There has been a large rise in Atlantic basin major hurricane numbers since 1995 (3.92/year). This contrasts sharply with the annual major hurricane activity during the prior 25 year period of 1970-1994 (1.52/year). This recent pick-up in major hurricane activity is comparable with the major hurricane numbers between the mid 1940s and the late decades of the 19th century. These changing activity levels are hypothesized to result from the multi-decadal variability of the Atlantic Ocean thermohaline circulation (THC) of which salinity variability plays a dominant role. Arguments are presented which suggest that human-induced greenhouse gases play no significant role in Atlantic variability or in hurricane variations in the other global storm basins.