Twentieth-century global-mean sea level rise: is the whole greater than the sum of the parts?

Gregory, J. M. and White, N. J. and Church, J. A. and Bierkens, M. F. P. and Box, J. E. and Van Den Broeke, M. R. and Cogley, J. G. and Fettweis, X. and Hanna, E. and Huybrechts, P. and Konikow, L. F. and Leclercq, P. W. and Marzeion, B. and Oerlemans, J. and Tamisiea, M. E. and Wada, Y. and Wake, L. M. and Van De Wal, R. S. W. (2013) Twentieth-century global-mean sea level rise: is the whole greater than the sum of the parts? Journal of Climate, 26 (13). pp. 4476-4499. ISSN 0894-8755

Full content URL: https://doi.org/10.1175/JCLI-D-12-00319.1

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Abstract

Confidence in projections of global-mean sea level rise (GMSLR) depends on an ability to account for GMSLR during the twentieth century. There are contributions from ocean thermal expansion, mass loss from glaciers and ice sheets, groundwater extraction, and reservoir impoundment. Progress has been made toward solving the "enigma" of twentieth-century GMSLR, which is that the observed GMSLR has previously been found to exceed the sum of estimated contributions, especially for the earlier decades. The authors propose the following: thermal expansion simulated by climate models may previously have been underestimated because of 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 half than in the second half of the century; the Greenland ice sheet could have made a positive contribution throughout the century; and groundwater depletion and reservoir impoundment, which are of opposite sign, may have been approximately equal in magnitude. It is possible to reconstruct the time series of GMSLR fromthe 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 observation that the rate of GMSLR was not much larger during the last 50 years than during the twentieth century as a whole, despite the increasing anthropogenic forcing. Semiempirical methods for projecting GMSLR depend on the existence of a relationship between global climate change and the rate of GMSLR, but the implication of the authors' closure of the budget is that such a relationship is weak or absent during the twentieth century. © 2013 American Meteorological Society.

Keywords:Antarctic ice sheets, Anthropogenic forcing, Global climate changes, Greenland Ice Sheet, Groundwater depletion, Groundwater extraction, Semi-empirical methods, Twentieth century, Climate change, Glacial geology, Glaciers, Groundwater, Sea level, Thermal expansion, Underground reservoirs, climate change, glacier, global change, ice sheet, reconstruction, reservoir, sea level change, thermal expansion, time series, twentieth century, Arctic, Greenland
Subjects:F Physical Sciences > F330 Environmental Physics
Divisions:College of Science > School of Geography
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ID Code:26018
Deposited On:24 Feb 2017 00:31

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