The Arctic Iris Effect, Dansgaard-Oeschger Events, and Climate Model Shortcomings. Lesson from Climate Past – part 1.

 

Guest essay by Jim Steele

Director emeritus Sierra Nevada Field Campus, San Francisco State University and author of Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism

Dansgaard Oeschger Events and the Arctic Iris Effect

During the last Ice Age, Greenland’s average temperatures dramatically rose on average every 1500 years by 10°C +/- 5°C in a just matter of one or two decades, and then more gradually cooled as illustrated in Figure 1 below (8 of the 25 D-O events are numbered in red on upper graph; from Ahn 2008). These extreme temperature fluctuations between cold “stadials” that lasted about a thousand years and warm “interstadials” lasting decades are dubbed Dansgaard-Oeschger events (D-O events). These rapid temperature fluctuations not only rivaled the 100,000‑year fluctuations between maximum glacial cold and warm interglacial temperatures but D‑O warm events coincided with expanding Eurasian forests (Sánchez Goñi 2008, Jimenez-Moreno 2009), northward shifts of subtropical currents along the California coast (Hendy 2000), and shifts in belts of precipitation in northern South America (Peterson 2001).

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Just 25 years ago most climate researchers were hesitant to accept initial Greenland ice core evidence suggesting such abrupt D‑O warming events (Dansgaard 1985). But as other Greenland ice cores verified their reality, it was clear that the only mechanism realistically capable of producing such abrupt warming was the sudden removal of insulating sea ice that allowed ventilation of heat previously stored in the Arctic as Dansgaard (1985) had first proposed. Still that begged the question ‘what caused the sudden loss of insulating sea ice’?

Changes in CO2 concentration are unlikely to have had much impact on D‑O events (3rd graph from the top in Figure 1). CO2 concentrations did fluctuate by about 20 ppm during a third of the D-O events (red numbers), but could contribute directly to no more than 0.4°C to only 30% of the largest warming events. In contrast during 68% of the other D-O events (not numbered), abrupt warming occurred while CO2 was declining. Thus rapid warming and cooling seems independent of any CO2 forcing.

Abrupt D‑O warming and cooling suggested to researchers (Broecker 1985) that the Atlantic Meridonal Overturning Circulation (AMOC) turned “on” and “off”. Based on the misleading belief in the existence of a simplistic “ocean conveyor belt” (Wunsch 2007), researchers incorrectly interpreted a lack of deep-water formation as evidence of a lack of warm water flowing into the Arctic. However based on increasing proxy evidence (Rasmussen 2004, Ezat 2014), it is now understood that the inflow of warm Atlantic Waters never “shut off” but continued to enter the Arctic and warmed the subsurface layers. As seen in Figure 2 (from Itkin 2015) the upper layer of fresh water and the halocline insulate the warm Atlantic water from the overlying ice. Together the thick sea ice and polar mixed layer simply “turn off“ any heat flux from the ocean to the air, thus maintaining cold stadial air temperatures. Furthermore if the salty Atlantic Water cannot be cooled by the cold Arctic air, then North Atlantic Deep Water is shut off as well.

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Although climate models have failed to simulate D‑O events, models were manipulated to shut off poleward heat transport by prescribing ad hoc floods of freshwater. As long as freshwater “hosing” was applied, the models prevented the cooling and sinking of North Atlantic waters, which shutoff the deep water formation and thus “ocean conveyor belt” resulting in contrived cooling. That interpretation became the reigning paradigm and researchers began searching for evidence of a flood of freshwater, while nearly every model engaged in “hosing” experiments to explain abrupt climate change. But evidence of the required freshwater flooding has yet to be found and a growing wealth of proxy evidence suggested there was as much freshwater during stadials as there was during interstadials. Even the notion of freshwater floods from an armada of melting icebergs was not consistent with the timing of D‑O events (Barker 2015). Freshwater shutdown of the Atlantic Meridonal Overturning Circulation is most likely just a figment of the models’ configuration.

Other researchers suggested drivers of past and present rapid temperature change were likely to be very similar (Bond 2001, 2005), and recent findings are now supporting that notion. More recent explanatory hypotheses for D‑O events are gaining widespread critical acceptance and do not require any massive floods of freshwater nor a shutdown of the AMOC (Rasmussen 2004, Li 2010, Peterson 2013, Dokken 2013, Hewitt 2015). When sea ice prevents heat ventilation, the inflow of warm and dense Atlantic Waters continues to store heat in the subsurface layers. As heat accumulated, the warm Atlantic Waters became more buoyant, upwelled and melted the insulating ice cover. The loss of an insulating ice cover “turns on” the heat flux causing a dramatic rise in surface temperatures to begin the D‑O interstadial. Although details of hypothesized D‑O mechanisms vary slightly, they all agree on the ability of growing and shrinking sea ice to affect the heating and cooling of the northern hemisphere. I refer to this sea ice control of heat ventilation the Arctic Iris Effect.

The signature of an Arctic Iris Effect is the opposing temperature trends in the ocean versus atmosphere: when ice is removed, warmer air temperatures coincide with cooler ocean temperatures. When ice returns cooler air temperatures coincide with a warmer ocean. The thicker the sea ice, as during the last Ice Age, the longer the period between ventilations such as the D‑O events. Thick sea ice is less sensitive to small changes in insolation and/or natural variations of inflowing Atlantic Waters. As discussed in Hewitt 2015 decreases in the freshwater layer that separates sea ice from the warm Atlantic Waters are also likely critical contributors to D‑O events. For example as the Laurentide Ice Sheet grew, sea levels fell shutting of the inflow of fresher Pacific water through the Bering Strait, coinciding with an increased frequency between D‑O events from 8 thousand to 1.5 thousand years.

Peterson 2013 suggested that in addition to thick multiyear sea ice, ice shelves were critical for maintaining the longer cold stadials by better resisting small oscillations of increased inflow of Atlantic Water. Likewise with the current reduction of Arctic ice shelves and reduced multiyear sea ice during our present interglacial, much smaller changes in insolation and/or Atlantic inflow could more easily initiate ventilation events. With smaller time spans between each ventilation event, less heat accumulates and warm spikes are more muted (1°C to 2°C) compared to 10°C +/- 5°C during the D‑O interstadials. Over the past 6000 years, decades of rapid ice loss resulted in 2°C to 6°C air temperatures warmer than today quickly followed by centuries of colder temperatures and more sea ice (Mudie 2005).

The 20th century ventilation events produced only a 1°C to 2°C increase yet the signature of the Arctic Iris Effect is still observed. In 2001, Dr. Vinje of the Norwegian Polar Institute reported on the opposing temperature effects as ice retreated in the Nordic Seas. Between 1850 and 1900 there was a rapid warming of 0.5°C ocean temperatures between 1850 and 1900 with very little change in atmospheric temperature. Then they reported, “The warming event during the first decades of this century is characterized by a significant decrease in the Nordic Seas’ April ice extent, an increase of ~3°C in the Arctic surface winter temperature, averaged over the circumpolar zone between 72.5° and 87.5°N, and an increase in the Spitsbergen mean winter temperature of as much ~9°C. During this warming event the temperature in the ocean was lower than normal.

An increasing preponderance of positive ice extent anomalies, with an optimum in the 1960s, is observed during the period 1949–66, concurrent with a cooling in the circumpolar zone of ~1°C, a fall in the Spitsbergen mean winter temperature of ~3°C, and an increase in the mean winter air pressure in the western Barents Sea of ~6 hPa. During this cooling event the temperature in the ocean was higher than normal.” [Emphasis Added]

Similarly the most recent Arctic warming again reveals the fingerprint of the Arctic Iris Effect. There was no atmospheric warming in Arctic when there was an insulating cover of multiyear sea ice. Measurements between 1950 and 1990 reported a cooling Arctic atmosphere prompting researchers to publish, “Absence Of Evidence For Greenhouse Warming Over The Arctic Ocean In The Past 40 Years”. They concluded, “This discrepancy suggests that present climate models do not adequately incorporate the physical processes that affect the Polar Regions.”

Abruptly rapid Arctic warming began in the 1990s with an initial loss and thinning of Arctic sea ice when the Arctic Oscillation’s shifted wind directions and below‑freezing winds from Siberia pushed multiyear ice out of the Arctic. Rigor 2002 correctly pointed out, “One could ask, did the warming of SAT [Surface Air Temperatures] act to thin and decrease the area of sea ice, or did the thinner and less expansive area of sea ice allow more heat to flux from the ocean to warm the atmosphere?” They concluded, “Intuitively, one might have expected the warming trends in SAT to cause the thinning of sea ice, but the results presented in this study imply the inverse causality; that is, that the thinning ice has warmed SAT by increasing the heat flux from the ocean.” [Emphasis Added] That conclusion has been further supported by recent analyses of ocean heat content by Wunsch and Heimbach 2014, two of the world’s premiere ocean scientists from Harvard and MIT. They reported the deep oceans are cooling suggesting the oceans and atmosphere are still not in equilibrium and oceans are still ventilating heat from below 2000 meters that was stored long ago. Also in their map illustrating changes in the upper 700 meters of the world’s oceans (their Figure shown below), we see the entire Arctic Ocean has cooled between 1993 and 2011, as would be expected from the Arctic Iris Effect. Keep in mind that the warm layer of Atlantic water on average occupies the depths between 100 and 900 meters.

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The Earth’s Energy Budget

The Earth’s energy budget depends on a balance between absorbed solar radiation and outgoing infrared radiation. While some atmospheric scientists have focused on a possible energy imbalance created by 2 watts/m2 generated by rising CO2, widespread regions of the ocean absorb and ventilate over 200 watts/m2 of heat each year. As illustrated in Figure 3 (from Liang 2015), the oceans absorb heat (blue shades, in watts/m2) along the equator and over the upwelling zones along the continents’ west coast. Intense tropical insolation and evaporation creates warm dense salty waters that sink below the surface storing heat at depth. Changes in insolation, tropical cloud cover, and ocean oscillations like El Nino affect how much heat the oceans absorb or ventilate. Excess heat absorbed in the tropics is transported poleward. To gain a proper perspective on the importance of heat transport from the tropics to the poles, currently Polar Regions average 30°C colder than the equator. If there was no heat transport, the poles would be 110°C colder than the tropics (Gill 1982, Lozier 2012).

On average, the greatest ventilation of ocean heat happens where heat transportation is most concentrated: along the east coast of Asia over the Kuroshio Current and along east coast of North America along the Gulf Stream. Additionally large amounts of heat are also ventilated over Arctic’s Nordic Seas region, a focal point of the Arctic Iris Effect. A comparison of the temperature changes at varying ice core locations from southeast to northwest Greenland, points to this North Atlantic region as the main source of heat ventilated during each D‑O event (Buizert 2014). Likewise modeling work (Li 2010) shows that reduced ice extent in this region exerts the greatest impact on Greenland temperatures and snow accumulation rates. And it is in this same region that Vinje 2001 reports the greatest reduction in ice cover coinciding with the rapid changes in Greenland’s instrumental data. While CO2 warming would predict the greatest rate of Greenland warming in the most recent decades, the Arctic Iris effect would predict a greater rate of warming in the 1920s because thick sea ice from the Little Ice Age would have caused a greater accumulation of heat. Indeed Chylek 2005 reported, “the rate of warming in 1920–1930 was about 50% higher than that in 1995–2005.”

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Climate Model Shortcomings

In 2008 leading climate scientists at the University of East Anglia’s Climatic Research Unit published Attribution Of Polar Warming To Human Influence. As seen in their graph below, their models completely failed to account for the 2°C Arctic warming event observed from 1920 to the 1940s, (illustrated by the black line labeled “Obs” for observed). This was a warming event that climate scientists called “the most spectacular event of the century” (Bengtsson 2004). Their modeled results of natural climate change grossly underestimated the 40s peak warming by ~0.8° C, and simulated a flat temperature trend throughout the 20th century as illustrated by the blue line labeled “NAT” for natural. More striking when the models added CO2 and sulfates, the modeled results (red line labeled all) cooled the observed warming event further. Despite their failure to model natural events they concluded, “We find that the observed changes in Arctic and Antarctic temperatures are not consistent with internal climate variability or natural climate drivers alone, and are directly attributable to human influence.

However their results only demonstrated that their models failed to account for natural climate change, the Arctic Iris Effect and ventilation of ocean heat during the 1930s and 40s. By all accounts the recent warming of the 1990s and 2000 was likewise a ventilation event that also cooled the upper layers of the Arctic Ocean. The failure to model ventilated heat events led to incorrectly attributing that warming to increasing concentrations of CO2. That failed modeling further led to explanations that reduced albedo effect allowed greater absorption of summer insolation, warming the Arctic Ocean and amplifying temperatures. But observations show the ocean has cooled. Like the 40s peak, it is likely 1990s/2000s ventilation similarly contributed a minimum of ~0.8° C to the recent rise in Arctic temperatures, and probably much more as the greater reduction in sea ice extent has allowed for much more ventilation.

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If climates models are correctly configured, they should be able to reproduce both D‑O events and the 1940s ventilation events. We don’t expect model perfection, but turning a massive warming event into a below average cool period is unacceptable. When the modeling community simulates the Arctic Iris Effect more accurately, only then will their attribution of polar warming to human vs. natural factors be trustworthy! Until then all the natural factors – lower insolation with reduced Atlantic inflow, cooler oceans, negative North Atlantic Oscillation, and increasing multiyear ice – all suggest the current ventilation event will soon come to a close. But the return to cooler surface temperatures and more sea ice has always been much slower than the abrupt warming. When sea ice is reduced, the winds are suddenly able to mix the ocean’s fresher upper layer with the saltier lower Atlantic Waters disrupting the halocline. But once the halocline and upper layers of freshwater are restored, the cooling is rapid.

In contrast, those who attribute Arctic warming to rising CO2 predict a continued sea ice death spiral. And those who also suggest global warming is slowing down the poleward flow of Atlantic Water, also argue CO2 warming will offset any cooling effects of that slowdown (Rhamstorf and Mann 2015). Within the next 2 decades, nature should demonstrate how well these competing models and competing interpretations extrapolate into the future. Good scientists always embrace 2 or more working hypotheses. But with the politicization of science, I sincerely doubt President Obama is travelling to the Arctic to advise the world to be good scientists!

Jim Steele is author of Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism

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194 thoughts on “The Arctic Iris Effect, Dansgaard-Oeschger Events, and Climate Model Shortcomings. Lesson from Climate Past – part 1.

  1. but, but, but……..it’s the dreaded carbon that wot did it, ain’t it so?? Our Glorious Leaders tell us, or are they wrong?

    • Pushing a hypothesis that most thinking people consider falsified we can see the political angles.In science lies are a sin (or use to be). In politics they are a virtue

      • I was very surprised by the brevity of the section on model short comings…one would have thought reams of paper would be necessary . Impossible for me to believe that any of the proponents of AGW actually believe this trash science. Are they all corrupt or is this a result of mail order PHD’s?

  2. There is a fundamental difference between millenial scale ocean oscillations in the north and south hemispheres.
    In the NH changes between cold and warm periods are abrupt and more frequent.
    In the SH, changes are smooth, gradual and less frequent.
    This is explained by the chaotic nonlinear (Lyapunov) stability of the oceans in both hemispheres.
    The Atlantic Meridional Overturning Circulation (AMOC) contains a positive feedback between North Atlantic Deep Water (NADW) formation in the Norwegian Sea, and salinity arising from the Gulf Stream.
    And as we all know, a positive feedback within a dissipative oscillatory system will introduce chaotic fluctuation, sure as night follows day.
    This was well described in this paper by Weaver et al 2003:
    http://home.sandiego.edu/~sgray/MARS350/deglaciation.pdf
    This constitutes a positive feedback between the overturning circulation and the salinity in the North Atlantic first described by Stommel (33). Specifically, the intensified formation of NADW advects more saline subtropical waters to the northern North Atlantic, which increases surface density there and further intensifies the overturning circulation.
    This positive feedback between the Gulf stream, which carries saline water to the North Atlantic, and NADW, drives the chaotic fluctuation of the AMOC and (consequently) NH temperatures, which contrast with the slow smooth and serene ocean temperature oscillations in the SH. This contrast is what makes oceanography on our planet interesting – at least in our current continental configuration.

    • phlogiston
      the muted warm events in Antarctica are also consistent with an Iris Effect. The Antarctic sea ice is annual with very little multiyear ice to insulate the ocean over any extended period. In addition the Antarctic circumpolar current inhibits the intrusions of warm tropical water that can tip the scales between stadials and interstadials as discussed http://landscapesandcycles.net/antarctic-sea-ice–climate-change-indicator.html
      So small changes in poleward heat transport, could explain the modest Antarctic warming. The warming in the Antarctic peaks at the same time as the Arctic’s major ice rafted debris events, the Heinrich events occur. The same poleward heat transport would not be observed in the Arctic as it must first melt the ice shelves and thicker sea ice. The increased icebergs of Heinrich events suggests the break up of ice shelves then allowed the ventilation events as suggested by Peterson 2013’s hypotheses.. It seems plausible that the polar see saw interpretations are at least in part a reflection of the time delay between heat transport that is immediately observed in Antarctica but delayed for centuries until the insulating Arctic sea ice is reduced.

      • Jim
        Thanks for your reply and the excellent article. Your Arctic ice “iris” and “ventilation” mechanism is very compelling indeed. I very much agree with your paradigm of natural climate variations and oscillations being driven by deep ocean circulation changes. The fact that the vast majority of climate heat energy is in the oceans means that on a “short term” timescale of mere centuries, climate heat is close to being a zero sum game – a kind of flip-flopping of heat between the oceans and atmosphere with ice sheets playing a critical role.
        By contrast, those who try to ascribe a forcing role of trace atmospheric CO2 to these vast shifts in ocean heat are trying to return the science to the dark ages when every alarming natural phenomenon was driven by evil spirits – anthropogenic evil spirts note – that had human attribution in the form of witches who could then be hunted.
        Concerning Antarctica, your paradigm makes good sense – the Antarctic started warming as early as about 20kya before the Bolling Allerod (presumably a D-O event) at 14-15kya. What caused Antarctic warming to start ~20 kya around the coldest depths of the Wisconsin glacial maximum? – that’s an interesting question. (CO2 need not apply.)

      • One is describing the nature of the system, the other describing its manifestation. The question is how many other chaotic oscillators are at work, how about synchronized oscillations and oscillators. These along with stadium wave and NH and SH albedo are steps in the correct direction IMO. Good article.

      • I must agree with D. B. below. Excellent article presenting a plausible, testable, and falsifiable hypothesis.

  3. There are a few mentions in this post of natural effects either offsetting warming from CO2 or overwhelming effects of CO2. Whilst it is always good to hear of theories that explain climate in terms of natural cycles and sensible heat transfer, insulation, heat capacity, etc, it is terribly frustrating to also keep seeing any credibility given to a Greenhouse Effect and proposed abilities of CO2 in it.
    All of the theories presented above can be explained quite nicely without back radiation, radiative forcing or any other nonsense. They don’t offset or overwhelm effects of CO2 because there is no effect to be offset or overwhelmed in the first place! It is not other theories that need to be accommodated into existing computer models, it is the scrapping of existing computer models to allow for new ones to be created based solely on natural theories.

    • “There are a few mentions in this post of natural effects either offsetting warming from CO2 or overwhelming effects of CO2.”
      What ‘overwhelming effects of CO2’?; when and where did this occur in the geologic record?

    • In the lab, CO2 absorbs IR radiation in various bands. To dismiss this is to open skeptics to the charge of anti-science. Let’s be a bit more imaginative and not be linear thinkers, which we can say about the simple-minded CO2 theory of thermageddon. There is ‘some’ effect, but with iris effect or W. Eschenbach’s ITCZ cloud/storm governor effect on temperature, the CO2 and all other heating effects (very democratic these negative feedbacks), CO2 is rendered marginally effective.
      Here is the logic (strawberries are red, therefore all red things are strawberries-type of reasoning here). Well known observations of CO2 absorption and emission effects OCCUR. The earth isn’t warming or it was and is cooling now. The conclusion that CO2 doesn’t behave as described is incorrect and always insisting that it is is the same problem we are having with the thermageddonites. That it becomes overwhelmed by negative feedbacks (governors/irises) is the more sophisticated thinking on the subject. Linear thinking on any natural phenomenon is neanderthal science. Please read up on CO2’s absorption and emission properties vis a vis IR radiation to save yourself from this linear thinking.

      • CO2 absorbs IR radiation in various bands
        ==============
        if CO2 is the cause of the warming, then the lower atmosphere must warm faster than the surface. Otherwise, if the surface was warming faster than the atmosphere, that would mean that the surface was actually warming the atmosphere.
        yet the major temperature indexes such as RSS,GISS show the surface temperature warming faster than the atmosphere. Given that the external heat source (the sun) remains constant, how is it physically possible for Object A, which is warming slower than Object B, how is it possible for the slower warming of Object A to be the cause of the faster warming of Object B?

      • Gary Pearce says “Please read up on CO2’s absorption and emission properties vis a vis IR radiation to save yourself from this linear thinking.”
        CO2 absorbs and emits in the exact same LWIR band centered at ~15 microns, which if CO2 was a perfect absorber blackbody equates to a blackbody temperature of 193K.
        Question: Can a blackbody at 193K warm (i.e. increase the temperature/energy/frequency) of a warmer blackbody at 288K?
        ferdberple: “how is it physically possible for Object A, which is warming slower than Object B, how is it possible for the slower warming of Object A to be the cause of the faster warming of Object B?”
        It’s not. To do so would be a gross violation of the principle of maximum entropy production/2nd LoT.

      • It is not a matter of ignoring it or not. It is a matter of determining how influential the property is. The short answer is that without essentially magical properties, that tiny amount of gas simply can’t be an important climate influence. It can’t store significant energy by itself. It would then have to transfer it to a more efficient medium (water vapor is the preferred choice), and that medium would have to also have to behave in nonphysical ways to retain the energy long enough to have an affect that is in addition to the basic warming the atmosphere provides, and which can be accounted for pretty efficiently by gravitational energy alone.

      • Gary Pearse
        ‘Please read up on CO2’s absorption and emission properties vis a vis IR radiation to save yourself from this linear thinking’.
        OK, try this thinking …. CO2 absorbs and emits infrared radiation in all directions – not just downwards but sideways and upwards as well. If more CO2 is added to the atmosphere then there will be more emissions in all directions, including upwards to space. If emissions to space increase then the earth will lose energy and cool down, not warm up. Seems like you are guilty of downward linear thinking!

      • “If more CO2 is added to the atmosphere then there will be more emissions in all directions, including upwards to space. If emissions to space increase then the earth will lose energy and cool down, not warm up. Seems like you are guilty of downward linear thinking!”
        Lol. Right, increased CO2 increases radiative surface area to space, which increases IR LOSS to space. The Arrhenius-believers openly admit this happens in the stratosphere through thermosphere to increase cooling, but then claim CO2 magically changes from a cooling agent to a warming agent in the troposphere only, and when asked why that is, can’t even agree on a bogus answer to that fundamental question.
        Pathetic non-linear chaotic thinking. CAGW is clearly a cognitive dissonance mental disorder.

  4. The warming of the Arctic during this venting must also reduce the atmospheric Hadley cell circulation from the tropics by reducing the differential in temperature between tropics and poleward areas. This likely results in less heat removal from the tropics and possibly the creation of big El Ninos.

    • Indeed. The Intertropical Convergence Zone (ITCZ) is the rising branch of the Hadley Cell and it determines the location of the belt of tropical rains. It shifts northward during warm interstadials and equatorward during colder stadials. That behavior explains the coincidence of shifting tropical rainfall and Dansgaard Oeschger events.

      • jim,
        It is good to see proper scientists looking more closely into natural climate variability rather than just religiously promulgating the CO2 meme.
        Since 2007 I have been trying to spread the idea that oceanic cycles in each ocean basin interact with each other and combine with variations in solar activity to shift the climate zones latitudinally. The latitudinal shifting is itself a negative system response during which convection seeks to neutralise radiative imbalances.
        I have also often mentioned that reduced Arctic ice is likely to result in faster transfer of energy from oceans to atmosphere to space for, ultimately, a system cooling effect.
        There is room for just such an Arctic Iris effect as a part of natural variability.
        Your Arctic Iris effect would count as part of the bottom up oceanic system response to top down solar effects on global cloudiness as described here:
        http://joannenova.com.au/2015/01/is-the-sun-driving-ozone-and-changing-the-climate/

  5. Possibly, as well, the warming in the arctic atmosphere accompanied by cooling of the Arctic Ocean would speed up the Gulf stream and the Kuroshio current, counter to the atmospheric cells. Reheating of the Arctic deeps and recooling of the atmosphere. Or maybe that is what you were saying.

  6. Interesting! I don’t think I’ve run into the Arctic Iris Effect before; at least not by that name. I need to compare it with what I’ve been thinking happens in the arctic.

  7. Mr. Steele,
    This Arctic Iris effect you have created the term for appears to be original science.
    Is the description and backup evidence in a state to be submitted for peer review?
    The mechanism appears at first glance to be very plausible – I did not know that the layer of water right underneath the ice was fresh (relatively) – something which Wikipedia validates. Said Wikipedia article further notes that “It(the top fresh layer) remains relatively stable, because the salinity effect on density is bigger than the temperature effect.”
    This would appear to be a mathematically calculable turning point: at what temperature of the Atlantic water layer does said temperature effect on density cause the Atlantic water layer to achieve a lower density than the layers above it – at which point said warm water starts rising with all the Iris effects you mention.
    Equally on the return path, there would seem to be another mathematically calculable turning point where increased ventilation of water heat/mixing of the warm layers with the colder layers above yields a point where the top layer temperatures are low enough for ice to reform and remain so for longer periods.

    • ticketstopper there are so many variables at work that a quantitative analysis might not add any more certainty than a qualitative analysis. In addition to changes in Atlantic and Pacific inflows, the freshwater inflows from rivers contribute a huge proportion of freshwater relative to any other ocean basin. Shifts if pressure systems then determine where that freshwater is transported and sequestered, and when it is released. The freshwater event in the subpolar gyre “The Great Salinity Anomaly” from 1968-1982 is associated with the colder temperatures of those decades, and I would imagine another such event could trigger Arctic sea ice recovery. The release of fresh water from the Arctic Basin appears to oscillation in decadal cycles but the amount of freshwater released since 1982 has been much less.

      • Mr. Steele,
        I agree a quantitative analysis would not be likely to show skill in a predictive sense due to the variables you note above.
        However, a quantitative analysis of the inflection points would serve to validate that such a mechanism can function, and give some clues as to when/where/how changes might occur. This in turn would create a proposed framework for other researchers to validate/invalidate.

  8. Something I read suggested that a glacial bridge forms between Greenland & Iceland that blocks the Fram Strait from flushing ice southward & sea-ice builds upstream, freezing over most of the N Atlantic & deflecting the gulf-stream southward. For some reason, that “bridge” breaks and a huge flush of sea-ice flows southward, greatly reducing the sea-ice, allowing the gulf-stream to flow northward again & resulting in a brief but dramatic warmup. Eventually the ice-bridge reforms & the cycle repeats.

    • That’s a very interesting idea, a boundary condition relaxation oscillator, just like ENSO. In the case of ENSO the Equatorial wind piles up warm water on the west coast of Asia which disperses and heats the atmosphere when the winds collapse. The time scales of these two oscillators are clearly very different, annual versus decades or centuries. There must a lot of these oscillators that affect the climate and are yet to be recognized.

    • Ice bridges between islands but yet continues to flow past them all over the arctic. Watch any animation of of annual ice movement. Something doesn’t add up in your explanation.

    • beng Peterson 2013 suggests growing ice shelves on Greenland’s east coast could indeed create the blocking that allows the build up of ice for a D-O stadial. However I do question how much it impacts the Gulf Stream and inflows of Atlantic water. Flushing of thick sea ice through the Canadian Archipelago also goes through cycles as ice bridges form in places like the Nares Strais controlling the flows of freshwater and ice into Baffin Bay on the western side Greenland.

      • Jim, you may be right & the D/O events might be a combination of these effects. This is serious research & might provide keys to understanding these events & maybe even the onset/terminations of interglacials. NOW we’re cooking with gas…
        But the climate-clique isn’t interested — it might upset the warmies’ grant-applecart.

    • This is a good thread. We haven’t seen much of this on the Arctic ice/ocean mechanics. It is an area on which the tipping point fellows have had pretty much free rein. Good on you Jim Steele and interesting contribution beng135. I suspect we will see some more of this here and, as with natural variability, ENSO, PDO, AMO, etc. it wakes climate science up to these effects. WUWT has long driven the directions that the whole science takes. They hate it, but they’ve come to realize they have to deal with it.
      With the former silence on such things by the main stream, they found themselves being left behind with a ‘pause’ they could no longer ignore. Willis’s, Jim Steele’s and others’ potent offerings here have become a pool of research ideas for a stunned and foundering ‘consensus’. I hope marginalized young scientists open up to the new on line journal OAS created by Anthony. It also presents a venue for Willis, Jim Steel, and others. Each effort of this kind shifts the centre of gravity away from cult science.

    • What would it take to freeze the sea between Alaska and Russia? It is not very deep there. That would cut off the warm inflow that persisted a couple of years ago, now reversed. Blocking the drain is as effective as blocking the inlet. A stagnant Arctic Ocean would freeze rapidly to spectacular low temperatures.

      • Bering Strait is indeed shallow at the sea floor’s highest point, between two lower lying areas that are lakes when the land bridge is exposed, as it is most of the time.
        The winter ice extends so far down toward this high spot that, I’ve been told, submarines have trouble scraping through.

    • Ron, As an iris effect would predict on a yearly basis, a year of less ice means more ventilation and suggests a the following year a rebound. Sea ice rebounded in 2013 and 2014, so this years reduction is not unexpected. But it is not the reduction in first year ice that is telling. What will turn the tide is the growth of multiyear ice and has been slowly increasing.

  9. An extremely interesting and informative and plausible article, thank you. It details very neatly what Prigogene would have called a self-organized critical phenomenon. In nonlinear chaotic dissipative systems, dissipation mechanism are not random at the macroscopic level as one would expect by doing simple averages. They self-organize for much more efficient transport of energy, often in large-scale oscillatory (but still chaotic) structures. Small changes in system tuning can lead to large changes in period or amplitude, or can abruptly switch the system from one dominant dissipation mode to another. The various fluid transport decadal oscillations all represent such modes, as does the complex pattern of thermohaline circulation.
    I agree dead on the money with Steele’s observation that until the models can, without being more or less hand-programmed to do so, exhibit self-organized critical behaviors that aren’t only “like” those of the Earth climate system but that without tweaking reproduce the primary frequencies (which range from years in the case of ENSO and countless unnamed smaller scale fluctuations, some of which have even shorter periods and more chaotic, noisy, switching, others (e.g. the recently emerged Pacific Hot Spot) can themselves be highly localized but emerge only on a multidecadal scale, to the very large scale multidecadal oscillations such as the PDO. Doubtless there are even longer time scale oscillations, and the top article details a mechanism for one.
    The emergence of the Pacific Hot Spot actually has some interesting ramifications along these lines. The warming of surface waters in the North Pacific also means that heat loss from that region is occurring at an anomalous rate, which means that colder water is being produced and stored in the deeper ocean at a prodigious rate. I have little faith in research estimates of the so-called TOA imbalance once I learned (directly from e.g. the CERES site) that they cannot resolve any such thing with current instrumentation and are more or less making numbers up when they assert an imbalance on the order of 0.5 W/m^2 or whatever. We don’t know the sign of the imbalance, let alone its value to within a couple of W/m^2. However, the stability of global temperatures over the last 15+ years suggests that it is small.
    These phenomena can easily couple. Will the water that has anomalously cooled due to upwelling of comparatively warm waters off the coast of Washington and Canada may well affect the Arctic in a few years. It may get pulled around south and affect (in years to decades) ENSO. The climate systems is highly non-Markovian, yet climate models are literally incapable of simulating the spectrum of self-organized structures that apparently dominate its long-period time evolution. The emergence or sudden change of a single component of the global thermohaline circulation could trigger abrupt NH cooling (while still more or less balancing heat flow through the system) by concentrating warm waters a bit further south.
    As I currently understand it, the tropics cannot be substantially warmed any more. There are strong negative feedback mechanisms that kick in in the vicinity of 30 C. One can widen the latitude band of these warmer waters and overall temperatures by a few degrees and increase heat loss there by enough to balance the extra CO2 forcing even as the arctic zone effectively expands and cools down through the temperate zone. All it would take is the diversion of the Gulf Stream (for example) a few hundred miles south and the consequent starvation of the Arctic Gyre (and most of Northern Europe) of the heat picked up in tropical waters and transported north, which is all that keeps most of the northern temperate zone warm.
    Interesting times for the climate.
    rgb

  10. I have one simple observation to make regarding the Iris affect.
    The water at the opening is going to be very close to 0˚C. It could never be 5˚ to 10˚ warmer simply because of the presence of ice in the area.
    All of the water in the Arctic is around 0ºC and there are no fish because they would freeze (except for some minnows with antifreeze for blood).
    Until the Arctic is Ice Free, there can be no warming of the Arctic.

    • Jinghis, re-freezing of this -2C water, does however give off the latent heat of fusion. Freezing water gives off heat! My father used to put sacks of potatoes in the basement (in Manitoba, Canada) with a couple of big zinc tubs of water to prevent freezing of the potatoes in the depth of winter. His father – homesteader on the prairies in the late 19th Century, taught my father that. These unsophisticated people knew stuff. Even if you are a social scientists, you should learn such stuff.

      • “My father used to put sacks of potatoes in the basement (in Manitoba, Canada) with a couple of big zinc tubs of water to prevent freezing of the potatoes in the depth of winter.”
        Thanks Gary, another tidbit added to my collection.

      • Yes that is the latent heat of the phase change, while there is mixed water and ice the temperature will stay at ~0˚C. The temperature of the mixture will always stay the same.

    • Steele has told us in an earlier article that the ringed seals, preferred prey of polar bears, feed largely on Arctic char. The char certainly do survive in Arctic waters – or at least close enough to them for the seals to reach! Remember that the sea surface may be near freezing – that’s where the ice grows from – but the deeper layers may be warmer. Also I found a paper on char that gives their temperature tolerance range as 0 to ~ 24 degrees C.

  11. excellent
    good to have natural science interrupt political posturing and it is very refreshing to have some actual climate science references
    thanks, looking forward to more

  12. If this mechanism is the cause of D/O events, i.e. turning the global conveyer belt on and off by changes in the Arctic/ North Atlantic, then climate changes in the Southern Hemisphere should lag those in the Northern Hemisphere by several hundred to a thousand years (the time it takes for transfer of deep, cold, dense ocean water between hemispheres). So a good test of the validity of this mechanism is to look at the timing of glacial events in both hemispheres. If this mechanism were true, we should see an easily detectable lag in the time of glacial advances and retreats in the late Pleistocene. However, recent accurate dating of the Younger Dryas and other D/O events shows that they are almost exactly synchronous in the Northern and Southern Hemispheres, showing that that Broecker’s global conveyor belt concept doesn’t work.

    • Don, I too am inclined to believe that warming events are synchronous but with a slight delay in how it is experienced replied to phlogiston above.
      “The warming in the Antarctic peaks at the same time as the Arctic’s major ice rafted debris events, the Heinrich events occur. The same poleward heat transport would not be observed in the Arctic as it must first melt the ice shelves and thicker sea ice. The increased icebergs of Heinrich events suggests the break up of ice shelves then allowed the ventilation events as suggested by Peterson 2013’s hypotheses.. It seems plausible that the polar see saw interpretations are at least in part a reflection of the time delay between heat transport that is immediately observed in Antarctica but delayed for centuries until the insulating Arctic sea ice is reduced.”

      • Recent 10Be dating of moraines in New Zealand and South America indicate that there was no ‘seesaw’ — both the YD and its immediate predecessor were synchronous in both hemispheres. Their magnitude isn’t exactly the same, but the timing is.

    • Don, Jim
      According to these papers by Bunier et al (1997) and Weaver et al (2003)
      http://www.climate.unibe.ch/~stocker/papers/blunier97grl.pdf
      http://home.sandiego.edu/~sgray/MARS350/deglaciation.pdf
      Antarctic warming began more than 20k years ago, several millenia in advance of the NH based B-A (14-15 kya). Weaver proposed a big Antarctic ice sheet collapse as the signal from SH to NH to set in motion the BA and then YD. However Jim casts doubt on the big meltwater hypotheses, so perhaps something along he lines of the Iris – Ventilation hypothesis would work better.
      My original point was about the contrast between a slow sinusoidal like temperature oscillation in the SH / Antarctica contrasted with the jittery abrupt oscillations of the NH / Arctic caused by the nonlinear instability of the AMOC due to the salinity positive feedback. (Just like ENSO is driven by the Bjerknes positive feedback.)

      • I have yet to read those papers and will return once I have read them but…
        I agree that warming around Antarctica began about 20 thousand years ago and can be seen in Figure 1 of this essay. Orbital insolation effects driven by precession would suggest summer warming in Antarctic would precede summer warming in the Arctic by about 11 thousand years.
        My question to you phlogiston is “how would you determine if there was a change in the AMOC versus an insignificant hemispheric difference in the AMOC that caused 1) poleward heat transport that was immediately experienced at the surface of Antarctic water where thick multiyear ice is rare versus 2) in the Arctic where poleward heat transport might not be observed in the surface temperatures for centuries due to the time required to undermine ice shelves and thicker sea ice. Also 3) what is your measure of the AMOC? Currently it is the summation of changes in both the upper and lower limbs. But a decrease in North Atlantic Deep Water formation does not mean inflows of warm water have changed. Only that the inflow has not cooled sufficiently to add to the deep water. It is increasing reported that return flows happen at intermediate depths. Furthermore the AMOC is the integration of several dynamics.
        If the Arctic Iris Effect is operating then subsurface planktonic paleothermometers would register a warming while surface metrics like GISP ice cores would not observe any change.

      • Jim
        I was referring to the really big NH changes such as the D-O events (I call these “micro-interglacials”) and the BA and YD. Events too big to miss.
        As to the precise multi-layer mechanisms, I really dont know.
        However I am sure that this is where to look to find the causes of climate change.
        And, again, I am sure that the AMOC salinity positive feedback drives nonlinear instability, which so contrasts the NH from the SH.

  13. There are more than twenty urban legends (Zombie theories) connected with the cause of the Dansgaard-Oeschger cycles, the existence of a discrete Gulf Stream, the effect of an interruption of the non-existent discrete Gulf Stream, the cause of the Younger Dryas, the cause of the cyclic abrupt climate change in the paleo record, the affect of a change in greenhouse gases, how solar cycle changes modulate planetary climate, the physics to explain how the solar cycle, can cyclically abruptly change, what causes the geomagnetic field, how and why the geomagnetic field can abruptly change, and the glacial/interglacial cycle.
    The following is a sample of three of the urban legends/zombie theories.
    1) Gulf Stream Myth – Cooling affect of stoppage, due to a melt pulse. The majority of heat transfer, the reason why Europe in the winter at latitudes above 60N is warmer than the east coast of the US is due to atmospheric transfer of heat, not due to ocean current transfer of heat. In a 2002 published paper that is supported by multiple papers previously published papers (i.e. this is not a new finding), a complete stoppage of the North Atlantic drift current (aka the ‘Gulf Stream’, as will be shown in the my next comment there is hard data that supports the assertion that is no discrete return ocean flow to interrupt) would only result in cooling of a few degrees in winter in Europe.
    The majority of heat transferred from the Atlantic ocean to Europe is due to summer warming of the Atlantic ocean and the prevailing westerly winds. Northern Europe is 10C warmer than the east coast of the Northern US, for the same reason that the west coast of Northern US is 10C to 15C than the east coast of the Northern US. The prevailing winds blow from the west, the ocean warms due to summer heating.
    Ignoring the fact that recent ocean probe data indicates there is no discrete Gulf stream to interrupt, stoppage of the ‘Gulf Stream’ could not and did not cause the Younger Dryas abrupt cooling event at which time the planet when from interglacial warm to glacial cold with 70% of the cooling occurring in less than a decade and the cold period lasting for 1200 years, all occurring when solar summer insolation at 65N was maximum. Stoppage of the ‘Gulf stream’ could not and did not cause the 8200 years before present abrupt cooling event at which time there was Northern Hemisphere cooling of 2C for 200 years.
    http://www.atmos.washington.edu/~david/Gulf.pdf

    Is the Gulf Stream responsible for Europe’s mild winters?
    By R. SEAGER1¤, D. S. BATTISTI2, J. YIN2, N. GORDON1, N. NAIK1, A. C. CLEMENT3 and M. A. CANE1

    http://www.americanscientist.org/issues/id.999,y.0,no.,content.true,page.1,css.print/issue.aspx

    The Source of Europe’s Mild Climate
    The notion that the Gulf Stream is responsible for keeping Europe anomalously warm turns out to be a myth

    The Gulf stream myth was started by Wally Broeker, in 1999 with the ‘climate is an angry beast’ paper which included a badly drawn picture of a guy with glasses poking a badly drawn dragon. Wally did not run models to provide support for the assertion that the Gulf Stream was the cause of what was observed.
    Wally include zero data or analysis to support the assertion that an increase in atmospheric CO2 has any effect on climate, there is no stick. Wally just noted that the climate has changed in the past. Wally completely ignored the fact that the current change in climate is exactly like past changes in the climate.
    http://all-geo.org/highlyallochthonous/2012/06/what-do-you-mean-the-gulf-stream-doesnt-keep-europe-warm-how-even-scientists-are-afflicted-by-urban-myths/

    What do you mean, the Gulf Stream doesn’t keep Europe warmer than North America? How even scientists are afflicted by urban myths (William, Do you think even scientists could be affected by urban myths/legends?)
    This is how a scientific urban myth is born: by the time you reach a citation 3 times removed from the supporting observations, a conclusion becomes something ‘everyone knows’ despite very few people ever being exposed to the evidence it was based on. “I’m telling you, this paper told that paper that this other paper has compelling evidence for this! Compelling! Well no, I haven’t actually read it myself…”
    I don’t believe this is a hugely common phenomenon. But science nowadays is such a vast body of knowledge that there are bound to be a few zombie ideas traipsing around in it, managing to survive because no-one has really properly examined them for a while. It is only when a scientist is inspired to chase one of these ideas back to its origin that they are brought into the light.

    Stoppage of the North Atlantic drift current is not ‘part of the solution’ of cyclic abrupt climate change. The abrupt cooling events in the paleo record are cyclic and have no explanation. The cyclic abrupt cooling events require a massive forcing function to cause the cyclic abrupt cooling.
    2) Gulf Stream myth – The existence of a discrete ‘thermalhaline conveyor’. There is no ‘thermalhaline conveyor’ in the Atlantic to interrupt.
    Wally Broeker hypothesized the existence of a discrete thermalhaline conveyor with no proof (Wally’s paper includes a picture of the hypothesized discrete conveyor which is repeated ad infinitum.)
    A melt pulse cannot stop the North Atlantic drift current as there is no discrete ‘thermalhaline conveyor’ to interrupt. Deep ocean flow data to support this comment will be included in my next comment. Wally later noted the ‘thermalhaline conveyor’ picture was only drawn to illustrate a possible hypothesis and noted there is no data to support the assertion that hypothesis is actually correct.
    3) The Tipping points or climate ‘jumping’ from one state to another myth, zombie theory. (Change without cause myth) It is a fact that there is cyclic abrupt climate change in the paleo record. The Younger Dryas is an example of cyclic abrupt climate change. As the massive forcing mechanism that causes cyclic abrupt climate change is not known Wally Broeker also started the urban legend of ‘tipping points’ which was later advanced to climate ‘jumping’ from one state to another.
    The tipping point and climate jumping ‘hypothesis’ infers there is a magical, a ‘smart’ amplification mechanism that can when necessary appear to amplify tiny forcing changes and then disappear so as to not enable massive short term forcing changes such as a super volcano eruption to cause the planet to return to the glacial phase or to cause the planet’s climate to wildly oscillate. The abrupt climate changes are cyclic. Internal earth systems are random. There is zero observational support, analysis support, or even a possible working mechanism, for a ‘smart’ amplification mechanism.
    We would not accept the assertion that occasionally rocks jump up hill. Climate science is part of physics. In physics there must be a physical explanation for what is observed.
    If there is no magical, ‘smart’ amplification mechanism. There is an ‘unknown’ (hand waving madly ask me, ask me, the super doper forcing mechanism is the sun, the sun is fundamentally different the standard model and can hence and does cause small, medium, and super large cyclic climate changes which explains why the climate changes are cyclic rather than random) forcing mechanism that causes cyclic abrupt climate change and that is capable of every 8000 years to 10,000 years of terminating an interglacial period.
    http://www.pik-potsdam.de/~stefan/Publications/Journals/rahmstorf_grl_2003.pdf

    Timing of abrupt climate change: A precise clock by Stefan Rahmstorf
    Many paleoclimatic data reveal a _1,500 year cyclicity of unknown origin. A crucial question is how stable and regular this cycle is. An analysis of the GISP2 ice core record from Greenland reveals that abrupt climate events appear to be paced by a 1,470-year cycle with a period that is probably stable to within a few percent; with 95% confidence the period is maintained to better than 12% over at least 23 cycles. This highly precise clock points to an origin outside the Earth system; oscillatory modes within the Earth system can be expected to be far more irregular in period.

    • Thank you for such an informative comment. I agree with you that an explanation of the regular pacing of D-O events is a requirement for any hypothesis trying to explain their cause and mechanisms. So far such pacing, whether extraterrestrial or not, is unexplained.
      The precise dating of D-O events between Arctic regions and Antarctica thanks to the methane signature has allowed to confirm that Antarctic warming precedes the D-O event, and that the higher this Antarctic warming, the longer the D-O lasts. This facts strongly suggest that Arctic heat piracy from a polar seesaw mechanism is involved in providing the energy for the abrupt D-O warming in a way not dissimilar to storing energy in a spring.
      The release mechanism of the D-O event could very well be what Jim Steel and others are proposing trough heat ventilation. So what we are lacking is a trigger mechanism with a 1470 years pacemaker.
      Such credible pacemaker has been proposed, as I have read on internet, but I have found no formal scientific article on the issue (it may exist though). Apparently (I don’t understand it very well myself due to its astronomical nature) there is a 1470 year Lunar cycle. The hypothesis is that such Lunar cycle could create a strong enough tidal force or pull as to significantly break a huge sea ice cover, as long as such sea ice cover a) is big enough, and b) is not too think. The breaking of the ice cover would then allow a much increased heat ventilation to take place amplificating the ice cover reduction in a positive feedback until the speed of ice melting diminishes or the heat differential is no longer big enough to continue the amplification.
      One of the predictions of such a model is that it should only operate:
      a) When the Northern Hemisphere is cold enough to allow a big enough sea ice cover
      b) When the Northern Hemisphere is not too cold so the ice can be broken.
      We find that D-O events are abundant and properly spaced between 25 and 60 kya, and present more irregularly between 70 and 80 kya. They were suppressed by too cold temperatures between 15-25 kya in what is know as the Last Glacial Maximum, and between 60-70 kya (MIS 4, the previous Glacial Maximum). D-O events also disappear between 105-80 kya due to the opposite reason, temperatures were too warm due to an obliquity Milankovitch cycle with high summer insolation. Of course this prediction is shared with any model that relies on heat ventilation from the ocean through the ice cover, so it maybe hard to prove any Lunar implication until the next cycle comes about in a few hundred years.

      • As I comment above, recent 10Be dating of moraines in New Zealand and South America indicate that there was no ‘seesaw’ — both the YD and its immediate predecessor were synchronous in both hemispheres. Their magnitude isn’t exactly the same, but the timing is.

      • This pattern supports my conclusion that glacial maxima are a third steady state of Pleistocene climate, along with “normal” glacial conditions and interglacials.

    • William. Javier
      Sorry guys, but the “peleton” of astro-cyclists are simply in denial of chaos and nonlinear oscillators, just as the CAGW folks are in denial of everything except their satan-gas.
      The climate is not passive. Not every tiny wiggle needs outside forcing. It moves by itself.

      • phlogiston,
        I wouldn’t call that a scientific argument for rejecting the possibility that the D-O events are a real cycle manifestation of astronomical origin. The same argumentation would lead you to reject that glaciations are locked by orbital cycles since the climate is not passive and moves by itself.
        It took MIlankovitch and his followers decades to gather evidence and convince the scientific community. Don’t expect me to equal that feat here. Let’s just leave it at that there is a Lunar hypothesis on the triggering of D-O events, that the hypothesis is consistent with the evidence available and that there is a physical mechanism that explains how the Lunar cycle can break sea ice shelves trough unusually large tides at a specific time. Since we lack evidence that supports the hypothesis and we are not likely to get it in a very long time I don’t see how anybody can prove it or disprove it. I like the hypothesis and you don’t. End of the story.
        By the way, in case anybody is interested the reference for this theory is:
        W.H. Berger, J. Patzold, G. Wefer
        A case for climate cycles: Orbit, Sun and Moon. In “Climate Development and History of the North Atlantic Realm.” pg. 115
        Springer 2002 edited by Gerold Wefer, Wolfgang H. Berger, Karl-Ernst Behre, Eystein Jansen
        “It will be noted that the main interference cycle between the two lunar master periods (18.6 and 17.7) is 366, almost precisely one fourth of the Greenland cycle (1464 vs. 1470). This is the strongest of the beats for periods of 100 y or more. We suggest it is the underlying cause of the prominent 1470-y cycle seen in the oxygen isotope record of Greenland ice (Fig. 9). This cycle apparently is modulated both by the amount of ice present on the globe (as seen in the oxygen isotope record of Ontong Java Plateau), and by the rate of change in the ice mass (Schultz et al. 1999). In a scenario of lunar forcing of this cycle, unusually large tides during the height of summer, when acting on marine-grounded unstable ice shelves, would tend to free large sheets of ice from the shelves, which would then drift south and change the climate periodically. The factor of 4 over the 17.7//18.6 beat would reflect the requirement that the maximum tidal action occur a relatively narrow window during the summer season.”
        Ian R. G. Wilson arrives to the same conclusion and a more precise 1470 y lunar cycle by a more complicated explanation in his blog, although I don’t think he has published it.
        http://astroclimateconnection.blogspot.com.es/2013_06_01_archive.html
        Let’s make it clear that I am not very fond of cyclemania myself, but I am willing to make an exception with the D-O 1470 y cycle, because as Ramhstorf says, it is difficult to think of an internal climate mechanism with such a precision over tens of thousands of years, perhaps hundreds of thousands.

      • I have no doubt that astronomical cycles have played a part, but by themselves cannot explain D-O events with frequencies that varied from 8000 to 1.5 thousand years apart

      • Jim,
        Thank you for your article.

        astronomical cycles … by themselves cannot explain D-O events with frequencies that varied from 8000 to 1.5 thousand years apart

        Then you should read:
        S. Rahmstorf. “Timing of abrupt climate change: A precise clock”. GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 10, 1510, doi:10.1029/2003GL017115, 2003
        http://www.pik-potsdam.de/~stefan/Publications/Journals/rahmstorf_grl_2003.pdf
        Specially figure 1 and the explanations about “the triggering error”, “the clock error” and “the dating error”.
        It is a remarkable clock.

      • Javier, Rhamstorf is wrong. There is no precise clock for D-O events. Their recurrence happened from 8 to 1.5 thousand years. Rhamstorf is also wrong about ocean conveyor belts and changes in the AMOC. While scientists have been increasingly abandinging the conveyor belt idea, Rhamstorf continues to defend it because his decades of publications are based on assuming the conveyor belt is a reality.
        That said there are rather good clocks found in nature. Most extratropical plants can determine change in seasons. The biological clocks are determined by the amount of time required to build or degrade a certain concentration of chemicals. Similarly the Arctic subsurface can have a “clock” determined by the build up of subsurface heat and its ability to contribute to basal melting.
        My queston to you is How would you determine oscillation determined by astronomical forcings versus oscillations due to internal variability?

      • Jim, I don’t know much about ocean conveyor belts, so I won’t argue that.
        Regarding Rahmstorf being wrong on the clock for D-O events, I think I will support his opinion unless new evidence makes me change it. I agree with him in that the numbers look too good for intrinsic variability.
        In my humble opinion oscillations coming from intrinsic variability tend to:
        a) move around depending on conditions so even if Fourier or wavelet clearly identify the oscillations, there is quite a lot of variability.
        b) Come and go. They sort of appear get strong and more precise and then start to fizzle and disappear.
        In the case of D-O events, they appear to be generated by climate which gives them some variability, but paced quite precisely by a trigger. Their variability comes from:
        a) The amount of previous warming in Antarctica that can make them very big and then the cooling after the D-O overlaps with the following cycles and damps them.
        b) They either trigger or not, and thus there are missing cycles.
        c) They depend on the right conditions for global temperature, so they do not appear when the world is too cold (glacial maxima) or when is not cold enough (early in the glacial period).
        When they do appear their spacing is generally very good as Fig 1 from Rahmstorf shows (link in comment above).
        That is why I believe D-O events are triggered by an extrinsic factor, and given its precision and reliability, and astronomical trigger does fit the bill.

      • Phlogiston, not every abrupt warming within the glacial period is a D-O event.
        a correct definition of the D-O event requires previous warming in Antarctica and an asymmetric shape in Greenland, with very fast warming and slower cooling.
        Those conditions lead to the rejection of the double peak at number 2 and the oddly placed peak at number 9 as not being D-O events. Without them the mathematical analysis is flawless for all Greenland records.
        Not all abrupt warmings are created equal.

    • I spent a significant part of my younger research life studying absorptive optical bistability in a specific open, driven system (resonant fluorescence in a tuned optical cavity). Such a system can be dynamically switched between a “transparent” state where the energy content of the resonant atoms is high and an “opaque” state where the incident energy is absorbed and dissipated by ordinary fluorescence. Note well that in the bistable regime one could hit the system with incoming light at a given intensity and the system could either be stable transparent or stable opaque depending on its history or preparation. The system also exhibits hysteresis when one uses light intensity itself to affect a switch between the two stable branches in the bistable regime.
      The interesting thing about this is/was that the system underwent a first order phase transition at the ends of the bistable regime. If you were driving it close to where the stability curve switched, and the system was small enough, it could easily spontaneously switch and undergo a rapid transition from an apparently locally stable lower/opaque branch to the upper/transparent branch or (at the other end) vice versa. These transitions would typically be very rapid — the system’s organization that permitted detailed balance (always satisfied, transparent or opaque) would abruptly switch from one to another.
      I would argue that an ice age, especially one like the current one with evident bistability, is very strong evidence for both nonlinear feedback mechanisms (the way to describe the optical bistability process in a mean-field regime yields a cubic state equation with an unstable middle branch of an S-curve and local stability up or down on either side of the unstable branch) and for precisely what you assert doesn’t happen — “tipping points” for the first order transition to the other branch. Indeed, although it is hardly a resonance phenomenon, the glacial/interglacial oscillation is a bistable optical system with the extra stored energy reflected as increased temperature and with a clear shift in the means of maintaining detailed balance. That isn’t to say that the climate system isn’t stably warm or stably cold when it is one or the other because there are doubtless driving/forcing regimes that will always be warm or always cold, both visible in the Phanerozoic record. But in the Pleistocene, we have not only a clear cycle of warm/cold phase oscillations, but several secular changes along the way, shifting the period and the cold phase amplitude (the former to longer periods, the latter to deeper glaciation). Fortunately the temperature regime of the warm phase interglacials has not shifted so dramatically, suggesting (to me) that while there are multiple possible organizations for the cold phase, there is likely some sort of nonlinear bound on the average temperature of the warm phase, a temperature probably within a degree or so of the current temperature with the Earth’s current tectonic and geological organization.
      To go one step further, there are many, many nonlinear systems that have strange attractors that appear, disappear, shift, and where the system orbits in limit cycles first around one attractor, then around another. These systems all also have or exhibit “tipping point” like behavior as they switch from one orbit to another with completely distinct local dynamics, again in a manner very comparable to the way the resonant optical bistability system works, but they might well be multistable and exhibit Hurst-Kolmogorov statistics (periods of comparative local stability punctuated by abrupt transitions to a different state of comparative local stability) much as both the weather and the temperature and rainfall and many other things do in the global and/or local climate.
      All of these systems are indeed characterized by a lack of stability near or past the transition regime so that small fluctuations can be amplified into a system spanning set of changes that eventually restabilize in the new phase.
      So I would definitely not assert that the concept of tipping points is a “myth” in climatology. What is mythical is that we know what they are, or can predict when the climate will become unstable. What is very mythical is the assertion that there is yet another phase, a “warmer still” phase in the bistable climate system, or that we can quickly tip out of the current interglacial into a “super interglacial” 6 C warmer than it is already. Antarctica last froze when the temperature was some 5 C warmer than it is today, and current temperatures — in addition to not being the warmest interglacial (yet) in even the last half a dozen cycles, in an event that would be temporally unresolvable in the earlier interglacials as it hasn’t lasted long enough yet — are still several degrees C from pushing us back to mid-Miocene (stable non-glacial) temperatures. In other words, there isn’t a shred of evidence in the meso-scale low-temporal resolution proxy (O18) derived climate record for a warm phase tipping point unless the world warms by around 5 to 6 C, which appears to be the general temperature range where Antarctica can actually melt. There is plenty of evidence, OTOH, that there is a cold phase tipping point, and the DO events suggest that there are probably all sorts of interesting nonlinear chaotic tipping points internal to glacial periods that do not last unless something else (such as orbital conditions) favor a warm-phase transition.
      rgb

      • RGB
        A very interesting analogy – your resonant fluorescent bistability. Chaotic nonlinear oscillation of a dissipative system is the best paradigm of the earth’s climate system. However it undermines too many self interested narratives on both sides of the climate debate, thus this fundamental insight will continue to be resisted and ignored.
        The central fallacy of those that argue that (a) only CO2 or (b) only direct astrophysical forcing, can move climate, is to assume that the climate system is inert, passive or neutrally stable and can only be moved by “brute forcing”. These belief systems close their eyes to the abundant evidence, ubiquitous in nature, of systems that oscillate from internal dynamics.

    • Each of the several major solar and oceanic oscillations has its own cycle or time period. It must be that the various cycles come in and out of phase such that at times they may match peaks or troughs and might engage in a sort of constructive interference or resonance. The Arctic Iris Effect, added to the Pacific Decadal and North Atlantic Oscillations, the Arctic Oscillation, the solar (sunspot) cycle, and perhaps others, might in mutual constructive interference result in large scale events, such as a Little Ice Age or Medieval Warm Period. The big events events then represent a resonance phenomenon of intrinsic oscillations rather than an external forcing.
      Since the various cycles each have an imprecise periodicity, the big events would also be imperfectly periodic. Even though the various oscillations might have changes as smooth as a sine wave, the big events could exhibit abrupt transitions, as talked about in the Arctic Iris above. The Fat Lady sings gradually louder and louder—the glasses suddenly breaks

      • kwintertorn,
        Yes.
        “So, to be able to monitor and predict changes in global temperature we need more than information about the past, current and expected future level of solar activity.
        We also need to identify all the separate oceanic cycles around the globe and ascertain both the current state of their respective warming or cooling modes and, moreover, the intensity of each, both at the time of measurement and in the future.
        Once we have a suitable formula I believe that changes in global temperature will no longer be a confusing phenomenon and we will be able to apportion the proper weight to other influencing factors ”
        from here:
        http://www.newclimatemodel.com/the-real-link-between-solar-energy-ocean-cycles-and-global-temperature/
        Published by Stephen Wilde May 21, 2008

      • Stephen Wilde
        Thanks for link. Good summary for this layman.
        I would add the insight that over geologic time, if looked at using Kelvin scale rather than degrees centigrade (better for sense of proportion re changes in total energy content of oceans and atmosphere), the striking fact is how stable the global temp has been over many different “forcings” over the last billions of years. To my eye this reveals a system that is dominated by buffers (eg. ocean heat sink) and negative feedbacks (eg cloud cover).
        The buffers and feedbacks all make the sorting out of the significance of any given “forcings” (eg solar changes or CO2) even harder.

  14. One problem with this analysis I see in the assumption that bathymetry of the Arctic-Atlantic main gates Denmark and Fram straits are constant. That is not so. Denmark strait which is currently at most of its width is at or less than 300 m deep with maximum depth less than 700m, further down has a soft sediment of additional 500m.
    Sediment is partially from the Greenaland’s glaciers and partially from the submarine volcanoes further north. Rise of sediment from short periods of intensive volcanic eruptions is rapid, while the erosion by the sea floor currents is slow. As a guide of the accumulation of the sediment it is possible to use nearby Iceland’s volcanic eruptions. Iceland during last 500 years had less than 5% of the world eruptions but produced more than 30% of volcanic tephra (total volume of volcanic rocks and lava).
    It is likely that the flow of warm/cold currents through the Denmark straits is rapidly reduced by the sea floor eruptions further north and slowly increased by calmer periods’ erosions.

    • There is no static bathymetry assumption. Sea Level fluctuates by 300 meters shutting off inflow of fresh Pacific waters and affecting transport of both warm and cold waters throughout the Arctic, especially onto the shallow sea shelfs.

      • Glacial maximum sea level is about 140 meters lower than today’s MSL, but of course much land is also lower, due to the weight of so much ice.

  15. Jim Steele,
    On a broader scale this demonstrates that the ebb and flow of sea ice has an overall negative feedback, to global system temperatures, through the insulating effects of sea ice. As I understand it, most of the AGW crowd assumed that the loss of sea ice provided a positive feedback through the change in albedo.
    I have always felt that the insulating effects of sea ice far outweighs the albedo changes at high latitudes.
    Positive feedbacks are the only way the dire aspects of AGW could ever possibly be justified.

    • Tom Yes and no. There is a short term positive feedback that has been noted for both 20th century warm ventilation events. The Barents Sea is critical and when sea ice declines there, an anomalous low pressure system gets established that increases southerly winds that push more warm air and warm water into the Arctic. Also on a seasonal time scale, the albedo effect can allow the surface to heat more during the summer but that only delays freezing in autumn. That extra heat usually does not accumulate over a whole year. The decadal cooling of the upper 700 meters of the Arctic Ocean as reported by Heimbach and Wunsch is strong evidence that an Arctic albedo positive feedback effect is insignificant.
      You are correct that longer term there are negative feedbacks. The default for the Arctic is to freeze unless there is adequate heat transport or insolation. Most of the ocean heat transport is subsurface and if it is not ventilated the oceans freeze. But that insulating ice cover creates a negative feedback due to heat accumulation that melts the ice. Once that heat is ventilated small changes in insolation and warm inflow allow the sea ice to return.The LIttle Ice Age experienced lower solar irradiance and an associated 10% decline in heat transport on the Gulf Stream (Lund 2006) That was enough to cover most of the Nordic Seas until a retreat began around 1850. The initiation of the last deglacial is considered to have had the balance tipped by greater summer insolation due to precession and obliquity orbital effects. Those orbital effect do not add to the averaage global insolation. Simulataneously there was greater inflows of warm water into the Arctic.

  16. Good to see that this sort of work is still going on despite the AGW disinformation campaign.
    The sun / cloud / ocean interaction is the key to climate change and there is no evidence that recent observations are due to anything else.

  17. This article is wrong about what causes the D- O events. Their explanation is but one small part of the puzzle.
    As was pointed out the YD was synchronous which does not validate this line of thought ,in addition the climate changes were very abrupt and occurred to often to be reconciled with there once cause climate effect pie in the sky argument which is what so many climatic scientist so wrongly try to do.
    They think incorrectly that one cause can explain all the many climate changes. Wrong!

  18. From the article below which I should have read more carefully before commenting on my previous post. The article is on to something and does not believe in the fresh water in flux shutting off the oceanic conveyor belt ,which I had thought they were trying to say due to not reading this in a careful manner.
    Other researchers suggested drivers of past and present rapid temperature change were likely to be very similar (Bond 2001, 2005), and recent findings are now supporting that notion. More recent explanatory hypotheses for D‑O events are gaining widespread critical acceptance and do not require any massive floods of freshwater nor a shutdown of the AMOC (Rasmussen 2004, Li 2010, Peterson 2013, Dokken 2013, Hewitt 2015). When sea ice prevents heat ventilation, the inflow of warm and dense Atlantic Waters continues to store heat in the subsurface layers. As heat accumulated, the warm Atlantic Waters became more buoyant, upwelled and melted the insulating ice cover. The loss of an insulating ice cover “turns on” the heat flux causing a dramatic rise in surface temperatures to begin the D‑O interstadial. Although details of hypothesized D‑O mechanisms vary slightly, they all agree on the ability of growing and shrinking sea ice to affect the heating and cooling of the northern hemisphere. I refer to this sea ice control of heat ventilation the Arctic Iris Effect.
    The signature of an Arctic Iris Effect is the opposing temperature trends in the ocean versus atmosphere: when ice is removed, warmer air temperatures coincide with cooler ocean temperatures. When ice returns cooler air temperatures coincide with a warmer ocean

  19. Please pardon my pedantry, but “begs the question” for “raises the question” is a pet peeve of mine. “Begging the question” is the name of the logical fallacy which means “assuming what you intend to show”. It is not the same as a raising a question.
    On a substantive note, I’d appreciate Dr. Steele’s consideration of Heinrich Events in context of his highly interesting hypothesis. These armadas of icebergs occur at fairly regular intervals during glaciations. Their melting causes a lens of freshwater to form in the North Atlantic.
    Also please consider that in winter during the coldest intervals of glaciations, such as the LGM, the North Atlantic freezes over, so that sea ice stretches from the exposed floor of the Celtic Sea between France and Ireland to the exposed Grand Banks of Newfoundland, which then has an ice shelf.
    As you might suppose, the effect on ocean currents is significant.

    • sturgis “begging the question” always seemed appropriate along with the phrases like the “elephant in the room” in most circumstances. Without being aware of that named logical fallacy, my usage is likely not problematic to most readers and this is the first time my use of that phrase has created an objection, Nonetheless I will keep that in mind for future usage as I strive for better universal clarity in my communications and I now understand how “begs the question” has a much different connotation in certain circles. I grew up in a tough urban environment and such grammatical distinctions were never an issue as our vocabulary centered more along creative and threatening profanity. Linguistically I am still evolving despite my elderly years. Once in a more academic world I frequently found myself asking forgiveness for my trespasses.
      Regards Heinrich events in the context of the Iris Effect it appears that Heinrich events are the result of the end of a stadial when ice shelves are finally undermined by basal melting from accumulated subsurface heat. , releasing an armada of icebergs thus opening the Arctic Oceans to rapid ventilation. Researchers have assumed that a lens of freshwater may result and thus affect the inflow of Atlantic water. But recent research does not suggest such a connection (Barker 2015 linked above)

      • The only correct usage of “begging the question” is as the name of the logical fallacy, in all circles. In recent years it has been misused even by writers who should be expected to know better, ie editors rather than scientists.
        http://begthequestion.info/
        Thanks for the Barker citation. Heinrich Events show what circulation patterns were when they occurred, since the material they drop can be traced in Atlantic cores.

  20. Jim;
    A great read and if you couple this with Willis’s tropical cloud theories and you have a simple self regulating system with strong negative feedbacks that would make for a very stable system at least on the positive side of the temperature range.

    • Earth is self-regulating, but its homeostasis presently works within two or three fairly steady states, ie glacial and interglacial, plus possibly a third superglacial condition, as during the LGM. The glacial and interglacial states show rapid shifts, of greater amplitude during glacials (D/O and Heinrich events) than interglacials (Bond cycles).
      IMO the AMO is largely responsible for the latter, if not the former as well.

      • Sturgis always great to hear from you. Just to restate.
        As they say if you can explain it to an 8 year old, Steele is basically saying the earth has a hat on it, when it warms that hat comes of and the head cools, once it cools enough the hat goes back on and the head starts warming again. Willis’s theory is the sun is shining down on the earth and when the earth gets too hot it pulls the shade down (clouds) until it cools again then it puts the shade up. either of these processes would easy counter any minor insolating effect of changes in the atmosphere. As Dr. Brown/ You and many others have said if there is a run away warming state possible in this system what has kept it from happening before.

      • Thanks. IMO Willis doesn’t claim to have invented the tropical thundercloud hypothesis.
        Warmunistas cite the PETM as a possible instance of runaway global warming from an infusion of CO2 or “carbon” into the climate system. I don’t buy it. Earth was already warm in the Cretaceous Period and following Paleocene Epoch. These Hot House conditions persisted into the Eocene. CO2 naturally came out of the oceans as a result of even warmer temperatures during the early Eocene.
        Then deep channels formed, separating Antarctica from South America and Australia, while earth entered an Ice House phase during the Oligocene. CO2 is an effect of climate change more than a cause.
        Within our own life times, climatstrologists need to explain why for more than thirty years after WWII, the planet cooled notably, despite a steady rise in CO2. Similarly they need to explain why earth is once again cooling now, under still increasing CO2.
        At least under present Ice House conditions and current continental alignments, earth appears to have ocean circulation cycles of roughly 60 and 1500 years, which operate in both glacial and interglacial states, but with greater magnitude when it’s icier.

    • Do you have a link to Willis’ tropical cloud essay. I might have missed it. I would like to see what he wrote as he has good insights. I am sure that changes in El Nino/LA Nina and associated effects on cloud and insolation exert a strong effect on ocean heat storage and transportation.

  21. This is a great article and the sea ice thickness as a modulator(through the ventilation process of warm sub-surface ocean water to atmosphere) of the atmospheric temperatures in the high latitudes makes sense.
    This is as good an explanation, as I have come across for D/O events.
    Both from article. It looks like the article ‘s conclusion is that a threshold of accumulated sub- surface warm Atlantic water must be reached which then is able to start to overcome the sea ice thickness. This in turn allows heat to escape from oceans to atmosphere. This is quite good.
    Although details of hypothesized D‑O mechanisms vary slightly, they all agree on the ability of growing and shrinking sea ice to affect the heating and cooling of the northern hemisphere. I refer to this sea ice control of heat ventilation the Arctic Iris Effect.
    Together the thick sea ice and polar mixed layer simply “turn off“ any heat flux from the ocean to the air, thus maintaining cold stadial air temperatures. Furthermore if the salty Atlantic

  22. l have a hard time believing that the swings in temp in Greenland during the ice age were down changes in the ocean currents without the weather allowing it to happened. Because these changes happened often and they were fast. l think its more likely that it was down to the weather patterns over the northern Atlantic during the ice age. What l believed happened during the ice age was that the weather patterns become bigger and much slower moving.lf this was so then the large swings in temp in Greenland during the ice age l believe were due to changes in the high pressure weather pattern that l believed often settled between Greenland and NW Russia. Because at times it was likely that the highs would settled more over towards Greenland then at other times. When this happened then Greenland would have been on the “warm side of the high with warm air pushing up over Greenland from the mid Atlantic. While over northern europe low pressure would have been able to move in bringing cold and heavy snowfall across northern europe and a increase in rainfall in southern europe. So with this increased rainfall it allowed the forests in southern europe to extend.

    • The Arctic Iris Effect does not exclude those changes in weather systems andthe jet stream and those effects are clearly seen today. For example the Arctic Oscillation shifted the winds that removed thick ice from the Arctic allowing heat to ventilate. Warmer waters ventilating in the Barents Sea create low pressure system that creates greater inflow of atmospheric and oceanic heat. Indeed the glacial ice sheets are believed to have forced the jet stream further south and minimize poleward heat flow. But by themselves those weather events can not explain the 10C abrupt warming or the subsequent abrupt cooling. But all those natural weather dynamics work hand and hand with the Iris Effect.

      • Jim its because these swings were so abrupt is what makes my think it was down the the weather.
        For example look what happened in the winters of 2009/10 and 2010/11, when there was blocking over the Greenland/ northern Atlantic area. lt brought bitter cold to Europe but record warmth in the NE Canada area.

      • taxed I am in full agreement that blocking high pressure systems cause abrupt extreme weather. Again the Iris Effect does not exclude those weather effects.

  23. THOUGHTS AND QUESTIONS
    The trigger point for climatic changes is the North Atlantic area of the globe as this article demonstrates. That is certain. Another possible trigger point could be Antarctic Sea Ice extent? Is there a SEA ICE threshold down in that part of the globe?
    In the large climatic picture it is still ocean/land arrangements, geo magnetic strength, Milankovitch Cycles , with solar variability superimposed upon these slow moving gradual cycles(which is moderated by those three moving gradual cycles) that bring the earth toward or away from a glacial /inter- glacial period, in my opinion.
    Then depending on the ice dynamic, initial state of the climate this makes the abrupt climatic changes more dramatic or less dramatic as this article shows.
    I think this is the correct path and will be proven to be so. I think how severe the quote ice age may or may not be with D/O events superimposed upon the ice age itself, is again depended upon how land/ocean arrangements, Milankovitch Cycles, geo magnetic field strength combined with solar variability phase with one another.
    In the big picture since the Holocene Optimum we are still in an overall cooling trend due to the above climate parameters.
    What is challenging for me is to now try to reconcile the lower solar insolation factor(post 2005) as a consequence of what is mentioned above to the resultant sea ice growth or lack of it in the Arctic , with a amplified climatic result being the result of the sea ice dynamic changing.
    I for one will be monitoring even more closely the Arctic Sea Ice Extent going forward and see how this ties into prolonged solar minimum effects ,despite the fact as the article says until recently or maybe still the Arctic Ocean has been cooling keeping the ventilation process intact raising the Arctic temperatures.
    The other item I want to monitor is the oceanic temperatures in general and atmospheric circulation changes as we move forward into this decade. I want to see how this contrast to very prolonged minimum solar conditions and how it plays out.
    Also the wild cards have to be taken into consideration which is a super volcanic eruption or extra terrestrial impact which can throw things upside down in the climate world and must happen from time to time in earth’s historical past.
    As far as ENSO,PDO,AMO, run of the mill Volcanic Activity they are transient climatic factors in my opinion and just refine the present climatic regime the climate may be in.
    As far as the tropic thermostat effect keeping the climate stable ,stable is in the eyes of the beholder and if one wants to say the climate is stable because it is bounded by an upper and lower temperature range that is fine, but on the other hand there is nothing stable about the climate going from a glacial state to an inter-glacial state or having D/O events superimposed upon those climatic states and those D/O events being very dramatic during glacial times.

    • Salvatore wrote, “What is challenging for me is to now try to reconcile the lower solar insolation factor(post 2005) as a consequence of what is mentioned above to the resultant sea ice growth or lack of it in the Arctic , with a amplified climatic result being the result of the sea ice dynamic changing.”
      If changes in insolation reduce the inflow of warm Atlantic Waters as evidenced during the Little Ice Age, it suggests the there will be a trend to cooler subsurface waters in the Arctic. However the connection with insolation must include lag periods. Warm water is pumped into the subtropical gyre and may have a residency of about 20 years. LIke a capacitor it stores and releases warm water years after the source has cooled. Similarly NAO can determine both the spin up of the gyres and the width of the sub polar gyre and how much warm water it allows to enter the Arctic. Furthermore the reduction of the halocline due to wind mixing when the loss of sea ice re-connects the surface winds with subsurface waters, requires time to be reinstated.
      So I think looking for any linear correlation with insolation over relatively short time spans of less than 50 years will never present significant statistical correlations.However on longer time scale that reduced insolation that began after 2005 predicts less warm water inflow and recovering sea ice. I suspect this will be obvious by 2030, but it may take a few more decades. On the other hand when insolation dropped after its 1950s peak, sea ice recovered substantially within a decade. But the background state of how much thick multiyear sea ice is present also determines how quickly the Arctic will respond, so due to progressive 20th century thinning, it will likely take a tad longer to recover now than it did in the 1960s.

    • Salvatore Del Prete
      THOUGHTS AND QUESTIONS
      The trigger point for climatic changes is the North Atlantic area of the globe as this article demonstrates.
      [IF THE TRIGGER POINT FOR CLIMATIC CHANGES LIE IN THE NORHT ATLANTIC, THEN THERE SHOULD BE A LAG EFFECT IN THE SOUTHERN HEMISPHERE–BUT THERE ISN’T–THE CLIMATE CHANGES ARE SYNCHRONOUS IN BOTH HEMISPHERES. THAT’S WHY THIS EFFECT DOESNT’ EXPLAIN D/O EVENTS]
      That is certain. Another possible trigger point could be Antarctic Sea Ice extent? Is there a SEA ICE threshold down in that part of the globe?
      In the large climatic picture it is still ocean/land arrangements, geo magnetic strength, Milankovitch Cycles , with solar variability superimposed upon these slow moving gradual cycles(which is moderated by those three moving gradual cycles) that bring the earth toward or away from a glacial /inter- glacial period, in my opinion.
      Then depending on the ice dynamic, initial state of the climate this makes the abrupt climatic changes more dramatic or less dramatic as this article shows.
      I think this is the correct path and will be proven to be so. I think how severe the quote ice age may or may not be with D/O events superimposed upon the ice age itself, is again depended upon how land/ocean arrangements, Milankovitch Cycles, geo magnetic field strength combined with solar variability phase with one another.
      [THIS IS WHAT BROECKER TRIED TO DO BUT IT DOESN’T WORK BECAUSE OF THE SYNCHRONOUS CLIMATE CHANGES IN BOTH HEMISPHERES]
      In the big picture since the Holocene Optimum we are still in an overall cooling trend due to the above climate parameters.
      What is challenging for me is to now try to reconcile the lower solar insolation factor(post 2005) as a consequence of what is mentioned above to the resultant sea ice growth or lack of it in the Arctic , with a amplified climatic result being the result of the sea ice dynamic changing.
      I for one will be monitoring even more closely the Arctic Sea Ice Extent going forward and see how this ties into prolonged solar minimum effects ,despite the fact as the article says until recently or maybe still the Arctic Ocean has been cooling keeping the ventilation process intact raising the Arctic temperatures.
      The other item I want to monitor is the oceanic temperatures in general and atmospheric circulation changes as we move forward into this decade. I want to see how this contrast to very prolonged minimum solar conditions and how it plays out.
      Also the wild cards have to be taken into consideration which is a super volcanic eruption or extra terrestrial impact which can throw things upside down in the climate world and must happen from time to time in earth’s historical past.
      [VOLCANIC ERUPTIONS ARE NOT A FACTOR BECAUSE THEIR EFFECT LAST ONLY A COUPE OF YEARS]
      As far as ENSO,PDO,AMO, run of the mill Volcanic Activity they are transient climatic factors in my opinion and just refine the present climatic regime the climate may be in.
      As far as the tropic thermostat effect keeping the climate stable ,stable is in the eyes of the beholder and if one wants to say the climate is stable because it is bounded by an upper and lower temperature range that is fine, but on the other hand there is nothing stable about the climate going from a glacial state to an inter-glacial state or having D/O events superimposed upon those climatic states and those D/O events being very dramatic during glacial times.

  24. “By all accounts the recent warming of the 1990s and 2000 was likewise a ventilation event that also cooled the upper layers of the Arctic Ocean. The failure to model ventilated heat events led to incorrectly attributing that warming to increasing concentrations of CO2.”
    The accelerated warming of the AMO and Arctic from the mid 1990’s was due to increasing negative NAO episodes, caused by the decline in solar plasma strength since then.
    http://snag.gy/HxdKY.jpg
    Nuclear warheads may be useful ordinance in the future for destroying ice shelves threatening to disrupt the AMOC.

  25. A few things for all of you to ponder:
    1. The abrupt termination of the late Pleistocene and the YD proved that you can go from full glacial to interglacial conditions, back into full glacial conditions, and finally the abrupt end of the Pleistocene in very short periods of time. These abrupt swings in glacial/interglacial conditions are far too rapid to have been caused by Milankovitch orbital changes and effectively spelled the demise of the Milankovitch theory. If you can produce abrupt full glacial/interglacial conditions without Milankovitch, then there must be some other cause of glaciations and interglaciations.
    2. Broecker attempt to explain these abrupt climate changes with interruptions to his global ocean conveyor belt system, but his explanation requires a lag in glacial/nonglacial conditions between the Northern and Southern Hemispheres. New isotope dates on the YD, Inter-allerod cool period, and preceding cold period show very clearly that even short term climate changes were highly synchronous in both hemispheres. The ‘iris effect’ suffers from the same problem.
    3. 10Be and 14C variations are a measure of cosmic radiation, which show interesting correlations with climate changes, suggesting possible cause-and-effect relationships. These relationships need additional study, but the correlation of multiple events is too good to be simply random.
    4. Whatever is the cause of the D/O events, it must be capable of producing what D&O called the ‘flickering’ of late Pleistocene climate changes. So far we have no good explanation of this phenomena, but we do know what it can’t be.

      • Jim — it depends on the dating method. For 14C-dated moraines it’s +/- 40 -80 years (for 19 ka) and for 10Be it’s about 0.2-0.4 ka (for -13 ka)

      • That range of uncertainty is why I ask, The 200 to 400 year uncertainty in 10Be can be used as proof of lag effects and a see saw effect OR a more synchronous behavior. I agree with you that the ultimate driver is most likely associated with solar effects but there are likely lag effects that determine how that solar forcing is detected.I do suggest there is a lag effect between the poles due to the way thick multiyear ice in the Arctic and thinner annual Antarctic ice respond to poleward transport of heat. While you see the Iris Effect as contrary to a synchronous driver, I am suggesting the Iris Effect supports a synchronous behavior while also explaining a perceived 200 year lag suggested by the recent WAIS paper, because it all happens within the bounds of dating uncertainty.

      • Don, How would you explain the difference in the Antarctic and Arctic warming presented in the graph from Ahn 2008 which I used as my first figure and it commonly agreed upon as being representative of the observed changes. It suggests a steady warming in the Antarctic but in the Arctic that warming trend has cyclic warming and cooling events superimposed. I suggest the Iris Effect explains the rapid changes in the B_A and D and YD events experienced mostly in the Arctic that are superimposed on a synchronous warming.
        http://wattsupwiththat.files.wordpress.com/2015/09/clip_image002_thumb.jpg?w=598&h=403

    • Don I am not sure why you argue synchronous behavior between the poles is a problem for the Arctic Iris effect. Te new WAIS paper suggests a stong synchronous behavior with the Antarctic lagging the Arctic by about 208 years. However if you examine their idealized relationship as their illustration suggests, and consider the Arctic Iris effect, the changes are even more synchronous
      http://www.nature.com/nature/journal/v520/n7549/images/520630a-f1.jpg
      The gradual warming in the Antarctic is readily observed because the thin annual ice does not isolate heat or cause it to accumulate. The Arctic expresses a more “digital” on off mode suddenly warming and suddenly cooling as predicted by an iris effect. What the WAIS team calls a lag effect, can easily be seen as a sudden warming in the Arctic that began in synchrony with Antarctic warming but was not observed until the heat was ventilated.

      • “The 200 to 400 year uncertainty in 10Be can be used as proof of lag effects and a see saw effect OR a more synchronous behavior.” YOU LOST ME HERE–HOW DOES 200-400 YEAR UNCERTAINTY HAVE ANYTHING TO DO WITH LAG EFFECTS AND SEE-SAW EFFECT? THE 10BE POSSIBLE RANGE OF VALUES DOEN’T PROVE ANYTHING–ALL IT MIGHT DO IS LEAVE THE QUESTION OPEN. THE SEVERAL HUNDRED TO 1000 YEARS LAG TIME MAKES A PRETTY BIG TARGET TO HIT. LOTS OF 14C DATES IN BOTH HEMISPHERES ON 10BE-DATED MORAINES ALSO HAVE 14C AGES THAT PROVIDE BETTER ACCURACY AND CONFIRM THAT THE MORAINES ARE SYNCHRONOUS.
        .I do suggest there is a lag effect between the poles due to the way thick multiyear ice in the Arctic and thinner annual Antarctic ice respond to poleward transport of heat. I DON’T SEE HOW THAT COULD IN ANY WAY SHOW THAT THE 10BE AND 14C DATES ARE WRONG.
        While you see the Iris Effect as contrary to a synchronous driver, I am suggesting the Iris Effect supports a synchronous behavior while also explaining a perceived 200 year lag suggested by the recent WAIS paper, because it all happens within the bounds of dating uncertainty. YOU LOST ME HERE–EVEN IF THE IRIS EFFECT WERE TRUE, YOU ARE STILL LEFT WITH THE 200-1000 YEAR LAG IN THE S. HEMISPHERE. THE IRIS EFFECT CERTAINLY DOESN’T DEMONSTRATE SYNCHRONOUS BEHAVIOR AND THERE IS NO 200 YEAR LAG.

    • Don Easterbrook says:
      September 1, 2015 at 10:09 pm
      “A few things for all of you to ponder:
      1. The abrupt termination of the late Pleistocene and the YD proved that you can go from full glacial to interglacial conditions, back into full glacial conditions, and finally the abrupt end of the Pleistocene in very short periods of time. These abrupt swings in glacial/interglacial conditions are far too rapid to have been caused by Milankovitch orbital changes and effectively spelled the demise of the Milankovitch theory. If you can produce abrupt full glacial/interglacial conditions without Milankovitch, then there must be some other cause of glaciations and interglaciations.
      [. . .]”

      Don Easterbrook,
      A question for you.
      It appears that you mean ’abrupt’ change from interglacial conditions to full glacial conditions only in context of a minimum approximate geologic timescale of at least a few thousands of years. So, my question is, looking at a period of the next decade up to the next century, if we were right now in a beginning part of an ’abrupt’ change from our current interglacial towards the next full glacial period then what change in temp would we expect in the next 10 years to next 100 years? Over the next 10 to 100 years, would the ‘abrupt’ change appear ‘abrupt’ to us while it was happening or would it only appear ‘abrupt’ in a ~1000+ year period?
      I would appreciate putting in context what such ‘abrupt’ change would look like to us on the short timescale of 10 to 100 years. I wonder if the ’abrupt’ it would look significant to us over that non-geological timespan.
      John

      • WHAT WE KNOW IS THAT WARMING AND COOLING EVENTS OF ~20 F OCCURRED IN A CENTURY OR LESS, ENOUGH TO PLUNGE THE EARTH INTO FULL GLACIAL OR INTERGLAIAL MODE.

      • Interglacial mode doesn’t occur until ice sheet melt is well under way.
        IMO you mean interstadial rather than interglacial. There aren’t interglacials until most of the NH ice sheets have melted. Then, a few thousand years at most into interglacials, they melt back about to present limits, ie mainly just on Greenland, with patches here and there in the Arctic.

      • Don J. Easterbrook on September 4, 2015 at 1:39 pm
        WHAT WE KNOW IS THAT WARMING AND COOLING EVENTS OF ~20 F OCCURRED IN A CENTURY OR LESS, ENOUGH TO PLUNGE THE EARTH INTO FULL GLACIAL OR INTERGLAIAL MODE.

        Don J. Easterbrook,
        Thanks for responding.
        Are you aware of anyone in your field who has a hypothesis that we are currently in a period of a swing toward glacial conditions of a D/O-like event? I am curious about what would be the claimed evidence supporting such a person’s hypothesis if there is anyone with such a hypothesis? NOTE: I am not suggesting there is anyone with such hypothesis or that there is any claimed evidence, just trying to understand the state of inquiry.
        John

      • Gloria Swansong on September 4, 2015 at 1:45 pm
        Interglacial mode doesn’t occur until ice sheet melt is well under way.
        IMO you mean interstadial rather than interglacial. There aren’t interglacials until most of the NH ice sheets have melted. Then, a few thousand years at most into interglacials, they melt back about to present limits, ie mainly just on Greenland, with patches here and there in the Arctic.

        Gloria Swansong,
        I do not know which person you are addressing, if anyone.
        Does using a pseudonym in this dialog create a self-perceived tactic? NOTE: I ask only because of my interest for many years on the problems of an epistemological nature created through anonymous commenting.
        John

    • Don Easterbrook says:

      1. The abrupt termination of the late Pleistocene and the YD proved that you can go from full glacial to interglacial conditions, back into full glacial conditions, and finally the abrupt end of the Pleistocene in very short periods of time. These abrupt swings in glacial/interglacial conditions are far too rapid to have been caused by Milankovitch orbital changes and effectively spelled the demise of the Milankovitch theory.

      I disagree with this.
      1. This rapid changes do not have enough time to re-build the ice sheets, so you are assuming that it was back to full glacial conditions just based on a proxy for temperature. Have you checked sea levels to see if they went back down to -120 m during the YD? It did become cold but it did not become full glacial.
      2. You are making the common mistake of assuming that Greenland Ice Cores reflect a global situation. They do not. While full glacial conditions affect the entire planet very drastically, the YD affected drastically the Arctic region, importantly the Northern Hemisphere areas around it, noticeably South East Asia, barely South America and was completely absent in Australia and other regions of the Southern Hemisphere.
      As the saying goes, the rumors of the demise of the Milankovitch theory have been greatly exaggerated.

      • 1. This rapid changes do not have enough time to re-build the ice sheets, so you are assuming that it was back to full glacial conditions just based on a proxy for temperature. Have you checked sea levels to see if they went back down to -120 m during the YD? It did become cold but it did not become full glacial.
        [OF COURSE THE ICE SHEETS DIDN’T REBUILD! YOU MISS THE POINT–WE’RE TALKING ABOUT RETURN TO GLACIAL CONDITIONS–IT TAKES TIMETO BUILD ICE SHEETS.]
        2. You are making the common mistake of assuming that Greenland Ice Cores reflect a global situation. They do not.
        [YOU’RE DEAD WRONG HERE–THE CORRELATION BETWEEN GLOBAL GLACIATIONS AND THE ICE CORE TEMPS ARE EXCELLENT. THE MAGNITUDE OF THE TEMP CHANES VARIES WITH LATIUTDE, BUT THE TIMING OF CHANGES IN THE CORES WITH PERIODS OF MORAINE BUILDING IS ALMOST EXACT]
        While full glacial conditions affect the entire planet very drastically, the YD affected drastically the Arctic region, importantly the Northern Hemisphere areas around it, noticeably South East Asia, barely South America and was completely absent in Australia and other regions of the Southern Hemisphere.
        [YOU’RE ALSO DEAD WRONG HERE–THE YD WAS NOT JUST REGIONAL, IT WAS GLOBAL (AS SHOWN BY MORE THAN 3,000 PUBLICATIONS]
        As the saying goes, the rumors of the demise of the Milankovitch theory have been greatly exaggerated.
        [AS THE SAYING GOES–SYNCHRONEITY OF GLACIATIONS IN BOTH HEMISPHERES IS THE FLY IN THE MILANKOVITCH OINTMENT]

      • Don,
        Synchronicity, such as it is, isn’t a fly in the ointment. There is no reason to suppose it is any such thing.

    • Don,
      Nothing you say has the least affect on the fact of Milankovitch Cycles, especially on the formation of NH ice sheets.
      Abrupt switches are visible in all glacial terminations. They result from the effect of meltwater pulses. The melting behind these rapid changes is driven by orbital and rotational mechanics, but the ups and downs during deglaciations need not be caused primarily directly by Milankovitch parameters.
      Neither do D/O events and Bond cycles in any way invalidate Milankovitch mechanics on insolation, hence on glaciation and deglaciation.

      • OF COURSE THEY DO! THE ABRUPTNESS OF D/O EVENTS PROVE THAT THEY CAN’T BE CAUSED BY MILANKOVITCH CYCLES AND THE MAGNITUDE OF D/O EVENTS SHOWS THAT FULL GLACIAL CONDITIONS CAN BE CREATED IN A CENTURY OR TWO
        [We request you avoid all capital letters. .mod]

      • Don,
        No, of course they don’t show any such thing.
        Milankovitch cycles are responsible for the big swings between glacial and interglacial conditions.
        D/O events occur within glacial conditions, so need not be caused by Milankovitch cycles. I don’t see why this fact is hard to grasp.
        Interglacial conditions do not occur within glacials, even during interstadials. This should be obvious, since the ice sheets are still largely intact then. Interglacial conditions means the spread of forests and grasslands into previously glaciated areas. Clearly, this can’t happen with the ice sheets still there, and periglacial conditions around their edges. The periglacial steppe-tundra biome doesn’t exist once interglacials are established.
        By interglacial conditions, do you mean temperatures rather than ecosystems? If so, that’s still not the case.
        Asserting your easily shown false conjecture in all caps doesn’t make your case more persuasive.

  26. Thanks, Jim good thoughtful article.
    Referring to Fig. 2, the polynya illustrated appears to be related to a katabatic winds with sinking water. Do all polynyas ventilate heat as an iris or does it depend on their origin ?

    • most polynyas are “latent heat” polynya due to the release of heat when new ice is formed in addition to any upwelling heat. Rigor 2002 concluded that the lack of ice was the cause of atmospheric warming due to observations such as:
      “the exchange of heat between the Arctic Ocean and atmosphere is strongly moderated by the thickness of sea ice. For example, during winter the sensible and latent heat flux into the atmosphere from a refreezing open lead is ~700 W/m2, as compared to ~10 W m2 into the ocean over 3 m thick”

  27. Something extraordinary is currently happening to the sun. We are going to see an abrupt switch to the cold phase of a Dansgaard-Oeschger cycle followed it appears by what causes a Heinrich event.
    It is fact that the paleo data shows evidence of cyclic rapid immense climate changes (cyclic changes require a cyclic forcing function rather than massive positive feedback to amplify tiny changes which would create a random oscillating pattern). The last event of this type is called the 8200 year before present event which is a 2C cooling event that lasted for 200 years. The Younger Dryas is the super large example of the cyclic abrupt forcing function. During the Younger Dryas abrupt cooling event the planet went from interglacial warm to glacial cold with 70% of the cooling occurring in less than a decade at a time when summer insolation at 65N was maximum. The YD abrupt cooling lasted for 1200 years. The massive YD forcing mechanism is capable of and does terminate interglacial periods.
    This is the Greenland Ice sheet temperature data for the last 100,000 years. Can you see the cyclic abrupt changes?
    http://oceanservice.noaa.gov/education/pd/tidescurrents/media/effect_influences_3.gif
    The climate does not ‘tip’ or ‘jump’ from one ‘state’ to another without a physical cause, a physical reason for the observed change. Euphemisms and analogues are used when there is no scientific basis for a claim. There is no magical, ‘smart’ amplification mechanism that can when required amplify tiny forcing changes to create what is observed. There are no peer reviewed papers that support the assertion of a massive ‘smart’ amplification mechanism. The ‘tip’ or ‘jump’ zombie theory stops people from looking for the physical reason for what is observed. Makes it impossible to solve the problem.
    You would not accept the assertion that now and then rocks jump up hill. There is no analytical data to support the assertion that planetary climate can or does have massive cyclic changes without a forcing function, a physical reason for what is observed. There is no evidence for a ‘smart’ amplification mechanism that appears when required to create for example the Younger Dryas abrupt climate change event. The Younger Dryas is an immense climate change which is an example of cyclic, abrupt, immense climate change.
    Meanwhile back to climate Urban Myths/Zombie Theories
    ClimateMyth/Zombie Theory 1- An interruption to the discrete Gulf Stream (a discrete deep water return for the North Atlantic Drift Current (aka The ‘Gulf Stream’) does not exist, see below, but even if it did so a melt pulse could interrupt it) would not result in significant cooling of Europe. The Gulf stream myth has been perpetuated for almost 20 years.
    http://www.americanscientist.org/issues/feature/2006/4/the-source-of-europes-mild-climate

    The Source of Europe’s Mild Climate
    The notion that the Gulf Stream is responsible for keeping Europe anomalously warm turns out to be a myth
    All Battisti and I did was put these pieces of evidence together and add in a few more illustrative numerical experiments
    …. shutdown of the North Atlantic thermohaline circulation. Their modeled climate cooled by a few degrees on both sides of the Atlantic and left the much larger difference in temperature across the ocean unchanged. Other published model experiments went on to show the same thing. Further, the distinction between maritime and continental climates had been a standard of climatology for decades, even centuries.
    Why hadn’t anyone done that before? Why had these collective studies not already led to the demise of claims in the media and scientific papers alike that the Gulf Stream keeps Europe’s climate just this side of glaciation?
    It seems this particular myth has grown to such a massive size that it exerts a great deal of pull on the minds of otherwise discerning people.
    This is not just an academic issue. The play that the doomsday scenario has gotten in the media—even from seemingly reputable outlets such as the British Broadcasting Corporation—could be dismissed as attention-grabbing sensationalism. But at root, it is the ignorance of how regional climates are determined that allows this misinformation to gain such traction. Maury should not be faulted; he could hardly have known better. The blame lies with modern-day climate scientists who either continue to promulgate the Gulf Stream-climate myth or who decline to clarify the relative roles of atmosphere and ocean in determining European climate.
    This abdication of responsibility leaves decades of folk wisdom unchallenged, still dominating the front pages, airwaves and Internet, ensuring that a well-worn piece of climatological nonsense will be passed down to yet another generation.

    Climate Myth/Zombie Theory 2- There is no North Atlantic discrete deep water return flow to interrupt. A melt pulse therefore cannot interrupt the North Atlantic Drift current (aka The ‘Gulf Stream’).
    http://www.sciencedaily.com/releases/2009/05/090513130942.htm

    Cold Water Ocean Circulation Doesn’t Work As Expected
    The familiar model of Atlantic ocean currents that shows a discrete “conveyor belt” of deep, cold water flowing southward from the Labrador Sea is probably all wet.
    A 50-year-old model of ocean currents had shown this southbound subsurface flow of cold water forming a continuous loop with the familiar northbound flow of warm water on the surface, called the Gulf Stream.
    To address those criticisms, Lozier and Bower launched 76 special Range and Fixing of Sound floats into the current south of the Labrador Sea between 2003 and 2006. Those “RAFOS” floats could stay submerged at 700 or 1,500 meters depth and still communicate their data for a range of about 1,000 kilometers using a network of special low frequency and amplitude seismic signals.
    But only 8 percent of the RAFOS floats’ followed the conveyor belt of the Deep Western Boundary Current, according to the Nature report. About 75 percent of them “escaped” that coast-hugging deep underwater pathway and instead drifted into the open ocean by the time they rounded the southern tail of the Grand Banks.
    Eight percent “is a remarkably low number in light of the expectation that the DWBC is the dominant pathway for Labrador Sea Water,” the researchers wrote.
    “Everybody always thought this deep flow operated like a conveyor belt, but what we are saying is that concept doesn’t hold anymore,” said Duke oceanographer Susan Lozier. “So it’s going to be more difficult to measure these climate change signals in the deep ocean.”

    • William, First I am not sure why you are repeating lengthy posts about the myth of the conveyor belt. But I agree that there is no such thing and it has supported bad hypotheses. Poleward transport of heat is the integration of several dynamics. That said heat transport does vary, and impacts the iris effect.
      2nd I disagree with your earlier statement that “The cyclic abrupt cooling events require a massive forcing function to cause the cyclic abrupt cooling.” The oceans have cooled over the past 35 million years into the icebox state such that the default condition of the arctic is to freeze unless there is sufficient heat transport. In all D-O events as well as glacial-interglacial events the initial cooling happens slowly as heat transport is reduced and ventilation begins to exhaust the stored heat. When enough ice forms to prevent further ventilation, the final cooling to the stadial condition is rapid.Abrupt warming, slow cooling followed by fast cooling is the shape of all D-O and deglacial events.
      3rd the iris effect does not dismiss contributions from solar forcing. As Don mentions the correlations with cosmogenic nuclides is too strong. I strongly suspect that changes in irradiance is part of the forcing that amplifies poleward heat transport to both hemispheres and increases the inflow of warm Atlantic Water by affecting both temperature and volume. But any solar forcing by itself can not explain the abrupt warming of 10C in just a decade based on how long it takes to heat the ocean.The impact of solar forcing provides too little energy over the short term. But if stored in the subsurface ocean can provide enough heat to explain the periodic warm events. I see solar forcing and the iris effect working in tandem.
      In addition to irradiance, the Milankovitch forcing helps tip the balance during deglacial periods by increasing the summer ablation of arctic ice. But Milankovitch forcing can not explain D-O events. Also there is a debate about which is more important, the ~21 thousand year precessional forcing vs ~45 thousand obliquity forcing. Although there was an abrupt change in the glacial cycles from about 45 thousand to 100,000 thousand years, no one believes the 100,000 eccentricity forcing have enough power to affect glacial cycles and the observed 100,000 is a function of multiple precessional and obliquity forcing. Here again the iris effect would support that notion as the thickness of the arctic ice determines how sensitive it is to solar forcing. As the planet continues to descend into the ice box condition, greater accumulation of heat is required to tip us into an interglacial.

      • Some of my Milankovitch Cycle thoughts
        One other point is the SH. and N.H. are not created equally when it comes to their response to Milankovitch Cycles.
        The S.H. is set up as such , that it does not really matter if summer time insolation increases or decreases because the area of land that is entrenched in snow/ice is going to remain the same regardless of summer time insolation changes , in contrast to the N.H. where a difference in summer time insolation can cause a significant difference in the land area covered by snow/ice, thus effecting the albedo of the entire planet.
        S.H. albedo remaining steady while N.H. albedo increasing due to favorable Milankovich Cycles.

      • Jim said:
        “I see solar forcing and the iris effect working in tandem.”
        Agreed, with ocean oscillations in various ocean basins interacting to mediate the speed and severity of the Iris effect.
        Latitudinal climate zone shifting and global cloudiness variations being the leading indicator of what is to come.

    • William
      The physical reason for a flip in climate, the mighty forcing that moves heaven and earth by several degrees centigrade and a trillion petajoules, is the flap of a butterfly’s wing.

  28. I probably didn’t read the article carefully enough, but I don’t understand what keeps the warm saline layer under the cold one. Is it more saline, and thus denser even though it is warmer?

    • The Gulf Stream experiences heavy evaporation thus making the Atlantic water extremely saline and dense. In a simplified version of the Arctic vertical structure, Atlantic Water occupies a middle zone between fresher but colder surface waters and the deepest cold salty bottom layer from brine rejection. The halocline is cold and salty but not saltier than the Atlantic Waters.

  29. Jim here is what my thinking was at one time. Your article however has changed my mind to a degree although some of what is said below may still have some merit.
    I have two questions and a statement. How accurate are the Arctic Ocean temperature measurements from 1993-2011 showing the cooling trend in the Arctic Ocean?
    What is the Arctic Ocean doing temperature wise post 2011?
    Statement
    Let me say the synchronous argument in no way diminishes the Arctic Iris Effect. Remember D/O events are short warm spells within Ice Age conditions. The globe overall is still overall in an Ice Age State as opposed to an inter-glacial state when D/O events take place.
    The D/O events to my way of thinking is strictly a function of the North Atlantic and Ice Coverage changes in the Arctic which gives these abrupt temperature changes but when happening during an Ice Age it is still within the ice Age. The D/O events during an Ice Age are not inter- glacial events which last some 10 to 20 thousand years.
    Thinking at one time below.
    Solar/Thermohaline Circulation/1470 year climate cycle connection – Southwest Weather, Inc. supports the theory that states the superposition of the DE VRIES – SUESS 210 year solar cycle, and the Gleissberg 87 year old solar cycle creates a solar variability every 1470 years, that impacts the fresh water concentrations put into the North Atlantic, which in turn either weakens or strengthens the Thermohaline Circulation. The effects, depending on the initial state of the climate; that being glacial or interglacial. Since we are currently in an interglacial period, we will examine the Solar/Thermohaline circulation possible connection for this initial state of the climate when solar activity is in a minimum state.
    OVERVIEW
    The connection between the Thermohaline Circulation and the Solar Cycle is if solar activity should reach a certain level of activity, it could through a modulating effect of the atmospheric circulation, either amplify or reduce the amount of sea ice entering the subpolar North Atlantic. This would then change the fresh water concentration of the subpolar North Atlantic, leading to a change in the North Atlantic Deep Water (NADW) production, which would either enhance or decrease the Thermohaline Circulation.
    FOR EXAMPLE:
    If solar activity were to reach a certain minimum magnitude (every 1470 years), it could modulate the atmospheric circulation, resulting in a negative Atlantic Oscillation (NAO), which in turn would amplify the transport (due to a stronger northerly wind flow over the North Sea to the Sub Polar North Atlantic, in response to a negative NAO) of drift ice into the Sub Polar North Atlantic, causing the salinity concentrations and the temperature of the Sub Polar North Atlantic waters to decrease. (Density decreases overall despite colder water temperatures)
    This would cause a reduction in NADW formation, which would lead to a weakening of the Thermohaline Circulation. The result would be a further cooling in the higher latitudes, due to less northward transport of heat via the Thermohaline Circulation.
    This would then have a PROFOUND EFFECT on the temperatures of the Northern Hemisphere much MORE, then what the solar reduction in activity itself would suggest.
    The present arrangement of the continents, versus oceans is conductive for glacial conditions presently. The reason is that most of the land mass in both hemispheres is located in high latitudes, with water exerting a modulation effect on both the land mass in the Northern Hemisphere, as well as the Southern Hemisphere.

    • I agree with your statement ” the synchronous argument in no way diminishes the Arctic Iris Effect” See my response to Easterbrook above with the graph from the recent WAIS paper.
      2nd I would be careful linking NADW formation with inflows of warm water. That linkage is a vestige of conveyor belt thinking. As Lozier 2010 wrote “the conveyor-belt model no longer serves the community well—not because it is a gross oversimplification but because it ignores crucial structure and mechanics of the ocean’s intricate global overturning”
      For example warm water still intrudes the Arctic during stadial conditions but no NADW is formed because the ice prevents contact with cold air that is needed to cool the water enough to sink to the bottom. Poleward ocean heat transport is driven by the winds not loss of buoyancy in the polar regions. There is no Pacific Deep water formed yet there is still poleward heat transport.
      I do see a solar connection based on observed changes in ocean heat content. During the LIttle ICe Age there both the Atlantic subtropical gyre (Keigwin 1997) and the Western Pacific Warm Pool (Roenthal 2014) cooled below todays temperatures , and conversely both warmed during the Medieval Warm Period. Furthermore there was less heat transport in the Gulf Stream during the LIA, and during the deglacial at peak insulation there was greater inflows of warm water.
      Thus I suspect that due to the correlations with cosmogenic nuclides, solar irradiance can modulate the poleward flow of heat.

      • jim said:
        “due to the correlations with cosmogenic nuclides, solar irradiance can modulate the poleward flow of heat.”
        That would be the Svensmark hypothesis then.
        May I suggest my alternative hypothesis of increased cloudiness from longer lines of air mass mixing when jet streams become more meridional ?

      • Stephen said “That would be the Svensmark hypothesis then. May I suggest my alternative hypothesis of increased cloudiness from longer lines of air mass mixing when jet streams become more meridional ?”
        I was not invoking Svensmark.
        Higher solar irradiance suggested for the MWP created a La NIna like zonal temperature gradient condition while lower irradiance during the LIA is associated with El Nino-like gradient.
        I see a La Nina-lke gradient creating less cloud cover over the eastern Pacfic and more upwelled water that absorb more heat. A spin up of the subtropical gyre and the northward shift of the ITCZ would help increase poleward heat transport.

      • Jim said:
        “Higher solar irradiance suggested for the MWP created a La NIna like zonal temperature gradient.”
        Later in this thread you said this:
        ” El Nino years would diminish the HIgh allowing for more zonal flow.”
        I can respond more intelligently if you resolve the discrepancy 🙂
        My view is that in the MWP solar top down effects caused a positive AO which pulled the climate zones poleward so as to allow a more zonal flow whereas in the LIA solar top down effects caused a negative AO which pushed the climate zones equatorward to cause a more meridional flow.

      • Stephen said ““Higher solar irradiance suggested for the MWP created a La NIna like zonal temperature gradient.”
        Later in this thread you said this:
        ” El Nino years would diminish the HIgh allowing for more zonal flow.”
        I can respond more intelligently if you resolve the discrepancy :)”
        There is no discrepancy. La Nina creates a colder eastern Pacific and a warmer western warm pool, hence a stronger zonal temperature gradient. The temperature gradients creates a stronger pressure gradient with a stronger HIgh over the cooler eastern Pacific that amplifies the Trade winds via the Walker Circulation and that HIgh directs the westerlies, jet stream and rains northward. Subtropical Highs block moisture carrying zonal westerlies to create the dry summer Mediterranean climate for California, Chile, and west Africa. However in the winter the temperature difference between land and oceans reverses, weakening the High and allowing winter rains. But in LA NIna years a much colder ocean helps maintain the High pressure system causing winter droughts as it forces the winds northward.
        In El Nino years the warm water that floods the eastern Pacific amplifies the weakening of the HIgh so that moire moisture bearing westerlies maintain their zonal flow, bring rains to California and the southwest

        • OK,
          Then are you suggesting that both La Nina and El Nino create a zonal flow but at different latitudes / locations ?
          If so, then that would not matter for my proposition that globally an active sun shifts everything poleward on average with a more zonal global flow whereas a quiet sun allows an equatorward shift and more meridional global flows.
          Your description would then be of regional / local significance only.

      • Stephen says, “Then are you suggesting that both La Nina and El Nino create a zonal flow but at different latitudes / locations ?
        If so, then that would not matter for my proposition ”
        No I am saying La Nina events force add a more meridonal vector causing a more wavy flow and El Nino events by virtue of minimizing the HIgh allow a more zonal flow.
        I am not arguing against your proposition, I am simply arguing that there are other bottom of dynamics that cause a wavier jet stream. I just dont know to what degree your top down dynamics contributes.

        • Some confusion was present but I think you have now clarified it.
          You previously said:
          “Higher solar irradiance suggested for the MWP created a La NIna like zonal temperature gradient.”
          and now you say:
          “No I am saying La Nina events force add a more meridonal vector causing a more wavy flow”
          I do accept that bottom up processes can also cause a wavier more meridional flow.
          It is all a matter of the net interaction between top down and bottom up processes but I think we can agree that zonality is greater when the sun is nore active and meridionality when the sun is less active.
          No doubt the ENSO process then modulates the top down solar influences from below.
          I only mentioned Svensmark because you referred to cosmogenic nucleides.

      • I use the term zonal only to refer to east-west coordinates vs meridonal referring to north-south.
        La NIna’s create a greater zonal temperature gradient meaning a cooler eastern tropical Pacific and a warmer western. Because La Ninas enhance the HIgh in the eastern Pacific, it blocks the zonal flow of westerly winds and directs winds and moisture northward, thus promoting a more wavy jet stream.
        In contrast El Ninos minimize the tropical Pacific’s zonal temperature gradient, weaken the HIgh pressure in the eastern Pacific thus allowing a more zonal flow of westerly winds and moisture.

  30. Salvatore,
    I greatly appreciate your questions and keeping the discussion alive. I need to step out but will reply when I return. For now regards your first question the cooling of the Arctic’s 700 meters is from Heimbach and Wunsch 2014. Their paper did not focus on the Arctic but provided their analyses of changes in global ocean heat at various depths. Wunsch’s attention to detail and careful identification of uncertainties, in my eyes makes him more trustworthy than most. In Wunsch and Heimbach (2014) the humbly admit that their “results differ in detail and in numerical values from other estimates, but the determining whether any are “correct” is probably not possible with the existing data sets.”

  31. Jim my question is how does this train of thought get promoted? This is where it is at and it is so OBVIOUSLY sensible.
    This combined with Milankovitch Cycles, Solar Variability ,Geo Magnetic Strength for the big picture etc is by far and away the best explanation for why/how the climate changes!

    • Well I started promoting the idea here at WUWT. I believe many eyes that visit this website are better than a few pal reviewers. I hope Judith Curry might give it some play. I tweeted her and she is swamped but she said she will try to post a comment on the Arctic Iris Effect. Based on peer reviewed papers from which evidence for this essay was gleaned, I also suspect there is a growing appreciation for the iris dynamics even though it has yet to be “officially” dubbed the Arctic Iris Effect. John Muir published in the popular press initially greeted with much push back but as academics began to embrace the validity of his observations, his ideas became a focus of discussion, despite being labeled by Whitney as just an “ignorant shepherd”. If this train of thought adequately synthesizes most observations, it will get promoted as well.

      • What is so good about this Arctic Iris Effect is it gets away from the rigid 1470 year climate cycle, it gets away from the fresh water rapid release scenario and slowing down of the AMOC ,it shows how a cycle leading to an abrupt climate change can take place and start the process over again, and it explains why the abrupt climate changes during an inter- glacial may not be as great in degree of magnitude as during a glacial.

  32. Jim says below which is correct. The 1470 year cyclic or semi cyclic climate oscillation never really held up and I thought was pretty much wrong.
    Javier, Rhamstorf is wrong. There is no precise clock for D-O events. Their recurrence happened from 8 to 1.5 thousand years. Rhamstorf is also wrong about ocean conveyor belts and changes in the AMOC. While scientists have been increasingly abandinging the conveyor belt idea, Rhamstorf continues to defend it because his decades of publications are based on assuming the conveyor belt is a reality.
    That said there are rather good clocks found in nature. Most extratropical plants can determine change in seasons. The biological clocks are determined by the amount of time required to build or degrade a certain concentration of chemicals. Similarly the Arctic subsurface can have a “clock” determined by the build up of subsurface heat and its ability to contribute to basal melting.
    My queston to you is How would you determine oscillation determined by astronomical forcings versus oscillations due to internal variability?

  33. The only way to get the 1470 cyclic cycle would be if the sun had a 1500 year cycle, or
    the superposition of the DE VRIES – SUESS 210 year solar cycle, and the Gleissberg 87 year old solar cycle creates a solar variability every 1470 years, that impacts the fresh water concentrations put into the North Atlantic, which in turn either weakens or strengthens the Thermohaline Circulation.
    This at one time I thought had a possibility but just that a possibility which I tried to reconcile to some degree.

  34. RIGOR – info. last paragraph is in conflict with findings of first two paragraphs on AO phase /sea level pressure relationship in Arctic which I think is correct.
    According to RIGOR as the AO went from a negative phase toward a more positive phase from 1979-1998 mean sea level pressure over the central Arctic Ocean drops which I think is opposite of what should happen when the AO is becoming more positive and supported by the paragraph just below which was from the Dec. 2009 Arctic Sea Ice report.
    These regional contrasts in temperature anomalies resulted from a strongly negative phase of the Arctic Oscillation (AO). The AO is a natural pattern of climate variability. It consists of opposing patterns of atmospheric pressure between the polar regions and middle latitudes. The positive phase of the AO exists when pressures are lower than normal over the Arctic, and higher than normal in middle latitude. In the negative phase, the opposite is true; pressures are higher than normal over the Arctic and lower than normal in middle latitudes. The negative and positive phases of the AO set up opposing temperature patterns. With the AO in its negative phase this season, the Arctic is warmer than average, while parts of the middle latitudes are colder than normal. .
    The phase of the AO is described in terms of an index value. In December 2009 the AO index value was -3.41, the most negative value since at least 1950, according to data from the NOAA Climate Prediction Center.
    The phase of the AO also affects patterns of precipitation, especially over Europe.Data collected by the International Arctic Buoy Programme from 1979 to 1998 are analyzed to obtain statistics of sea level pressure (SLP) and sea ice motion (SIM). The annual and seasonal mean fields agree with those obtained in previous studies of Arctic climatology. The data show a 3-hPa decrease in decadal mean SLP over the central Arctic Ocean between 1979–88 and 1989–98. This decrease in SLP drives a cyclonic trend in SIM, which resembles the structure of the Arctic Oscillation (AO).

  35. . The data show a 3-hPa decrease in decadal mean SLP over the central Arctic Ocean between 1979–88 and 1989–98. This decrease in SLP drives a cyclonic trend in SIM, which resembles the structure of the Arctic Oscillation (AO)
    Now to think about it he may be correct neg. AO 1979-1988 then more positive 1989-1998, pressure becomes lower.
    -ao equates to high slp and vice versa.
    I just wasted my time.

    • No you didn’t. You cleared up your own misunderstanding. Give yourself a pat on the back for digging deeper until you gained clarity. Most people do not.

    • Hey, Salvatore, you had me worried for a moment there.
      Positive AO involves a tall polar vortex with a small surface footprint and the climate zones shift poleward. Low SLP at the poles. Less clouds globally for more solar energy penetrating the oceans.
      Negative AO involves a less tall, flabby, polar vortex with a larger surface footprint and the climate zones are pushed equatorward. High SLP. at the poles. More clouds globally for less solar energy penetrating the oceans.
      The thing is that the polar vortices are unlike surface pressure cells. They involve columns of descending air in the mesosphere and stratosphere (not the troposphere) and are caused by the Earth’s rotation rather than surface pressure differentials.
      When the sun is quiet, more ozone is created higher up which warms the stratosphere and pushes the tropopause down which causes higher pressure in the troposphere and at the surface. Negative AO.
      When the sun is active less ozone is created higher up which cools the stratosphere and allows the tropopause to rise which causes lower pressure in the tropopause and at the surface. Positive AO.
      The thing is that that is precisely the opposite of standard climatology which focuses on ozone changes above the equator and at lower levels which are of opposite sign as regards the ozone creation / destruction process.
      In order to achieve the right sign of ozone changes and latitudinal climate zone shifting in conjunction with solar variability to explain the MWP, LIA and late 20th century observations of stratospheric ozone decline at the poles one needs the reverse sign ozone response that I have been putting forward since 2010.
      An Arctic Iris Effect fits in neatly and potentially resolves the nonsense of the AGW theory whereby albedo variations from changes in ice area somehow outweight the ability of open water to release more heat to cold air. That concept always struck me as daft because, being bald, I know just how fast one’s entire body can cool when going out in the cold without a hat 🙂

      • Stephen I read your links and will need to do so again to make sure I understand them correctly. As you have noted I have been lookiing at natural climate change from primarily a bottom up perspective while believing small changes in insolation (orbital or irradiance and resulting cloud cover change). So your perspective holds great interest as complimenting my perspective. But I have a fee questions.
        1) I was not aware of the different solar impacts on equatorial and polar ozone. I always thought stronger sun causes more ozone creation. Is the difference that there is greater destruction at the poles? Are there other published papers.
        2) I am a little dubious about attributing changes in a wavy jet stream simply to changes in the polar vortex but do not dismiss its contribution. Looking from the bottom up I first see a wavy jet stream as a predisposition due to the Rocky Mountains. Second the quasi permanent HIgh Pressure system in the northeastern Pacific also exerts a powerful influence. And third La Nina years would strengthen that High causing greater waviness while El Nino years would diminish the HIgh allowing for more zonal flow. I see those dynamics as more powerful determinants of the jet stream path, yet I still allow for the polar vortex influence of which I admittedly have only a marginal understanding.
        I appreciate your comments

      • Hi Jim,
        1) Conventional climatology does indeed suggest that a more active sun creates more ozone above equatorial regions which forces the equatorial tropopause down to create more zonal poleward jets and decrease cloudiness thereby allowing more sunlight into the oceans for a warming climate system. The problem with that is that when the sun was more active during the late 20th century warming spell stratospheric ozone actually declined which is why CFCs were blamed for the reducing ozone above the poles.
        I noted that if ozone declined above the poles when the sun was more active then it was more likely that the tropopause was being pulled up at the poles rather than being pushed down above the equator and that since that was happening at a time of more active sun there was something wrong with the conventional viewpoint. I formed that opinion around 2008.
        Then in 2010 I saw this:
        http://www.nature.com/nature/journal/v467/n7316/full/nature09426.html
        ” Here we show that these spectral changes appear to have led to a significant decline from 2004 to 2007 in stratospheric ozone below an altitude of 45 km, with an increase above this altitude”.
        Hence my hypothesis which I have already linked you to.
        2) The Rocky Mountains certainly contribute to the waviness of the northern hemisphere jets but I am more interested in the changes in the degree of waviness over time which are mirrored although to a lesser extent in the southern hemisphere.
        I’m not sure that we are in disagreement over the effect of changes in the high pressure cell over the north eastern Pacific. Presumably, like the Azores high pressure cell in the Atlantic it would respond to the net interaction between the top down solar influence and the bottom up oceanic influence. La Nina years would be associated with more jet stream waviness because the cooler equatorial oceans would allow greater incursions of polar air towards the equator and El Nino years would push equatorial air more poleward and reduce polar incursions towards the equator which would manifest in a more zonal poleward flow.
        I think point 1 above is the more fundamental issue.
        The reduction of ozone above 45km and especially towards the poles via a change in the level of solar activity is the feature required to account for both observations of reducing stratospheric temperatures at a time of active sun AND poleward migration of climate zones at a time of active sun.
        If conventional climatology were correct then we would have seen an INCREASE in stratospheric ozone when the sun was more active.
        That is pretty much the peg upon which my hypothesis hangs so unless there is recent data contradicting the findings reported by Jo Haigh from 2004 to 2007 then I may well be correct. I doubt that such contradictory data exists since it is becoming accepted that stratospheric cooling has ceased and there has recently been some stratospheric warming. That would be impossible at a time of less active sun under the conventional climatology.
        Your Arctic Iris Effect remains intact under my hypothesis and for the reason stated previously in this thread I agree with it. Heat loss from open water is bound to be far more influential than any decline of albedo allowing more solar absorption at such high latitudes, contrary to AGW theory.
        You have made a very good point which could well account for another layer of variability within the hypothesis which I have presented.

      • Salvatore,
        We’ve all done it 🙂
        The great thing about these blogs is that those of us who are honest and unbiased seekers of truth leave an uncensored and unalterable trail of our thought processes.

  36. Thanks Jim. I am going to try to push this Arctic Iris Effect as much as possible each time the subject of abrupt climate change comes up.
    In-fact I just sent this Arctic Iris Effect theory to the article that just came out on WUWT in regards to an ancient cold period.

  37. Parting thoughts (I have to move on)
    In reading the various comments, it’s obvious how important the absence of a lag effect is, but a number of the comments continue to ignore it. The point I’m trying to make is that if conditions in the Arctic trigger global climate effects (including the Iris Effect), then there has to be a 200-1000 lag before it is felt in the S Hemisphere. The oceans provide the link for heat transfer between hemispheres and the Broeker conveyor belt system is the delivery system. That transfer takes 200-1000 years. So since climate changes in both hemispheres are synchronous, the Iris System can’t explain D/O events.

    • Don you have lost me here. In earlier post you said Broecker’s converyor belt doesnt work to which I agree, But here to seem to advocate for the conveyor belt, and a lag period but then argue for synchronous behavior. Yet you havent provided a link or reference to evidence that documents the synchronous behavior.

      • Jim–
        No, I’m not advocating the conveyor belt to explain D/O events–what I said was that you need a mechanism to transfer climate changes that originate in the Arctic to the S. Hemisphere. That requires oceanic transfer and that requires a time lag. I’ve published a bunch of papers on the synchronous moraines in both hemispheres as has George Denton’s group (U. Maine).

      • Don, I am still confused about the basis of your disagreement. Like your observations of synchronous glacier retreats, the Arctic Iris effect alos refutes the ocean conveyor belt and does not dispute synchronous behavior of glacier retreats. I am not arguing that changes originate in the Arctic. Due to the high correlations with solar proxies, I suspect climate change originates in the tropics where changes in insolation will have the greatest impact and results in changes in poleward heat transport that will be experienced in both hemispheres. All the Arctic Iris effect suggests is that synchronous warming via heat transport will be experienced with a lag. Antarctica’s annual sea ice will respond quickly but subtly, while depending on the thickness of Arctic sea ice, the Arctic will lag before transported ocean heat is ventilated.
        The Arctic Iris Effect disputes the lag effect suggested by the recent WAIS paper that suggests warming in Antarctic lags the Arctic by 200 years. It suggests that warming is more synchronous but WAIS’ observed differences are due to a lag in ventilation caused by differences in sea ice thickness. No conveyor belt explanation is required.
        http://www.nature.com/nature/journal/v520/n7549/images/520630a-f1.jpg
        I suspect changes in sea ice caused by changes in ocean heat transport will be synchronous with glacier retreats +/- a few hundred years. Svalgaard’s new sunspot series show a peak in solar activity in the 1700s and 1800s. Likewise Vinje reports the oceans begin to warm in the mid 1800s and alludes to a sea ice minimum in the mids 1700s. The early retreat of glaciers in Glacier Bay Alaska noticed by MUir in the late 1800s. is synchronous with warming beneath the sea ice in the Nordic Seas, but it predates many reports of retreating non-tidewater glaciers. That’s why I ask about what papers you are referring to regards synchronous behavior.

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