The Labor Day, 1935 hurricane was the most intense hurricane to ever make landfall in the US. It came on shore with an unbelievably low atmospheric pressure of 892 mbar (Katrina was 920 mbar.)

http://en.wikipedia.org/wiki/1935_Labor_Day_hurricane

Atmospheric CO2 was 309 ppm at the time. If this same hurricane occurred today, it would absolutely, positively be blamed on CO2 and “global warming.”