Climate stage· The columns of time

MIS 7

243 ka → 191 ka

Warm by convention, complicated in detail: not one interglacial but a set of mild intervals separated by cold ones, a useful reminder of how much these bands smooth over.

What the evidence shows

MIS 7 appears here as a single band, but the underlying curve shows several distinct peaks and the cold troughs between them; specialists number these substages 7a to 7e. The frieze draws the stage and not its parts, because at this width each part would be a few pixels wide. That is a legitimate simplification and also a real loss: for anyone living through them, these fifty millennia were not one long warm spell.

Bounds and conventions

The band hides its own structure. Where a stage is drawn as one colour, the reader should assume oscillation underneath: the LR04 curve is continuous, and every boundary placed on it is a decision about where a gradient becomes a threshold.

An interglacial, broken by cool episodes (7b, 7d).

Sources

  1. Lisiecki, L. E., Raymo, M. E. (2005). A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20, PA1003.
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Elsewhere on the column

A period boundary is a decision before it is a date. Where the two disagree, this entry says which is which.