[redpoint5]

So the key to stemming global warming is to measure with Mercury thermometers. :P

I'm pretty well convinced burning fossil fuels is most responsible for the increased CO2 levels. As I've said before, it doesn't matter the cause though, as what to do about something has little to nothing to do with cause, and more to do with what will happen if you don't respond to the threat. In other words, if solar irregularity were causing the majority of warming and it posed enough of a threat, we should be responding to that threat just as much as if any other thing were causing warming. If long-term well-being depends on the average temperature being within a certain range, we need to respond reasonably to keep it within that range. Cause is meaningless insofar as if we should act.

If a tree is falling in your direction, the cause is irrelevant. The only relevant consideration is what direction and what speed is an appropriate response. In my view, this is the relevant and interesting discussion. Cause doesn't matter. What can be done and what SHOULD be done in response to change?