title: Sea level: measuring the bounding surfaces of the ocean.
abstract: The practical need to understand sea level along the coasts, such as for safe navigation given the spatially variable tides, has resulted in tide gauge observations having the distinction of being some of the longest instrumental ocean records. Archives of these records, along with geological constraints, have allowed us to identify the century-scale rise in global sea level. Additional data sources, particularly satellite altimetry missions, have helped us to better identify the rates and causes of sea-level rise and the mechanisms leading to spatial variability in the observed rates. Analysis of all of the data reveals the need for long-term and stable observation systems to assess accurately the regional changes as well as to improve our ability to estimate future changes in sea level. While information from many scientific disciplines is needed to understand sea-level change, this review focuses on contributions from geodesy and the role of the ocean's bounding surfaces: the sea surface and the Earth's crust.
authors.affiliation: National Oceanography Centre, Joseph Proudman Building, 6 Brownlow Street, Liverpool L3 5DA, UK mtam@noc.ac.uk.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Tamisiea
authors.affiliation: National Oceanography Centre, Joseph Proudman Building, 6 Brownlow Street, Liverpool L3 5DA, UK School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP, UK.
authors.forename: Chris W
authors.initials: CW
authors.lastname: Hughes
authors.affiliation: National Oceanography Centre, Joseph Proudman Building, 6 Brownlow Street, Liverpool L3 5DA, UK.
authors.forename: Simon D P
authors.initials: SD
authors.lastname: Williams
authors.affiliation: Nottingham Geospatial Institute and Department of Civil Engineering, University of Nottingham, Nottingham NG7 2TU, UK.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Bingley
keywords: geodesy; observing systems; sea level