Australia: The Land Where Time Began

A biography of the Australian continent 

Southern Ocean Buoyancy Forcing of Ocean Ventilation and Glacial Atmospheric CO2

According to Watson et al., concentrations of atmospheric CO2 over cycles of glacial and interglacial phases correspond to temperature patterns in the Antarctic (Siegenthaler et al., 2005). As these are distinct from variations of temperature in the mid- to northern latitudes (Shakun et al., 2012) this suggests the Southern Ocean is pivotal in controlling concentrations of natural CO2 (Sigman, Hain & Haug, 2010). In this study Watson et al. assessed the sensitivity of atmospheric concentrations of CO2 to glacial-interglacial changes in the meridional overturning circulation by using a circulation model (Nikurashin & Vallis, 2011; Nikurashin & Vallis, 2012) for upwelling and eddy transport in the Southern Ocean coupled with a simple biogeochemical description. A broader region of surface buoyancy loss results in upwelling farther north under glacial conditions. Outgassing of CO2, and stronger carbon sequestration in the deep ocean, results from the northern location of upwelling: Watson et al. calculating that the shift to this glacial style of circulation can draw down 30-60 ppm of atmospheric CO2. Therefore they suggest much of the strong correlation between temperature variations in the Antarctic and concentrations of CO2 over glacial-interglacial cycles explains the direct effect of temperature on buoyancy forcing in the Southern Ocean, and hence the residual overturning circulation.

Sources & Further reading

  1. Watson, A. J., G. K. Vallis and M. Nikurashin (2015). "Southern Ocean buoyancy forcing of ocean ventilation and glacial atmospheric CO2." Nature Geosci 8(11): 861-864.


Author: M. H. Monroe
Last Updated 02/11/2015
Journey Back Through Time
Experience Australia
Aboriginal Australia
National Parks
Photo Galleries
Site Map
                                                                                           Author: M.H.Monroe  Email:     Sources & Further reading