Special Feature: Original Article

Sustainability Science

, Volume 3, Issue 1, pp 9-22

Understanding global sea levels: past, present and future

  • John A. ChurchAffiliated withCentre for Australian Weather and Climate Research—A Partnership Between CSIRO and the Australian Bureau of Meteorology and CSIRO, CSIRO Marine and Atmospheric ResearchAntarctic Climate and Ecosystems Cooperative Research Centre Email author 
  • , Neil J. WhiteAffiliated withCentre for Australian Weather and Climate Research—A Partnership Between CSIRO and the Australian Bureau of Meteorology and CSIRO, CSIRO Marine and Atmospheric ResearchAntarctic Climate and Ecosystems Cooperative Research Centre
  • , Thorkild AarupAffiliated withIntergovernmental Oceanographic Commission, UNESCO
  • , W. Stanley WilsonAffiliated withU.S. National Oceanic and Atmospheric Administration (NOAA)
  • , Philip L. WoodworthAffiliated withPermanent Service for Mean Sea Level, Proudman Oceanographic Laboratory
  • , Catia M. DominguesAffiliated withCentre for Australian Weather and Climate Research—A Partnership Between CSIRO and the Australian Bureau of Meteorology and CSIRO, CSIRO Marine and Atmospheric Research
  • , John R. HunterAffiliated withAntarctic Climate and Ecosystems Cooperative Research Centre
  • , Kurt LambeckAffiliated withAntarctic Climate and Ecosystems Cooperative Research CentreResearch School of Earth Sciences, Australian National University

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Abstract

The coastal zone has changed profoundly during the 20th century and, as a result, society is becoming increasingly vulnerable to the impact of sea-level rise and variability. This demands improved understanding to facilitate appropriate planning to minimise potential losses. With this in mind, the World Climate Research Programme organised a workshop (held in June 2006) to document current understanding and to identify research and observations required to reduce current uncertainties associated with sea-level rise and variability. While sea levels have varied by over 120 m during glacial/interglacial cycles, there has been little net rise over the past several millennia until the 19th century and early 20th century, when geological and tide-gauge data indicate an increase in the rate of sea-level rise. Recent satellite-altimeter data and tide-gauge data have indicated that sea levels are now rising at over 3 mm year−1. The major contributions to 20th and 21st century sea-level rise are thought to be a result of ocean thermal expansion and the melting of glaciers and ice caps. Ice sheets are thought to have been a minor contributor to 20th century sea-level rise, but are potentially the largest contributor in the longer term. Sea levels are currently rising at the upper limit of the projections of the Third Assessment Report of the Intergovernmental Panel on Climate Change (TAR IPCC), and there is increasing concern of potentially large ice-sheet contributions during the 21st century and beyond, particularly if greenhouse gas emissions continue unabated. A suite of ongoing satellite and in situ observational activities need to be sustained and new activities supported. To the extent that we are able to sustain these observations, research programmes utilising the resulting data should be able to significantly improve our understanding and narrow projections of future sea-level rise and variability.

Keywords

Sea-level rise Climate change Coasts Extreme events IPCC Greenhouse