The role of mean ocean salinity in climate

• Published in: Dynamics of Atmospheres and Oceans
• Main Authors: Williams, P. D., Guilyardi, E., Madec, G., Gualdi, S., Scoccimarro, E.
• Other Authors: Williams, P. D.; NationalCentreforAtmosphericScience, DepartmentofMeteorology, UniversityofReading, UK, Guilyardi, E.; NationalCentreforAtmosphericScience, DepartmentofMeteorology, UniversityofReading, UK, Madec, G.; Laboratoired’OcéanographieetdeClimat:ExpérimentationetApprocheNumérique(LOCEAN/IPSL),CNRS/UniversitéParisVI,France, Gualdi, S.; Centro Euro-Mediterraneo per i Cambiamenti Climatici CMCC/INGV, Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia, NationalCentreforAtmosphericScience, DepartmentofMeteorology, UniversityofReading, UK, Laboratoired’OcéanographieetdeClimat:ExpérimentationetApprocheNumérique(LOCEAN/IPSL),CNRS/UniversitéParisVI,France, Centro Euro-Mediterraneo per i Cambiamenti Climatici CMCC/INGV, Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia
• Format: Article in Journal/Newspaper
• Language: English
• Published: elsevier 2010
• Subjects: ocean; salinity; climate; thermohaline circulation; 03. Hydrosphere::03.01. General::03.01.03. Global climate models; North Atlantic Deep Water; North Atlantic
• Online Access: http://hdl.handle.net/2122/5804; https://doi.org/10.1016/j.dynatmoce.2009.02.001

We describe numerical simulations designed to help elucidate the role of ocean salinity in climate. Using a general circulation model, we study a 100-year sensitivity experiment in which the global-mean salinity is doubled from its present observed value, by adding 35 psu everywhere. The salinity increase produces a rapid global-mean sea-surface warming of 0.8◦ within a few years, caused by reduced vertical mixing associated with changes in cabbeling. The warming is followed by a gradual global mean sea-surface cooling of 0.4 ◦C over the next few decades, caused by an increase in the vertical (downward) component of the isopycnal diffusive heat flux. We find no evidence of impacts on the variability of either the Atlantic thermohaline circulation or the El Ni ̃no/Southern Oscillation. The mean strength of the Atlantic meridional overturning is slightly reduced and the North Atlantic Deep Water penetrates less deeply. Nevertheless, our results dispute claims that higher salinities for the world ocean have profound consequences for the thermohaline circulation. In additional experiments with doubled atmospheric carbon dioxide, we find that the amplitude and spatial pattern of the global warming signal are modified in the hypersaline ocean. In particular, the ocean’s contribution to the climate sensitivity is significantly reduced. We infer the existence of a non-linear interaction between the climate responses to modified carbon dioxide and modified salinity. Published 108-123 3A. Geofisica marina e osservazioni multiparametriche a fondo mare JCR Journal reserved