 15 people on board, was adrift in heavy seas for 2 days before being taken back under tow by the Admiral Makarov on Oct 16. All 15 crew members were reported in good health. (Mon. Oct. 18 1999)

  34. 34
    Arch Stanton says:

    Hank Roberts (29)
    >I’d speculate they used icebreakers.
    Anyone know for sure?

    “…In 1999, the first non-American
    passage for commercial shipping pur-
    poses took place when a Russian com-
    pany sold a floating dry dock based in
    Vladivostok. Its new owners decided
    to move the dock to Bermuda. With
    the aid of a Russian icebreaker and an
    ocean-going tug, the dry dock was
    successfully towed through the

  35. 35
    pat n says:

    Re 4 … The Arctic sea ice is rapidly disappearing …

    The latest data by NSIDC for Arctic sea ice extent shows that 2008 ice coverage has fallen to 2007 levels for the end of May:

    Also see ice age (Figure 4):

  36. 36
    Hank Roberts says:

    P.S. for Richard Ordway:

    It’s a tourist attraction; it used to be a research ship:

    “… the Kapitan Khlebnikov, a Russian ice breaker from Vladivostok, now under charter to Quark Expeditions…. (a purpose-built ice breaker, as opposed to merely having an ice-strengthened hull) was a working vessel before she became our cruise ship; cabins previously assigned to scientists and technical staff are now passenger cabins. …”

  37. 37
    Lawrence Brown says:

    Thank you Gavin, very informative contribution. It also gives a new meaning to the exprssion “kick the bucket”. News that SST temperature readings are kaput because of differences in methods of drawing sea water samples are highly exaggerated, to paraphrase Mark Twain.

  38. 38
    Arch Stanton says:

    John Lederer (32)

    Before WWII the Brits and others were good about measuring SST. They mostly used buckets. During WWII they had better things to do. Few SST measurements were taken during the war but the Yanks did most of them. They mostly used engine intake measurements that had a slightly higher bias. After the war others once again began to measure the SST using buckets. This caused the Yank’s (warmer) engine room temps to be “diluted” by the (cooler) bucket temps and caused a largely unexplained drop in (average) SSTs after the war. This paper explains the curious drop after the war.

    SSTs have continued to rise since the war, and surpassed war levels in the 70’s This paper mostly only addresses the (dip) artifact from 1945-1970.

    Does that help?

  39. 39
    John Lederer says:

    Arch Stanton,

    Thank you very much.

    But in the very recent past (say 1990- 2000) Igather measurements were largely water intakes?

    So after the immediate post WWII reversion to buckets, we changed again, presumably more gradually, to intakes.

    So if I look at a trend from say just after WWII (largely bucket) to around 2000 (largely intake), there will be .3 degrees (assuming that is the difference) of warming attributable not to an actual temperature change,but to the switch in measurement method?

    Or am I missing something?


  40. 40

    I’m really curious here as I’ve only read a few dozen of the climate-centric blogs, but I’m under the impression that only a small fraction are written by AGW “deniers” and perhaps 5% of the total would fall into the “skeptic” category? In terms of mainstream media it would seem that only a handful of stories (plus uninformed ranters at FOX) are critical of the basic AGW ideas held so dear here.

  41. 41

    #18 Ike Solem, #27 Wayne Davidson, #25 Tenney Naumer …

    This might be an opportune time to remind everyone of how organized tobacco’s astroturf “sound science” movement morphed into attacks on science in other areas like global warming, as ably revealed by George Monbiot, among others:

    Whenever I read this stuff I marvel at how little pride some people have.

    Thanks again, RC, for providing some balance – and the ammo to fight back.

  42. 42
    Ray Ladbury says:

    Joseph Hunkins, there are plenty of denialist sites on the Web. There are also sites that say the moon landing was a hoax and that allow posters to compare their anal-probing experiences by aliens. There are a few “skeptic” sites, but most of them are not run by scientists, and the “science” presented there is only of value in terms of entertainment. A very few actually raise some valid points, but grossly exaggerate their importance.
    In terms of mainstream media, the proportion of stories that question climate change or the “balance” of the stories (e.g. presenting “both sides”) is grossly out of proportion to the actual level of scientific consensus. And if you look at scientists who actually publish on climate in peer reviewed journals, there is pretty much universal agreement that CO2 has contributed significantly to recent warming and the vast majority say CO2 is responsible for the vast majority.
    There are many things we do not yet know about climate. The importance of CO2 is not among these things.

  43. 43
    Hank Roberts says:

    Here’s a list that will include a good many:

    +joeduck +climate

  44. 44
    Arch Stanton says:

    John Lederer,

    Ah, I think I understand your question now. It looks more like .4-.5C (but honestly I am extrapolating from a small graph. I will refer you back up to Gavin’s OP however and ask you to click on the second graph, this will take you to the Nature blog: ClimateFeedback. The first two line graphs are very interesting, although they are somewhat hard to see.

    “a” shows SSTs for the century; uncorrected on top, the bottom has had ENSO and COWL (Cold Oceans Warm Land) reconstructions subtracted from it. The dashed vertical line represents the drop after WWII the solid vertical lines represent major volcanic eruptions. It looks to me as though if the drop in temps in 1945 is .3C then the subsequent rise to today must be around .4-.5C (?)

  45. 45
    Richard Pauli says:

    Perhaps denialism is waning.

    Deep denial is rooted in human nature that wants look at the positive and ignore anything that is not causing real pain right now. AGW is uncomfortable news. No one wants to see it. But any science has to lay out all the models, scenarios, and systems analysis that will butt heads with economies, politics and will-power. The crux is an informed populace. Passive denial is like being asleep. Active denial is often traced to selfish monetary interests – carbon industries, etc. And so much recalcitrance is just momentum.

    How does one describe, label and then halt the AGW practices that are too dangerous for civilization? Science can only describe, label, predict and advise. Halting requires political involvement. And the lessons we failed to learn have been repeated. And will be repeated again.

    Sometimes I wish RC would be more political. Physics trumps all eventually, but politics and power rules humans – for now.

  46. 46
    The Wonderer says:

    Speaking of the media: Charles Krauthammer wrote a run-of-the-mill denialist diatribe in the Washington Post last Friday in anticipation of the Lieberman-Warner Climate Security bill making it to the full Senate this week. I urge you to respond to that column with a letter to the editor, given this current visibility. And with the NASA IG’s report also in the news, the more and higher-profile NASA scientist signatories to that letter, the better.

  47. 47
    Timo Hämeranta says:

    In his response to 23. Gavin argues “Either water vapour is stabilising or it isn’t (and it isn’t by the way…”


    “Cloud climate feedback constitutes the most important uncertainty in climate modelling, and currently even its sign is still unknown. In the recently published report of the intergovernmental panel on climate change (IPCC), 6 out of 20 climate models showed a positive and 14 a negative cloud radiative feedback in a doubled CO2 scenario.”

    Ref: Wagner, Thomas, S. Beirle, T. Deutschmann, M. Grzegorski, and U. Platt, 2008. Dependence of cloud properties derived from spectrally resolved visible satellite observations on surface temperature. Atmospheric Chemistry and Physics Vol. 8, No 9, pp. 2299-2312, May 5, 2008

    [Response: Perhaps if you read what I wrote we’d communicate better. Water vapour feedback is not the same as cloud feedback (clouds are condensate – not vapour). – gavin]

    Please see also:

    “By comparing the response of clouds and water vapor to ENSO forcing in nature with that in
    AMIP simulations by some leading climate models, an earlier evaluation of tropical cloud and water vapor feedbacks has revealed two common biases in the models: (1) an underestimate of the
    strength of the negative cloud albedo feedback and (2) an overestimate of the positive feedback
    from the greenhouse effect of water vapor. Extending the same analysis to the fully coupled
    simulations of these models as well as to other IPCC coupled models, we find that these two
    common biases persist.”

    Ref: Sun, De-Zheng, Yongqiang Yu, Tao Zhang, 2008. Tropical Water Vapor and Cloud Feedbacks in Climate Models: A Further Assessment Using Coupled Simulations. Submitted March 2008 to Journal of Climate

  48. 48
    Geoff Sherrington says:

    Re # 4 Alastair McDonald

    You claim

    “Wild fires, a symptom of desertification are being reported from Alaska to California, and from the north Mediterranean coast of Europe to the main populated regions of Australia”.

    You can leave my country, Australia, off the list. Please don’t invent to make a point. Stick to what you know is measured accurately, both as to desertification and fires, and quote your source.

  49. 49
    Geoff Sherrington says:

    Re # 12 Gavin’s response

    But Phil Jones knew SST work was wrong early in 2006 but failed to do much if anything about it by the time the IPCC published. Here is what he emailed to me:

    First, I’m attaching a paper. This shows that it is necessary
    to adjust the marine data (SSTs) for the change from buckets
    to engine intakes. If models are forced by SSTs (which is one
    way climate models can be run) then they estimate land
    temperatures which are too cool if the original bucket
    temps are used. The estimated land temps are much
    closer to those measured if the adjusted SSTs are used.
    Jonesandmoberg.pdf follandetal200.pdf ”

    So how can you justify writing that

    “Nick Rayner, Liz Kent, Phil Jones etc. are perfectly capable of working it out and I’d suggest deferring to their experience in these matters.”


    [Response: Possibly you did not read those papers. They show that the pre-1941 changes because of the Folland and Parker (1995) correction are in much better agreement than the raw data (ie. the correction seen in the first figure above). The changes we are talking about now are much smaller, but yes, they do know what they are doing. Read Rayner et al 2006 for instance. – gavin]

  50. 50
    Geoff Sherrington says:

    Re # 14 Gavin
    [Response: GISTEMP uses HadISST up to 1982 and Reynolds thereafter – there may still be issues in melding the two approaches because small potential offsets between the buoys and other methods of determining SST. – gavin]

    Is it so hard to use realspeak on realclimate and simply say “At least one is wrong”.

    [Response: Well down here in the reality-based community things don’t come in neat packages labelled perfect or useless. Instead everything comes with uncertainties and we use all the available data to get closer to what was likely to be the truth. It’s really not that hard a concept. -gavin]