Comments 1 to 25:

1. WheelsOC at 09:25 AM on 12 March, 2011
   Thank you, I've been looking for more information about the "Roman Warming." Usually data presented is only from the northern hemisphere, but it's used to allegedly put the current global climate "in perspective."
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2. Camburn at 11:11 AM on 12 March, 2011
   This paper shows a correlation between Bond Events and precip in Peru/Bolivia http://eas.unl.edu/~sfritz/pubs/BakerJQS05.pdf
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   Moderator Response: [DB] (Converted URL to Link) Personally I think it's great that you're referencing primary source literature. But your description of it lacks an evaluation of whether you think it supports the topic of this post or serves to undermine it. Perhaps if you could add some further characterization of the study you reference it would serve to better enhance the discussion here. Thanks!
3. Camburn at 14:50 PM on 12 March, 2011
   Thank you DB. I tried to convert the link but still have not figured out how to do that. What the paper shows, at least to me, is that there is an obvious link to the hydrological cycle world wide and Bond events. The changing of the thermocline in the Northern Hemisphere that happens during a bonna fide Bond event affects not only the Western NA continent, but also South America. Even tho the temperature may cool in the NH and rise in the SH, the overall affect is a world wide phenomenon.
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   Moderator Response: [DB] If you go here, you find tips on how to do that. For links or documents like pdf's, copy the first indented line of html string (everything between the leftmost-arrow and rightmost-arrow, including the arrows), replacing the text between the double-quotes with your desired source url plus giving some kind of description/name of the linked page/source.

   For images, look under the section that says IMPORTANT. Copy the html tag string that appears there into your comment box, insert your desired url string for your link source between the double-quote marks and then Bob's-your-uncle (you're ready-to-go).

4. pbjamm at 15:37 PM on 12 March, 2011
   Camburn, I think the point is (and I am sure I will be corrected if wrong) that the Bond Event may be a global temperature variation but it is not all in one direction. So the net change is neither positive nor negative, more flat.
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5. Camburn at 03:15 AM on 13 March, 2011
   pbjamm: I am not sure that it is all in one direction. The ice core data from Volstock is for Volstock. An isolated area with a small change in actual temperature verses the lower latitudes. Comparing Greenland to Volstock is not a fair comparison, but must be taken into consideration and evaluated further to a more regional perspective and then graduated out to a global perspective. I am more interested in the hydro cycles that accompany a Bond type event. There are large shifts in that cycle that occur when a Bond event happens and they take 100's of years to move back to "normal".
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6. Rob Honeycutt at 03:34 AM on 13 March, 2011
   Camburn @ 5... I think you are correct, to an extent. I believe that, in general, Vostok is actually considered to be more representative of the planet as a whole. Reading through a bunch of papers on ice cores I find that the Byrd ice core is used as often Vostok for comparing NH/SH. The interesting thing you find there is that Byrd shows an overall warming trend over the Holocene, and also shows the same D-O and Bond antiphase events you see in Vostok. I'm currently trying to locate the actual data for Byrd during the Holocene. All the data at NOAA ends prior to the Holocene.
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7. Camburn at 04:20 AM on 13 March, 2011
   From the papers I have read it seems to me that the regional hydrological cycles have more information in them than "temperature" cycles. To change regional hydrocycles, such as the Sahara changing to desert, or Western NA having 400+ years of drought and then turning to a wet cycle show global circulation changes. These events are tied to temperature, but temperature does not always lead to these events occuring. There are indications that temperature shift are a result of these hydrological shifts, rather than the hydrological shift being a result of a change in temperature. Bond events from the past are tied to the suns strength. I am not only talking about TSI, but rather isotope data showing the changes in UV etc. TSI is not always a predictor of temperature. There have been several long term basin studies done throughout the world showing the correlation between solar cycle strength and precipitation over a large area. One thing that is certain, when a Bond event occurs, hydrological cycles throughout the world change very very quickly and this is off concern as we are about due for a Bond type event cycle wise. If we could only be sure what causes this event it would certainly make it easier to understand its scope and total dynamics.
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8. Camburn at 04:25 AM on 13 March, 2011
   Rob: The Byrd ice core is interesting in itself because it does show continued warmth during the Holocene. This is in direct contrast to some of the proxy literature of lower latitudes. I have to thank you for posting about the Bond events. These events allow good discussion about world wide climate without the "political" flare. I appreciate this.
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9. Camburn at 07:02 AM on 13 March, 2011
   Took me some digging, but I finally found this again: Relates to the validity of Bond cycles. Are they real or imaginary correlations? http://geography.cz/sbornik/wp-content/uploads/2009/09/g08-4-1wanner.pdf
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   Moderator Response: [DB] You were almost there. The html tag string has an interior set of right-and-left arrows, between which goes the name of the link or whatever you're calling whatever you're linking to, which was missing. Here's the string with no arrows, substituting the number 1 for the left arrow (shares the same key as the comma on my keyboard) and the number 2 for the right arrow (shares the same key as the period on my keyboard):

   1a href="http://geography.cz/sbornik/wp-content/uploads/2009/09/g08-4-1wanner.pdf"2http://geography.cz/sbornik/wp-content/uploads/2009/09/g08-4-1wanner.pdf1/a2

   or

   1a href="http://geography.cz/sbornik/wp-content/uploads/2009/09/g08-4-1wanner.pdf"2Here's a link to an interesting study I found1/a2

   Which (substituting the appropriate arrows back in for the 1's & 2's) yields:

   Here's a link to an interesting study I found

10. Camburn at 07:04 AM on 13 March, 2011
    Moderator: I am somewhat frustrated. I have tried to do the link correctly, but it seems to disappear. DB: Your eplanation was good, but I must be missing a step.
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    Moderator Response: [DB] See my response to you in the previous comment. You'll get it. Without the interior label, your link (though constructed properly) would not echo back to the screen (the interior label serves as a graphical placeholder for the link).

    I figured it out, eventually. If I can, anybody can.

11. Phil at 08:30 AM on 13 March, 2011
    Camburn and Daniel #9 and #10 This is the syntax exactly: <a href="http://geography.cz/sbornik/wp-content/uploads/2009/09/g08-4-1wanner.pdf">http://geography.cz/sbornik/wp-content/uploads/2009/09/g08-4-1wanner.pdf</a>
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12. Rob Honeycutt at 08:44 AM on 13 March, 2011
    Camburn @ 9... There are definitely differing opinions on Bonds events. That's why I linked that last paper, Maslin 2009. That's the most recent paper I could find on the topic, which suggests that Bond events are there. My biggest takeaway from this topic is that the planet often redistributes temperature around the planet. And the difference with today is that we see nearly all indicators of temperature going in one direction. I believe that is the unprecedented nature of warming this past century.
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13. Tom Curtis at 10:01 AM on 13 March, 2011
    Camburn, the paper you linked to @9 shows strong evidence of Bond events in the North Atlantic, but ambiguous evidence for it elsewhere in the globe. It also shows the correlation of Bond events to solar activity it hotly contested. I am not sure how it helps your case. @7 you make several claims, none of which you support with evidence. One at least, is very dubious. The wet conditions in the Sahara arrived suddenly with the warmer conditions following the Younger Dryas, and dissipated slowly in the period 5000 to 3000 before the present. As such, it shows no significant correlation with Bond events that I know of. If you have evidence of such a correlation, please show it. Otherwise it is most logically treated as a consequence of global warmth during the Holocene Climactic Optimum. Your claim that we are "about due" for a Bond event is certainly false. Quite apart from the fallacy of claiming that a recurring event with durations between events varying between 900 and 2300 years is "periodic" and can be "due"; the peaks of the Bond events are "... around 400, 1,400, 2,800, 4,300, 5,900, 8,100, 9,400, 10,300 and 11,100 cal years BP." (Wanner and Büttikoffer (2008)) Clearly the next Bond event will not be "due" for several hundred years at least, and probably not for another thousand years.
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14. Camburn at 10:36 AM on 13 March, 2011
    Tom: I thought I was very clear that the stimuli for the Bond events is not known but only suggested at. I don't have the paper at hand, and am only speaking from memory of the paper that showed a shift in hydrological trends in the Sahara that started while a Bond event was in place and continued on after that event was over. There is question that the LIA was an actual Bond type event. If it wasn't, then we are about due for another. I can't seem to find your Wanner and Buttikoffer paper.
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    Moderator Response: [DB] Another Wanner and Bütikofer 2008 can be found here.
15. Tom Curtis at 12:07 PM on 13 March, 2011
    Camburn @14, Wanner and Bütikoffer is the paper you linked @9. I am not sure why there is doubt about classifying the LIA as a Bond event, as it shows all the appropriate characteristics. Nor is the interval between it and the preceding Bond event the shortest. The interval between the Bond event of 9400 BP and that of 10300 BP is shorter. So, if we do consider the LIA to not be a "Bond event", then the claim of any of the Bond events to be one is also impeached. We then left with occasional coolings of the NH with not single causation, or periodic nature. In that case, talking about such an event being "due" is a form of the gambler's fallacy. Finally, the gradual drying of the Sahara over the period 5000 BP to 3000 BP seems well confirmed by a number of studies, including near the Nile (previously linked article) and near Lake Chad. This has been a consistent pattern recorded across 5 or so papers I have read on the subject. Interestingly, more southerly locations have a delayed onset of drying, as would be expected if the drying was a result of a shrinking of the northern Hadley cell, with a resulting shrink of the area of monsoonal rainfall, an expected consequence of a cooling climate. Further, models driven by reductions in NH summer insolation, or increased GHG forcing both show an increase in size of the Hadley cell, with a resulting moister Sahara; although there are subtle differences between the two cases. So, unless you can produce a contrary paper as evidence, I think we are wise to assume Saharan drying was not a consequence of Bond events.
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16. robert way at 13:10 PM on 13 March, 2011
    It isn't quite so simple as to say warm periods cause the IRD events. In fact evidence suggests that these occurred simultaneously across difference ice regions of the northern hemisphere. Very complicated subject.
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17. Rob Honeycutt at 05:12 AM on 14 March, 2011
    Robert... I think you're one of the experts in this field who frequents SkS. Do you think it's fair to say that Bond events suggest that heat is frequently redistributed around the planet? I definitely got from the reading I did that this is a very complicated topic. In fact, global temperature during the Holocene, in general, seems to be a very complicated topic. I did two other posts (Crux of a Core 1 and 2) talking about the error of pointing to a single proxy as evidence of what global temperatures were. I wanted to use Bond events to start to paint a larger picture of the Holocene. What we don't see is various proxies going up and down in unison. We see somewhat chaotic signals where it's difficult to pinpoint why and how heat is being redistributed from one place to another. Correct? From the perspective on someone deep into the science of these events it's controversial. The exact why, how, where, are up for debate. From the perspective of the more general public it seems to me Bond events suggest that the Holocene is very stable compared to glacial periods, but still involves redistribution of heat around the planet.
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18. PhysSci at 18:21 PM on 14 March, 2011
    Rob Honeycutt - yes, the Holocene is much more stable than glacial periods, no doubt, and this has to do with orbital variations. Also, we currently live in one of the warmest (if not THE warmest) periods of the Holocene contrary to some skeptics, who try to prove that the global temperature has been much higher 7-8 thousands years ago. All these discussions about how warm the present is or how big the rate of temperature change over the past 100 years has been compared to past periods are besides the point. The point is, where is the empirical evidence that any of the temperature changes (past and present) were caused by variations in CO2 or any other so-called 'greenhouse gases'? I have researched this topic in detail, I can tell you with full confidence that is NO credible empirical evidence in the entire historical record that CO2 has had ever any impact on Earth's climate! The CO2-climate 'connection' ONLY exists is virtual realities generated by models, but not in our physical reality. In fact, the whole GH theory is based on radiative transfer models from the 1960s and 70s ...
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19. Arkadiusz Semczyszak at 22:05 PM on 16 March, 2011
    I was late to this interesting discussion. But II have to give a few remarks ... Wikipedia says: “Bond et al. (1997) argue for a climate cyclicity close to 1470 ± 500 years in the North Atlantic region.” I feel the most convincing explanation of the paper (with references the paper cited by Cambrun): Holocene climate variability in northernmost Europe, Allen et al., 2007.: “Time-series analysis of pollen analytical and sediment geochemical data indicates that each exhibits statistically significant periodic behaviour (at periods of ca 190, 410, 1050, 1650 and 1810 yr). The periods detected suggest this behaviour may reflect regional expression of climate system responses to solar variability and/or of effects upon tides and ocean circulation of periodic lunar orbital variation.” The Sun This figure (panel solar cycles) explains part of differences in the length and intensity of events Bond. I I also recommend this work: Linking solar forcing with climate and primary productivity changes in the Northeast Pacific: evidence from mid to late Holocene laminated sediments, Patterson et al., 2011. The Moon Impacts of late Holocene rapid climate changes as recorded in a macrotidal coastal setting (Mont-Saint-Michel Bay, France), Billeaud, Tessier and Lesueur, 2009.: “The sedimentary expressions of rapid climate changes vary according to the different subenvironments within Mont-Saint-Michel Bay; cycles, a few meters thick, can be correlated throughout the bay, and radiocarbon dating suggests that they have a millennial time scale. The various changes reflect an increase in wave dynamics in association with Bond cold events, possibly in conjunction with long-term (1800 year periodicity) tidal cycles.” It is worth noting that the solar cycle Hallstad - c. 2300 years - is about c. 500 years longer than the tidal cycles. The events of Bond - in the past - there asynchrony between NH and SH but in two points, however, we notice the coincidence. Both the end of the last glaciation and the optimum - the middle Holocene occur synchronously on the NH and SH (like the current warming). Here we see a periodicity of about six thousand. years. Most likely, the recently discovered solar cycle 6 thousand. years is so strong that it (through the effects of second-order?) - can be a superposition of cycles - equally affecting - globally at the same time - climate change in the SH and NH. The optimum climate synchronicity middle and late Holocene in both hemispheres-evidenced by numerous works on southern hemisphere (also shows warmth at the same time - NH): Antarctic ice cores, cave stalagmites, glaciers, alkenones in seabed cores off Chile, etc.. The latest paper I recommend: Ice core: Antarctic lakes suggest millennial reorganizations of Southern Hemisphere atmospheric and oceanic circulation, Hall et al. 2010.: “Here, we present new data from closed-basin lakes in the Dry Valleys region of East Antarctica that show high-magnitude, high-frequency oscillations in surface level during the late Pleistocene synchronous with climate fluctuations elsewhere in the Southern Hemisphere. These data suggest a coherent Southern Hemisphere pattern of climate change on millennial time scales, at least in the Pacific sector, and indicate that any hypothesis concerning the origin of these events must account for synchronous changes in both high and temperate latitudes.” Marine sediment core: Holocene Southern Ocean surface temperature variability west of the Antarctic Peninsula, Shevenell et al., 2011.: “On millennial timescales, abrupt SST fluctuations of 2–4 °C coincide with globally recognized climate variability8. Similarities between our SSTs, Southern Hemisphere westerly wind reconstructions9 and El Niño/Southern Oscillation variability10 indicate that present climate teleconnections between the tropical Pacific Ocean and the western Antarctic Peninsula11 strengthened late in the Holocene epoch.”
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20. Arkadiusz Semczyszak at 22:08 PM on 16 March, 2011
    #Tom Curtis Sahara “... and dissipated slowly in the period 5000 to 3000 before the present.” That's not true. wikipedia: “A curious discovery from the marine sediments is that the transitions into and out of this wet period occurred within decades, not millennia as previously thought.” A major widespread climatic change around 5300 cal. yr BP at the time of the Alpine Iceman Magny & Haas, 2004.: “It has possible equivalents in many records from various regions in both hemispheres dating to 5600–5000 cal. yr BP and corresponds to global cooling and contrasting patterns of hydrological changes.” Sahara is the result of synchronous global cooling for the SH and NH.
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21. Tom Curtis at 22:29 PM on 16 March, 2011
    AS @20, if you want to trump the variety of papers I linked in suport of the slow drying of the Sahara, perhaps you coud find something more recent than a seminar in 1998 (the source of the Wikipedia claim). For your edication: The onsite evidence clearly shows a gradual drying. Your scientific link, by the way, does not discuss the drying of the Sahara.
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22. Arkadiusz Semczyszak at 00:33 AM on 17 March, 2011
    @Tom Curtis I agree ... Information from Wikipedia might already be outdated. Changes may be slow. See here. Sorry is my "oversight" - should verify the information in Wikipedia. P.S. About my link - it’s refers to a global phenomenon that affects the Sahara.
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23. Rob Honeycutt at 06:57 AM on 17 March, 2011
    PhySci @ 18... "I have researched this topic in detail, I can tell you with full confidence that is NO credible empirical evidence in the entire historical record that CO2 has had ever any impact on Earth's climate! " I can tell you with equal (or more confidence) that there are many thousands of other scientists who have researched this in excruciating detail and have come to the conclusion that CO2 is the "largest control knob" on the planet's climate. You have a daunting uphill battle to convince the broader scientific community of your position.
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24. desertphile at 00:39 AM on 28 July, 2012
    A very fine article: thank you. Bond Events don't look cyclical, judging from _Bond_et_al_ (1997) but it is possible they are, or were: one needs a much longer series of data to answer the question. It seems very odd to me that denialists and professional liars insist that proxy data going back 600 years are all wrong when Dr. Mann _et_al_ published the data, but proxy data going back 10,000 years are Gospel if they give the verisimilitude of causing doubt on the evidence for human-caused climate change.
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25. desertphile at 00:44 AM on 28 July, 2012
    ".... I can tell you with full confidence that is NO credible empirical evidence in the entire historical record that CO2 has had ever any impact on Earth's climate! I am told my many people, with full confidence, that ghosts are real; I am also told by many people, with full confidence, that "fee energy" is possible. Meanwhile, the PPMCC between atmospheric CO2 increase and global average temperature increase is 0.90642
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