Original data is archived at WDCP here. I compared this data to Mann's versions and noticed some puzzling differences. The coronatus data (both C13 and O18) contains only one value in the 20th century. Although the Mann version is consistent with interpolation in the pre-modern period, Mann's modern values contain values that do not exist in the official archive. Where on earth did Mann's 20th century values come from?

The original publication clearly marks a MWP, though it ends in the 950-1100 period that is often highlighted by other data. I'm not convinced that a lot of weight can be placed on the author's dates.
The sediments are dated by 5 dates from terrestrial wood (as there is a large reservoir effect in the gastropod radiocarbon dates) with only 2 dates from the last millennium. Dates are interpolated assuming that each date is exact i.e. varying sedimentation rates. If a uniform rate were assumed (and there are only 5 dates), this would reduce the estimated age of sediments in this period by about 90 years or so and would delay the estimated date of the end of the MWP in this region. (Craig Loehle has always emphasized these sorts of dating issues as a potential source of incoherence.)

Alimate Audit

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