I drove over the Bonnet Carre Spillway this morning and the water is high and flowing at a pretty good pace. For those of you who don't know southern Louisiana, the spillway is a man-made channel a little over a mile wide between the Mississippi River and Lake Ponchartrain, located about 25 miles upstream of New Orleans. The Army Corps of Engineers maintains the spillway for recreation purposes when it is not being used for its designed purpose, which is to divert part of the Mississipi River to the lake during very high river stages. This reduces the possibility of the river breaching or topping a levee in the more populated downstream Jefferson and Orleans Parishes.
The last time the spillway was opened was back in 1997. At that time, I remember the environmentalist uproar on how it was going to kill all the oysters and upset the delicate-ecological-balance. (Never mind that mankind had already upset the delicate-ecological-balance when the river levees were built. For thousands or millions of years, the river had periodically overflowed its natural banks, self-diverting to the lake).
Of course, now in 2008, two-and-a-half years after Katrina, which put 75% of the area underwater, I do not hear ANYTHING from anybody about upsetting the delicate-ecological-balance. Even if the spillway had not been opened, the experts believe that it is unlikely that the levees would have breached or over-topped. But in the post-Katrina world that we live in, even a teeny-weeny chance of causing flooding completely overshadows the delicate-ecological-balance argument.
I beleive environmental concerns should be part of the decision making process, but they should not be the only or even the overwhemling concern.
Someone who fervently believes in man-made global warming might apply this example to the global warming debate as follows: even if there is only a small chance that global warming will harm the earth's biosphere, shouldn't we do something to prevent that harm. OK, I agree, with the following two caveats:
(1) we positively know that the actions we take will reduce the potential for the harm to occur and/or will reduce the severity of the predicted consequences. In the levee situation, we absolutely know that opening the spillway will divert water around New Orleans and thus will reduce the risk to New Orleans. I do not know that the actions proposed by GW proponents will indeed reduce potential risks.
(2) The costs of our preventative actions are relatively well understood and the future costs of inaction are also well understood. In that way, as a society, we can do a cost-benefit analysis to decide if we want to take the preventative actions. In the case of the levee, we know that flooding the brackish Lake Ponchartrain with fresh river water does have an affect on the flora and fauna. Oyster beds and fish schools are affected. We also know from experience that these effects correct themselves after the spillway is closed. I don't think we yet have enough information to make a decision regarding "Global Warming" or "Climate Change".
