This is silly. Climate is a huge chaotic system. The FIRST thing you learn about a chaotic system is that if you reduce the energy fed into it, you simplify it and can even calm it down to periodic states. Past a threshold (long passed for climate) you get chaotic flow, which is well understood.
If you increase the energy in the system, it is not mysterious at all what happens. You increase the range and unpredictability of the chaos.
In that light, it is not automatically 'increase the number' of hurricanes, that's merely the most likely outcome. What's really happening is you're increasing the whole range of possible behavior. You're increasing the insanity of the system. Four hurricanes? Try six all on top of each other, then nothing for months, then bam, the largest hurricane in recorded history, completely impossible to cope with. It becomes impossible to make ANY prediction, even to the extent of 'what a hurricane can be'.
This is inherent in the math of chaos and totally inescapable. By its very nature, you will never get 'a nice linear increase in number of hurricanes', instead you get a widening of the possibility space to include stuff that was not possible at all in the 1800s. The amount of energy in the system wouldn't support it, but that's changed.