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The Dansgaard paper I've seen shows a roughly linear relationship between the delta-O18 in precipitation and mean annual temperature (at a given location). See Figure 3 in the paper.

When converting delta-O18 into a corresponding delta-temperature, is this simple linear relationship assumed? Or is it more complex than that? What caveats or assumptions go into such a conversion?

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  • $\begingroup$ Very inaccurately, because precise measurements of the various isotopes are difficult to make, and you don't know where these isotopes were picked up from before they were precipitated into your Ice core. It might have been the Gulf of Mexico in summer, or the Denmark Straits in winter, so a great variety of sources and temperatures.. $\endgroup$ – Michael Walsby Sep 15 '19 at 16:58
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    $\begingroup$ Note that the Dansgaard paper cited in the question uses the mean annual temperature at the 'target' not the 'source'. In this case, the 'target' is simply the location of the ice core. (You shouldn't use the comment feature to provide an answer.) $\endgroup$ – John O Sep 15 '19 at 18:09
  • $\begingroup$ The ratio of heavy isotopes to light isotopes in the precipitation depends on the temperature and evaporation rate of the source, not the target. It also depends on the amount of fresh water in the source (fresh water has less of the heavy isotopes). $\endgroup$ – Michael Walsby Sep 15 '19 at 19:15

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