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Present day sea level changes: observation and causes; Les variations actuelles du niveau de la mer: observations et causes

Abstract

Whereas sea level has changed little over the last 2000 years, it has risen at a rate of about 2 mm/year during the 20. century. This unexpected sea level rise has been attributed to the anthropogenic global warming, recorded over several decades. Sea level variations have been measured globally and precisely for about 12 years due to satellite altimeter missions Topex/Poseidon and Jason-1. These observations indicate a global mean sea level rise of about 3 mm/year since 1993, a value significantly larger than observed during previous decades. Recent observations have allowed us to quantify the various climatic factors contributing to observed sea level change: thermal expansion of sea water due to ocean warming, melting of mountain glaciers and ice sheets, and changes in the land water reservoirs. A water budget based on these new observations allows us to partly explain the observed sea level rise. In particular, we show that the thermal expansion explains only 25% of the secular sea level rise as recorded by tide-gauges over the last 50 years, while it contributes about 50% of sea level rise observed over the last decade. Meanwhile, recent studies show that glacier and ice sheet melting could contribute the equivalent of  More>>
Authors:
Publication Date:
Nov 15, 2005
Product Type:
Thesis/Dissertation
Report Number:
FRNC-TH-7058
Resource Relation:
Other Information: TH: These oceanographie spatiale; Also available from Universite Paul Sabatier, S.C.D. Toulouse-3 B.U. de Sciences, 118 route de Narbonne, 31062 - Toulouse Cedex (France)
Subject:
54 ENVIRONMENTAL SCIENCES; ANNUAL VARIATIONS; CLIMATIC CHANGE; GENERAL CIRCULATION MODELS; GEOGRAPHICAL VARIATIONS; ICE CAPS; SEA LEVEL; SEAS; SEASONAL VARIATIONS; SPATIAL DISTRIBUTION; TEMPERATURE DISTRIBUTION; THERMAL EXPANSION
OSTI ID:
20943038
Research Organizations:
Toulouse-3 Univ. Paul Sabatier, 31 (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR0702413096510
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
159 pages
Announcement Date:
Dec 13, 2007

Citation Formats

Lombard, A. Present day sea level changes: observation and causes; Les variations actuelles du niveau de la mer: observations et causes. France: N. p., 2005. Web.
Lombard, A. Present day sea level changes: observation and causes; Les variations actuelles du niveau de la mer: observations et causes. France.
Lombard, A. 2005. "Present day sea level changes: observation and causes; Les variations actuelles du niveau de la mer: observations et causes." France.
@misc{etde_20943038,
title = {Present day sea level changes: observation and causes; Les variations actuelles du niveau de la mer: observations et causes}
author = {Lombard, A}
abstractNote = {Whereas sea level has changed little over the last 2000 years, it has risen at a rate of about 2 mm/year during the 20. century. This unexpected sea level rise has been attributed to the anthropogenic global warming, recorded over several decades. Sea level variations have been measured globally and precisely for about 12 years due to satellite altimeter missions Topex/Poseidon and Jason-1. These observations indicate a global mean sea level rise of about 3 mm/year since 1993, a value significantly larger than observed during previous decades. Recent observations have allowed us to quantify the various climatic factors contributing to observed sea level change: thermal expansion of sea water due to ocean warming, melting of mountain glaciers and ice sheets, and changes in the land water reservoirs. A water budget based on these new observations allows us to partly explain the observed sea level rise. In particular, we show that the thermal expansion explains only 25% of the secular sea level rise as recorded by tide-gauges over the last 50 years, while it contributes about 50% of sea level rise observed over the last decade. Meanwhile, recent studies show that glacier and ice sheet melting could contribute the equivalent of 1 mm/year in sea level rise over the last decade. In addition, the high regional variability of sea level trends revealed by satellite altimetry is mainly due to thermal expansion. There is also an important decadal spatio-temporal variability in the ocean thermal expansion over the last 50 years, which seems to be controlled by natural climate fluctuations. We question for the first time the link between the decadal fluctuations in the ocean thermal expansion and in the land reservoirs, and indeed their climatic contribution to sea level change. Finally a preliminary analysis of GRACE spatial gravimetric observations over the oceans allows us to estimate the seasonal variations in mean sea level due to ocean water mass balance variations. (author)}
place = {France}
year = {2005}
month = {Nov}
}