WHOI PO

The last deglaciation was a two-step process, a sudden warming (Bolling-Allerod) followed by a gradual cooling over a 3000 year period (Younger Dryas), followed by another sudden warming to near-modern conditions. The ice sheets have been implicated in this rapid climate change, but a recent study of ancient corals has implicated the deep oceans (Thiagarajan et al. Abrupt pre-Bolling-Allerod warming and circulation changes in the deep ocean. Nature 511, 75-81, 2014). I will first review the climate data and then report on some numerical modeling with Zhan Su, a Caltech graduate student, that seems to support the oceanic hypothesis. The mechanism is thermobaric instability, which depends on the increase of the thermal coefficient of expansion with depth and can lead to a sudden release of stored potential energy (Ingersoll. Boussinesq and anelastic approximations revisited: Potential energy release during thermobaric instability. J. Phys. Oceanogr. 35, 1359-1369, 2005; Adkins et al. Rapid Climate Change and Conditional Instability of the Glacial Deep Ocean from the Thermobaric Effect and Geothermal Heating. Quaternary Sci. Rev. 24, 581-594, 2005). We have run our model with realistic parameters and will compare the results with the deglaciation record.