Millennial Scale Variability

Most climate and ice sheet modelling that addresses Pleistocene millennial-scale variability has been in the form of snapshots for individual times or modes, and not in long-term time sequences. This is true for mechanisms involving see-saw connections, ocean response to meltwater discharge, and thermohaline interactions between southern and northern high latitudes (reviewed in Rahmstorf, 2002; Clark et al., 2007). One exception is the modelling of the ice-sheet binge-purge mechanism for Heinrich Events (HEs) by Calov et al. (2002) who used a three-dimensional Laurentide ice sheet coupled to an EMIC. They integrated the coupled system through 200,000 years and obtained quasi-periodic HE-like surges due to basal melting and refreezing over Hudson Bay and Strait. However, the true causes of HEs and whether they are internal ice sheet oscillations or manifestations of oceanic sea-saw behaviour are active research questions (Clark et al., 2007).

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