Let's assume the Mayor did FEMA's job and put out an alert for citizens of New Orleans to come to designated locations to board the busses.
Where was he supposed to send them? Would hotels have accepted 30,000 people gratis? Would gas stations have filled their tanks for free?
There is a reason Hurricane Katrina is a national disaster.
The possibility also exists of nonlinear phenomena such as massive climate shifts - but from what I have heard this is extremely difficult to model accurately.. Still, what we do know is not very reassuring..
Scientists are talking about things like increased storm intensity (which we are seeing), the migration of tropical diseases and fungi/bacteria environments northward and southward (this also has major public health implications - especially if healthcare is not available to large segments of a population, say, because of its cost or their immigration status)
Its also possible that some temperate areas (most of the US is in the temperate zone) that are currently viable for human habitation or farming might become hotter or sometimes, colder, and also perhaps somewhat nonviable for people.. (too hot for example.. without entailing prohibitive energy costs for cooling - or too dry...)
and also that areas currently not very viable.. (like some of the subarctic parts of Canada) might become viable, or even optimal....
This would be happening all over the world.. not just in any one country.. so we could see massive migrations of people trying to flee the suddenly inhispitable weather conditions..
At least, that is what one (unclassified) Pentagon report I saw forsaw..
NIH's Environmental Health Perspectives magazine also has done a lot of good articles about the health implications of climate change..
Worth reading..
See http://ehp.niehs.nih.gov/topic/climate.html
