Séminaire
Previous work has highlighted salinity pattern amplification (PA) in long-term trend estimates from observations and modelled historical and future climate simulations. These results suggest that fresh ocean regions are becoming fresher, and salty regions saltier in response to evaporation minus precipitation (E-P; water cycle) changes driven by a warming Earth - an ocean proxy for the 'rich get richer' (wet gets wetter, dry gets drier) mechanism. The global evaporation (E) and precipitation (P) surface fluxes over the ocean comprise 75-85% of the climatological annual mean global water cycle of the entire Earth surface and are a good place to look for temporal variations in the observed record.
Using the CMIP (Coupled Model Intercomparison Project phase 3 & 5) 20C3M/historical (20th century), SRES/RCP (future 21st century) and pre-industrial (piControl; unforced) simulations, we diagnose the relationship between the simulated ocean surface salinity and the simulated E-P (water cycle) changes. We investigate the intrinsic variability of both the modelled salinity and E-P fields to ascertain an envelope of modelled unforced (piControl) climate variability. We compare these unforced distributions to those of weakly (20C3M/historical) and strongly-forced (SRES/RCP) simulations to determine the emergence of an anthropogenic-forced fingerprint from intrinsic variability as defined by the models.
Using these forced-signal versus variability estimates from models, we revisit the observed salinity PA, investigate the significance of resolved changes over 1950-present and discuss implications to previous conclusions discovered by this updated analysis.