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).
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.
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.
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.”
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.
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
AMO cycle fully confirms this theory. Changes in temperature can be clearly noted.
http://woodfortrees.org/graph/esrl-amo
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?
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.
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?
You might have read the entire post before commenting.
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.
this was directed at wicked above.
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.
Wonderful article.
Yes, and I especially like the mentioned phrase ‘natural climate change’.
Excellent article.
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/
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.
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.
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.
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.
No. It has allready been settled. 😉
Thanks Mark
Nit pick: The west coast of Asia is Europe.
West Pacific, East Coast of Asia. 🙂
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.
Thanks Jim Steele for this well-written article. The subject is timely, since this year the ocean is winning in its contest with the Arctic ice. Due to a recent major storm event, ice extent is down and water extents are up, well ahead of last year’s season. It looks like the next ice age has been postponed this year.
https://rclutz.wordpress.com/2015/08/31/arctic-storm-postpones-ice-age/
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.
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
Dr. Brown
You were correct that 60 year periodicity could be the spectral analysis end effect
(see more here: http://wattsupwiththat.com/2015/08/28/how-fast-is-the-earth-warming/#comment-2018349 )
Vukcevic
Palaeo data show the PDO/AMO periodicity meanders significantly away from 60 years in past centuries-millenia. If there is astrophysical forcing i.e. like Milankovich but on shorter time scales, then it is likely weak (chaotic), not strong.
RGB
This video shows some nice dissipative self-organisation:
http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3827
I very much welcome bringing Prigogine into the discussion. About the Pacific hot spot – I believe Joe Bastardi mentioned that the same thing happened in the 50’s, prior to a period of cooling.
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.
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
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.
Broecker’s man-made global warming concept also doesn’t work.
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
http://www.americanscientist.org/issues/id.999,y.0,no.,content.true,page.1,css.print/issue.aspx
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/
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
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.
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.
Javier, Jim
The ~1500 year periodicity spectral line must be treated with caution:
http://onlinelibrary.wiley.com/doi/10.1029/1999PA000468/pdf
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.
1999? I read the Gulf Stream myths long before then.
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.
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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.
kwintercorn said:
“To my eye this reveals a system that is dominated by buffers (eg. ocean heat sink) and negative feedbacks (eg cloud cover). ”
Correct.
You may be interested in this:
http://hockeyschtick.blogspot.co.uk/2015/07/erasing-agw-how-convection-responds-to.html
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.
Very important is the strength of the wind, which comes from the state of the polar vortex.
Yes.
That is why the top down solar effect is important:
The state of the polar vortices appears to vary with solar activity, presumably due to wavelength and particle changes rather than variations in Total Solar Irradiance (TSI):
http://joannenova.com.au/2015/01/is-the-sun-driving-ozone-and-changing-the-climate/
An active sun appears to produce a tighter polar vortex, a smaller surface ‘footprint’ and zonal, poleward jet streams whereas low solar activity produces a flabby polar vortex with a larger surface ‘footprint’ and meridional, equatorward jet streams.
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.
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.
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.
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!
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
I appreciate your correction.
Thanks. I am so use to reading articles that I disagree with. This one was refreshing.
Salvatore
I’ve always been skeptical of fresh meltwater having global oceanographic effects, Jim’s article adds substance to this. We may think of ocean currents as being smooth and monolithic but the reality as shown in this video:
http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3827
is much more complex, chaotic-fractal like.
Fresh water is not going to stay fresh long in the ocean – it’s vigorously mixed.
There is much more salty sea water than fresh ice in the world.
Good article. “Iris effect” is that consciously named for the light absorbing mechanism in the eye?
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.
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.
I believe these are what you are looking for. In my opinion, they illustrate Le Chatelier’s principle as applied to climate.
http://wattsupwiththat.com/2013/02/08/slow-drift-in-thermoregulated-emergent-systems/
http://wattsupwiththat.com/2013/02/07/emergent-climate-phenomena/
Thanks Werner
Jim
He did a series of them this was the only one i found for now.
http://wattsupwiththat.com/2015/08/18/cooling-and-warming-clouds-and-thunderstorms/
Thanks Bob
J.Steele
You are welcome, there at least 3 or 4 other posts around this that Willis has done and they are all interesting and build on each other. I have toyed with all of these ideas in the past but not with the discipline that you and Willis both have, but my basic view has always been that the earth has very strong negative feedbacks to any significant warming event and the only thing that could through the climate dramatically out of whack would be a significant change in solar input. Short term fluctuations ( less then 1000 years) are dominated by the warming and cooling of the oceans with the upper limit being controlled by the mechanism that your are discussing here. The fun part would be to think about what would happen if both poles where cover by a large land mass.