Sea-level rise and decadal variability along the northwestern coast of the North Atlantic Ocean are studied in a self-consistent framework that takes into account the effects of solid-earth deformation and geoid changes due to large-scale mass redistribution processes. Observations of sea and land level changes from tide gauges and GPS are compared to the cumulative effect of GIA, present-day mass redistribution, and ocean dynamics over a 50 year period (1965–2014). GIA explains the majority of the observed sea-level and land motion trends, as well as almost all interstation variability. Present-day mass redistribution resulting from ice melt and land hydrology causes both land uplift and sea-level rise in the region. We find a strong correlation between decadal steric variability in the Subpolar Gyre and coastal sea level, which is likely caused by variability in the Labrador Sea that is propagated southward. The steric signal explains the majority of the observed decadal sea-level variability and shows an upward trend and a significant acceleration, which are also found along the coast. The sum of all contributors explains the observed trends in both sea-level rise and vertical land motion in the region, as well as the decadal variability. The sum of contributors also explains the observed acceleration within confidence intervals. The sea-level acceleration coincides with an accelerating density decrease at high latitudes.

Timeseries of observed and projected sea level changes for the 20th and 21st century are analyzed at various coastal locations around the world that are vulnerable to climate change. Observed time series are from tide gauges and altimetry, as well as from reconstructions over the last 50 years. CMIP5 coupled atmosphere-ocean model output of regional sea-level and associated uncertainty estimates are merged with scenario-independent contributions from GIA and dynamic ice to provide time series of coastal sea-level projections to the end of the 21st century. We focus on better quantifying the regional departure of coastal sea level rise from its global average, identify the reasons for the regional departure, and quantify the reasons for the uncertainty in these regional projections. Many of these coastal sea level projections are lower than the global mean change in sea level due to glacial isostatic adjustment, and gravitational changes from loss of land ice and terrestrially stored ground water. In most coastal regions, local deviations from the global mean vary up to ±20 cm which, depending on the location, differ substantially in their underlying causes.

Data from 21 years of satellite altimeter measurements are used to identify and understand the major contributing components of sea surface height variability (SSV) on monthly time-scales in the North East Atlantic. A number of SSV drivers is considered, which are categorised into two groups; local (wind and sea surface temperature) and remote (sea level pressure and the North Atlantic oscillation index). A multiple linear regression model is constructed to model the SSV for a specific target area in the North Sea basin. Cross-correlations between candidate regressors potentially lead to ambiguity in the interpretation of the results. We therefore use an objective hierarchical selection method based on variance inflation factors to select the optimal number of regressors for the target area and accept these into the regression model if they can be associated to SSV through a direct underlying physical forcing mechanism. Results show that a region of high SSV exists off the west coast of Denmark and that it can be represented well with a regression model that uses local wind, sea surface temperature and sea level pressure as primary regressors. The regression model developed here helps to understand sea level change in the North East Atlantic. The methodology is generalised and easily applied to other regions.