Of all the potential woes bandied about with regards to “global warming,” the only one which really is in uncharted territory is a large and rapid rise in sea level. Otherwise we are rather routinely exposed to all nature of weather extremes as they are a part of the natural climate. Droughts, floods, heat waves, tornadoes, hurricanes, etc. have impacted human societies in the past and they will continue to do so into the future—with or without “global warming.”
The degree to which we are affected by extreme weather depends on a number of factors, especially preparedness.
One of the driving forces motivating us to “be prepared” (aside from our scout leader), is the frequency with which extreme weather occurs. Generally, the more frequent something negative occurs, the more we act to prepare ourselves. So, in this sense, if weather extremes do be more common in the future, we’ll more than likely quickly become better prepared to deal with them—lessening their negative impacts and probably boosting the economy along the way as we build the necessary precautions into our way of life (consider the improved building codes in Florida after Hurricane Andrew, or the response in Chicago (and France) in the aftermath of killer heat waves). In truth, the impact of climate change is very low compared to the impact of climate itself.
However, one exception to this could be sea level rise. As an organized society, we have pretty much experienced the global ocean level being pretty close (within a couple of feet) to where they are now. True, the global sea level has been creeping upwards for the past 10,000 years (after the big jump up at the end of last ice age) and true, we have had to make some adjustments to a few of our particularly vulnerable coastal cities, but by and large the sea level hasn’t been rising at a rate so great as to cause large societal disruptions or reorganizations.