rose colored glasses? wrote:
Still, when I look at these reconstructions, I see that either the current decade isn't particularly anomalous in consideration of the uncertainties in the reconstructions, OR temperatures have been increasing since long before human-induced atmospheric CO2, depending on whether I like their lower or upper reconstruction.
You've said a couple times that, if you believe the lower (orange) reconstruction, that temperatures have been rising since 800 AD or so. I find that a strange interpretation of that graph. What I see is a minimum there followed by a warm period consistent with the Medieval Warm Period which is documented in various histories (i.e. Vikings colonizing Greenland), followed in turn by other more or less stable periods of a few hundred years, most reecently by the "Little Ice Age" 1500-1900 or so, and finally by a big jump. Drawing a line from the lowest point you can find to the highest seems disingenuous.
I will admit, though, that if the data are RIGHT, the last 10 years in their curve does seem to be relatively anomalous. I'm just not really convinced, though, that we can make direct comparisons between recorded temprature data and "reconstructed" temperature trends and draw meaningful, defensible conclusions.
It's often the case that the strength of a scientific theory isn't so much evidence supporting a theory as it is the absence of evidence contradicting the theory. I agree that we can't with certainty conclude that global temperature is warmer now than it has been in the last couple millenia, but neither is there evidence that says it's not. Such contradictory evidence would be a significant blow to the AGW theory unless there were some other strong forcing in play. A similar observation can be made about the CO2 levels from ice core samples we discussed earlier in the thread. That's the basis for my ongoing contention that it is the ensemble of evidence that is important. There is no single piece of evidence that conclusively demonstrates the validity of the theory, but as long as the theory is consistent with available data, has value in suggesting additional lines of investigation to test the theory, and is not contradicted, it is a "good theory" in the scientific sense.