A Simple The 100-Kyr Tidal Cycle?

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Discussion Overview

The discussion revolves around the 100,000-year tidal cycle and its potential implications for climate change, particularly in relation to orbital eccentricity and tidal variations. Participants explore various scientific reports and their interpretations, focusing on the interplay between tidal forces and climatic events over different timescales.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant expresses frustration that the tidal cycle due to eccentricity variations is not given adequate consideration in climate discussions, suggesting that gravitational entropy may amplify tidal variations affecting deep-sea temperatures and CO2 cycles.
  • Another participant notes the discrepancy between the 1,800-year tidal cycle discussed in a referenced report and the 100,000-year cycle, questioning how these cycles might theoretically influence climate and whether they match in amplitude and phase.
  • A later reply highlights that the referenced report tentatively concludes that varying eccentricity could contribute to the 100-kyr cycle of glaciation, suggesting a possible connection between tidal forcing and glaciation cycles.
  • Participants discuss the interpretation of sediment cores by Bond et al., which indicate a 1- to 2-kyr periodicity linked to cooling events, including the Little Ice Age, and question how volcanic eruptions, such as the Huaynaputina eruption in 1600, fit into this narrative.
  • One participant argues that the persistence of the millennial cycle into the Holocene does not negate the impact of volcanic eruptions on climate, asserting that the 1,800-year tidal cycle could convincingly explain the millennial cycle.

Areas of Agreement / Disagreement

Participants express differing views on the significance of tidal cycles in relation to climatic events, with some supporting the tidal explanation while others raise questions about the connections and implications of various cycles. The discussion remains unresolved with multiple competing perspectives presented.

Contextual Notes

Participants reference various scientific reports and interpretations, indicating a need for clarity on the relationships between different timescales of tidal cycles and their climatic impacts. There is an acknowledgment of the complexity involved in understanding these interactions.

Mammo
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I was slightly exasperated with this http://www.sciencemag.org/cgi/content/abstract/289/5486/1897 report:

"It is difficult to explain this predominant cycle in terms of orbital eccentricity because the 100,000-year radiation cycle (arising from eccentricity variations) is much too small in amplitude and too late in phase to produce the corresponding climatic cycle by direct forcing"

Why isn't the tidal cycle due to eccentricity variations given due consideration? The http://pangea.stanford.edu/research/Oceans/GES205/1800yrTidalCycleForcingAbruptClimateChange.pdf give the tidal explanation much credibility. I further propose that the tidal variation could be amplified due to the effect of gravitational entropy (this is a subtle proposal which links the Earth science mysteries with those of modern physics). All of the major components of the system discussed are affected by tidal forces i.e. deep-sea temperature, the CO2 cycle, and the Dole effect. So why it is so blatantly ignored?
 
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That report talks of tidal variations at a period of 1,800 yrs which differs from the 100,000 yr cycle that you originally referred to. Granted, you might expect tidal cycles to match up with eccentricity cycles, in which case you would need to explain the amplitude and the phase that these cycles would theoretically have on climate (I guess you would need to understand how the oceans interacted at these scales)- do they match?
 
billiards said:
That report talks of tidal variations at a period of 1,800 yrs which differs from the 100,000 yr cycle that you originally referred to. Granted, you might expect tidal cycles to match up with eccentricity cycles, in which case you would need to explain the amplitude and the phase that these cycles would theoretically have on climate (I guess you would need to understand how the oceans interacted at these scales)- do they match?

The end of the report touches on the application of the idea to explain the 100-kyr orbital cycle:

"We tentatively conclude that, although varying eccentricity strongly affects tidal forcing, and could possibly contribute to the 100-kyr cycle of glaciation.."

The depth of the report suggests that there is a good match with the millennial cycle. I'm not an expert, but I can see that this is a distinct possibility of an explanation made by recognised scientists in the field. I just don't know why the tidal cycle is not more widely discussed.
 
The Keeling paper makes the following statement on the first page:

Interpretations of sediment-cores by Bond et el indicate, however, that a 1- to 2-kyr periodicity persisted almost to the present, characterized by distinct cooling events, including the Little Ice Age that climaxed near A.D. 1600.

The problem with this is that it is well established that the Huaynaputina stratovolcano in Peru exploded in the year 1600. Sulfuric acid levels (aerosal cooling) in the Greenland ice sheets were extremely high. Numerous records of famines, tree rings and ice conditions show that 1601 was one of the coldest in history and not surprisingly it took years for the climate to recover.
 
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Xnn said:
The Keeling paper makes the following statement on the first page:

Interpretations of sediment-cores by Bond et el indicate, however, that a 1- to 2-kyr periodicity persisted almost to the present, characterized by distinct cooling events, including the Little Ice Age that climaxed near A.D. 1600.

The problem with this is that it is well established that the Huaynaputina stratovolcano in Peru exploded in the year 1600. Sulfuric acid levels (aerosal cooling) in the Greenland ice sheets were extremely high. Numerous records of famines, tree rings and ice conditions show that 1601 was one of the coldest in history and not surprisingly it took years for the climate to recover.

I don't understand how you interpret the Huaynaputina eruption as a problem. The millennial cycle is shown to persist into the Holocene. This doesn't exclude the notion of climatic events being caused by the occassional volcanic eruption as well. The 1,800-yr tidal cycle of the Moon to explain the millennial cycle is a convincing one in my mind.