Why did the last 8 glacial periods only end when the earth’s orbit around the sun reached maximum eccentricity ? This is the real unsolved mystery of the Ice Ages as discussed in previous posts and recently on scienceofdoom.
With the last of these posts I finally thought there could be a solution to this mystery based on resonant interplanetary dust, but alas I could find no evidence whatsoeverin TSI dataand dismissed the idea. However I now realise that perhaps there is another solution which may have been looking us in the face all the time. The Earth already has a large resonant interplanetary body – the moon. There is no need to invent some hypothetical resonant dust. The trigger for interglacials is not changes in insolation but instead changes in tidal forces acting on the oceans and cryosphere. Every 100,000 years super-tides must occur whenever the decreased perihelion distance of the earth from the sun and the moon coincide and are synchronised with maximum eccentricity. These tidal forces combined with already known increases in insolation could well be the trigger that initiates the rapid break up and melting of the northern glaciers
THOUGH OFF BASE BY SEVERAL ORDERS OF MAGNITUDE, THIS STILL BEATS :
This post proposes that regular variations in interplanetary dust between the Earth and the Sun is the primary cause of recent ice ages whose oscillations have been parameterised here. The Milankowitz theory of insolation is able to well explain the continuous 41,000y climate oscillation but it cannot explain why a 100,000y cycle became prevalent during the last million years, even though it is in phase with orbital eccentricity of the Earth’s orbit around the sun. A different origin for the emergence of the 100,000y cycle of major ice ages is proposed. This is based on the hypothesis that a large comet broke up close to Earth’s orbit about 3.3 million years ago, leading to an increase in inter-planetary dust whose density eventually phase locked to variations in Earth’s eccentricity. This process is able to explain the cooling trend starting 3 million years ago eventually leading to major eccentricity driven glaciations with persistent modulation in insolation from the obliqueness cycle. Evidence in support of regular cycles in inter-planetary dust density have been found in ocean sediments, and there is some evidence of a comet fragment impacting with Earth at 3.3 million years ago.