Obie
I agree with TIA- as well as a background in geophysics I've spent the last decade in dynamics research- particularly paleoclimate. We need to be real careful using statistics- as they throw away a lot of the time order that things happened in stats tend to obscure dynamics.

Dynamically, systems do a weird thing called bifurcation (the Russians call it perestroika btw). Anyway at these bifurcations a system 'jumps' state. The way the system works at each side of the jump is utterly different. A topologist Rene Thom called these jumps 'catastrophes' back in the 70s. Funnily enough there are only 7 kinds of jump (they have weird/beautiful names). The reason climate warming might be very very nasty is that there is reason to believe that our present state is quite delicate- the ocean conveyor belt is totally interconnected. It didn't used to be. During the most recent glaciation (ended 9000 years back) Ireland and Britain were mostly iced over. However Florida was considerably hotter. Turtles that lived there then have died out due to the temperature drop. If the system goes back to the way it was (which has happened several times) the earth doesn't care but our arable land area drops big time. Figuring out exactly what these alternative climates are is the challenge.
So the earth does have different states (cycles is a rubbish word- they don't cycle- more jog). The worry is that we jog it into a nasty state- most of the other states that we have recovered are much tougher on living systems than the present very nice temperate one.

This stuff is not rocket science- rocket science is dead easy in comparison. I've yet to meet a politician with the requisite background to even follow the science and it gets WAY more complicated when the whole thing moves from the physics, chem and dynamics to the world of computer modeling the setup. This is where the action is- especially in Japan at the moment.

Personally I have mapped out some areas that survived with ecosystems relatively unchanged during the big shifts and bought some real estate there. I'm not the only one either. I don't think many of us modelers believe any of the governments can deal with this. They can't agree on farming!!!

Keep to the high ground ;-)

Pat