When Did Arctic Warming Start?

Guest Post By Arnd Bernaerts as previously posted by Verity Jones at Digging in the Clay.


Figure 1.

The posting “Mapping global warming” (Jan. 18, 2010 by “KevinUK”) demonstrated convincingly that “much of the claimed global warming is hardly global at all. In fact it looks to be more accurately Northern Hemisphere warming, and for that matter primarily Northern Hemisphere WINTER warming!”. With interesting access to data and maps it is an enjoyable read, confirming that since 1880 there had been four distinct warming/cooling time periods i.e. from 1880 to 1909 (cold), 1910 to 1939 (warm)[1], 1940 to 1969 (cold) and 1970 to 2010 (warm). From the dates given, I would like to object the date 1909/10, which should not be considered as the change from a cold to a warm period, as this happened some years later towards the end of the decade beginning in 1910, between 1916 to 1920, presumably in winter 1918/19. Figure 1 reflects the situation from 1921 to 1930 (Details in the figures in the annex). Does it matter if we are precise in this respect? The answer is clearly yes. The more precisely a shift from a warm to cold period, and the region where it occurred is identified, the more it might be possible to identify the cause. For this reason the following discussion is about the start of the first pronounced warming period after the end of the Little Ice Age, which actually commenced as an Arctic warming, primarily close to the Fram Strait region.


Figure 2.

A substantial point observed by ‘KevinUK’, as already mentioned, is the more pronounced warming of the Northern Hemisphere and primarily during the winter season. That is exactly what the warming period in the early 20th Century is primarily about. While the summer temperatures increased only modestly, the winters generated the steep warming as observed at Spitsbergen (Fig.2), which is also well reflected in the annual data set for north of latitude 70°N (Fig. 3 & 4). The decade from 1921 to 1930 showed a remarkable winter warming (Fig. 5 & 6), which lasted until 1940 (Fig. 3 & 4). This fact is a paramount aspect to identify the reason for this significant shift during the winter period the influence of the sun is remote north of 50°N (i.e. London, Vancouver), but any warming must have been coming from somewhere.







Figure 3.
Figure 4.

Time and Region

Figure 5
Figure 6

Figures 1, 5 & 6, give a clear indication that the previous warming period in the 1920s and 1930s was primarily located in the North Atlantic section of the Arctic Ocean. Figure 2, 3 & 4 demonstrate equally that the temperature rise commenced before 1920 (Fig. 5 & 6), probably in 1918 (Fig. 2). This date (1918) should be regarded as the time the Arctic suddenly moved into a strong warming period. Actually, the warming started in the Spitsbergen region in winter 1918/19 (Fig 7, Spitsbergen D/J/F), and was only subsequently observed beyond this station. Under these circumstances it seems difficult to regard the year 1910 as starting point. With some generalisation there had been a modest temperature increase before 1910 (Fig. 4), with a significant decrease from 1910 to 1917. At Spitsbergen the shift between DJF-1912/18 and DJF-1919/23 is about 8°C, for the whole Arctic region the increase between the decades before and after 1919 (Fig.3 & 4) is about 2°C.

Figure 7.


Causation I: West Spitsbergen Current

Having established the time and region of the sudden temperature shift close to Spitsbergen and narrowed it to the winter of 1918/19, it is time to ask, what caused and sustained the warming for two decades. For example ‘KevinUK’ states in the analysis of his Figure 8 that: “This is demonstrates clear and significant natural climatic variability during this time period in different parts of the world”, and is reasoning in one comment that: “I’ve personally far happy to convinced that these observable difference in differential warming/cooling trend could be caused by differences in water vapour concentration/relative cloud cover, particularly late evening/night-time cloud cover.” The cause is presumably another one.



Figure 8.

The Arctic Ocean winter weather is dominated by a sunless period over more than 6 months, full sea ice cover, extreme cold, low humidity, low cloudiness, and anticyclones. Neither sun spots, nor carbon dioxide, nor water vapor can be considered as a significant direct contributor to generate a sudden remarkable shift and keep it sustained over two decades. As there is no indication that this warming was generated elsewhere, and subsequently moved to the polar region (Fig. 1, 5 & 6), it must have been a local source, namely warm high saline Atlantic water carried by the West Spitsbergen Current to the Arctic Ocean. Whether this change was due to an increase of the water masses, or due to a change in the structure of the various sea levels over a considerable depth around the gate to the Arctic Ocean, the Fram Strait, is not known. It seems that the latter is the more likely reason. (More details in Book-Chapter 7)

Figure 9 (left) to 12 (right)

Causation II: Shift of sea level structure.

Little is known about an extraordinary North Atlantic sea ice season in 1917. To my knowledge, such a long and extensive sea ice cover occurred only once throughout the 20th Century. Usually there remains a sea ice-free tongue off the shore of Spitsbergen (Fig. 9). Against all rules, the tongue disappeared in April 1917, the sea ice extended far to the South (Fig.10), remained very high throughout June (Fig.11), and only retreated in July 1917 (Fig. 12). About the consequences one can only speculate, but it was certainly not without any.

Throughout the long freezing process the ice-covered sea surface level must release salt, which makes the sea water heavy, and thus increases the vertical water exchange with deeper levels. During the subsequent melting process through July 1917 the sea surface would have received a huge amount of fresh water; this stays at the surface level, until the salinity and/or water temperature is back to the normal. This highly unusual event in the Northern North Atlantic from April to July 1917 could well have contributed to a shift in the ocean structure between Spitsbergen and the Fram Strait, which subsequently caused the warming of the Northern Hemisphere from winter 1918/19 to 1940.

Causation III: The change in the northern NA ocean structure.

This is worth further discussion at another time – for now only I will make this comment. As there was nothing in “the air” (for example a volcanic eruption, a major earthquake, a tsunami, a meteorite plunging on land or into the sea), perhaps we should recall what happened in Europe from 1914 to November 1918. Over four years a devastating battle on land, in the air and at sea took place. Huge naval forces battled in the waters in the east and west of Great Britain, it is my view that this may have changed the sea structure with respect to heat and salinity over many meters depth. All this water moved north with the Norwegian Current, and the West Spitsbergen Current, to enter the Arctic Ocean after a time period of several weeks or months (Fig. 8). This could have influenced the exceptional sea ice conditions during summer 1917, or even may have contributed alone, via a change in the ocean structure between Spitsbergen and Greenland, the climatic shift in the high north in winter 1918/19. (More details in Book-Chapter 8 )

Further Reading:

WebBook (2009) “Arctic Heats Up. Spitsbergen 1919 to 1939”; http://www.arctic-heats-up.com

Paper (2010) “Indian Drought and North Atlantic 1917 & 1918” (PDF, 1MB)

Paper (2009)“The Circumstances of the Arctic Warming in the early 20th Century” (PDF, 0,9MB)

Home Page http://www.arctic-warming.com/


Fig. 1; based on material by: R. Scherhag, (1936), “Die Zunahme der atmosphärischen Zirkulation in den letzten 25 Jahren.”, Annalen der Hydrographischen Meteorologie, Vol. 64, p. 397ff, Tafel 62, Figure 10.

Fig. 2; based on material by: Hesselberg, Th., Johannessen, T. Werner; (1958); in: R.C. Sutcliffe, ed.; ‘Polar Atmosphere Symposium – Part I, Meteorology Section; Symposium at Oslo 2-8 July 1956, London, pp. 18ff; Figure 2.

Fig. 3; download from: http://www.climate4you.com/index.htm >>“Temperature in Polar regions: Arctic and Antarctic”, >> Arctic temperature change, showing the mean annual surface air temperature (MAAT) anomaly 70-90oN compared to the WMO normal period 1961-1990, as estimated by Hadley CRUT. HadCRUT3 temperature data from the Climatic Research Unit (CRU) has been used to prepare the diagram.

Fig.4; Download from http://www.pi-news.net/wp/uploads/2008/10/arktis3.jpg

Fig. 5; based on material by: R. Scherhag, (1936), see Fig. 1; Tafel 58, Fig. 2 (Temperature deviation from November to March 1921-1930 versus long term mean.

Fig. 6; based on material by: Ola M. Johannessen, Lennart Bengtsson, Martin W. Miles, Svetlana I. Kuzmina, Vladimir A. Semenov, Genrikh V. Alekseev, Andrei P. Nagurnyi, Victor F. Zakharov, Leonid Bobylev, Lasse H. Pettersson, Klaus Hasselmann and Howard P. Cattle; “Arctic climate change – Observed and modeled temperature and sea ice variability”; Nansen Environmental and Remote Sensing Center, Report No. 218, Bergen 2002; Tellus 56A, (2004), p. 328 –341, Figure 2 (SAT trends north of 30°N in the winter period from November to April, 1920-1939)

Fig. 7; based on Giss data: Source: Paper (2010)__“Indian Drought and North Atlantic 1917 & 1918”

Fig. 8; Source: http://www.arctic-warming.com/the-warming-event-in-detail.php (here: amended)

Fig. 9 – 12: based on data from: http://polar.ncep.noaa.gov/seaice/climatology/months.shtml; Source: Paper (2010)__“Indian Drought and North Atlantic 1917 & 1918”

[1] This time period is not generally acknowledged, as many authors identify as period the 1920s and 1930s (i.e. Drinkwater, 2006; Bengtsson, 2004, Johannessen, 2004), and the IPCC Report 2007 mention the time from 1925 to 1945; details at “Arctic Heats Up”, Chapter 2, p. 16f (see Further Reading).

34 thoughts on “When Did Arctic Warming Start?

  1. The Great War as a cause of ocean circulation shifts? That’s certainly a novel idea. I doubt if the energy accounts could be made to balance on that one, tho’.

  2. Brian,

    I have posted Arnd’s stuff here once before. Even thought the oceans surface warm layer is thin and even though the war’s had higher than average shipping, I very much doubt that there was more ocean traffic than today.

  3. #1, ADE
    At http://www.climate4you.com/index.htm is the following text:
    ____1930: Birkeland draws attention to Arctic warming One of the first scientists to publish in a scientific journal considerations on the ongoing warming in the Arctic around Svalbard was the Norwegian scientist Birkeland (1930). Apparently he was surprised to see the considerable temperature increase 1917-1923, and stated in his paper that “I would like to stress that the mean deviation results in very high figures, probably the greatest yet known on Earth”.

    The Birkeland data are here: http://www.arctic-warming.com/a.php ; Source: Birkeland, B.J.; ‘Temperaturvariationen auf Spitzbergen’, Meteorologische Zeitschrift, Juni 1930, p. 234-236.

  4. #4, Jeff, your kind generosity with regard to my research is highly appreciated. This paper is about the timing and location of the previous Arctic warming , whereby the very suddenness of the shift within a time span of three to 15 months needs an explanation.
    Many thanks and best regards

  5. #2

    Frank, not sure how you figure ADE has made any kind of “claim”, he merely noted the obvious feature of the graph and offered a plausible explanation. A step change could also be legit – especially in the arctic which has much greater variability than a global average.

  6. #3 – Instead of looking at the cart before the horse, turn it around. Perhaps the wars began because the war mongers saw a longer fighting season. Since the turn happened around the start of the war, they just decided to attack after noticing a long (in human lifetime measurement) trend. indeed, the trends are 25-30 years – about the span of a human experience before they start talking about “the good old days”.

  7. Nature Geoscience 3, 688 – 694 (2010)
    Published online: 12 September 2010 | doi:10.1038/ngeo955

    External forcing as a metronome for Atlantic multidecadal variability

    Odd Helge Otterå1,2,3, Mats Bentsen1,2,3, Helge Drange1,2,4 & Lingling Suo2,3


    Instrumental records, proxy data and climate modelling show that multidecadal variability is a dominant feature of North Atlantic sea-surface temperature variations1, 2, 3, 4, with potential impacts on regional climate5. To understand the observed variability and to gauge any potential for climate predictions it is essential to identify the physical mechanisms that lead to this variability, and to explore the spatial and temporal characteristics of multidecadal variability modes. Here we use a coupled ocean–atmosphere general circulation model to show that the phasing of the multidecadal fluctuations in the North Atlantic during the past 600 years is, to a large degree, governed by changes in the external solar and volcanic forcings. We find that volcanoes play a particularly important part in the phasing of the multidecadal variability through their direct influence on tropical sea-surface temperatures, on the leading mode of northern-hemisphere atmosphere circulation and on the Atlantic thermohaline circulation. We suggest that the implications of our findings for decadal climate prediction are twofold: because volcanic eruptions cannot be predicted a decade in advance, longer-term climate predictability may prove challenging, whereas the systematic post-eruption changes in ocean and atmosphere may hold promise for shorter-term climate prediction.

  8. #10PhilJourdan said: „Since the turn happened around the start of the war”.

    No the shift from a cold to a warm phase happened at the end of WWI. That is a very important aspect, although you presumably mentioned this to make another point. Actually the naval war started to get very serious only in autumn 1916, after new weaponry had been developed and mass production possible. Since October 1916 until the end of 1917 the Allies lost every month between 70 and 350 ships (April 1917), followed by a summer with the exceptional sea icing in the North Atlantic.

  9. #4 Jeff Id said: “I very much doubt that there was more ocean traffic than today.”

    This is an interesting aspect, but is a point which should be addressed when the impact of naval war during WWI & WWII is more clear. For a long time I even suppressed this idea. However since ships are screw driven they might have had an impact on the general warming trend since about 1850 at least in higher latitude, and in such sea areas as the North Sea and Baltic Sea. But to discuss this subject makes only sense if the role of the naval war on the warming period (1919-1940), and the cooling period from (1940-1975) is better understood. Particularly with regard to the three extreme cold war winters in Europe, 1939/40, 1940/41, and 1941/42, I hope I can proof it even by my modest means.

  10. It is known that the early final melting of the NH Laurentide ice-sheet induced an early Holocene global sea temperature maximum which even in the SH extended from ~12.5 – ~8.5 kyr BP possibly amplified by reduced sea-ice cover in the Southern Ocean, consistent with the SH paleodata.

    Virtually every Pleistocene interglacial was characterized by multi-modal peaks. The Last Interglacial (Oxygen Isotope Sub-stage 5e) at ~120 kyr was bimodal with the two peaks separated by an interval which is comparable with the duration of the current interglacial (Holocene).

    What I find particularly intriguing about the now well established AGW scientific ‘consensus’ is that nowhere can we find the logical pre-requisite to such a consensus: a solid set of critical assessments of the likely magnitude of global climatic effects of actual Late Holocene trends in NH insolation. After there is plenty of literature agreement on the effects of NH insolation on the patterns many previous interglacials!

    I would have thought that was a logical pre-requisite to granting that high degree of consensual agreement (and for accepting the recommendations of the IPCC for example).

    Only now are we beginning to see a trend towards publication in the mainstream literature of many studies assessing the effects of Late Holocene trends in NH insolation but perhaps they are all, to a significant extent, subject to the continuing uncertainty (lack of consensus?) surrounding the magnitude of the multi-decadal trend in the Sun’s activity over even just the last 200 years (refer Svalgaard etc.)

  11. @14 Steve Short said
    November 29, 2010 at 7:09 pm

    It is known that the early final melting of the NH Laurentide ice-sheet induced

    You might like to give that another look. I seem to recall a study disputing that, on the basis that none of the flow effects on the landscape that would have been inevitable actually show up. Sorry, I don’t have a link to that report, though.

  12. Fair enough Brian. FYI, my reference to the early final melting of the NH Laurentide ice-sheet almost 13,000 years ago is:

    Murton, J.B.; Bateman, M.D., Dallimore, S.R, Teller, J.T., Yang, Z. (2010). Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean. Nature 464 (7289): 740–743. doi:10.1038/nature08954

  13. ArndB #12 – I should have been more specific in my wars. I was referring to WWII. I think WWI was just a stumbling into a war (whereas WWII was a planned war). Although we call both of them “World Wars”, WWI was essentially a European war started by the old ties and monarchies that were holdovers from the colonial era of Europe. They stumbled into that one and I do not think any wanted to fight one then (it was never really resolved, and that is part of the reason WWII came about).

    WWII was planned – by Japan and Germany. While Japan started much earlier in its imperialistic conquests, it did not really get going until 1941, about the end of the warm period. Germany planned and then executed its war starting in September 39, after almost a generation of warm winters – figuring at worst it would be fighting a mud war in the winter.

    I agree my thoughts on this are pure speculation. We have many historians that would love to tell me the intrigue and back room planning that lead up to the war and totally discounting the weather. But the reality is battles are planned based upon expected weather – and Germany was very interested in using every advantage (the Japanese – being they were mostly island hopping in the tropics were less so, altough mindful of the Typhoon season).

  14. #20, PhilJourdan

    Indeed, WWI was a European war and the actors presumably had been very surprised that it took longer than expected. The Kaiser told his soldiers in August 1914 that they would be back home before the leaves fall. Nevertheless after the naval war machinery was in full gear in summer 1916 and the impact on the sea around Great Britain immense. More than 200’000 sea mines were placed, of which about 75’000 had been used to build the Northern Barrage between Orkney Is and Norway during summer 1918. Only few months later the temperatures at Spitsbergen went into a steep rise in winter 1918/19.

    The situation was very different during the first few months of WWII. There were plenty of naval activities in the North Sea and Baltic Sea. The west-wind drift was blocked, the wind shifted from SW to NE, plenty rain along the Rhine (stopping Hitler to ambush France already in November 1939), early and severe winter conditions, particularly miscalculated by the Soviets when they ambushed Finland on about the 30th November, as they had been in no way prepared for an unusual early and cold winter, and had to pay for it heavily. In Northern Europe it became the coldest winter for more than 100 years. This did not came out of the blue, but naval war activities contributed. (in detail at: http://climate-ocean.com/, Chapter B, pp. 7-147)

    In so far the notion: “the reality is battles are planned based upon expected weather”, is primarily a question of competence, which seem, to speak only about the war times, to have been extreme low 70 years ago. The North and Baltic Sea play a very crucial role for the weather, but nobody cared about a possible impact of naval warfare. Surprise was the most one could hear, for example: __” “The present century has been marked by such a widespread tendency towards mild winters that the ‘old-fashioned winters’, of which one had heard so much, seemed to have gone for ever. The sudden arrival at the end of 1939 of what was to be the beginning of a series of cold winters was therefore all the more surprising,” reported the British scientist A. J. Drummond in the QJoR Met. Society in 1943.”, see the paper “Extreme Winter 1939/40” left column, at: http://www.oceanclimate.de/
    Regards Arnd Bernaerts

  15. I’ve seen speculation on the web (and I don’t regard it as anything more than that) that WWI’s effect on North Atlantic climate wasn’t due to the increased amount of shipping itself, but the vastly increased amount of shipping sunk and therefore oil leaked to the surface, with its effect on surface processes of evaporation and wave formation.

    I don’t put much stock in it, because my sense is that the effect would still be quite small on a global scale, and because the much larger Battle of the Atlantic in WWII did not seem to have any similar effect at all.

  16. To those who think the 1920’s Arctic warming was a measurement anomaly, there are many contemporaneous accounts talking about sudden and surprising warming. This one comes from the US consulate in Norway:

    November, 1922. Monthly Weather Review
    The Changing Arctic
    By Geroge Nicolas Ifft

    [Under date of October 10, 1922, the American consul at Bergen, Norway, submitted the following report to the State Department, Washington, D.C.]

    The Arctic seems to be warming up. Reports from fishermen, seal hunters, and explorers who sail the seas about Spitzbergen and the eastern Arctic, all point to a radical change in climatic conditions, and hitherto unheard-of high temperatures in that part of the earth’s surface.
    In August, 1922, the Norwegian Department of Commerce sent an expedition to Spitzbergen and Bear Island under the leadership of Dr. Adolf Hoel, lecturer on geology at the University of Christiania. Its purpose was to survey and chart the lands adjacent to the Norwegian mines on those islands, take soundings of the adjacent waters, and make other oceanographic investigations.
    Dr. Hoel, who has just returned, reports the location of hitherto unknown coal deposits on the eastern shores of Advent Bay – deposits of vast extent and superior quality. This is regarded as of first importance, as so far most of the coal mined by the Norewegain companies on those islands has not been of the best quality.
    The oceanographic observations have, however, been even more interesting. Ice conditions were exceptional. In fact, so little ice has never before been noted. The expedition all but established a reconrd, sailing as far north as 81o 29’ in ice-free water. This is the farthest north ever reached with modern oceanographic apparatus.
    The character of the waters of the great polar basin has heretofore been practically unknown. Dr. Hoel reports that he made a section of the Buof Steream at 81o north latitude and took soundings to a depth of 3,100 meters. These show the Bulf Stream very warm, and it could be traced as a surface current till beyond the 81st parallel. The warmth of the waters makes it probable that the favorable ice conditions will continue for some time.

  17. #22, and #23 Curt

    The shift in the sea level structure off Spitsbergen around winter 1918/19 had such a big impact on temperatures, sea ice and glaciers in the high north that the Norwegian scientist Ahlmann regarded this warming period as a ‘climatic revolution’ (Ahlmann, 1946), which indicates that this event had presumably little to do with natural variation, or sun spot cycles, and so on, while even today the event is merely called “one of the most puzzling climate anomalies of the 20th century” (Bengtsson, 2004), while other offer i.a. the conclusion “that the earlier warming was natural internal climate-system variability” (Johannessen, 2004).

    Although the ‘climatic revolution’ is on record for more than 80 years, science is only offering meaningless speculations. The role of the ocean and seas is rarely investigated; the role of the West Spitsbergen Current not even considered. At least V.F. Zakharov (1997) asked this questions few years ago:
    · Why are the maximum climate fluctuations confined to the Atlantic sector of the Arctic?
    · Why are these fluctuations pronounced, first of all, right here?
    · Should the Atlantic sector of the Arctic be considered as a center of some kind, a source of climate change over the Hemisphere?

    Any reasonable explanation is welcome, but to generate a “climatic revolution” around winter 1918/19 something extraordinary must have happened. The intensity of the naval war in the seas of Northern Europe since summer 1916 makes it to a highly probable candidate.

  18. ArndB #21 – In so far the notion: “the reality is battles are planned based upon expected weather”, is primarily a question of competence, which seem, to speak only about the war times, to have been extreme low 70 years ago.

    I fear we are getting too far afield, but only wanted to state that I do agree with you. My original post was merely a response to a thought that the war caused the climate, whereas I was saying the war was a result of the climate (timing).

    But I loved your whole response! great reading!

  19. Curt said
    November 30, 2010 at 5:13 pm

    November, 1922. Monthly Weather Review
    The Changing Arctic
    By Geroge Nicolas Ifft

    The oceanographic observations have, however, been even more interesting. Ice conditions were exceptional. In fact, so little ice has never before been noted…The warmth of the waters makes it probable that the favorable ice conditions will continue for some time.

    It’s interesting that there was a time (less than a century ago) that less ice in the Arctic was actually considered a favorable ice condition. They also didn’t seem to be too concerned with the Poly Bears, but they seemed to have been able to survive.

  20. I love people who pinch things without giving attribution. I had the damn video up way before anyone. I dug it up and brought it out of the basement.
    Ron If you’re out there, you’re on my shit list.

  21. Re 22.
    Curt said
    []…WWI’s effect on North Atlantic climate wasn’t due to the increased amount of shipping itself, []oil leaked to the surface, with its effect on surface processes of evaporation and wave formation.
    I don’t put much stock in it, because my sense is that the effect would still be quite small on a global scale, and because the much larger Battle of the Atlantic in WWII did not seem to have any similar effect at all.

    On the contrary, WWII had a pronounced temperature blip: the problem is that the ‘blip’ was massaged away by Wigley et al and corrected away by Folland and Parker (see ‘bucket correction’). The massaging can be examined by searching for “Wigley blip” on Google. The Folland and Parker correction has been extensively examined on Climate Audit and, to my mind, has been shown to be wrong — it was designed to hide the abrupt fall of .3 deg C at the end of 1945.

    from the UEA emails:
    From: Tom Wigley <
    To: Phil Jones <p
    Subject: 1940s
    Date: Sun, 27 Sep 2009 2
    Cc: Ben Santer <


    Here are some speculations on correcting SSTs to partly
    explain the 1940s warming blip.

    If you look at the attached plot you will see that the
    land also shows the 1940s blip (as I'm sure you know).

    So, if we could reduce the ocean blip by, say, 0.15 degC,
    then this would be significant for the global mean — but
    we'd still have to explain the land blip.

    I've chosen 0.15 here deliberately. This still leaves an
    ocean blip, and i think one needs to have some form of
    ocean blip to explain the land blip (via either some common
    forcing, or ocean forcing land, or vice versa, or all of
    these). When you look at other blips, the land blips are
    1.5 to 2 times (roughly) the ocean blips — higher sensitivity
    plus thermal inertia effects. My 0.15 adjustment leaves things
    consistent with this, so you can see where I am coming from.

    Removing ENSO does not affect this.

    It would be good to remove at least part of the 1940s blip,
    but we are still left with "why the blip".

    Why indeed.

    http://www.nature.com/news/2008/080528/full/453569a.html comments about how the bucket correction sorts out the problem. Why data that doesn't fit has to be explained away rather than explained is a topic for psychology, not climate science.

    Re 24.

    ArndB said

    Any reasonable explanation is welcome, but to generate a “climatic revolution” around winter 1918/19 something extraordinary must have happened. The intensity of the naval war in the seas of Northern Europe since summer 1916 makes it to a highly probable candidate.

    A lot of the WWI shipping was, I suppose, coal-fired. However, the use of oil in production and for engines was just beginning. The industrial gearing up for war was intense and, I speculate, extremely polluting.

    Here's what I think happened: oil and surfactant spill from hurried industrial expansion on both sides of the Atlantic led to the same effect as the submarine war produced during WWII, namely massive smoothing of the North Atlantic. Judith Curry has kindly provided a thread for lunatic fringe theories of GW and I detail the Kriegesmarine hypothesis at Sceptics: make your best case Julian Flood | November 27, 2010 at 9:12 am . (Although I'm more of a lukewarmer.)

    I was unaware of the WWI warming — perhaps some detail will read across. If I dumped a floating object in the North Sea, where would it drift? And from the east coast of the USA?

    Let me add a cautionary note: neither Dr Curry nor Prof. Lindzen think that the Kriegesmarine effect is large enough to be a thorough explanation, but I don't think they are allowing for the many different ways this effect causes warming.

    Finally, a plea. I've lost a very old FAO paper on fish productivity which has a series of graphs of windspeeds over the various ocean basins during WWII. In each basin there is an excursion upwards matching the uncorrected SST blip in time, with the NA leading at plus 7m/s. It's a scan, not text, and is proving impossible to track down. I read it as a measure of the uncoupling between the atmosphere and the ocean as wave generation is suppressed by oil and surfactant spills.

    And… er… finally again, have a look at the image at
    I interpret this as showing the ice releasing some sort of smoothing agent as it melts*, which is what one would expect if ice sequesters light oil. If we've polluted the edge of the ice then will it retain enough of the stuff to influence the next year's melt? If it does then the problem will slowly compound. Google iceberg polar bear images for more.

    * But then I would. When all you've got is a hammer, everything looks like a nail.

  22. 30 Julian Flood said, December 3, 2010 at 6:25 am ,
    ___“WWII had a pronounced temperature blip”

    The war SST data in the Pacific and Atlantic have been subject to two conference papers (1977 & 1978) concluding that the circumstances of their collection is to various and dubious that they are presumably completely worthless ( right column at:http://www.oceanclimate.de/ )

    Julian Flood said:
    ___” Let me add a cautionary note: neither Dr Curry nor Prof. Lindzen think that the Kriegesmarine effect is large enough to be a thorough explanation”

    I do not know what they have said, and I am not aware that they have done and published any research in this respect, and presumably know nothing about the extreme war winters in Europe 1939/40, 1940/41, and 1941/42. Once it could be established that naval war contributed to these winters in Europe, the role of the North-Atlantic Battle 1942-1945 on the initiation of the global cooling would inevitable become a serious issues.
    Regards ArndB

  23. On WW1/WW2 ocean effects:

    To paraphrase the distinguished scientist Douglas Adams, the Atlantic is a BIG place. Huge. Look, you may think it’s a long way to the chemist’s, but that’s peanuts compared to the Atlantic.

    I would have a lot of trouble believing that any combination of ships doing anything at all could have any noticeable effect on Atlantic temperature or currents.

    Has anyone looked at the AMO or the Arctic Oscillation? Also we know that the PDO was ready for a regime change sometime in the 1900-1920 time frame.

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