I thought I’d touch on a science topic briefly, as it has popped up rather a lot recently in the MSM. I’m assuming you’ve all at least heard of the Pacific Decadal Oscillation?
For some time now it’s been known that the Pacific Ocean goes through alternating warming and cooling phases, each lasting several decades—hence the name. From at least 1915 to about the mid 1940s, the ocean was in a warming phase; from then until 1977, in a cooling phase. From 1977 until 1998, the PDO was again in a warming phase, and in that year reverted to a cooling phase, in which it remains today.
Warming phases are characterized by warmer water down the North American Pacific west coast, encircling a body of cooler water in the mid-Pacific Ocean. In cooling phases, this pattern is reversed, as shown here:
The current cooling phase is complicated by the concurrent La Niña event, which has the effect of cooling the Pacific Ocean in the equatorial latitudes.
Yes, yes, that’s well and good Ozboy, fascinating science and all, but so bloody what?
I’m glad you asked.
You see, it just so happens that global temperature changes over the 20th Century have paralleled the PDO with uncanny accuracy.
It makes a lot of sense when you think about it. The Pacific Ocean is by far the world’s largest body of water. It covers one-third of our planet’s surface area, and merely the top few metres of it represents a heat sink many thousands of times greater than the earth’s atmosphere as a whole. When the Pacific Ocean gets warmer, so does the atmosphere. And vice versa.
Given the clear correlation between the PDO and global atmospheric temperature trends, and given also that the PDO has been in a cooling phase since 1998 and based on past behaviour probably will continue to do so for some decades, it makes sense to infer that global temperatures, having also peaked in 1998, are likely to mirror this cooling.
The best-known authority on the PDO is Don Easterbrook, Professor Emeritus of the Department of Geology at Western Washington University (call me biased, but it’s so often geologists, whose line of work requires them to take the long view, who are the strongest sceptics of Anthropogenic Global Warming. And why so many warmistas have become suddenly prone to pontificate on geology, something I find profoundly irritating). I urge all of you, when you have a spare moment, to navigate here and read his take on the likely immediate future of our planet’s climate.
To be sure, there are those who dispute the PDO/global temperature relationship. You probably don’t want to know the gory details, but for a textbook example of quibbling, cavilling, nit-picking and nay-saying, check out this thread on Watts Up with That (from which I lifted the excellent illustrations, which were in turn taken from Easterbrook’s paper). There are some statistical issues with the precise “switching point” from warm to cool phases, and some grumblings about temperature shifts in lesser bodies of water. Stand back from these trees however, and observe the forest as a whole, and the significance of the PDO appears pretty compelling.
Right now at my place it’s -1°C (30°F) outside. So I’ll leave you to ponder the cooling Pacific as I throw some more wood on the fire, get a hot cuppa and start knitting that new scarf.