The stabilization of the thermohaline circulation by the temperature-precipitation feedback

The meridional freshwater flux in the atmosphere, and hence the strength of the hydrological cycle, undergoes variations on glacial-interglacial as well as on some shorter timescales. A significant portion of these changes to the hydrological cycle are due to the temperature-precipitation feedback according to which there is more precipitation over the higher latitudes during warm periods when the moisture holding capacity of the atmosphere is higher. It is proposed here that this feedback may play an important role in determining the stability of the thermohaline circulation (THC). The THC stability to different parameterizations of the meridional atmospheric freshwater flux is therefore investigated using a simple box model of the ocean, atmosphere, and sea ice. It is demonstrated that parameterizations that are consistent with the temperature-precipitation feedback, and hence with the observed variations of the hydrological cycle during glacial-interglacial cycles, stabilize the THC for a wide range of forcing parameters.