Quaternary Sea-Level Research

Sea level variations have been, are, and will always be taking place on local, regional, and global scales as well as on all temporal scales. Ranging from changes with frequencies of less than 1 Hz, such as capillary and small wind waves, to changes on time scales of several million years, regional and global sea-level changes have an enormous impact on coastal processes as well as on the coastal population. Sea level changes have been part of the earth history and, on geological time scales (millions of years), have been related to the geophysical processes forming the earth surface, such as plate tectonics and associated changes in the land-sea distribution. On shorter time scales, changes in the earth’s climate and associated sea-ice distributions seem to be responsible for much of the observed variations. With the discussion about modern climate change and the impact of the anthropogenic contribution, studies about past sea-level changes, driven by climate change, have gained huge interest. A specific focus is, thereby, put on past periods, when sea levels have been higher or rising faster than what we currently experience. Both situations have previously occurred, although it should be noted that during those times the world’s coasts had not yet been populated. During the last c. 7000 years, however, global sea levels have been remarkably stable as compared to previous time periods. The currently observed rapid increase in global sea levels is strongly related to anthropogenic emissions of greenhouse gases and will, in the future, lead to rates of sea level rise (SLR) that make it necessary for the coastal population to better adapt and protect themselves against marine hazards, such as storm surges. However, uncertainties related to the projection of future sea levels are high, with the largest uncertainties related to the nonlinear, threshold-driven behavior of the Greenland and Antarctic ice sheets. Hence, the analysis of Quaternary sea-level changes is particularly relevant, as these are primarily driven by glacial cycles, with extensive glaciers and ice sheets during cold climate periods (glacials) and small extents of glacier and ice sheets during warm climate periods (interglacials). This article gives an overview on the currently available literature about the causes and magnitudes of Quaternary sea-level changes as well as the potential impacts of current and future sea-level changes on the world’s coastlines