Enviro,
While it's true that some people don't like change; others accept change as part of the course of life. Even if we could, would we settle on the climate as it was 120 years ago as being an ideal period to return to simply because it is the date that so often comes up as a time that preceeds the warming trend of the contemporary era? It is a given that the North American climate was probably much cooler at that time. Does that somehow suggest the existence of a more "natural" or ideal climate? According to whom, and by what measure?
But then again, what makes 120 years ago so special? It is just an arbitrary date in time from which to mark off a warming trend. Go back further in time and there is pattern of constant shifts and changes in climate. Variation, or change, is not the exception; it is the norm - regardless of the influence of GHG's originating from human activity or not.
As for a "cascade of events" caused by a small change in GHG's, remember that the greatest output of GHG's originates in nature. The human contribution is very small in comparison. To isolate just that small portion against a large backdrop of GHG emissions originating from the rest of the environment appears to be splitting hairs. The natural carbon cycle is not an absolute constant. There is variability that can match human outputs of GHG's in terms of quantity. Along with that, there are other elements in the mix that bring change to climate, many of which human beings have little or no control over. Any of those could operate far more effectively as the trigger you are concerned about because they already have done so in the past, and there would be nothing that we could do.
People may not like the idea of an ice-free arctic, but it remains to be seen whether they will ever see one. They may not like moving cities away from coasts (because of of worries over worse hurricanes - a question still open to debate), but even now there are cities built in what are well-established paths of seasonal hurricanes. They can and do get hit by those hurricanes quite frequently.
I wasn't aware anyone was considering triggering a nuclear winter to stop global warming. If there is such an idea floating around, it's got to be among the dumbest ever floated. As for blocking out the sun, or dumping huge amounts of iron in the ocean in some dubious effort to cool the planet, these too are anthropocentric environmental manipulations. Such efforts ought to be a moral conondrum for environmentalists. Why would one manipulation be better than another if the ends are pursued only to suit human desires of what the environment ought to be like?
As for mountains out of molehills, I think it is safe to say that you are over-simplifying the issue. Are there sources of energy beyond oil and gas? Sure, but they will have to be improved on before they can replace oil and gas effectively. Infrastructure may have to established and new processes and technologies will have to be put into place. I don't think I'm telling you anything new by pointing out that numerous small changes can be just as beneficial as extremely large changes. With respect to oil and natural gas, there is a simple fact that availability of the cheapest sources appears to have peaked. New sources will probably be more costly and more risky to acquire. To mitigate this cost, energy use will have to become more efficient in the relative short term. In the long term, oil and gas will have to be replaced with other sources of energy. Heat and light still offer up two very large potentials for future energy needs, and are quite plentiful. There pursuit and improvement are simply overshadowed by the cheapness of oil - for now.
