North Atlantic Sea Surface Temperature Variability: Impacts, Mechanisms, and Challenges

ABSTRACT

North Atlantic sea surface temperatures (SST) exhibit variability on interannual to centennial timescales with significant regional and global impacts on Atlantic hurricane activity, marine heat waves, and other weather extremes. This review synthesizes current understanding of North Atlantic SST variability, its mechanisms, impacts, and challenges across multiple timescales with help of a conceptual stochastic climate model hierarchy and a focus on the extratropical region, where many outstanding questions remain. On interannual timescales, SST variability is driven primarily by the North Atlantic oscillation (NAO), though oceanic processes in regions like the Gulf Stream are increasingly recognized to play active roles. On decadal‐to‐multidecadal timescales, the relative contributions to Atlantic multidecadal variability (AMV) from internal variability versus external forcing remain debated, with emerging evidence suggesting externally forced signals may be more significant than previously thought. Fundamental disagreements also persist over whether the Atlantic Meridional Overturning Circulation (AMOC) or stochastic atmospheric forcing (e.g., NAO) drives internal AMV. At centennial scales, the North Atlantic “warming hole” emerges as a critical phenomenon, with ongoing debates whether the observed trend results from weakened AMOC or enhanced atmospheric westerlies. Growing concerns about potential collapse of the AMOC highlight the importance of understanding these longer‐term variations. Major challenges persist including the respective roles of the atmosphere and ocean in these variabilities, substantial model spreads and biases, and the signal‐to‐noise problem, all related to how SST variability will respond to continued warming. These fundamental questions may be addressed using model hierarchy and high‐resolution models.

This article is categorized under:

Paleoclimates and Current Trends > Modern Climate Change