Dynamics and Vulnerability of Delta Systems - loicz

2.3 Sea-Level Change
For a given deltaic coast, changes in its elevation relative to sea level depends on three factors
(Syvitski et al., in review): (1) Changes to the volume of the global ocean (Eustasy), as influenced
by fluctuations in the storage of terrestrial water (e.g. glaciers, ice sheets, groundwater, lakes, and
reservoirs), and fluctuations in temperature of the ocean’s surface waters (Warrick & Oerlemans
1990, Bindoff et al. 2007). Sea level is presently increasing at a rate of 1.8 to 3 mm/y under the
anthropogenic influence of global warming. (2) Vertical movements of the land surface, as influenced
by hydro-isostasy related to sea level fluctuation, loading due to the weight of delta deposits,
glacio-isostasy related to the growth or shrinkage of nearby ice masses, tectonics, and deepseated
thermal subsidence (Syvitski 2008). Isostatic changes can cause deltas to subside at rates of
1-5 mm/y. (3) Changes to the sedimentary volume of the delta, through natural compaction (�3
mm/y), accelerated compaction (�150 mm/y), and aggradation or sediment deposition onto the
delta’s surface (�50 mm/y). Aggradation depends on both the rate sediment is delivered to a
delta, and the amount of sediment retained on the delta during its transport across the delta surface.
Climate
Scenarios
Temperature
Change in °C
Sea Level Rise
in m
B1 1.8 0.18 - 0.38
A1T 2.4 0.20 - 0.45
B2 2.4 0.20 - 0.43
A1B 2.8 0.21 - 0.48
A2 3.4 0.23 - 0.51
A1F1 4.0 0.26 - 0.59
Fig. 2.1: IPCC comparison of observed continental changes in temperature over the last century; blue envelop is
model predictions using only natural forces, pink envelop are model predictions including anthropogenic forces.
Lower panel shows the projected emissions and tabelizes the projected associated temperature changes and sea
level rise for 2090-2099 as compared to 1980-1999 (Bindoff et al. 2007).
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