Originally posted by mjp2
Again, I suggest you be careful not to parse what I said into what you think I said. I've made no comment about certainty.
I have said - three times now, I think, that;
1. The range of uncertainty of climate sensitivity is robust. Studies over thirty years or so have not violated that. More, the great majority of the studies have tended to strongly support values in the mid range of that uncertainty.
So, as far as that aspect of the science goes, it is indeed robust, in my view.
2. Whatever value in that range is the actuality, we need to take action. So in a practical sense the findings of the science - that we need to take action to address AGW - is robust. For any of the values in that range we risk severe consequences, and the cost of action is vastly outweighed by the potential huge risks of inaction.
So in at least those two respects I regard the science as robust.
I'll add that the rest of the elements of the science - that it's greenhouse gasses causing warming, that those are human caused, that it's not the sun or volcanos, that it is warming at rates predicted by the science, etc etc, are also robust, based on all the evidence I've read.
To me uncertainty indicates that we have much to learn and premature large scale changes will waste precious resources and time although they would be a great experiment. I support individual choices to reduce carbon usage. Humans certainly contribute to warming but we don't have much certainty on the proportion of contribution.
If it is 1.501 degrees C per doubling of CO2 (which is within the likely range) then it will be another 150 years till temperature increases by 1.5 degrees from 1950 levels. There is still a chance, according to the IPCC that sensitivity is less than 1 degree and could be more than 6. This is a good way of saying we have no real idea what role CO2 plays other than it is > 0.
We don't understand natural variability very well at all hence the uncertainty in sensitivity. There is general denial of cyclical climate change due to natural causes and tendancy to attribute all changes to human cause hence poor decisions and excessive government control are seen as valid responses. Ignorance of natural causes of climate change could be costly and brutal to humanity in the medium term.
We need to focus funding on research - energy, climate and climate adaptation (in case natural forces are more of a contributor than man).
