What does varve analysis dating mean
Nature Unbound V – The elusive 1500-year Holocene cycle
The existence of a 1500-year climatic cycle during the Holocene, related to the glacial Dansgaard-Oeschger cycle, is a matter of intense debate. However, by introducing precise timing requirements it can be shown that the 1500-year cycle displayed in Northern Hemisphere glacial records is also observed in Holocene records from all over the world.
The cycle is most prominently displayed in oceanic subsurface water temperatures, Arctic atmospheric circulation, wind deposits, Arctic drift ice, and storminess records. A lunisolar tidal hypothesis is uniquely capable of explaining the cycle’s timing, features, and effects. The hypothesis allows for the observed power in the 750-year harmonic, apparent lack of temperature signal in the cycle, and a phase shift during the Holocene Climatic Optimum observed in some proxies. While the Holocene 1500-year cycle is associated with cooling indicators in the Northern Hemisphere, its effect on global temperatures is undetermined. The next peak effect of the 1500-year cycle is expected in about 160 years.
Continuing the series of articles about abrupt climate change that started with the glacial-interglacial cycle, and the Dansgaard-Oeschger cycle, and followed with the nature of Holocene climate variability (Part A, and Part B), I last reviewed the
2400-year Bray climate cycle (Part A), and its solar origin (Part B and Part C). In this article, I hunt through the literature for solid evidence on “The enigmatic 1,500-year cycle,” in the words of Raimund Muscheler (2012), and “one of the outstanding puzzles of climate variability,” according to Maxime Debret and colleagues. (2007).
The discovery of the 1500-year glacial Dansgaard-Oechsger cycle (DO) in Greenland ice cores, started a quest to identify this cycle in Holocene records, where its absence was puzzling. In 1995 Gerard Bond and Rusty Lotti demonstrated in deep sea cores that glacial-time DO events matched periods of increased iceberg activity and that they were linked to Heinrich events (periods of very high iceberg activity in the N. Atlantic). The records showed 3-4 DO periods taking place between Heinrich events. This oceanic sedimentary pattern from the glacial period became known as the “Bond cycle.” Since 1996 researchers started to report a 1500-year periodicity in Holocene proxies, and it became Bond’s goal to extend his cycle to the Holocene. He claimed to have achieved that in 2001 when he reported his famous drift-ice petrological record that revealed a series of cold events in the Holocene (Bond et al., 2001; figure 48). Bond’s report sparked a paradigm shift because at the time the Holocene was generally viewed as climatically stable, despite contrary evidence from glacier studies. We have seen that Bond was wrong (figure 48), and his misleading numbering of the cold events to try to fit them into a 1500-year series has caused unnecessary confusion in the field. Researchers all over the world have tried to match negative temperature anomalies and even precipitation fluctuations in their proxy records to Bond events, perpetuating the myth. As the evidence is contradictory among reports, the existence of a 1500-yr cycle in the Holocene has become more contentious with time. After an extensive research Wanner et al. (2011) concluded that “multicentury cold events were not strictly regular or cyclic, and one single process cannot explain their complex spatiotemporal pattern.”
Could Bond be wrong, Wanner be right, and still there be a manifestation of the 1500-yr DO cycle in the Holocene? That is what the evidence supports, and the nature of the evidence points once more to the process that is the likely cause of this climatic cycle.
Over the last decade we have greatly increased our knowledge of the DO cycle. We know that DO events are abrupt warming events, that take place at the North Atlantic-Nordic seas area. They appear to take place when the water stratification is abruptly disturbed, allowing a surge of warm subsurface waters that have accumulated for long periods of time, to melt surface ice and release heat to the atmosphere (figure 29). They require high ice conditions and low sea level, between 45 and 90 m below the present level (figure 25). Their trigger is very precise, taking place every
1500 years (figure 18) and maintaining this precise pacing through periods when the conditions are not met and the events do not take place, sometimes for over 10,000 years. That new events after such long attenuation periods still occur at the specified timing, without significant drift, strongly supports the existence of an external pacing control mechanism for DO events. The precision of this mechanism over time suggests an astronomical control. Wolfgang Berger and Ulrich von Rad (2002) proposed that the 1500-year cycle is a harmonic of the beat between the moon’s nodal and apsidal precessions, a hypothesis that fits not only the observed period, but also the required mechanism for vertical water mixing through tidal forcing.
As described, DO events cannot take place during the Holocene. It is too warm, there is too little ice, and sea level is too high. New DO events will have to wait until the next glacial period. However, the trigger clock is ticking all the time to keep its pace, and it is fair to ask if it might have other effects that could cause a 1500-year climate cycle during the Holocene.
We already know some characteristics that the 1500-year cycle should present: It should take place when the trigger indicates, and thus in phase with the DO cycle; its manifestation should be compatible with a mechanism that promotes vertical water mixing (mainly wind and tidal forces); and it might not be due to internal variability of the climate. Given that the warming nature of the DO events relies on the presence of abundant warm subsurface waters in a specific region, the 1500-year Holocene cycle doesn’t have to be a warming cycle. In fact, if the trigger promotes vertical water mixing, in most places this would mean sea surface cooling.
To my knowledge no author has set any requirements on the 1500-year cycle, except the periodicity, and since almost every proxy presents some periodicity, often for no reason, several of the reported 1500-year proxy periodicities might not correspond to the cycle that caused DO events during glacial periods.
The next question is where to look for the 1500-year cycle. As Bond identified the DO cycle in North Atlantic sediments, he set out to identify the 1500-year Holocene cycle there too. However, as we saw with the
2400-year Bray cycle, the North Atlantic is especially sensitive to solar activity decreases (see figure 67), and therefore, most Bond events represent solar-induced cooling events. Some of the peaks in the Bond series cannot be assigned to solar activity and could represent cooling from the 1500-year cycle. In fact, it has been shown that during the Neoglacial the Bond series can be better fitted to a 1500-year periodicity (Debret et al., 2007; figure 48). However, given the strength of the solar variability signal in the North Atlantic, proxy records from that area usually present mixed periodicities more difficult to interpret. This has created another problem, as most authors have looked for the cycle in the North Atlantic area, following Bond’s steps. The result has been more confusion in the scientific literature and some claims that the 1500-year cycle was perhaps of solar origin.
Before reviewing the evidence for the 1500-year cycle let’s see where the DO cycle stands at the start of the Holocene. According to Rahmstorf (2003) the abrupt warming changes that started the Bolling period and the Holocene correspond to DO events 1 and 0 respectively, and they are separated by 3000 years (figure 69). He also places another event in the middle (DO-A) as possibly responsible for the warming after the Intra-Allerod cold period.
Figure 69. The Dansgaard-Oechsger cycle at the end of the last glacial period. Temperature curve derived from GISP2 ice core. DO events are indicated with continuous grey lines. Dashed and dotted grey lines represent harmonics of the DO cycle. Cold periods are indicated above the curve, and warm periods below. IACP: Intra-Allerod cold period. Sources: S. Rahmstorf 2003. Geo. Res. Let. 30, 10. R.B. Alley 2000. Quat. Sci. Rev. 19, 213-226.
To check the time relationship between proxy records and the DO clock, I have projected the DO periodicity observed in the 15,000-11,000 year BP interval to the rest of the Holocene.
For the last 20 years researchers have been reporting a
1500-year periodicity in Holocene climate proxies. In 2007 Maxime Debret et al., carried out a wavelet analysis of some of these proxy records. The wavelet technique allows to determine two-dimensionally not only the periodicities present in the record, but also the times at which those periodicities are found. The results from their analysis are shown in figure 70.
Figure 70. Wavelet analysis of climate proxies over the Holocene period. Occurrence of the periods with respect to the time is given by the bright yellow-red colors. Black boxes indicate the position of the
1500-year periodicity. a) Percentage of ice-rafted detrital petrology in marine sediments. b) Sediment grain size as a proxy for ocean current intensity. c) Emiliania Huxleyi concentration, a proxy of surface hydrology. d) Sodium flux in GISP2 ice core, a proxy for atmospheric circulation. e) Magnetic susceptibility from loess aeolian deposits, a proxy for wind activity. f) Marine ice core sediment lightness (color) as a proxy for changes in North Atlantic deep-water circulation. The spread in the
1500-year period can be due to differences in the age model for each proxy. Source: M. Debret et al., 2007. Clim. Past, 3, 569–575.
The authors conclude from the wavelet analysis that the Holocene millennial variability is composed of three main periodicities, 1000, 1500, and 2500-year cycles. Based on the coincidence of the 1000 and 2500-year cycles with the wavelet analysis profile of 14 C production rates they defend their solar origin. They assign an oceanic origin for the 1500-year periodicity because it is absent from the solar proxy and present in oceanic proxies. The wavelet analysis also shows that in some of the proxies the 1500-year cycle is not continuous through the Holocene, being absent or very attenuated during the early Holocene (figure 70, a, b, d, e), while in other, perhaps more sensitive, records the 1500-year periodic signal appears a few thousand years earlier (figure 70, c, f). It is possible that some of the climatic manifestations of the 1500-year cycle might have been masked by the conditions of the Holocene Climatic Optimum while becoming easier to detect during the Neoglacial.
Among the possible explanations for the 1500-year cycle proposed by different authors, most appear to attribute it to an oceanic oscillation, whether externally forced or due to internal variability. However most oceanic proxies that contain a 1500-year frequency signal display a very complex pattern, indicating that the proxy is affected by other climate cycles and changes, and precluding a clear identification of the 1500-year cycle.
Sea-surface temperature (SST), is affected by changes in wind patterns, wind strength, insolation, cloud cover, pressure, and precipitation patterns, among other factors. Thus, most SST proxy records, especially those from the North Atlantic, do not display a recognizable 1500-year cycle. One exception is the northwestern Pacific SST alkenone-based proxy record from the coast off Japan reported by Isono et al. (2009; figure 71 a). Although the temperature reconstruction does present a 1500-year periodicity that matches the DO pattern, the match is not very good and presents a clear 180° phase shift at 7 kyr BP (figure 71 a, black bar), when higher temperatures went from taking place at mid-cycle before the shift, to lower temperatures taking place at mid-cycle afterwards.
The effect of the DO cycle on thermocline water temperatures was already reviewed in the DO cycle article (see figure 29; Dokken et al., 2013), and was one of the arguments used to support its possible tidal nature. It is therefore very interesting that the Holocene 1500-year cycle displays the same manifestation, not only in the Northwest Pacific, but also in the Southern Ocean. Moros et al. (2009) determined thermocline water temperature changes during the Holocene at Murray Canyon (Great Australian Bight) using the oxygen isotopic signature of another thermocline foram, Globigerina bulloides. Interestingly the record not only displays a clear 1500-year periodicity in phase with the DO cycle (figure 71 d), but it also has a characteristic saw-tooth aspect quite similar to the reported proxy record from the last glacial period in the Norwegian Sea (figure 29). And again, we find a period between 9-8,000 years BP when the record displays a 180° phase shift (figure 71 d, black bar).
Although these oceanic proxy records are all very consistent in displaying an in-phase 1500-year periodicity, they don’t give a consistent temperature signal. The NW Pacific SST proxy and the Kuroshio Current subsurface temperature proxy display a warming signal at the specified DO periodicity, while the Southern Ocean proxy displays the opposite signal. The warming nature of the glacial DO cycle appears to respond to the specific conditions of warm water accumulation below a fresh cold thermocline layer in the Nordic Seas and is not intrinsic to the cycle nature. At the position where the SST were determined by Isono et al. (2009; figure 71 a) the warm Kuroshio Current and the cold Oyashio Current mix, while the Great Australian Bight record site is close to the present northern limit of sub-Antarctic water. Therefore, the temperature response to the 1500-year pacing might be determined by regional or hemispheric climatic conditions and thus the cycle does not appear to convey a temperature signal by itself.
In 1997 Paul Mayewski and colleagues reported that the chemical ions found in GISP2 ice core presented a 1450-year periodicity during the last glacial period, that extended into the Holocene. The chemical species that precipitate on polar snow are introduced into the atmosphere by sea salt aerosols and continental dust, and their abundance depends on atmospheric conditions. Using the relative abundance of these chemical tracers, Mayewski et al. (1997) reconstructed a Polar Circulation Index (PCI) that provides a relative measure of the average size and intensity of polar atmospheric circulation. In general terms, PCI values increase (e.g., more continental dusts and marine contributions) during colder portions of the record (stadials) and decrease during warmer periods (interstadials and interglacials). Although the amplitude of the PCI changes decreases markedly during the Holocene, due to its much tamer climate variability, the 1450-year cycle persists in the record. This indicates that the nature of the periodicity is the same, and that the increase in PCI that accompanies the cycle is associated with more active atmospheric circulation, due to colder winter conditions. A periodogram for the last 11,500 years shows that not only the 1450-year peak is significant at the >99% level, but also the 725 and 2900-year harmonics, and that neither of these peaks can be assigned to 14 C production variability indicative of a solar origin (Mayewski et al., 1997; figure 72).
Figure 72. Power spectra for the Polar Circulation Index during the Holocene. PCI series covering the last 11,500 years (continuous line) and the 14 C residual series (dashed line) for the same period. Spectral peaks above the respective horizontal lines are significant at the >99% significance level. Source: P.A. Mayewski et al. 1997. J. Geophys. Res. 102, 26345-26366.
Another atmospheric-link proxy record that displays a very clear, in phase, 1500-year periodicity comes from the Arabian Sea, where dust from the Arabian desert containing rare-earth elements is deposited after being transported by northwesterlies (Sirocko et al., 1996). Determination of the variability of a group of these rare-earth elements in a marine core efficiently removes analytical errors for each of them, and the resulting REE-score shows a very significant 1500-year periodicity that is in phase with the DO cycle (figure 73 a). In addition, this proxy record displays a 1500-year cycle continuously for the past 19,000 years (only 11,700 shown in figure 73 a) supporting that the pacing mechanism is always ticking and not affected by the drastic climatic changes that took place between 19-11 kyr ago. Furthermore, for the first 10,000 years (19-9 kyr BP) the increase in dust took place at mid-cycle, while for the last 8,000 years the mid-cycle showed a decrease in dust. Between 9 and 8 kyr BP the cycle displayed a 180° phase shift (figure 73 a, black bar) as in previous cases. This phase shift is probably affecting the cycle periodicity determination, reported as 1450-year (Sirocko et al., 1996). When plotted, the oscillations are clearly 1500-year long on both sides of the shift, but the introduction of a half length oscillation, to produce the 180° phase shift, changes the average to
Figure 73. Atmospheric proxies for the 1500-year cycle. a) Changes in Arabian dust rare-earth elements abundance in an Arabian Sea sediment core. Black bar: Period with an apparent 180° phase shift in data periodicity. Source: F. Sirocko et al. 1996. Science 272, 526-529. b) Isothermal Remanent Magnetization as a moisture proxy in two lake cores (WL 03-1 continuous, WL 03-2 dotted) from White Lake, New Jersey, USA. Source: Y-X. Li et al. 2007. The Holocene 17, 3-8. Purple bar: Position of the 4.2 kyr arid event.
The cyclic increase in Arabian rare-earth element containing dust probably reflects an increase in northwesterlies strength, although a cyclic increase in aridity reflected in a higher dust production cannot be ruled out. In fact, evidence of the association between the 1500-year cycle and precipitation has been found in the Mid-Atlantic region of the US, where two lake sediment cores show that periods of low lake levels took place at a 1500-year periodicity (Li et al., 2007; figure 73 b). Exposure of marls due to low lake levels led to their oxidization and magnetic intensity increase, followed by their transport and re-sedimentation. Despite the age-depth model imprecision of this proxy and both cores showing different peaks, the coincidence of the peaks with the DO periodicity appears clearly within dating error. The question of the possible 1500-yr cycle association with a precipitation cycle in certain regions is an interesting one that deserves more research, as we approach a new cycle peak (
2180 AD) and precipitation is so critical to our society.
At about 4,200 yr BP an abrupt climate change took place that had a strong aridity effect at middle and low latitudes in Africa, the Middle East and southern Asia. The intense drought reduced precipitation by about 30% for about 100-200 years likely causing the end of the Egyptian Old Kingdom, the collapse of the Akkadian Empire in Mesopotamia, and initiated the dispersion of the urban Harrapan civilization in the Indus Valley. The 4.2 kyr event is also seen throughout the Northern hemisphere but in a more complex and irregular manner, unlike most Holocene cold events. Although intense cooling is detected in Iceland lake sediments at 4.2 kyr BP (Geirsdottir et al., 2013), it is brief and completely reversed in about 100 years. Glacier advances are also recorded at the time in Central Asia, the Southern Hemisphere and North America (Mayewski et al., 2004). Interestingly, the 4.2 kyr event is also seen in the GISP2 Greenland ice core. It shows as a significant drop in chlorides (sea salt) concentration (a sea ice proxy; Mayewski et al., 2002), unlike most cold events of the Holocene, suggesting that the cold might have been accompanied by reduced precipitation.
Proxies indicate that the 4.2 kyr event is centered in the Arabian sea region, affecting the East African and Asian monsoons, the Mediterranean and Southern Europe, with a smaller effect on the North Atlantic region and South America, while the cooling appears global. A Kilimanjaro (East Africa) ice core presents a 200-fold increase in dust particles at the time (Thompson et al., 2002; figure 74 a), while a marine sediment core in the Gulf of Oman presents a 10-fold increase in wind transported dolomite from the Mesopotamian region (Cullen et al., 2000; figure 74 b).
Figure 74. The 4.2 kyr event. a) 50-year average of the Holocene dust history from Kilimanjaro ice core NIF3. Dust concentration measured as 0.63-16.0 µm diameter particles per ml sample. Source: L.G. Thompson et al. 2002. Science 298, 589-593. b) Gulf of Oman core M5-422 changes in dolomite which reflect eolian mineral supply from Mesopotamian sources. Source: H.M. Cullen et al. 2000. Geology 28, 379-382. c) Deuterium changes in sedimentary plant leaf wax ?Dwax measured as ‰ vs. Vienna standard, as a proxy for East African monsoon strength at Lake Challa (Kenya). Source: J.E. Tierney et al. 2011. Quat. Sci. Rev. 30, 798-807.
Tierney at al. (2011) analyzed in detail the hydrology of Lake Challa, close to Kilimanjaro. One of the proxies they used was the proportion of deuterium in lake sediment plant leaf waxes, interpreted as a proxy for the strength of the East African monsoon. While other proxies indicate Lake Challa did not have low lake levels at the time, ?Dwax indicates the monsoon decoupled at the time from the total rainfall amount in the local basin. The East African monsoon showed at the time its weakest values in the entire Holocene (Tierney et al., 2011; figure 74 c). The 4.2 kyr event coincides also with a period of great weakness of the Asian monsoon (figure 54 f). The general monsoonal weakness during the 4.2 kyr event must have contributed to its unusual aridity.
We must conclude that the 4.2 kyr event is a uniquely abrupt regional arid event that also caused global cooling. The proxies that show it best do not display a clear periodicity (figure 74), indicating that Holocene climate cycles were not the cause. The very strong monsoon weakening and severe aridification are different to the rest of Holocene cooling events and underscore a primary atmospheric manifestation. Its cause is a complete mystery. Most authors talk about shifts and thresholds in oceanic/atmospheric systems. No big volcanic eruption or asteroid impact capable of such global effect has been convincingly linked to the event, although the abruptness, nature and development of the arid-cold event is compatible with a big tropical volcanic eruption or asteroid impact. Since 1998 soil scientist Marie-Agnes Courty has been defending that soil micro-fabrics bear the signature of a cosmic impact at the time (Courty et al., 2008). However, the lack of more substantive evidence, like iridium, nickel or platinum spikes, or a well-dated crater, has made her research largely ignored.
Whatever its cause, the 4.2 kyr event had a brutal impact on human societies, wiping out the most advanced civilizations at the time and changing the course of history. The world is now 100 times more populated and, despite civilization advances, no less vulnerable to the effects of the changes described. The success of the Akkadian empire was partly due to the sophisticated measures (at the time) they implemented to cope with recurrent droughts in the region. They were just unprepared for the unimaginable scale of what came their way.
The proposed lunisolar tidal basis for the 1500-year cycle has an outstanding prediction. One of the most salient effects of high tides is that they multiply the water rise due to storms (storm surge). Hurricane Sandy in New York City, 2012, had a storm surge of 4.2 m (14 ft) due to high tides at the time. By analyzing past storminess records we should be able to detect the effect of the 1500-year cycle if indeed it is a tidal cycle. The difficulty is that storms have a random nature and it is necessary to combine multiple records from different locations. Sorrel et al. (2012) analyzed high-energy estuarine and coastal sedimentary records from the macrotidal Seine Estuary and Mont-Saint-Michel Bay in the southern coast of the English Channel and defined five Holocene storm periods that also reflected periods of high storm activity at other northern European locations (Sorrel et al., 2012; figure 75 a). According to the authors, these periods of high storm activity occurred periodically with a frequency of about 1,500 years, closely related to cold and windy periods identified by Bond et al. (2001), and Wanner et al. (2011).
The tidal hypothesis for the 1500-year cycle is strengthened by the storminess evidence. As expected, the cycle displays a clear association with storminess intensity. In the tidal hypothesis, as proposed by Berger and von Rad (2002), the 1500-year periodicity is a harmonic of the beat between the moon’s nodal and apsidal precession. This configuration allows the manifestation of power at the other harmonic periodicities, and indeed that is the case, as storminess also displays an increase at the 750-year periodicity (figure 75 b arrows), and the LIA storminess maximum coincides with this half cycle periodicity.
Wolfgang Berger proposed the tidal hypothesis of the 1500-year cycle after studying the varved sediments in an oxygen-minimum zone of the continental slope off the coast of Pakistan in the Arabian Sea. Varve thickness and the presence of turbidites (sedimentary storm deposits) display a large proportion of multiples of the basic tidal cycles of the lunar perigee and the lunar half-nodal. Three of the four longest cycles detected in the 5000-year sedimentary record are 366, 490 and 750 years which are one fourth, one third, and half the 1500-year cycle (Berger & von Rad, 2002). The authors link the tidal cycle to Bond events of increased drift ice through a periodical removal of marine-based glacial ice from the shelves by unusually high tidal waves.
This conjecture might have support from drift ice data off the coast of Alaska obtained by Darby et al. (2012), although the authors appear unaware of Berger’s work. Darby and colleagues assessed patterns of sea-ice drift in the Arctic Ocean over the past 8,000 years by geochemically determining the source of ice-rafted iron grains in a sediment core off the coast of Alaska. They identified pulses of sediment carried by sea ice from the Kara Sea, that display a 1500-year periodicity (Darby et al., 2012; figure 76). The periodicity is coherent and in phase with the DO periodicity (figure 76 b) supporting the same causality. Furthermore, spectral analysis of the data shows not only the 1500-year peak, but also the two lower harmonics (figure 76 a, red ovals). This composite nature of the 1500-year cycle also agrees well with the tidal hypothesis.
Figure 76. The 1500-year cycle in Holocene Arctic sea ice drift. a). Time series analysis of the iron grains, by the maximum entropy method, originated in the Kara Sea and deposited on the coast off Alaska by sea-ice drift (black line) and the Total Solar Irradiance reconstruction (blue line). The dashed curves are the 0.99 confidence limit for both records. A prominent 1.5 kyr cycle is present in the Kara dataset but absent from the TSI. Its harmonics are indicated by red ovals. b). 100-year average of the Kara Sea iron grain-weighted percentage in core JPC16. DO periodicity is indicated with continuous grey lines. Dashed and dotted grey lines represent harmonics of the DO periodicity. Source: D.A. Darby et al., 2012. Nature Geosci. 5, 897-900.
For historical reasons and through researchers mistakes the Holocene 1500-year cycle has been mired in confusion, however as highlighted in this article, the evidence to clarify its timing, cause and effects is already available in the published scientific literature. It is simply awaiting critical reading and integration.
As the glacial DO cycle and the Holocene 1500-year cycle display phase coherence and similar manifestations (subsurface water stratification disruption at the halocline, polar atmospheric circulation intensification, and enhanced Arctic drift ice), it can be assumed that they represent different states of the same cycle, due to the very different climatic conditions at those two periods. Over the last decade the DO cycle has become increasingly questioned (Ditlevsen et al., 2007; Obrochta et al., 2012). The observed DO 1470-year periodicity is based mainly on the original GISP2 timescale. When using the more recent GICC05 age model that is considered superior, the strong 1470-peak weakens considerable and shifts to
1500 years. However, this is consistent with what is observed in the more recent Holocene proxies. The 1500-year cycle has undergone 8 oscillations in the past 11,700 years. If the cycle had a periodicity of 1470 years, instead of the observed
1500 years, the accumulated drift would be of 240 years which is larger than what is observed in the proxy data presented. As the Holocene data is also in agreement with the new GICC05 age model, the DO cycle must actually be closer to 1500 than 1470 years.
While some proxies show the 1500-year cycle taking place regardless of climatic conditions (Sirocko et al., 1996, for the past 19 kyr), other proxies indicate that some manifestations of the cycle became muted or absent during the warmer Holocene Climatic Optimum (figure 70). Although this behavior is also mirrored by the DO cycle, that only displays DO events when climatic conditions (sea levels, obliquity, ice) allow it, some researchers have problems accepting that a real cycle might be responsible. To them such behavior is better explained by the chaotic response to internal variability (Ditlevsen & Ditlevsen, 2009). However, we must accept that the final output of a cycle depends as much on the forcing behind the cycle as on the response to the forcing by a climate system that can be in such different conditions as in a glacial maximum, an interglacial optimum, or a number of intermediate conditions.
When discussing the cause of the 1500-year cycle we must take into account the nature and distribution of the proxies that display it. These proxies are spread all over the world (figure 77), making it very difficult to argue that the cycle might be caused by internal variability or specific oceanic currents.
Figure 77. Global distribution of proxies displaying the 1500-year cycle. Evidence from proxies reflecting oceanic (blue), wind (red), storm (green), tidal (purple) and drift ice (black) manifestations. References for these proxies are given in figures 71-76.
Any hypothesis for the cycle must explain the exact timing and global synchroneity of these events. Authors of the studies on the Northwest Pacific proxies have proposed teleconnections linking the North Pacific Gyre with the North Atlantic through the westerlies, but this explanation falls short since this also requires teleconnections with the Southern Ocean. As there are no inter-hemisphere tropospheric winds, and currents would have a delay of decades to centuries, this seems implausible. The only consistent explanation is an external pacer. This pacer cannot be the sun for multiple reasons. There is no 1500-year solar cycle; the effect on subsurface waters takes place above the halocline, at 50-100 m depth, and even below sea ice during the glacial period. These characteristics are difficult to explain with a solar cause. Further, the cycle can cause either cooling or warming depending on location and conditions.
The lunisolar tidal hypothesis, however, can explain a global synchronous effect and the variety of manifestations, as it enhances both atmospheric and oceanic tides. Unlike a solar cycle, a tidal cycle does not carry a temperature signal, and temperature changes are determined within the climate system depending on conditions. Furthermore, the tidal hypothesis is built over shorter harmonics, and some of those harmonics described by Berger & von Rad in 2002 have been observed (figures 72, 75 & 76; Mayewski et al., 1997; Darby et al., 2012).
One of the problems of the tidal hypothesis is that the cycle is composed of a basic unit of
375 years, while most of the power is displayed at the 1500-year harmonic. Berger & von Rad, 2002, advanced a possible explanation:
“…these tidal maxima [have to] occur in the correct seasonal window. The [1500-year cycle] would thus have a plausible mechanism, that is, lunar forcing tied to season.”
During the glacial cycle that season would be the summer, when sea ice is at a minimum, while during the Holocene the season could be the winter, when the cooling effect would be maximal. If this explanation is correct it should have two important predictions. The first one is that in the transition from the glacial period to the Holocene, the change to the opposite season should cause a 180° phase shift in the cycle. This is exactly what we find in several proxies (figure 71 a, b & d; figure 73 a; black bars). The other prediction is that if the effect of the 1500-year cycle is tied to the season, it should be opposite in each hemisphere, as the seasons are inverted. Again, that is what is found, as the cycle tied to subsurface water temperatures is inverted between the Southern Ocean and the Northwest Pacific (compare figure 71 b & d).
Regardless of its cause, by knowing its timing, we can analyze the effects of the 1500-year cycle during the Holocene. The Polar Circulation Index reconstruction (Mayewski et al., 1997) suggests in the Arctic region the cycle is associated with increased cooling and more winter-like conditions. North Atlantic proxies, however, support that the cooling effect was muted during the Holocene Climatic Optimum (Debret et al., 2007; figure 70). Comparison of the 1500-year cycle with the Bond series of ice-drift activity in the North Atlantic further confirms the lack of effect during this period (figure 78, downward arrow). It is only during the Neoglacial cooling of the past 6000 years when the cycle is consistent with an increase in drift ice (figure 78, upward arrows) responsible for giving the record its 1500-year apparent periodicity, but indicative that the 1500-year cycle is only contributing to the drift ice record, and not its primary driver.
Figure 78. The 1500-year cycle and Bond events. Holocene record of North Atlantic iceberg activity (black curve) determined by the presence of drift-ice petrological tracers. Source: G. Bond et al., 2001. Science 294, 2130-2136. The 1500-year cycle is represented by grey lines indicating the DO periodicity (continuous lines) or its harmonics (dashed and dotted lines), and by the fitted 1500-year cyclic periodicity (olive green curve). A downward arrow marks the lack of correlation during the first half of the Holocene, while upward arrows suggest some correlation during the last 6000 years.
Unlike in the case of the 2400-year cycle, a Holocene temperature reconstruction (Marcott et al., 2013; figure 37) does not show a clear effect of the 1500-year cycle on global temperatures. If Berger’s tidal, season-link, hypothesis is correct, global temperatures would see less effect from the cycle than hemispheric temperatures. This is clearly not the “Earth’s unstoppable 1,500-year climate cycle” proposed by Fred Singer (Singer & Avery, 2005).
The 1500-year climate cycle is the millennial cycle whose peak effect is scheduled to take place next, at
2180 AD. What should we reasonably expect from such cyclic occurrence? If our knowledge of the cycle is correct we should see bigger tides and an increase in storm flooding events. There should be an increase in Arctic sea ice and iceberg activity. We should also see an increase in zonal wind circulation and associated precipitation changes. Most of the effects could be smaller than in previous instances of the cycle if global temperatures continue at the current level or increase in the next 150 years. Any decrease in Northern Hemisphere surface temperatures caused by the cycle should be limited, and global average temperatures should not be reduced by much, probably not more than 0.2°C, as suggested by the standard deviation in a global reconstruction where its effect cannot be detected (Marcott et al., 2013; figure 37). It will be however an outstanding opportunity to study the 1500-year cycle and establish the reality of climate cycles at the millennial level, if any observed effect is correctly attributed.
1) The 1500-year cycle displayed in Northern Hemisphere glacial records is also observed in Holocene records from all over the world.
2) The cycle is most prominently displayed in oceanic subsurface water temperatures, Arctic atmospheric circulation, wind deposits, Arctic drift ice, and storminess records.
3) Proxies indicate the cycle also displays power at the 750-year harmonic and might have undergone a phase shift during the Holocene Climatic Optimum.
4) A lunisolar tidal hypothesis currently best explains the cycle’s timing, features, and effects. The hypothesis proposes that the cycle is season linked and thus has different manifestations in each hemisphere.
5) The tidal hypothesis also provides an explanation for the cycle’s lack of a temperature signal, a phase shift observed during the Holocene Climatic Optimum, as well as the apparent opposite response from a Southern Hemisphere proxy.
6) Although the 1500-year cycle is associated with cooling indicators in the Northern Hemisphere, its effect on global temperatures remains to be determined.
7) The next peak effect of the 1500-year cycle is expected in about 160 years, and will provide a rare opportunity to clarify its causes and effects.
I thank Andy May for reading the manuscript and improving its English.
Moderation note: As with all guest posts, please keep your comments civil and relevant.
The previous Nature Unbound articles are also available as pdf documents at:
There is much ice on land in cold places in both hemispheres, much more on Antarctic than in the Northern Hemisphere. Ice provides cooling by reflecting and by melting and by dissolution. Ice melts at the freeze thaw point. Ice dissolves, which is different than melting, at temperatures below freezing, when contacted by salt water, providing even more cooling. This occurs on the underside of sea ice sheets and on the underside of ice shelves. This occurs around icebergs, even more as they flow into warmer oceans. Warm tropical ocean currents flow to Polar Regions and get chilled, some of it to below the freeze thaw point. This cold water sinks and flows back to the Tropics. This provides much cooling that is neglected by climate scientists. Graeme Stevens (JPL) and Jerry North (Texas A&M) told me that after Graeme gave a presentation at A&M. Dr Neil Frank also has mentioned to me it is not considered. I believe that this is a major flaw in consensus and skeptic climate theory and therefore in models. The Little Ice Age was colder than the Roman and Medieval warm periods. Cold periods are associated with more ice extent and warm periods are associated with less ice extent. This is cause and not result. Ice volume on land grows due to ocean effect snowfall that falls on land when oceans are thawed and ice shelf and sea ice extent is small. Ice volume on land depletes when oceans are frozen due to lack of ocean effect snowfall that reaches land when ice shelf and sea ice extent is large. Ice advances as and after ice volume grows. Ice retreats as and after ice volume decreases. This is clearly shown by the ice core data. Ice core temperature is not the temperature of an ice core, it is the temperature of the oceans, determined by isotopes, that supplied the water for the snowfall. Ice cores are the best proxies for ocean temperatures in both hemispheres which is the best measure of earth temperature. This does not conflict with other theories, many factors influence temperature, they resonate in and out of phase with temperature, but if temperature tries to go out of bounds it snows more when oceans thaw and it snows less when oceans freeze. Ice extent resonates in phase with temperature, driving, not driven. That supplies bounding that has a set thermostat which is the freeze thaw point for oceans. This does not cause an equilibrium temperature, this creates a robust cycle, that cycles toward an upper bound after it snows too much, that cycles toward a lower bound after it snows to little. This repeats, in the same bounds, in both hemispheres, even while, over the past ten thousand years, almost 40 watts per square meter left the Northern Hemisphere above 60 degrees and entered the Southern Hemisphere below 60 degrees. These climate cycles are robust, resilient, self-regulating, and self-correcting. The NH and SH have cycled inside the same temperature bounds as each self regulated itself, not in phase with each other, for ten thousand years. Past warmer periods, before twenty thousand years ago, occurred because there was more water in the oceans to be warmed. Major ice ages, before twenty thousand years ago, occurred because the more, warmer water promoted more massive ocean effect snowfall on land in cold and more temperate places. The major ice ages ended because the less water in the oceans was ice covered and could not provide enough snowfall to maintain the ice. Ice ages occur when there is huge amounts of ice on land. The snowfall that puts the ice on land can only occur when oceans are higher and warmer. The ice chest stays cold until the ice is depleted. The earth stayed cold until the ice was depleted. The earth warmed as the depleted and thinned ice sheets finally retreated. The amount of ice and water that took part in these cycles, increased over the past few million years until the last major warm period and last major ice age had removed enough water and sequestered it on the Antarctic, Greenland and the High Mountain Glaciers. There is not enough water left to promote another major warm period. Without another warm period, there cannot be another major cold period. The most recent ten thousand years is the new normal. The Little Ice Age occurred after it snowed more during the Medieval Warm Period. Earth cooled as the ice advanced. The Little Ice Age ended after it snowed less during the Little Ice Age. Earth warmed as the ice retreated. We are in a temperature increase hiatus because oceans are thawed and it is snowing enough to halt the ice retreat. The ice volume that will advance into the next Little Ice Age is already falling. This warm period will last about as long as the Roman or Medieval warm periods lasted and then we will cool again. It is a normal, natural and necessary cycle and we did not and cannot cause it. This is not the whole story, it is the most important part, but, read more on my website:
Retired Aerospace Engineer
BS Engineering Mechanics VPI/Virginia Tech 1967
Sea level is important in this cycle. Sea level rises and falls as the ice volumes grow and deplete. Sea level rose as we came out of the Little Ice Age, as ice turned to water and reentered the oceans. Sea level rose, over the past ten thousand years because the solar insolation, above 60 degrees north, decreased by almost 40 watts per meter squared and increased in the south, below 60 degrees, by about the same amount. The Southern Hemisphere has more water and is warmed more by that change and needs more cooling. The oceans rose to provide more snowfall for the Antarctic to increase ice volume enough to shed more ice for cooling the southern oceans. This solar cycle has just about peaked, so the ocean rise has just about peaked. Major ice ages go with major ocean level changes and both hemispheres go into and out of major ice ages somewhat together. The cycles of the most recent ten thousand years do cause ocean level changes that allow some influence that crosses the hemispheres but ice extent is the major player that keeps both hemispheres in bounds separately, not in phase, not with equal length cycles. The Southern Hemisphere has much more ice and ocean. The SH regulates major sea level changes. The Northern Hemisphere must follow the Southern Hemisphere, with major cycles of ten thousand years and more. Sea level determines how much snow can be provided when oceans are thawed. The NH follows the SH large cycles because the sea level does. Shorter cycles, such as during the past ten thousand years, each hemisphere regulates using more snowfall in warmer times to increase ice volume and less snowfall in colder times to allow ice volume to deplete. Both hemispheres have the ice volume cycles, following with a ice extent cycles. Ice extent is about 90 degrees ahead of ice volume in the full 360 degree cycle.
Consensus and most skeptic ice theory put ice extent and ice volume in lockstep phase. The last glacial max was an ice extent max but not an ice volume max.
Start: In a warming period, ice extent decreases while ice volume is decreasing, as it warms, the snowfall rate increases to the point it snows enough to surpass the melt rate. Ice continues to retreat as ice volume starts to increase. When ice extent reaches a minimum, temperature is at the max and ice volume is about half way. The ice advances, temperature cools, snowfall rate decreases but ice volume is still increasing. At some point, the snowfall rate reduces to less than enough to balance the ice depletion. At this time ice extent is still increasing and it is still getting colder. Ice extent reaches the max and temperature reaches the lowest point. Go back to start:
The oceans are connected, the circulation in the NH an SH are separated, they do not mix much. The ocean level is connected. When the oceans are higher, they get warmer, it snows more in both hemispheres, lowering all the oceans and allowing cooling of all the oceans. When all the oceans are lower and colder and more frozen, it snows less in both hemispheres and ice depletes in both hemispheres which allows warming in both hemispheres.
Climate in the two hemispheres follow the same timing because the principles are the same in both hemispheres.
It snows more when oceans are higher, warmer and more thawed. More ice causes colder.
It snows less when oceans are lower, colder and more frozen. Less ice allows warmer.
Thus a cycle. Bigger and smaller cycles with different periods, due to different balance between ice on land and water in the oceans.
External forcing with no feedback from earth could not work this well in two very different hemispheres with very different alternating solar input to each!
Ewing and Donn figured this out without ice core data.
The ice cycles resonate with other factors and there are many correlations with other factors that distract people from considering that ice is used to control temperature, it is not the result. We add ice to cool things, Mother Earth does that too. We remove ice to allow things to warm, Mother Earth does that too.
People treat ice only as a result of external forcing.
Ice must be included in any analysis. It snows more in warm times increasing ice volume and the more ice later spreads on land and dumps into oceans causing ice events and cooling. The cold times are times of lower, more frozen, oceans and times of drought because the moisture is not available from a lower more frozen ocean. More dust due to less precipitation.
The ice cycles resonate with external forcing giving people false correlations that they believe are only causes. Milankovitch is the primary one. Milankovitch alternates warming the NH and SH but the ocean and ice cycles do major warming and cooling together.
The ice core data is a real treasure, spend some time understanding the ice cycles. Ice cycles are a major part of the cause of climate change and self regulation. The two hemispheres would not stay inside the same temperature bounds without the oceans and ice.
People continue to treat ice as only a result and not part of the cause.
Ice must be included in the analysis, it is not just a result.
The two hemispheres cycle in the same temperature bounds because water freezes and thaws at the same temperature in both hemispheres. No other factor explains this. Each hemisphere is self regulated in the same temperature bounds using the same method when external forcing alternates a huge amount.
This posting was complicated. It was interesting. Very few people understand the complicated and many just agree, thinking how could anyone make all that up and it still be wrong. There is likely some right and wrong stuff in this. Ice core data shows correlations between the NH and SH over 150 thousand years. The ice cores show that over the most recent ten thousand years, the temperature bounds in both hemispheres were in the same limits but the timing was not the same. There was no ice core plots that were presented to support their claim that the 1500 year cycle occurred the same in both hemispheres.
Clearly, they do not have this figured out correctly yet!
But, they are working on it. We must work together better with all of the honest scientists who are working on this.
Everyone, almost everyone, uses thermometer data. Thermometers were invented during the warming from the last little ice age. Thermometer data does not include a complete climate cycle. Thermometer data includes part of the warming phase, between 100 and 200 years. The analysis of that data is straight lined to unbelievable values that have not happened in ten thousand years. This is not any kind of real science.
I’m still puzzled by the spectral peaks. They’re very noisy, having a negative exponential (not gaussian!) distribution, which has a huge tail upwards. 99% would be a huge peak.
(also 99% per what? There are lots of independent trails at neighboring frequencies, which reduces the significance hugely.)
The punctual spikes in “figure 18” look fairly convincing. However they are very short lived and will not show up in a spectral analysis. I think the idea of a 1500y component to climate is questionable. Though there does seem to be regular spikes which are interesting.
Figure 77. Global distribution of proxies displaying the 1500-year cycle.
The Antarctic Ice Cores were not included in the distribution of Global Proxies. I guess the author realized it did not agree with the most recent ten thousand years of NH ice cores. Why else would you leave out one of the best and most famous proxies?
If our knowledge of the cycle is correct we should see bigger tides and an increase in storm flooding events.
Your understanding is not knowledge and is very wrong.
It rains and snows more when oceans are higher and warmer and thawed. It rains and snows less when oceans are lower and colder and more frozen.
You got that wrong, that will be a colder time with lower oceans and less precipitation.
There should be an increase in Arctic sea ice and iceberg activity.
You got that right, it is snowing more now to increase the ice volume, the more ice volume will promote more sea ice and iceberg activity later.
“Their trigger is very precise, taking place every
The most common pitch there is a tad under 1000 years. Between 11&10, 6&5, 4&3, 1&A, and A&0.
The size of those boxes is 1500 years not 1000. That’s why 3.3 boxes every 5000 years.
Ah yes sorry, so that’s the claimed 1470 year pitch. There is a mean period of 1542 years in the solar system, the synodic period of the outer three Jovian bodies.
Wolfgang Berger and Ulrich von Rad (2002) proposed that the 1500-year cycle is a harmonic of the beat between the moon’s nodal and apsidal precessions, a hypothesis that fits not only the observed period, but also the required mechanism for vertical water mixing through tidal forcing.
So what is this “beat” thing? In a very long article you do not seem to really say what it is.
You also claim “lunisolar” twice , without further explanation or evidence.
I’m not saying either of these do not exist, I fully expect that they might, but if this is one of you key conclusions, why say to little about it?
So what is this “beat” thing?
Beat is not a climate concept. When the values of two periodicities are close, they produce an interaction, called a beat. This is simply a mechanical interaction due to the slowly moving in and out of phase of the two frequencies producing oscillations. When they are exactly in phase the sum of their effects is a maximum. As they slip out of phase the sum decreases until, when they are exactly out of phase, the sum is a minimum. In the period from one maximum to the next, the higher frequency will have oscillated by exactly one cycle more than the lower frequency. Considering two frequencies F1 and F2, the period of the beat will be 1/(F1-F2), while the frequency of the beat will be (F1-F2).
You also claim “lunisolar” twice , without further explanation or evidence.
Tides on Earth depend mainly on the position of the Moon, because it is very close, and the position of the Sun, because it is very massive. Thus tides are a lunisolar phenomenon from an Earth perspective, like eclipses.
I try to reach a compromise between the length of my articles and the amount of evidence to be presented and discussed. But that is what comments are for.
Well thanks again for taking the time to reply but I am not asking what “beats” I have written articles about this, I did not not ask for a lay introduction to the effect but exactly what phenomena you are suggesting are doing this.
I also suggested that the famous 60y cycle may be such a modulation effect formed by a superposition of solar and lunar cycles.
So maybe you could say exactly what you are proposing instead of such flighting comments without substance that can not be evaluated, validated or refuted.
re lunisolar: jeez, yes I do realise that the sun has a tidal effect too, I’m pushing 60 , not 16. Now can you say what exactly you think the climatic effect of tides is and were we can see evidence of it?
Again, if you look at my Ace in the Hole article linked above you will see that I found a probably lunar 9.1y periodicity in cross-correlation of ACE and SST.
What I’m asking you is what evidence you have for your claim. Just mentioning the term lunisolar a couple of times is not meaningful.
So maybe you could say exactly what you are proposing
If you have read the article you would have noticed that I am not proposing anything. I am subscribing to the lunisolar tidal hypothesis first proposed by Berger & Von Rad, 2002
Berger, W. H., and U. Von Rad. “Decadal to millennial cyclicity in varves and turbidites from the Arabian Sea: hypothesis of tidal origin.” Global and Planetary Change 34.3 (2002): 313-325.
I find that the best evidence reviewed by me from scores of studies fits the hypothesis quite well.
I also suggested that the famous 60y cycle may be such a modulation effect formed by a superposition of solar and lunar cycles.
8 years before you suggested it, the solar and tidal forcing of NAO, that also presents the 60-year oscillation, had already been published, precisely by Wolfgang Berger:
Berger, W. H. “Solar modulation of the North Atlantic Oscillation: Assisted by the tides?” Quaternary International 188.1 (2008): 24-30.
It never hurts to check the bibliography. That’s part of the scientific work, although not all scientists are as thorough as they should as I show in the article.
It would be interesting to get the data for that Rahmstorf graph. There does seem to be regular pattern to the strongest peaks. Rather than eye-balling this it would be good to look at rate of change in that data. The peaks should then be identifiable as a threshold and precise dates and intervals calculated.
The bibliography is provided, and google scholar is your friend. If you introduce the title from that article’s bibliography:
You can see that there are 13 versions available, several of them in pdf format for free. But in this case not needed because the article is open:
In general people that read scientific articles frequently know how to locate many of them free. If anybody wants an article discussed by me and can’t locate it for free, I’ll make it available for download. Most readers of my articles will not be interested in going to the original articles, so providing a scientific citation saves me a lot of useless work.
Thanks for the link. I know Google is my friend, that is why I use it to find free copies of any articles I cite when I write a post here. I similarly clearly state what sources are and where to find them, so that anyone reading is encouraged to go an read the papers and does not have to play hind and seek to get the data. I do not consider such effort “useless”.
Now at least we know what the captionless “figure 18” is representing as “climate”. It is the GISP2 d18O record.
anyone reading is encouraged to go an read the papers and does not have to play hind and seek to get the data
Excuse me, scientific citations are the standard way of citing other researchers work. It is telling that you have a problem with that. I find better uses for my time that collect links that perhaps nobody is going to hit. If somebody wants to check the source it has the necessary information. I do that all the time and don’t expect other people to use their time to prepare links for me when it is so easy to run a search: Just copy from one place to another and hit the search button. Some people are just spoiled nowadays.
Why do we have to make comments on a 1500 years’ old research, when ‘climate change theory’ is only 45 years old? Is it because, like in the Monopoly game use, mention Climate change in your research, go past GO and collect $1,000 from the Al Gore Foundation?
All this farrago has caused in Australia is to double electricity prices in just 2 years. It isn’t obvious that unaccountable scientists and disrupting, hysterical and most probably mentally disturbed environmental organisations, like Greenpeace, WWF, and others are overplaying their hands?
Ewing and Donn wrote correct theory 60 years ago. Before there was ice core data.
Climate is the result of entropy in a physically isolated system. Energy comes into the system from the sun and leaves as both reflected light and infrared emissions. Milankovitch cycles may modulate relentless Quaternary cooling and warming epochs – but warming and cooling is more or less abrupt and intense. The Earth system response to small changes in insolation is intensified by energy changes in the system through ice primarily and thus planetary albedo. Intensity, extent and duration of ice fields is determined by internal abruptly shifting, spatio/temporal chaotic, globally coupled flow fields in oceans and atmosphere.
Data – especially hydrological – shifts from a state with one mean and variance to another repeatedly and reflecting climate variability on multi-decadal to millennial and longer scales. Over a very long time – all possible states of climate may be sampled in an ergodic – as Earth’s system is presumed to be – chaotic system. But I am thinking Quaternary rather than Holocene. An epic of climate since the shoaling of the Isthmus of Panama.
Moy’s well known ENSO proxy plot shows the so-call mid Holocene transition – as seen in cosmogenic isotopes. Although there are hints at other periodicity – the mid-Holocene break is unique in this record.
Can it repeat? Could we get back to a millennial scale La Nina normal regime if the sun’s intensity declines sufficiently? Could great herds repopulate the Sahel? Can we predict the future with cyclomania? Well – yes – that’s the question Javier.
Cycling through some of the many cycles, Singer and Avery posit global warming every 1,500 years whereas, looking at Tibetan ice cores going back to more than 500 million years, Lonnie Thompson talks about 21,000 tropical rainfall cycles due to, “the slow wobbling of Earth’s rotational axis,” and also a
200-year tropical rainfall cycle in Tibet for as yet mysterious reasons although it is posited it may be, “related to the 205-year cycle of solar activity,” and, when also talking about Earth’s 1,500-Climate Cycles, Craig Loehle said in 2009 that, “We must face the fact that the earth is now cooling.”
Wagathon, You wrote: looking at Tibetan ice cores going back to more than 500 million years,
I have never heard of an ice core going back before the Antarctic Ice Cores. Some, more than 800 thousand but nothing older than even one million. Ice is continually being depleted and replenished.
Ooops– you’re right… it should be half a million (500 thousand).
I am not sure where any of this gets us, if we agree that climate science already has jumped the shark in so far it willingly abandons the scientific method for ideological and political convenience– i.e., the AGW hypothesis is essentially a scientifically untestable prediction that continuing global warming is our future because natural climate cycles are simply being overwhelmed by humanity’s activities.
AGW hypothesis is essentially a worse than useless idea
These proxies are spread all over the world (figure 77), making it very difficult to argue that the cycle might be caused by internal variability or specific oceanic currents.
These proxies are spread all over the world (figure 77), “they left out Antarctic ice core data”, making it very difficult to argue that the cycle might be caused by anything other than internal climate self regulation!
These proxies are spread all over the world (figure 77), making it very difficult to argue that the cycle might not be caused by internal variability and specific oceanic currents that work the same way in both hemispheres.
it snows more when oceans are high and warm and thawed and it gets colder after that. it snows less when oceans are low and cold and frozen and it gets warmer after that.
This is Occam Razor simple stuff. water changes state at a fixed temperature. Water and ice are abundant. Look at something abundant and a theory that is simple to explain stuff.
How many storms we will have next year and where they will hit is not easy. The fact that it snows more when oceans are thawed and it snows less when oceans are frozen is easy.
water freezes and thaws at the same temperature in both hemispheres and causes more snowfall when oceans are thawed and causes less snowfall when oceans are frozen and that limits the bounds of temperatures in both hemispheres.
Both hemispheres are warmer when oceans are higher. Both hemispheres are colder when oceans are lower.
This is Occam Razor Simple Stuff. Look at the Ice Core Data for both hemispheres.
Two hugely different hemispheres are regulated in the same temperature bounds because the oceans thaw and cause more snow when needed and freeze and cause less snow when not needed.
Even the IPCC accept that the atmosphere is a chaotic system.
Humans love cycles. See them even where they don’t exist.
No one wants to believe that detailed examination of the past still won’t predict the future. After a run of 100 heads, the chance of another remains 50:50.
The climate does have a memory, and it has been demonstrated. The chances of a new interglacial depend critically, among other things, on the time elapsed since the previous one.
“Combined with the time since the previous deglaciation ?t (in kyr), the discount rate provides a measure of accumulated instability that lowers the insolation threshold required for deglaciation. For each caloric summer insolation peak, Ipeak (GJ m?2), the effective energy E(Ipeak, ?t) (in GJ m?2) is here defined as
Javier this has been a great addition to conversation and perspective. Thanks for collecting all the knowledge and coherently liking it together.
Coin tosses are really random. Climate switches back and forth. Not at all the same. We have a warm period now. This warm period followed a little ice age. A little ice age will follow this warm period. It will happen after a few hundred years of more snowfall that is rebuilding the ice volume now. The ice extent and cooling will happen after the ice volume and weight grows enough. Open Arctic is necessary to promote more snowfall that halts warming and brings on cooling later. Study ice core data, the facts are clear.
Even the IPCC accept that the atmosphere is a chaotic system.
SO, THE IPCC ACCEPTS THAT THEY DO NOT REALLY KNOW ANYTHING.
Despite the historic accounts that warm periods and cold periods alternate, despite the success of Milankovitch theory to explain glaciations and interglacials, despite the multiple observations that climate change is subject to multidecadal oscillations, despite proxy evidence that glaciers grow and recede, the obvious conclusion that climate operates in quasi-cycles, so prevalent in the past, is not accepted by most people today.
This refusal to accept the evidence in favor of more fashionable hypotheses, like a chaotic climate besprent with tipping points, leads to constant surprises when the phases of the cycles change, like the pause in global warming, or the more recent pause in Arctic melting. It is also assumed by nearly all that the current warming will continue nearly forever. It will not. We might not see it, but the end of the warming trend is only decades, perhaps a century, away. Most of the problems we discuss are not problems at all. The problems from climate are nearly all on the cooling side, and thus something to worry future generations as the end of the interglacial approaches.
Why are they quasi-cycles instead of cycles, complicating their analysis? Because the response of the complex climate system to periodical forcings is mutable in the time variable. Obliquity is cyclical, yet sometimes it produces an interglacial and sometimes it doesn’t, depending on ice sheet extent and other factors. We had no problem accepting that tides were produced by astronomical cycles, yet the only way to predict tides was and still is to analyze their periodicity at every port, because the ocean system is so complex that produces different tidal periodicities at every place.
Cycles are a reality in climate. Their study leads to a better predictability of climate, that with other explanations is abysmal.
“the obvious conclusion that climate operates in quasi-cycles,”
Not so “obvious”. As soon as cycles become quasi-cycles with occasional phase shifts one has to ask if we are not just seeing dogs or faces in the clouds. Chaos theory is more able to explain that kind of thing than strict cyclic reasoning. That is one reason why is has gained traction, not because it is fashionable.
“Why are they quasi-cycles instead of cycles, complicating their analysis? Because the response of the complex climate system to periodical forcings is mutable in the time variable. ”
and it is because climate is complex and non linear that chaos theory becomes applicable.
Chaos plays a clear role in climate and weather, but gives the wrong explanation to cyclical-based phenomena like glaciations. The climate system is chaotic, over which cyclical forcings impose quasi-cyclical responses. Chaos does play its role, but if you take it too far instead of explaining and predicting, it confuses and obscures, while negating the little predictability the system allows.
Their study leads to a better predictability of climate
Can you give an example of a detected cycle on any scale which has successfully predicted something in the future rather than sort of roughly matched selected events in the past?
The claim better predictability you need to be able to point to a prediction that worked. At least ONCE.
Obliquity is cyclical, yet sometimes it produces an interglacial and sometimes it doesn’t, depending on ice sheet extent and other factors.
Exactly, ice volume on land and ice extent on land plays an important role and it is totally ignored and treated as a result by consensus and skeptical people, many, “so called scientists” totally ignore data that could make this easily understood. Climate is not rocket science and there is plenty of actual data, there is no need for calculations or models.
Obliquity is cyclical, yet sometimes it produces an interglacial and sometimes it doesn’t, depending on ice sheet extent and other factors.
Ice cycles are cyclical, and they always produce warming and cooling and sometimes the Obliquity is in phase and sometimes out of phase with the overpowering ice cycles. “Really think about this!”
When earth is colder, there is “always more ice” When earth is warmer, there is “always less ice. Obliquity is in phase with this sometimes and out of phase with this sometimes.
DATA IS DATA! LOOK AT THE ACTUAL DATA! MORE ICE CAUSES COLDER! LESS ICE ALLOWS WARMER!
Almost no one understands cause and effect when it comes to climate. Ewing and Donn had it right 60 years ago.
What the DATA shows simply and unmistakably is that the induction of interglacials depends on two Milankovich oscillations. These are (1) obliquity and (2) eccentricity (EPMI).
What is EPMI? This stands for eccentricity – precession modulation – insolation (at 65N in the summer). All three of these things are correlated by causation, and move in lockstep. Note I did not say just “precession”, but the modulation of precession – i.e. the wavelike oscillation in the amplitude of precession.
Note also that obliquity’s causative relationship with the glacial cycle ?? is lagged by 6500 years. This is the time it takes for changes to insolation to change the temperature of the whole ocean.
In short, obliquity – lagged by 6500 years – always causes glacial termination and interglacial inception when when the lagged obliquity upward oscillation coincides with a wave crest or high value of EPMI as described above. If lagged obliquity upswings but EPMI is low, there is either no interglacial inception or only an abortive “stump” of an interglacial. All the last 8-10 100k year long glacial cycles ?? since the MPR have one or two such abortive stumps of interglacials within them.
When a peak of EPMI falls halfway between two lagged obliquity peaks, then you get a “double-headed” interglacial. This is also a regular occurrence and predictable from the phasing of obliquity and EMPI. It happened 600k and 200k years ago, and will happen again 200k years from now.
There are so many examples that I could write one of my notoriously long articles just on them.
Arctic sea ice and AMO:
Divine, Dmitry V., and Chad Dick. “Historical variability of sea ice edge position in the Nordic Seas.” Journal of Geophysical Research: Oceans 111.C1 (2006).
Based on the relationship between sea ice edge position and the Atlantic Multidecadal Oscillation, Dmitry Divine and Chad Dick, from the Norwegian Polar Institute, were capable of predicting in 2006 the following:
“Wavelet analysis of the time series presented in this work gives evidence that this decreasing trend is being superimposed on multidecadal oscillations in ice edge position in the Nordic Seas. The analysis suggests the presence of a 60 – 80 year variability and also of two- to three-decadal oscillations in ice extent.
We suppose therefore that during decades to come, as the negative phase of the thermohaline circulation evolves, the retreat of ice cover may change to an expansion.”
This was one year before Al Gore convinced humankind Arctic sea ice was going the do-do way. Since 2007 September Arctic sea ice extent has actually been growing.
Of the 54 SC24 predictions published or submitted to the SC24 Prediction Panel in six general categories, spectral analysis predictions (Pesnell, 2008) based on Fourier, wavelet, or autoregressive-based forecasts, outperformed all other categories, predicting a below average SC24 activity. Of the spectral predictions, there was one published:
Clilverd, Mark A., et al. “Predicting solar cycle 24 and beyond.” Space weather 4.9 (2006).
They used a low-frequency modulation model that includes solar variability periodicities that I am discussing in my articles (shorter ones that will be discussed in a future article). The model predicted very low activity for SC24, and indeed SC24 turned out to be the less active cycle in 100 years. The model also predicted in 2006 that SC25 will again be a below average cycle of similar amplitude to SC24. So the prolonged solar minimum that we are experiencing was predicted by cycle analysis while most solar physicists were not expecting it because their models can’t explain centennial periodicities in the Sun.
So yes, quasi-periodicities lead to a better prediction. The AMO was discovered in the late 90’s and its relationship with Northern Hemisphere temperatures evident from the beginning. The pause was predictable in its timing, yet it was observed in 2006 by outsiders and acknowledged by climate scientists around 2013. As far as I know chaos is quite unproductive in terms of predictions.
Thanks for the reply Javier, but is that the best you can do?
The second is about the sun not climate so is not germain to the question. The first thing about Arctic ice may well be true but Al Gore being wrong is not the same thing as their cyclic analysis having made a prediction which has been verified.
If you want to suggest there is a “60 – 80 y cycle” you are not going validate the claim after ten years.
So I post the same question again. Do you have any examples of climate cycles which have predicted anything which has later been found to be true? ie scientific validation.
As usual I provide the requested information, and then it is summarily dismissed because not enough time has passed, or because predicting solar cycles ain’t the same as predicting climate cycles.
Sorry it wasn’t good enough for you, but I really don’t care enough about what you believe about this issue to continue providing information until you find it satisfactory to your criteria.
“There are so many examples that I could write one of my notoriously long articles just on them.”
Well so far you have clearly failed to provide anything showing a detected climate cycle which has predicted something in the future which has come to pass.
You claim to have a list so long you write an entire lengthy article about it but so far you have not provided a single example. That strongly suggests that you have zero examples. I am well aware of AMO, it is seen in global sea level rise and I suspect that it is a significant factor in Arctic sea ice variation. However, I am unaware that anyone has predicted anything using AMO that has come to pass. So all we have so far is two cycles of undetermined importance.
Sorry it wasn’t good enough for you, but I really don’t care enough about what you believe about this issue to continue providing information until you find it satisfactory to your criteria.
It is not me who invented the rules of science. I’m sorry you are not aware how it works and prefer to walk away. You made a specific claim :
Cycles are a reality in climate. Their study leads to a better predictability of climate, that with other explanations is abysmal.
Clearly you were not talking about astrophysics, so citing cycle24 just underlines the paucity of evidence you have of successful predictions.
Where is this “better predictability? You are unable to provide a single example of a cyclic prediction which has been validated so what is this claim of “better predictability” based on? Please feel free to use any criteria you like as long as you state what they are.
If someone had applied AMO back in 1990 maybe they would have been able to predict “the pause”.
Nicola Scafetta did a purely harmonic analysis that works better than GCMs but that did not attempt to identify climate cycles, it was purely a harmonic decomposition.
If more effort was put into understanding climate cycles predictions probably would improve. Maybe that is what you meant.
Climate cycles like everything else in the climate are made to be broken.
You make some conclusions on this latest piece of work
Would you draw any conclusions if you looked at the sweep of time from all those four articles together, or should we treat each part as being entirely separate to each other?
I am reviewing what science knows about “abrupt” climate change at different time frames. The conclusions presented are specific to each time frame or cycle analyzed. The main conclusions from the entire series are that:
– The majority of “abrupt” climate changes observed in the past are due to cyclical changes in forcing from the Sun, the Moon, and the planets over the Earth’s climate system.
– The magnitude of those natural climate changes can be far larger than what we are currently experiencing. There is no exceptionality.
– Natural cycles are not properly accounted for in current climate understanding.
The result is that most of our scientists don’t understand the climate change we are experiencing. Those that do are not being listened to.
“What defines a climate change as abrupt? Technically, an abrupt climate change occurs when the climate system is forced to cross some threshold, triggering a transition to a new state at a rate determined by the climate system itself and faster than the cause. Chaotic processes in the climate system may allow the cause of such an abrupt climate change to be undetectably small.” https://www.nap.edu/read/10136/chapter/3#14
“The sequence often forms a distinctive saw-tooth shaped time series, epitomized by the deep-sea records of the last million years and the Dansgaard-Oeschger (D/O) oscillations of the last glacial. Here I introduce a simplified mathematical model consisting of a novel arrangement of coupled nonlinear differential equations that appears to capture some important physics of climate change at Milankovitch and millennial scales, closely reproducing the saw-tooth shape of the deep-sea sediment and ice core time series, the relatively abrupt mid-Pleistocene climate switch, and the intriguing D/O oscillations. Named LODE for its use of the logistic-delayed differential equation, the model combines simplicity in the formulation (two equations, small number of adjustable parameters) and sufficient complexity in the dynamics (infinite-dimensional nonlinear delay differential equation) to accurately simulate details of climate change other simplified models cannot. Close agreement with available data suggests that the D/O oscillations are frequency modulated by the third harmonic of the precession forcing, and by the precession itself, but the entrained response is intermittent, mixed with intervals of noise, which corresponds well with the idea that the climate operates at the edge between chaos and order. LODE also predicts a persistent ?1.5 ky oscillation that results from the frequency modulated regional climate oscillation.” https://uncch.pure.elsevier.com/en/publications/abrupt-climate-change-chaos-and-order-at-orbital-and-millennial-s
It is the ‘entrained response’ we are interested in – and you would benefit from exiting your cognitive box. Until that happens you will be pointlessly off track. Making comments that are merely of the declaratory type – as in – no – I have studied it and it is not abrupt – impresses me as much as anything you have ever said.
Do you have a link to the full paper? That page has the abstract, but the hot links at that page to the full paper do not work for me.
Your fig 71 is interesting, but as I have found, is somewhat anomalous, when compared to fig2 in Bond paper and fig 4 in Balascio paper in the below links:
This will sound crazy, but see in the third link, changes in ‘calendar viewing angle’, indicative of changes in obliquity. None of the proxies will indicate that. What the astronomer Dodwell perceived in 1936 is corroborated by both the calendar structures (functional and tested) and the proxies. Incidentally
My figure 71 looks anomalous when compared to Bond figure because the proxies in figure 71 are selected for their strong response to the 1500 year cycle forcing, and weak or no response to solar forcing that is the primary driver of Bond events.
I recently read Dodwell manuscript. It is a very interesting reading. As a fiction I would give it high marks, but I don’t believe what it says. Although very suggestive it cannot be correct. The climate responds hugely to changes in obliquity. Even a half degree change in obliquity would lead to a huge climate change. And he is proposing a huge change in obliquity in 4000 years that had left no climate trace. There are no discontinuities in Holocene climate beyond the 8.2 kyr event for which we have a fair explanation. So even if we don’t know which one, there must be another explanation for his findings. As a safeguard, I tend to not subscribe theories defended by essentially one person that require to go against all we know in a field. No amount of information from ancient temples is going to make me ditch all I know about paleoclimatology.
See also Fred Singer’s timely old book on the 1500 year cycle.
I did see him and listened to him talked to him at a conference last month.
Regretfully Fred Singer’s book on the 1500 year cycle is almost completely wrong. Most of the things he describes have nothing to do with the 1500-year cycle.
Most of the information available on the 1500-year cycle, not only over internet, but also in scientific articles, is incorrect.
I doubt that the science of the 1500 year cycle is settled.
Precisely my point. It is so unsettled that most of the information of climate effects attributed to the 1500-year cycle is contradictory. That means it is wrong.
The next climate shift is due in a 2018-2028 window. Predictable only because of the long history of multi-decadal regimes in global flow fields.
Could you explain what are describing as a “climate shift” , what evidence you have and how you derive this “window”.
There is far too much of this hand-waving kind of claim going on here. It neither identifiable nor falsifiable, therefore of little scientific meaning.
“Specifically, when the major modes of Northern Hemisphere climate variability are synchronized, or resonate, and the coupling between those modes simultaneously increases, the climate system appears to be thrown into a new state, marked by a break in the global mean temperature trend and in the character of El Nino/Southern Oscillation variability. Here, a new and improved means to quantify the coupling between climate modes confirms that another synchronization of these modes, followed by an increase in coupling occurred in 2001/02. This suggests that a break in the global mean temperature trend from the consistent warming over the 1976/77–2001/02 period may have occurred.” http://onlinelibrary.wiley.com/doi/10.1029/2008GL037022/full
If you have not heard of climate shifts – then I guess it will come as a surprise. But I lack the patience to go back to baby steps in what should be common background information. Here’s a couple of articles to get you going. Focus on the underlying patterns of any climate series you care to examine – including the 20th century surface temperature.
Tell you what – why don’t you google it and come back with a more informed and less bellicose attitude.
Well if I took the time to research every unfounded yet confidently asserted claim I read in comments on the internet, I would not have time to eat and breath. I’m well aware of the basics of chaos theory and don’t need your baby steps. Just point to what your claim is based on.
If you are going make such a claim at least make some attempt to explain where it comes. I have heard plenty of claims about various “shifts” mostly based on where people chose to start drawing their straight lines.
“The next climate shift is due in a 2018-2028 window”
What is that based on , or are we all supposed to spend time on google trying to work out if that is your own personal fantasy or has some founding in science?
It’s based on it is used to be predicted to have started in 2011.
I predicted the PDO was about to go positive (and that the GMST would surge.) Then the PDO did go positive, and the GMST surged. This was based on a hunch.
I have made many explanations – and your eating and sleeping is not my problem. But I am nothing if not helpful.
Nor is JCH’s more than typically incoherent rant my problem.
Robert I Ellison: I have made many explanations – and your eating and sleeping is not my problem. But I am nothing if not helpful.
The problem is that you never go beyond the “explanatory framework” (i.e. bunches of analogies) to a tested model of anything in particular. Is there a tested model of Earth surface temperature on which you base your claim that “the next climate shift is due in the 2018-2028 window”? [italics added] How, and when, will the shift be recognizable? For example, will the trend of diminishing summer Arctic Sea ice cover clearly reverse? Will there be a statistically significant step change in the peaks or troughs of the multivariate ENSO index?
Clearly he has nothing and that comment was a baseless as I initially suspected it was. That is why he get defensive and uppity and avoids answering the question by diverting into banalities like “try googling climate shift”.
I just found out that Wolfgang Helmut Berger, the scientist that proposed the tidal nature of the 1500 year cycle, passed away last month.
I dedicate this article to him.
I am sorry he could not read the article and hope his contribution to this subject is properly acknowledged in the future.
‘Wolfgang Berger and Ulrich von Rad (2002) proposed that the 1500-year cycle is a harmonic of the beat between the moon’s nodal and apsidal precessions’
Willy de Rop of the Royal Observatory of Belgium proposed that the fundamental nodal/apsidal cycle is an
and the line of apsides (the Moon in its perigee)
orbit and the position of the Earth in the
the tidal forces exerted by Sun and Moon will
In unrelated research Keeling and Whorf found the same period.
‘The 1,800-year oceanic tidal cycle: A possible cause of rapid climate change’
1800-year cycle is 5 x the 370-year tidal unit, while the
1500-year cycle is 4 x the same unit. This unit is the apsidal and nodal beat frequency.
Keeling and Whorf results are important because they explore how a tidal cycle could actually exert its effect, but paleoclimatology identifies the cycle as
1800 years. My approach to the cycle is from evidence, not theory.
The apsidal and nodal beat frequency is just under 6 tropical years. Longer periods are a multiple of that.
See the diagram in de Rop’s paper (Fig. 2: 180 degrees in
My knowledge of lunar cycles is quite poor, but plenty of cycles to play with. The long beats could result from the closeness of the nodal precession (18.6 years) and twice the apsidal precession (8.86 years).
Lots of cycles can be derived, but only climate will tell us which ones end up being relevant for climate. I have seen Ian deduce a lunar 1470-year cycle, yet the climatic evidence supports a 1500-year cycle, not 1470, not 1800. How that cycle is achieved I don’t know, but if the experts get to work on that they will find out before 2180 AD for sure.
375 basic period, and the next peak is in
160 years, that means that (375/2 = 187.5) since 2000 we have started the upswing of this tidal cycle and we should see tides, winds, upwelling, and storm surges, going up increasing more and decreasing less with each tidal cycle known. That’s a pretty good prediction that we don’t have to wait 160 years to check.
Thank you for the reply above. Considering that my post above veered way beyond the fringe, the/any reply is appreciated.
But please allow me a bit more space here, for anyone interested. Do not stop with Dodwell. That subject was also investigated by Axel Wittmann, here: http://adsabs.harvard.edu/full/1979A%26A….73..129W Wittmann acknowledges that there exists an enigma and an anomaly. Wittmann also proposes his own formula for obliquity in same paper, but like the others, disagrees with the old measurements. I have started looking into these anomalies only after coming across the archaeological anomalous evidence (which is not easy to stomach). Present ‘belief’ in the nature of obliquity goes back to JN Stockwell, as the IAU acknowledges in its 2005 working group report (on obliquity and precession). As Dodwell found, the ancient measurements of obliquity do not correspond to Stockwell’s polynomial curve fitting, but are more of an exponential decay, starting from near the 4.2ky event. Note also Stockwell’s work ignores, but does not preclude transients/step changes.
To be clear, Wittmann later attributed the anomaly to errors in the old measurements. I have shown by experiment that simple ancient techniques (previously unknown) are extremely accurate; in fact as a solstice day and hour prediction, far batter than what simple methods we have today. So, no, there are no errors in the ancient readings. What I am stating here can easily be checked out by most of your readers.
I do not doubt the precision of past measurements of obliquity. The measurement of obliquity is fairly simple, even for non-technological civilizations. What I doubt is the conclusion that obliquity must have changed by a lot more than we currently accept. Obliquity has a huge effect on climate, and the climate of the Holocene has been very tame by comparison to glaciations and deglaciations. The answer to this riddle must lie somewhere else.
“The answer to the riddle” is important because it points to a fox in the chicken coop of what is considered established knowledge. I leave the case with two points to ponder.
1. The engineered manmade structures I refer to, once their workings were unravelled, leave little or no option for doubt -or escape-. They are simple and the dimensions tell the story plainly.
2. Quoting from this link: http://news.nationalgeographic.com/news/2011/03/110316-japan-earthquake-shortened-days-earth-axis-spin-nasa-science/ “Similar changes to Earth’s mass distribution were calculated from GPS data obtained during the 2004 Sumatra earthquake and the 2010 Chile earthquake. In the case of Sumatra, the change in the length of the day was larger: 6.8 microseconds.” And “But for the Japan earthquake, the change in Earth’s wobble was more than twice as large as those calculated for the 2004 and 2010 events.” We have proof of ‘transients’ and abrupt changes, though these are on the micro level. But so were the events that cause them, when compared to what took place early in the holocene as is evident in geology.
I am not saying that conjecture is impossible. I am just saying that the evidence is simply not solid enough to abandon everything we know about changes in obliquity with time. So I am not going to espouse such fringe conjecture in the absence of massive evidence. As it is frequently said, extraordinary claims require extraordinary evidence. Nevertheless I consider myself an open minded person, so I am more than willing to read and consider this and other conjectures,as it has happened on occasion that a fringe conjecture has turned out right.
Thanks a lot for these wonderful articles, Javier! They are very helpful. Dare we hope they are shaping up into a book?
A note on scientific methodology (where, unlike climate, I do know a bit), “prediction” in science is not exclusively about the future (no joke). If a theory implies that something happened half a million years ago, and you look for traces of that event and find that it did (or did not) occur, you are testing your theory by one of its “predictions”. What we call a “prediction” is simply any testable implication of a theory.
David Ramsay Steel: You never reflected my Climate Etc. response to your la-blog article, explaining your many errors and false assumptions, which you had undertaken so to do (or alternatively take down the article). Please can you make good on your offer. As no doubt you are well aware your blog is a private one with membership subject to approval, nor do I want to join this political forum, hence I am not able to do this myself. This is the third ask, please make good your offer:
Comment explaining the many issues (and 1st ask) here:
At the moment your essay still stands, yet with no indication that you have acknowledged the issues with it. Are you not a man of your word?
If anybody wants an article discussed by me and can’t locate it for free, I’ll make it available for download.
I’ve done some spectral analysis of NAO, it would be interesting to compare with what Berger did. Shame he’s not longer with us.
I don’t have that one available, sorry. Only the ones I discuss in my articles.
Fred Singer had a book “Unstoppable global warming every 1,500 years” about the D-O cycle
Just to play the devil’s advocate, I’m sure you are aware of Wunsch’s aliasing conjecture, quoted here in Maslin, Stickley and Ettwein 2001 in “Holocebe Climate Variability (doi:10.1006/rwos.2001.0246):
One cautionary note is that Wunsch has suggested a more radical explanation for the pervasive 1500- year cycle seen in both deep-sea and ice core, glacial and interglacial records. Wunsch suggests that the extremely narrow spectral lines (less than two bandwidths) that have been found at about 1500 years in many paleo-records may be due to aliasing. The 1500-year peak appears precisely at the period predicted for a simple alias of the seasonal cycle sampled inadequately (under the Nyquist criterion) at integer multiples of the common year. When Wunsch removes this peak from the Greenland ice core data and deep-sea spectral records, the climate variability appears as expected to be a continuum process in the millennial band. This work suggests that finding a cyclicity of 1500 years in a dataset may not represent the true periodicity of the millennial-scale events. The Holocene Dansgaard> Oeschger events are quasi periodic, with different and possibly stochastic influences.
Yes, I read Wunsch conjecture, however I disagreed with it and didn’t think it was worth mentioning it. Carl Wunsch published his criticism in 2000 using only the Polar Circulation Index from Paul Mayewski. The PCI peak at 1452-year periodicity is the result of using the original GISP2 age model, and using the new GICC05 age model the peak is shifted to
Wunsch explanation would not apply to other proxies that don’t have the required narrow spectral line.
Additionally Wunsch article was contested by no less than Meeker, Mayewski, Grootes, Alley, and Bond:
Meeker, L. D., et al. “Comment on “On sharp spectral lines in the climate record and the millennial peak” by Carl Wunsch.” Paleoceanography 16.5 (2001): 544-547.
For all these reasons I don’t think many authors consider that the 1500-year cycle is due to an aliasing artifact.
A post on this blog has been brought to my attention. May I just say that Andy West is under a misapprehension. He is free and welcome to post to the LA blog and any “approval” is automatically granted subject to the normal conventions regarding civility. He would not be joining a political group or expressing agreement with the Libertarian Alliance, but merely registering to participate in the London Libertarian blog.
Indeed. on the LA blog, anyone need not even join but can post to LA blog that I will then just post on for them.
One thought is entirely missing concerning the question: Is the DO cycle 1470 fix or 1500 yr fix? …… The answer is: The cycle is GROWING from 1470 into 1500 yr – growth is natural ….even the Earth orbit grows by 3 seconds per year….
The DO ice age cycle reaches its max of 1500 yr at 8,000 BC, followed by temps stay above in the interglacial mode and the 1500 yr cycle starts from scratch anew, at 8108 BC with
a cycle length of 576 yr with a cyclic growth of 6.93 yr. Combining those
500 – 600 year cycles will produce pure artifact 1000, 1500 and 2500 yr. cycles.