My current global warming/climate change opinion can be summed up as the opposite of what I had summed up previously as my opinion, although in truth there is no facts previously accepted that I no longer hold true nor visa versa.
To sum up: Previously I believed this: Anthropogenic Global Warming is a fact but we shouldn't do anything about it.
Now - I believe that Global Warming is a scientific assertion with little predictive value. However, it has high *proscriptive* value ie. there is value of various kinds in acting against Green House Gases.
The issue to me is that the value of science to predict is that you can adjust what you do to optimise for that prediction. If you know a cyclone is heading your way, you can batten down the hatches - the three to ten day forecasts of cyclones is very valuable. The prediction that my house might be threatened by a storm surge in ten years time is valueless both in a future discounting sense, and in a probability sense.
The idea that there is proscriptive "value" in what climate scientists say comes from the fact that there is benefit in being able to say, "all other things being equal, it is unequivocally better to reduce ghg's!"
This is the same proscriptive value as economists saying "We should reduce trade barriers" among the many correctly proscriptive things experts say in their fields without being able to valuably predict the future (eg. what stocks will go up.)
We do not know how many generations it will take to see the benefits of doing so. It is entirely possible that the next several generations will suffer more by attempting, or even succeeding in a large way to reduce ghg's. It is not a thing that can be predicted. Nor can things that actually make a significant difference - costs associated with actual extreme wheather events. We will be lucky to even have right the most basic easiest question of the next 40 years - will global average temperatures go up steadily, go down steadily, go up and down like a yo-yo or what? Most bets are that it will go up but with several peaks and troughs on the way to confuse things and correctly make a mockery of experts' authority on the matter.