Twentieth-century global-mean sea-level rise

Material Information

Title:
Twentieth-century global-mean sea-level rise is the whole greater than the sum of the parts?
Series Title:
Journal of Climate Volume 26 Issue 13
Creator:
Gregory, J.M.
White, N.J.
Church, J.A.
Bierken, M.F.P.
Box, J.E.
van den Broeke, M.R.
Cogley, J.G.
Fettweis, X.
Hanna, E.
Huybrechts, P.
Konikov, L.F.
Leclercq, P.W.
Marzeion, B.
Oerlemans, J.
Tamisiea, M.E.
Wada, Y.
Wake, L.M.
van de Wal, R.S.W.
Publisher:
American Meteorological Society
Publication Date:
Language:
English

Subjects

Subjects / Keywords:
Climate Change ( lcsh )
Sea Level Rise ( lcsh )
Thermal expansion ( lcsh )

Notes

Abstract:
Confidence in projections of global-mean sea-level rise (GMSLR) depends on an ability to account for GMSLR during the 20th century. There are contributions from ocean thermal expansion, mass loss from glaciers and ice sheets, groundwater extraction and reservoir impoundment. We have made progress towards solving the “enigma” of 20th-century GMSLR—that is, the observed GMSLR has been found to exceed the sum of estimated contributions, especially for the earlier decades. We propose that: thermal expansion simulated by climate models may previously have been underestimated owing to their not including volcanic forcing in their control state; the rate of glacier mass loss was larger than previously estimated, and was not smaller in the first than in the second half of the century; the Greenland ice-sheet could have made a positive contribution throughout the century; groundwater depletion and reservoir impoundment, which are of opposite sign, may have been approximately equal in magnitude. We show that it is possible to reconstruct the timeseries of GMSLR from the quantified contributions, apart from a constant residual term which is small enough to be explained as a long-term contribution from the Antarctic ice-sheet. The reconstructions account for the approximate constancy of the rate of GMSLR during the 20th century, which shows small or no acceleration,despite the increasing anthropogenic forcing. Semi-empirical methods for projecting GMSLR depend on the existence of a relationship between global climate change and the rate of GMSLR, but the implication of our closure of the budget is that such a relationship is weak or absent during the 20th century. ( English )

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Source Institution:
Florida International University
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Sea Level Rise