Very nice day fishing yesterday. Jim and family from Michigan experienced a day in my back yard fishing for Spanish Mackerel mainly, with enough Snapper volunteering for dinner to make a good day. The one that got away remains unidentified, but Cobia is suspected.
Webhubtelescope, the pseudonym of one of the Curry blog denizens, is fishing for climate sensitivity and natural variability. He appears to be a good angler for those tasks. With the Antarctic ice cores he found a range for natural variability of ~0.2C. When I asked him if 0.4C was possible, he stated it was, but only at a 5% level of confidence :) He has a Schimittner Analysis here to check the estimated range of climate sensitivity.
He is now using the Greenland ice cores to do the same thing, but is yet to finish. When he is finished, he should find the range is at least twice the range he found for the Antarctic. If he had access to equatorial alpine cores, he would find a range lower than the Antarctic. If I am right, the root mean squared of the three changes would be the approximate global average, placing natural variability in the range of 0.3 to 0.4 C for the global or half, maybe a little more of the modern warming. But equatorial ice cores are pretty rare.
So Web will probably determine that the range of natural variability is 0.x and there is only a 5% that that range will be exceeded. Five percent of 100,000 is 5000, and 5% chance of that is 250. So with great confident, natural variability could only exceed the estimates determined by ice cores for about 250years. Very useful information :) Compare that to the typical frequencies of a non ergodic system and what would you get? So if there is only a 5% chance or so that we could have a climate like we are experiencing now, what are the alternatives?