J. Atmos. Sci. http://doi.org/j63 (2013)

An understanding of recent variability in the Atlantic Ocean is needed to predict changes in the coming years, and the associated impacts on global weather patterns. Recent work has indicated that atmospheric aerosols were a primary driver of multi-decadal climate variability in the North Atlantic though the twentieth century. Evidence for this hypothesis is based on model simulations using the indirect effects of aerosols, which closely reproduced observations of North Atlantic basin-averaged sea surface temperature

A study by Rong Zhang at the Geophysical Fluid Dynamics Laboratory of the National Ocean and Atmospheric Administration, Princeton, USA, and colleagues, challenges this work by including additional oceanic parameters in their analysis. They show major discrepancies between the recently published simulations and observations in the North Atlantic for upper-ocean heat content, the spatial pattern of changes in sea surface temperature and subpolar sea surface salinity. Zhang et al. suggest that these differences are influenced and largely caused by aerosol effects, casting doubt on the claims that aerosol forcing is a prime driver of multi-decadal variability.