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Earth's Tilt Increase Averted Ice Age?

  1. Feb 17, 2009 #1
    There is a lot of speculation about why the Earth has not entered into a new ice age, following on from the pattern of glacial cycles recorded in the polar ice cores. It is a possibility that the Earth's tilt towards the Sun actually increased in the recent past. I know this sounds slightly crazy, but it is a possibility. This would have the effect of increasing the summer temperatures of the high latitudes, which is a vital factor in determining whether there is snow accumulation which leads to glaciation. Here is an article which validates this idea:article.
     
    Last edited: Feb 17, 2009
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  3. Feb 17, 2009 #2

    mgb_phys

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    Re: Earth's Tilt Increase Overted Ice Age?

    We aren't due another ice age just yet (at least not for another 15-20,000 years). Interglacials last around 30,000yrs and we only had the last one 11,000 years ago.
    By another definition we are in an ice age, in that there is ice at the north pole which isn't usual taken over the history of the earth.
     
  4. Feb 17, 2009 #3
    Where do you get your information from?

    The Encyclopedia Britannica (link) states:
    Is this idea a valid explanation for global warming trends?
     
    Last edited: Feb 17, 2009
  5. Feb 17, 2009 #4

    mgb_phys

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    http://www.up.ethz.ch/people/flueckiger/publications/epica04nat.pdf [Broken]
    The idea that 11,000 years between recent ice ages doesn't look good. Especially because we are 11,000 years form the last one and the ice is still retreating - although to be fair, ice ages might start a lot quicker than they end.
     
    Last edited by a moderator: May 4, 2017
  6. Feb 17, 2009 #5
    The obliquity is currently decreasing which according to the Milankovitch hypothesis makes the earth more sensitive to glaciation.

    As we have seen that isotopes and actual other Earth temperature geologic proxies and records do not match, and we have seen that the dominant 100,000 isotope cycle cannot be associated with Milankovitch cycles, it's probably somewhat different.
     
  7. Feb 17, 2009 #6
    No. The Holocene thermal optimum peaked ~7000-8000 years ago. The long term trend has generally been one of cooling until recently.

    http://www.globalwarmingart.com/wiki/Image:Holocene_Temperature_Variations_Rev_png

    We are now in a new geologic epoch that is being termed the http://www.eoearth.org/article/Anthropocene"

    The alteration of the chemical and thermal structure of the atmosphere by human activity is more than enough to offset the small insolation distribution shifts. Human activity will prevent another glaciation.

    http://www.sciencedaily.com/releases/2008/12/081217190433.htm
     
    Last edited by a moderator: Apr 24, 2017
  8. Feb 17, 2009 #7

    Gokul43201

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    Even if the onset and retreat of interglacials looked symmetric, doesn't this assume that orbital forcing far outweighs all anthropogenic forcings? What kind of impact on the length of the interglacial would a 30% contribution from greenhouse gas forcings have?
     
  9. Feb 17, 2009 #8
    "No. The Holocene thermal optimum peaked ~7000-8000 years ago. The long term trend has generally been one of cooling until recently."
    That statement might not be accurate!
     
  10. Feb 17, 2009 #9

    Evo

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    Hi Mike, please use the "quote" button when replying to a post, not only does it separate your comment from the one you are responding to, it also serves as a link to the post you are quoting.

    Also, a response such as "That statement might not be accurate!" doesn't tell us anything. Please furnish information to substantiate why you believe this.

    Thanks.
     
  11. Feb 17, 2009 #10
    Not at all. There were no significant anthropogenic forcings until the Holocene. The orbital forcings themselves are very slight. Without the low frequency feedback from albedo changes and the carbon cycle there would be no interglacial periods. The dominant anthropogenic forcings are atmospheric emissions and albedo.

    Here is one perspective.

    http://www.columbia.edu/~jeh1/mailings/2008/20080910_Kingsnorth.pdf [Broken]
     
    Last edited by a moderator: May 4, 2017
  12. Feb 17, 2009 #11
    You could be right.

    http://en.wikipedia.org/wiki/Holocene_climatic_optimum
     
  13. Feb 17, 2009 #12

    Gokul43201

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    But we are talking about today (and tomorrow), not before the Holocene. Couldn't current anthropogenic forcings affect the timing of the next glacial?
     
  14. Feb 17, 2009 #13
  15. Feb 18, 2009 #14
    I see People using a trend in one cycle to claim a change in the current trend of a longer cycle. I would relate this to me claiming that I can use this morning to prove that the year has changed.
     
  16. Feb 18, 2009 #15
    The idea that I have is that in the last glacial cycle, a very large celestial body could have had a near-miss with the Earth. This could have significantly increased the Earth's tilt due to gravitational interaction. We are familiar with the Earth's tilt today, along with it's nutational cycle, and we assume that this is how it has always been. But it is not necessarily so. In the past the tilt could have been a lot less. There is no easy way to tell.

    In another thread, we have discussed the possibility of a massive body near-miss being responsible for the unusually well preserved mammoth finds around 40,000 B.P. See post #30 in this thread link. This idea has the potential to solve a number of Earth Science problems. All it requires is a bit of lateral thinking.

    Note that an increase in the Earth's tilt wouldn't increase the overall insolation reaching the Earth (i.e. it wouldn't cause global warming), but it would have the possibility of terminating the end of the pleistocene cycle of the ice ages. (article)
     
    Last edited: Feb 18, 2009
  17. Feb 18, 2009 #16
    I encourage you to explore your idea.

    What first order evidence is there to support such a hypothesis?

    If there was such an event there should be lots of supporting evidence.

    Have you looked into the geomagnetic record? Is there evidence of a major shift in the geomagnetic field? tidal disruptions would also be evident, and the moon's orbit would also likely be altered.

    Personally I think that most of climate history is explained by the interactions of the major forcings. The NH record is dominated by temperature spikes known as http://www2.ocean.washington.edu/oc540/lec01-31/" [Broken]

    I suspect that these events are dominated by ocean circulation. As one area cools another warms. Regional ice sheets begin to disintegrate until the rate of fresh melt water once again speeds up the THC.
     
    Last edited by a moderator: May 4, 2017
  18. Feb 18, 2009 #17
    In my lateral thinking, the close passing of a hypothetical large body would do a lot of other things before changing the obliquity of the spin axis. It's gravity would exert unusual forces on Earth with two main effects, both an unpredictable assymetric tide change, which could be generating massive floods and a major exchange of energy disrupting the orbit around the sun, which would be causing a noticeable shift in yearly day count and eccentricity.

    Do we see that?
     
  19. Feb 19, 2009 #18
    The magnetic field has "flipped" more than just once. The globe appears to be following/experienceing a cause and effect group of cycles for some time and other than speculation there is insuffecient evidence to suppport a major shift in that pattern recently. (within the last 100k years)
     
  20. Feb 20, 2009 #19
    No-one is talking about magnetic pole reversals. This is something completely different.
     
  21. Feb 20, 2009 #20

    Evo

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    Mammo, we do not allow overly speculative posts without any serious scientific backup, such as published peer reviewed papers.
     
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