If Katrina hit with no warming, as in 1900 in Galveston TX, the death toll would have been in the tens of thousands. Even the poorly executed evacuation that did happened can be credited with keeping deaths in New Orleans to only around 1,800.
If a comparable major quake and fire hit San Francisco today the death toll would likely be about the same as in 1906. While better building codes would save lives, the much higher population density would put far more people at risk. Liquefaction was a killer in parts of San Francisco in 1906. From an infrastructure standpoint the problem is worse now because the number of areas backfilled and developed around the bay has increased since 1906. Up to 25 percent of the 9 county region is susceptible to liquefaction.
http://geomaps.wr.usgs.gov/sfgeo/liquefaction/maps.htmlThe Great Colonial Hurricane of 1635 had few recorded fatalities because there were only European 2 colonies at the time. (There was no record kept of native American fatalities, but there had to be many) If such a storm hit the east coast today the damage would be massive. The death toll would be very high. In large part because as a society we have been dumb enough to allow building in areas that historically are pounded in rare storms.
There were parts of the east coast that saw flooding in 2011 with Irene that had not seen such weather since the 1938 hurricane. They suffered from Irene because decades of complacency lulled them into a false sense of security to rebuild what had been destroyed in 1938.
This insurance industry report does an nice job of objectively noting the problems with poor development and the cost if history repeats its self.
Note there is not one mention of climate change. The damage projections are based on history.
http://www.propertycasualty360.com/2012/06/06/industry-headed-for-bankruptcy-when-a-hurricane-hi?t=es-specialty-business&utm_source=PC360DailyeNews&utm_medium=eNL&utm_campaign=PC360_eNLs 
