The land-ice contribution to 21st-century dynamic sea level rise

Abstract

Abstract. Climate change has the potential to influence global mean sea level through a number of processes including (but not limited to) thermal expansion of the oceans and enhanced land ice melt. In addition to their contribution to global mean sea level change, these two processes (among others) lead to local departures from the global mean sea level change, through a number of mechanisms including the effect on spatial variations in the change of water density and transport, usually termed dynamic sea level changes.In this study, we focus on the component of dynamic sea level change that might be given by additional freshwater inflow to the ocean under scenarios of 21st-century land-based ice melt. We present regional patterns of dynamic sea level change given by a global-coupled atmosphere-ocean climate model forced by spatially and temporally varying projected ice-melt fluxes from three sources: the Antarctic ice sheet, the Greenland Ice Sheet and small glaciers and ice caps. The largest ice melt flux we consider is equivalent to almost 0.7 m of global mean sea level rise over the 21st century. The temporal evolution of the dynamic sea level changes, in the presence of considerable variations in the ice melt flux, is also analysed.We find that the dynamic sea level change associated with the ice melt is small, with the largest changes occurring in the North Atlantic amounting to 3 cm above the global mean rise. Furthermore, the dynamic sea level change associated with the ice melt is similar regardless of whether the simulated ice fluxes are applied to a simulation with fixed CO 2 or under a business-as-usual greenhouse gas warming scenario of increasing CO 2 .

Sources of 21st century regional sea-level rise along the coast of northwest Europe

“…However, it is also noticeable that the local sea-level rise is greater than the global mean in our study, but smaller in the other two. The main reason for this is the smaller contribution from the Greenland ice sheet in our projections (see Howard et al, 2014). (The fingerprint of Greenland melt is characterised by less-than-global-mean increases around NW Europe).…”

“…Our TIM and Mn_GCFF are based on work described in Spada et al (2013). Our Mn_IDSL contribution is discussed extensively by Howard et al (2014). Consequently, we focus here on the SRG contribution for NW Europe.…”

“…Sterl et al, 2009;Howard et al, 2010) have shown that it is reasonable to combine surge changes additively with mean sealevel change. Similarly Howard et al (2014) show that for their model IDSL and ADSL changes appear to be additive. Therefore we present an illustrative addition of HE contributions to the change in the height of the 50-year storm surge, for seven locations around NW Europe in Fig.…”

“…We partitioned each time series into a global mean (TIM 1 ) and spatially varying component (GCFF). We selected data for the 2080-2099 period, calculating changes with respect to 1992 (see Howard et al, 2014 for further details). This model output was provided on a grid (described by Spada and Stocchi, 2007) with lower resolution than our surge model grid (shown, for example, in Fig.…”

“…In this study, we use projections of regional sea-level change arising from 21st century ice loss from ice sheets and glaciers (Spada et al, 2013;Howard et al, 2014), including the effects of changes to the gravity field and Earth rotation. We also include modelled changes in the climate of storm surges produced in support of the UK Climate Projections, Marine and Coastal Projections 2009 (UKCP09; Lowe et al, 2009) -a project to investigate the projected major contributions to 21st century change in coastal flood risk and shelfsea hydrology around the coast of the United Kingdom.…”