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The CfA Space Geodesy Homepage Sea Level Hazards: Increased flood and storm damage Increased salinity of estuaries and aquifers This webpage was created by Stacey Archfield |
Impact to coastal wetlands
A 50-cm rise in sea level would inundate 50 percent of coastal wetlands in the next 100 years [IPCC, 1998]. In this scenario, beaches would be squeezed between advancing seas and engineering structures [IPCC, 1998]. The IPCC predicts a net loss of 17-43% of wetlands during this time and increased storm surges will topple protective barriers currently in place to protect wetlands [IPCC, 1998]. Human response to sea level rise will also affect the reaction of coastal wetlands to sea level rise [IPCC, 1998].
In barrier islands, migration will occur with rising sea level. Depending on whether the rate of sea level remains constant, Michener et al. suggests three consequences: 1- The lagoonal area between the barrier island may remain constant, 2- The area may expand or 3- The area may shrink. Coastal wetlands will also naturally migrate upland as sea level rises unless coastal development impedes their regeneration [Michener et al., 1997]. The degree to which a wetland will migrate is not only dependent on engineering structures but also the slope of the land. If the slope is too great, the wetland cannot migrate and will be lost [Gornitz, 1991].
Coastal wetlands will be the most affected area expected to be drowned by rising sea level because wetlands form in the intertidal zone [Gornitz, 1991]. Currently, marsh accretion is proportional to sea level rise. However, in the US, areas of Louisiana, and the Chesapeake Bay, have a rate of accretion that is faster due to GIA-induced crustal sinking With the additional component of GIA, wetland regeneration is not proportional to sea level in these areas and the wetlands cannot accrete fast enough [Gornitz, 1991].
If a 2.2 m rise in sea level occurred by 2100, 73% of all wetlands would be drowned [Gornitz, 1991]. Only 56% would be lost if some of those wetlands were given the opportunity to migrate upland [Gorntiz, 1991]. If sea level were to rise 1.4 m by 2100, 22% of the wetlands would be inundated [Gornitz, 1991]. In the tropics, if sea level were to rise at a rate of 10-12 mm/yr., sea level would be rising faster than the maximum calcification rates for coral species [Gornitz, 1991]. Coral species would not be able to keep up and would die off.