Talk:Dansgaard-Oeschger event

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(William M. Connolley 10:19, 6 Mar 2005 (UTC)) I'll read the paper tomorrow. For now, my opinion is that relying on *one* paper for information this precise is inappropriate. The text, as it stands on the page, is far too definite.

Well, the study is about the precision. As for "relying on one paper for information this precise is inappropriate", let's all keep that in mind. Temperature record of the past 1000 years (SEWilco 19:27, 6 Mar 2005 (UTC))

I am far from an expert, so please feel free to point out any egregious errors in the plots and revert if necessary - just trying to inject a little aesthetics. Leland McInnes 08:41, 5 February 2006 (UTC)

[edit] Rapidity?

JimR added:

typically over 1-100 years,

I'm fairly doubtful about this. The gas stuff doesn't have 1y resolution. The isotopes might, in theory, but I don't think they show changes that fast. There is a recent paper (GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L24703, doi:10.1029/2005GL024486, 2005) wot sez:

Extremely rapid fluctuations observed in records of electrical conductivity measurements (ECM) from Greenland ice-cores provoked the idea that the climate system may be capable of flickering between two states during rapid climate transitions. Here it is shown that in general, the flickers seen in ECM records probably reflect the highly non-linear response of electrical conductivity as ice approaches acid/base neutrality, rather than significant changes in the climate system. High frequency, relatively low amplitude changes in chemistry, superimposed upon the broader changes typical of climate transitions would be capable of producing the observed characteristics of ECM records. It must be stated that this result does not detract from the observation of extremely rapid changes in, for example, ice core chemistry and isotopes, which clearly demonstrate that Earth’s climate is capable of very rapid and major reorganisations.

which suggests that some elements of the "rapidity" seen may not be real. William M. Connolley 11:41, 19 February 2006 (UTC)

The paper William mentions is by Stephen Barker, at [1]. Alley (2000), which I cited in the article, says that the GICP and GISP2 ice-core records "provide annual resolution for some indicators", but also that "The warming as recorded in gas isotopes occurred in decades or less" (in line with William's point about gas resolution being less precise than annual). Alley (2000) also refers to an earlier paper, Taylor et al (1997) Science 278 825-827 The Holocene-Younger Dryas Transition Recorded at Summit, Greenland (free abstract; full text). This does refer to increases in non-sea-salt sulphate and direct-current electrical conductivity over periods of less than 5 years: the Barker article's cautions would seem apply to these measurements. However, Taylor et al also say:

Between 11,645 and 11,612 B.P., there are excursions in delta D, deuterium excess, mean particle size, non-sea-salt calcium, and accumulation that last <5 years.

Aren't these data free of the caveats Barker makes about ECM? -- JimR 01:46, 26 February 2006 (UTC)