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Abstract:
While there is evidence for an acceleration in global mean sea-level (MSL) since the 1960s, its detection at local levels has been hampered by the considerable influence of natural variability on the rate of MSL change. Here we report an MSL acceleration in tide gauge records along the U.S. Southeast and Gulf coasts that has led to rates (>10 mmyr-1 since 2010) that are unprecedented in at least 120 years. Using a variety of remote sensing and in-situ measurements in combination with climate model outputs, we show that this acceleration is primarily induced by an ocean dynamic signal exceeding the externally forced response from historical climate model simulations. However, when the simulated forced response is removed from observations, the residuals are neither historically unprecedented nor inconsistent with unforced variability in simulations. Furthermore, a large fraction of the residuals can be explained by remote wind forcing (via Rossby waves) over the tropical North Atlantic. This indicates that the acceleration represents the compounding effects of external forcing and internal climate variability.
