Understanding regional sea-level changes in the recent past and future

/ February 4, 2013/ Ice and Climate, IMAU

Sea-level rise is  an important result of global warming, affecting many densely populated coastal communities. However, sea-level rise is not uniform around the globe: substantial regional deviations from the global mean sea-level change occur, which are caused by gravitational effects (for instance because of melting glaciers and ice sheets), groundwater extraction, variations in ocean density and dynamics, glacial isostatic adjustment and, to a lesser extent, atmospheric loading.

To make regional sea-level projections, we must first have a good understanding of these contributing processes. The research presented in my PhD-thesis focuses on the contribution of these processes to regional sea-level change patterns. First, we computed regional patterns of sea-level change for the period 1961-2003, and compared these to sea-level measurements over the same period. The  agreement supported our interpretation of regional variations in sea-level change.

The same approach was then used to make future projections (see Figure). These projections suggest that regional variations result in up to 30% more sea level rise in coastal regions along the north Atlantic Ocean and the Southern Ocean. Values up to 20% are found in equatorial and subtropical regions, while reduced sea-level rise down to 50% of the global mean value is projected for the Arctic Ocean, the subpolar north Atlantic Ocean and near West Antarctica (Figure 1). Our analysis shows that each individual process may dominate sea-level change regionally, stressing the need to explicitly include all these processes in sea level projections.

Aimée Slangen

Aimée’s thesis can be downloaded here.

Aimée worked at IMAU as a PhD student in the group of Prof. Hans Oerlemans. Since December 2012, when she obtained her PhD degree, she continued as a Post Doc at IMAU. You can view her personal page here.


Figure 1: Relative regional deviations from the global mean sea-level change (%) for the period 1986-2005 to 2081-2100, based on CMIP5 climate model data.