Talk:100,000-year problem

GA review --Pass

The GA criteria are:

1. High quality prose, including proper spelling, grammar, and clear language. Also look for proper formatting and organization of the article, with appropriate use of wikilinks, sections, table of contents, and general organization as spelled out in the Manual of Style.
2. Adequate referencing, preferably with the use of either inline or Harvard citations
   • --Passed
3. There is appropriate broadness of coverage of the topic
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4. It is written from a neutral point of view
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5. It has not been the subject of recent editwars (check the history)
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On the first point, the article can use some additional minor copyedit, but I'll just do it rather than quibbling about it here. -Arch dude 15:11, 26 May 2007 (UTC)

For what it's worth, I'm not so sure that this article is particularly good. It seems to be angled to favour the minority "inclination" theory of the 100ka cycle, and while it is nice to see a discussion of Nick Shackleton's 2000 paper, the summary of it here is a bit simplistic. Shackleton did not presume to know what the ice volume response to orbital forcing would be: rather he obtained the linear component of that response by identifying it by spectral analysis. The comparison of the response between the marine record and that recorded in the Antarctic ice at Vostok indicated the component of the record that could be attributed to ice volume, and most of the (substantial) remainder is attributed to deep water temperature changes.

The orbital tuning of the ice record used in Shackleton's 2000 paper has been criticised in a recent Nature paper, (Kawamura et al. Nature Vol. 448, No. 7156, pp. 912-917, 23 August 2007), but it should be noted that Shackleton's chronology was far closer to Kawamura's chronology than any of the chronologies based on ice accumulation calculations. The Dole effect implications of Kawamura's timescale do not yet appear to have been worked out (or at least published), whereas Nick Shackleton's model was explicit.

A couple of other points that may be of interest: one million years is sufficient for a spectral analysis, even one of the 100,000 year component. As far as I know the only people who discount longer isotopic records (such as the Lisiecki and Raymo LR04 stack) tend to be people who don't like these records for other reasons - eg because these records make it clear that the "inclination" theory is untenable. The Kawamura et al. paper is also, incidentally, inconsistent with the "inclination" idea and favours the traditional Milankovitch hypothesis. In climate research circles, in my experience, the inclination theory is widely regarded as "old hat". That is not to say it isn't interesting, or that it is necessarily wrong, but it shouldn't be put over as if it is the currently most plausibly explanation of the ca. 100,000 year component of climate cyclicity. Nick Shackleton himself thought that the mechanism was a nonlinear response to orbital eccentricity involving carbon dioxide, and presented a poster on the subject at AGU shortly before his death. In general, as the Wikipedia orbital forcing page asserts, orbital eccentricity is thought to be responsible for the 100,000 year cycle. This is not, of course, to doubt the good intentions of those who put the page together. Orbitalforam 15:04, 12 September 2007 (UTC)

Hi, many thanks for your comments! My intention on writing this article was not to give undue weight to any one theory - apologies if it's come across that way! From my (admittedly limited) understanding of the subject, I'm not thoroughly convinced that we've got enough evidence to support or oppose any one theory with any real clamour - although I'm not sure I fully understand the Milankovic theory, which I'll have to look further into. For now, I've made some minor re-wordings to try to address any perceived weighting towards that theory, which will hopefully rebalance things a little: I'll work to address your other points when I've more time and energy!

Thanks, Verisimilus T 17:38, 12 September 2007 (UTC)

Thanks very much, Verisimilus, and I'm sorry if I phrased my reservations too strongly earlier - the work you've put in is much appreciated and I'm sure that something excellent will develop if we all do our bit. I might edit the summary of Nick Shackleton's paper to some extent, but the "gist" of it is there and it is good to see it discussed - it was a spectacularly elegant use of spectral analysis, even if if wasn't completely correct - and Nick would have been the first person to admit its flaws. He would have truly appreciated the Kawamura et al paper, and the insights it provides into orbital mechanisms. If only the ice core people had been a bit less reluctant to accept orbital tuning as a valid approach, as a viable alternative chronological hypothesis - so much time could have been saved. But scepticism is a virtue in science, quite rightly! Nick's 2000 paper also showed that, looked at in his way, the marine isotopic signal of ice volume change lags orbital eccentricity, which is crucial to understanding the mechanisms involved.

You're quite correct that no-one can say - even now - what the definitive answer is to the 100k problem: it still is a problem, because the 100k nonlinearity is massive and badly needs to be understood: it is one of the greatest current problems in palaeoclimatology. The solution appears rather unlikely to be orbital inclination, though, for the reasons discussed, and I think the article would be better if it reflected that. The essence of the 100k problem seems to be precisely that there is a huge nonlinearity in the climate system's response to the eccentricity forcing, rather than uncertainty about the broad chronology of deglaciations. Others may disagree, but that is my guage of the current consensus as far as there is one.Orbitalforam 09:53, 13 September 2007 (UTC)

GA Sweeps Review: Pass

As part of the WikiProject Good Articles, we're doing sweeps to go over all of the current GAs and see if they still meet the GA criteria. I'm specifically going over all of the "Meteorology and atmospheric sciences" articles. I believe the article currently meets the criteria and should remain listed as a Good article. I have made several minor corrections throughout the article. Altogether the article is well-written and is still in great shape after its passing in 2007. Continue to improve and expand the article making sure all new information is properly sourced and neutral. It would be beneficial to go through the article and update all of the access dates of the inline citations and fix any dead links. If you have any questions, let me know on my talk page and I'll get back to you as soon as I can. I have updated the article history to reflect this review. Happy editing! --Nehrams2020 (talk) 23:44, 19 March 2008 (UTC)

Another hypothesis - obliquity & "skip a beat"

I've heard some talk of the 100,000 changes to actually be 80,000 or 120,000 changes due to ~40,000 year obliquity changes, but with some cycles missed (from feedbacks). This hypothesis isn't listed as one currently. It may be worth adding? (Note: I only read abstract, but have heard of the "skip a beat" elsewhere). Jacobkhed (talk) 21:53, 26 February 2016 (UTC)

References

Dust-Ice Albedo Theory

Per Wikipedia:Fringe_theories/Noticeboard#Peer_reviewed_journal_with_a_climate_change_denier.27s_article, is http://www.sciencedirect.com/science/article/pii/S1674987116300305 reliable? I'm not sure; but I'm dubious that a theory with only one source paper belongs in the article William M. Connolley (talk) 19:46, 19 September 2017 (UTC)

It makes reasonable amount of sense, but the sentence Yet this common assumption, which has been endorsed yet not fully explained by the IPCC, is by no means universally accepted sounds a little off. Probably better that we wait until more people are citing this bit of research, as is it might be a fringe theory. Jo-Jo Eumerus (talk, contributions) 15:02, 20 September 2017 (UTC)

Possibly unreliable citation and section it supports

Doug Weller has stated here, that Ralph Ellis is not published in peer reviewed journals. Does that mean that the section at Dust-ice albedo theory, depending on a sole Ellis citation, is not valid? ☆ Bri (talk) 03:44, 15 October 2017 (UTC)

See the section above. But yes: no-one has spoken up for it so I've taken it out William M. Connolley (talk) 07:52, 15 October 2017 (UTC)

Just to clarify, he hasn't been cited. He has been published in an Elsevier journal published by a Chinese University, which is puzzling because he is basically a self-published author[1] writing about " revisionary religious history", particularly about the "real King Jesus" and is described on his website thus: "He started as a software engineer, but moved into the equally technical spheres of mineral surveying, aviation, and palaeoclimatology,".[2] His views on climate change are more pithily described here. One of his now blocked sockpuppets, Tatelyle, added the material. Thanks William. Doug Weller talk 09:41, 15 October 2017 (UTC)