Speculations on a schematic theory of the Younger Dryas

Abstract

The possible implications of a change in deep ocean mixing generated by the abrupt coverage of continental shelves during deglaciation is explored schematically. A simple Cartesian continental shelf/deep ocean tidal model is used to mimic the behavior of tidal dissipation at a variety of frequencies relative to a basin-near-resonance. The actual estimated sea level curve is then used to calculate a representative deep water tidal dissipation through time, which is then translated by means of a one-dimensional loop flow to explore the implications of a change in deep ocean mixing. It is possible to pick parameters for the loop model, which is analogous to the Stommel two-state box model, such that interesting transitions occur when diffusion alone is changed, including oscillatory responses. To the extent that the box model is believed to mimic the ocean circulation, it can produce shifts analogous to the re-glaciation and subsequent de-glaciation characterizing the Younger Dryas interval. That changing topography and winds would likely also have a profound influence on mixing by mesoscale disturbances is noted but not pursued.