For now, we have about 1 year of significant cold phase tendency in the Pacific Decadal Oscillation (PDO), here is the last 108 years of the PDO index, plotted from monthly values:
Click for larger image – source Steven Hare, University of Washington
Compared to the negative magnitudes seen from 1946 to 1977, our current PDO phase shift magnitude is relatively mild. But that could change. Don J. Easterbrook, a retired professor from the Dept. of Geology, Western Washington University, in Bellingham, WA sends this analysis:
The announcement by NASA’s Jet Propulsion Laboratory that the Pacific Decadal Oscillation (PDO) had shifted to its cool phase (Fig. 1) is right on schedule as predicted by past climate and PDO changes.
Global temperatures peaked in 1998 and have not been exceeded since then. Pacific Ocean temperatures began a cooling phase in 1999 that was briefly interrupted by El Nino and dramatic cooling in 2007-2008 appears to be a continuation of a global cooling trend set up by the PDO cool phase (Fig. 1) as predicted [shown in the figure below].
Thus, we seem to be headed toward several decades of global cooling, rather than the catastrophic global warming predicted by IPCC.
If we are lucky, this PDO will be a short event. 2-4 years. If we are unlucky, and it is the “full Monty” phase switch at 20-30 years as Easterbrook suggests, we may be in for extended cooler times. This may result in some significant extended worldwide effects, notably on agriculture.
UPDATE! Professor Easterbrook adds in comments:
“The projected warming from ~2040 to ~2070 is NOT driven by CO2, it’s merely a continuation of warm/cool cycles over the past 500 years, long before man-made CO2 could have been a factor. We’ve been warming up from the Little Ice Age at rate of about 1 degree or so per century and the 2040-70 projection is simply a continuation of non-AGW cycles.
An interesting question is the similarity between what we are seeing now with sun spots and global temperature and the drop into the Little Ice Age from the Medieval Warm Period. Could we be about to repeat that? Only time will tell–We might see a more pronounced cool period like the 1880 to 1910 cool cycle (when many temp records were set) or a milder cooling like the 1945-1977 cool cycle. In any case, the setting up of the cool phase of the PDO seems to suggest cooler times ahead, not the catastrophic warming predicted by IPCC and Al Gore.”