evidence: Regional Relative Sea-Level Change Although changes in global mean sea level (GMSL) provide an important measure of the warming climate, when assessing potential impacts at the coast, it is the change in regional relative sea level that is most important. Regional relative sea-level change is influenced by multiple physical processes that vary both in space and time and can lead to large regional departures from the long-term rate of global mean sea-level rise. For each process, a brief description is provided, in addition to a summary of the observing systems used to measure that process, and a future outlook for the understanding of that process. While there are different ways to separate and group the contributing processes, we define regional relative sea-level change as follows, with each process changing in both space and time: Regional Relative Sea Level = Short-Term Effects + Sterodynamic Variability + Glaciers + Land Water Storage + Ice Sheets + Subsidence