there have been conjectures made as to a theoretical threshold of hurricane strength in a GW world. the thing is, the IPCC guys won't go further and say anything about whether such storms are possible since there isn't any science to back it up. there are lots of signals that can mix things up, and considering how good of a job current dedicated hurricane models do (i.e., the top-dog gfdl in all of its glory creating monster hurricanes and then open waves from run to run)... and that the global warming models in existence are trying to model a much more complex system at extremely coarse, global resolution... it's safe to say that no empirical evidence for stronger storms exists.
global warming is an agenda mechanism for the global change community--which is a weird mix of scientists and international bureaucrats who are both do-gooders and control freaks at the same time. dependent on what your politics are, you either like these guys and think they're going to save us all, or wish they'd spend their money researching things without the purpose of finding evidence that people are altering the earth and more about how it actually works, sans the agenda. the agenda is of course to regulate the power of nations by dictating what they can and can't do, and bring more of the world's management under the cloak of the UN-types. with the issue as politicized as it is, it's really hard to get at the truth of what's really going on with the world's climate. both sides want you to believe their story so that their agenda can go forward.. not because it's fact or bad science-fiction. and of course the fact is nobody REALLY understands it well enough to call heads or tails.

as a climate scientist in training, what i can say is this:
the earth is really really really complex. there are all kinds of built-in controls.. i.e. global warming can lead to global cooling by increasing glacial meltwater, shutting down poleward heat flow, and creating compounding feedbacks like colder temperatures, more snowfall, and higher albedo from the snowfall which compounds the effect. this is a negative feedback. their are positive feedbacks as well--i.e. higher co2 leads to more warming, and increases the water vapor content further increasing heat retention. upscale these processes to the patchwork different surfaces, and the complex heat transport in the atmosphere and ocean, and it makes for some pretty complex problems.
but anyway, at shorter timescales, we do get temporary warming and cooling periods in parts of the globe. you're familiar with el nino? it puts parts of the pacific into tropical overdrive, and turns the atlantic into a whisper. not to mention reworks the weather patterns over much of the world. will global warming lead to more hurricanes in some places and fewer in others.. you betcha. has the earth existed in modes warmer and colder than the current one? yep. we're in an interglacial warm spell, but when viewed at larger timescales its really friggen cold, compared to much of the earth's history. personally i hope that global warming acts as a buffer to prevent the coming ice age that we are on a course for, as the earth's orbital and solar forcing parameters are inevitably sliding that way over thousands of years. the last interglacial peaked early and slowly, in swoops and dives. it put much of the northern hemisphere under an ice sheet, and made the earth a place that was generally colder and drier than our world. the population our relatively warmer planet supports today would be culled and starved into a fragment, were an ice age to befall people not equipped to handle it.
man, i'll take global warming any day, if you ask me. it's really pick your poison.. unless you happen to think that people can modulate the climate outside of the inevitable natural cycles over the ages. we don't know if it is possible yet, but we're going to find out... one way or another.
probably not in my lifetime.
HF 0754z25november