Blaming the Pacific Decadal Oscillation
by Riccardo, Skeptical Science, March 5, 2011
The Pacific Decadal Oscillation
Figure 1. Typical wintertime Sea Surface Temperature (colors), Sea Level Pressure (contours) and surface windstress (arrows) anomaly patterns during warm and cool phases of PDO. Left panel: postive (warm) phase; right panel: negative (cold) phase. (from JISAO).
[...] the leading PC of monthly SST anomalies in the North Pacific Ocean, poleward of 20° N. The monthly mean global average SST anomalies are removed to separate this pattern of variability from any "global warming" signal that may be present in the data.
The causes of the PDO
Thus, the PDO is a response to something else; treating it as a forcing must be taken with caution.
The impact of PDO on global temperature
where C is the heat capacity, λ the climate sensitivity and F(t) the forcing; it can be shown that the response time of the system is given by τ = C λ .
(Note: you might want to read a similar and more authoritative explanation on how to cook a graph or Barry Bickmore's take.)