that reducing C0 2 emissions with bans on coal, shale oil, and synfuels (but not oil and gas) would 

 delay a projected two degree (C) warming from 2040 to 2065; because of the thermal delay of the 

 oceans, the resulting thermal expansion of ocean water would be delayed ten to fifteen years. 15 

 Other trace gases might also be controlled. Hoffman et al. (1986) showed that the acceleration of 

 sea level rise could be significantly delayed through controls of greenhouse gas emissions. 



Although limiting the rise in sea level from the greenhouse effect might be the preferred 

 solution for most parties involved in the wetland protection process, it would also be largely 

 outside of their control. The nations of the world would have to agree to replace many industrial 

 activities with processes that do not release greenhouse gases, perhaps at great cost. A decision 

 to limit the warming would have to weigh these costs against many other possible impacts of the 

 greenhouse warming which are understood far less than wetland loss from a rise in sea level, 

 including the economic impacts of sea level rise; environmental consequences for interior areas, 

 such as an increase in desertification; and possible disruptions of the world's food supply. Perhaps 

 the most important challenge related to this option is that it would have to be implemented at 

 least fifty years before the consequences it attempts to avert would have taken place. 



Because we may have passed the time when it would be feasible to completely prevent an 

 accelerated rise in sea level, wetland protection officials may also want to consider measures that 

 would enable wetlands to adapt to rising sea level. Enhancing the ability of wetlands to keep pace 

 with sea level rise has the advantage that such measures, which include marsh building, 

 enhanced sedimentation, and enhanced peat formation, would not have to be implemented until 

 sea level rise has accelerated. 



Current environmental policies often require marsh building to mitigate destruction of 

 wetlands. Although this measure will continue to be appropriate in many instances, it can cost 

 tens of thousands of dollars per acre, which would imply tens of billions of dollars through 2100 if 

 applied universally. Enhanced sedimentation may be more cost-effective; it is generally cheaper to 

 save an acre of marsh than to create an acre of new marsh. Technologies that promote vertical 

 growth of marshes generally spray sediment in a manner that imitates natural flooding (Deal 

 1984). Although these technologies look promising, they are barely past the development stage 

 and may also prove too costly to apply everywhere. Although processes for enhancing peat 

 formation might prove feasible, reduced peat formation might also result from climate change. 



Allowing wetlands to adapt naturally to sea level rise would not prevent a large reduction in 

 acreage, but might allow the ecosystems themselves to survive. This option would consist 

 primarily of removing human impediments to sedimentation and the landward migration of wet- 

 lands. The sediment washing down the Mississippi River, for example, would be sufficient to 

 sustain a large part of Louisiana's wetlands, if human activities do not continue to force sediment 

 into the deep waters of the Gulf of Mexico. However, the costs of restoring the delta would be 

 immediate, while the benefits would accrue over many decades. Similarly, measures could be 

 taken to ensure that the wedands in tidal deltas adjacent to barrier island inlets are not deprived 

 of sediment by groins and jetties built to keep sand on the islands and out of the inlet. 



For the extensive mainland marshes not part of a tidal delta, a natural adaptation would 

 require the wedands to migrate landward and up the coastal plain. Such a policy would also be 

 costiy. It would be necessary to either prevent development of areas just upland of existing 

 wedands, or to remove structures at a later date if and when the sea rises. Preventing the 

 development of the upland areas would require either purchasing all the undeveloped land 

 adjacent to coastal marshes or instituting regulations that curtailed the right to build on this 

 property. The former option would be cosdy to taxpayers, while the latter option would be costiy 

 to property owners and would face legal challenges that might result in requirements for 

 compensation. 



Developing upland areas and later removing structures as the sea rises would allow costs to 

 be deferred until better information about sea level rise could be obtained. This option could be 



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