Below is a plot comparing sediment BSi (biological silica) to depth (cm) from two of Kaufman’s lakes (done by different students). I’ve shown it by depth (rather than ascribed age) since the dating of these sediment series is not without some hairiness. I’ve shown equal lengths for each lake, both covering at least 800AD-present on their assigned dates. The dotted red line shows where 1963 is assigned in each study (1963 is a key date in radiogenic sediment testing.)
Kaufman et al 2009 used only one of these series (and I’m sure that the reasons are impeccable.) Similarly only one of the two series is archived in the NCDC paleo archive (I’ve extracted the other data from an online M.Sc. thesis). Again I’m sure that the reasons for only placing one of the two series in the NCDC paleo archive are impeccable.
The question for CA readers: which of the two series is used in Kaufman et al 2009? No prize for guessing the correct answer.
BTW I wish that site reports for climate proxies were as well presented as the MSc theses of Kaufman’s students – the attention to detail in these theses makes them infinitely better resources than journal publications by their professors.
UPDATE: Here’s another Alaskan BSi series from a Kaufman student – a site also not used in Kaufman et al 2009 and not archived. In this case, the thesis has a photoimage of the data (which, as a result, cannot be readily extracted as it could from the other two theses):