Decomposition of projected regional sea level rise in the North Atlantic and its relation to the AMOC

Abstract

While it is well understood that thermal expansion dominates global mean steric sea level rise, climate models show large differences in spatial patterns. This study aims to decompose regional steric sea level rise in the North Atlantic into thermal and saline effects in a fully coupled model. In contrast to other studies we focus on the differences between two climate change scenarios and establish a link between the sea level changes and the differences in the response of the overturning circulation. While overturning is reduced in the phase of the greenhouse gas increase, differences between the scenarios are not significant until the stabilization in the 22nd century. The influence from thermosteric and halosteric contributions on the meridional density gradient is of the same size during the increase of greenhouse gas concentrations. The haline effect becomes prominent afterwards, reducing the meridional density gradient and preventing the overturning from recovery. Copyright 2009 by the American Geophysical Union.