Physicsdave – if you want to trust Judith Curry, fine, I do not.
There is a group of climate scientists who made decadal predictions based upon the North Atlantic. Latif is one of them. They were spectacularly wrong. Because the AMO is a puny little punk ocean cycle. It’s either along for the global train ride or off doing its own thing with almost no global consequence. The AMOC is another story; it’ not the AMO. DM Smith did the first decadal forecast model that looks about right, and on his first try. Natural variability in the equatorial Pacific was approximately captured. Every time I mention it on this blog they trash it as hard as they can. From the water chef to the capt.
He predicted 2014 would be the burner; he missed it; instead it’s 2015. What a colossal model failure. Weather models go haywire in a very short time span. A decadal forecast model is as much a weather model as it is a climate model. Smith’s model is still holding together.
They know way more about natural variability than the folks on this blog can admit.
… JC: I thought that it might account for at least half of the observed warming, and hence my questioning of the IPCC’s highly confident attribution of ‘most’ to AGW.
From an author of the paper:
I have a different take on this. The IPCC conclusion applies to centennial warming from 1880. Much of the 0.8 C warming since 1900 is indeed due to anthropogenic forcing, because natural variability like PDO and AMO has been averaged out over this long period of time.
Our results concern the effect of tropical Pacific SST on global mean temperature over the past 15 years. It is large enough to offset the anthropogenic warming for this period, but the effect weakens as the period for trend calculation gets longer simply because it is oscillatory and being averaged out. – Xie
Xie’s only error is the PDO and the equatorial Pacific have been dragging against AGW since around 1985. 15 years does cover it. The PDO flipped positive at the end of 2013, and the last 24 months are warming at 5 times the IPCC’s prediction of .2C per decade. And some day that will average out… hopefully. But don’t be surprised if the GMST hits the IPCC number by 2020.
