Since Redneck's aren't statisticians or logicians in the formal sense, all I can do is question the "common sense" in assuming something is "normal" and negligible when from the looks of it the formal statisticians and logicians seem to have underestimated the potential impact by a factor of 5.
Dr. Pratt does seem to be more impressed with the Pacific Decadal Oscillations (PDO) because that has a larger swing so by his logic it can have more impact. The PDO is based on how North Western Pacific fish stocks respond to climate oscillations which varies more in the North Western Pacific than it the whole northern Pacific. Same basin range of fluctuation just a different region picked out for different fish. If he looked at the entire northern oceans from 20N to 70N he would find that the whole shebang fluctuates pseudo-cyclicly.
I used both axis to highlight things with this one for the northern oceans. It has been noted that the northern hemisphere with a larger percentage of land tends to amplify temperature changes which some seem to think indicates that it's "worse than it looks" because they assume they know what "normal" is supposed to be pretty much like they assume that defined oscillations mean more than they are supposed to mean.
I have to admit though that thanks to Dr. Pratt and Greg Goodman I now know how to smooth the crap out of any time series.
I would not dismiss AMO so easily.
ReplyDeleteIn fact I don't like detrending or "anomaly" calculations. Now we know how to apply a good low-pass let's do it. (Please note the arbitrary 0.1 adjustment around 1925)
This is gaussian filter, non detrended N. Atl SST and and ACE (cyclone energy)
http://climategrog.wordpress.com/?attachment_id=215
PDO was _discovered_ because of fishing data, it is not calculated that way. It is derived from SST. Look it up for details.
The PDO and ENSO were discovered because of fish stock changes and then "defined" to relate to the changes. I am not dismissing either, I am just not assuming they are the best form to use related to "global" climate since they aren't causes they are effects.
ReplyDeleteVaughan, " I would have been less cheerful about agreeing with your suggestion of 0.5 °C however, at least when AMO is interpreted as "multidecadal" (there are indeed larger subdecadal swings as you say)."
ReplyDeleteAs I said I don't consider the AMO as defined to be very good climate index, but a good weather index. For climate though, the north Atlantic covers ~11% of the total ocean surface and has the amplified impact on land of ~1.8 times the actual SST variation. So if you consider ~.2 plausible the ~.38 is just as plausible including the land amplification typically neglected.
However, since it is the entire northern oceans, not just the AMO region that fluctuates, 0.5 is likely for a properly considered "climate" index.