Friday, April 27, 2007

"The Cost of Holding Back the Sea" - EPA, 1991

The Environmental Protection Agency responded to the threat of global sea level rise in 1991 with an analysis of the costs of protecting vulnerable coast-side communities, wetlands, properties and facilities. The report, titled Greenhouse Effect and Sea Level Rise: The Cost of Holding Back the Sea. This report demonstrates that the EPA fully recognized the threats of global warming when George H. W. Bush was still in office. It's full of interesting statistics, charts, tables and drawings. The techniques and technologies it describes haven't changed much in the past 16 years...

Possible responses fall broadly into three categories: erecting walls to hold back the sea; allowing the sea to advance and adapting to it; and raising the land
...though the value of the dollar and the value of property located in coastal areas have certainly changed a lot. The total cost the report projects ($270-475 billion) looks laughably small today. Probably, current satellite mapping allows for a much more accurate assessment today.

From the abstract of the report we get some impressive numbers, which may still hold fairly accurate if corrected for the amount of coastal development that's happened since 1991. (Think of how much dot com money must have gone into building homes on the coastline):
We estimate that if no measures are taken to hold back the sea, a one meter rise in sea level would inundate 14,000 square miles, with wet and dry land each accounting for about half the loss. The 1500 square kilometers (600-700 square miles) of densely developed coastal lowlands could be protected for approximately one to two thousand dollars per year for a typical coastal lot. Given high coastal property values, holding back the sea would probably be cost-effective.

The authors offer some cautions for implementation and the ultimate solution:
The environmental consequences of doing so, however, may not be acceptable. Although the most common engineering solution for protecting the ocean coast• pumping sand• would allow us to keep our beaches, levees and bulkheads along sheltered waters would gradually eliminate most of the nation's wetland shorelines. To ensure the long-term survival of coastal wetlands, federal and state environmental agencies should begin to lay the groundwork for a gradual abandonment of coastal lowlands as sea level rises.
I'll be looking around to see if there's a more up-to-date assessment by the EPA, but in the meanwhile, this report serves as a good overview and intro to the challenge that we face in dealing with even minimal sea level rise.

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