Now that the 15 year global warming "pause" is confirmed dead, it is fascinating, if at times painful, to look back at the sharp disagreements among important scientific figures in the climate community stemming from Kevin Trenberth's "travesty" -- a word he used in one of the so-called Climategate emails to express his frustration about the seemingly unbalanced books of our planet's energy balance, stemming from this supposed pause in global surface warming since the 1997-1998 El Niño, which led to his hunt to account for the supposedly "missing energy" from our atmosphere. In fact, there is virtually no missing energy, but it has been getting up into the Arctic, where it has gone underrepresented in climate data collection systems until now, and where it is already helping to destabilize weather systems around the Northern Hemisphere, at enormous cost to society.
Trenberth himself, for example, was quite critical, just a few months ago, of the Kosaka and Xie Nature paper, discussed in Part I, while agreeing that it accurately described part of the situation: he said, "What this paper does not do is analyze the role of changes in 'forcing': effects external to the system such as from small volcanoes, changes in the sun, etc. Nor does it deal with where the energy is going, such as our work on the deep ocean. Nor does it deal with why." Susan Solomon piled on, agreeing that the Kosaka paper didn't address the Why. But seen from another perspective, however, both the Trenberth and Kosaka papers are relatively limited model studies, and both lack the higher levels of Why.
One person who I will dare to mention here -- someone who the climate establishment, especially here in the United States, often seems afraid even to mention by name these days -- is James Lovelock. Lovelock had been intrigued by Trenberth's 2010 Science article when it appeared, and his own musings on the misconceived pause are precisely what led him, somewhat controversially, to dial back his estimates on the rate at which catastrophic disruption might evolve. In one of the nastiest moments of recent climate science, Kevin Trenberth then said of Lovelock, "The fact is he knows little or nothing about climate change." Given that Lovelock had been pondering such things as how Archean methanogens might have contributed to our planet's first greenhouse even before the rest of the scientific world recognized that methane was a greenhouse gas, this exposed a terribly distasteful underbelly of "Big" government-led climate science, an almost Nixonian nastiness flavoring this minor little private Climategate hidden within the big phony public one.
El Niño, referring to the Christ child, is so named because it was usually first seen in South America around Christmas time. I suspect that Trenberth might be right, for the time being at least, that the pulses of increasing heat into the climate system will be tied to the ENSO cycle. But this year, we had a Christmas day announcement not of a new El Niño, but of a totally unexpected new kind of energy dump within the global energy budget, far from the Pacific and having nothing to do with Trenberth's assumptions, and exactly the kind of thing that had been central to Lovelock's musing over the global energy balance the year before Trenberth's paper, in his 2009 book, The Vanishing Face of Gaia, in which he described the sea level as a reliable thermometer of the heat energy balance. Of course, Trenberth wrote much the same thing the following year, with the qualification that this still left a good deal of unaccounted for energy. Now we know both that Trenberth's unaccounted for energy was largely an illusion, and that the thermometer they were both looking at is not so trustworthy a gauge in the near-term (and Lovelock, through Trenberth's influence, was temporarily taken on a climate caper from the incomplete Hadley data as thoroughly as Trenberth was). The picture looks increasingly as though Kevin Trenberth, with his "Niñocentric" view, and by having mistakenly helped lead a chunk of the climate world down a largely phantom path, might need to swallow some of his nastier words for the holiday, and my guess is that Jim Lovelock, as he so often has in the past, will, now in his mid-90s, get the last laugh.
After all, could it be that the varying decadal patterns of ENSO are actually part of a system that dynamically sheds excess energy by increasing heat transport poleward to preserve low-latitude stasis at least for the short term? If I were to call this "Gaian," as in Lovelock's Gaia theory, I don't mean in a strict sense of necessarily involving biological influence (although a paper like this one, on biophysical mechanisms involved in ENSO, should give one, well, pause, before dismissing such possibilities out of hand), but rather I mean Gaian in the sense of an emerging property of the Earth System as a whole, and of its self-regulation, a property fundamental to Earth System Science, initiated almost a half century ago now by Lovelock and Lynn Margulis.
Trenberth's explanation for the "missing energy" was reasonable, but I also wouldn't be too surprised to learn, if anyone could ever record it precisely, that not a single extra joule went below 700 meters of ocean during 1998-2013. Look again at the NASA graph back in Part I: note that following the previous big El Niño, there was no similar pattern of poles warming and the mid- and lower latitudes remaining flat. Indeed, what has been going on since 1998 has no prior parallel in the above zonal graph, and so along with the Cowtan paper showing definitively that there has been little if any missing energy, to begin with, because of greater Arctic warming than believed, one might also reasonably question whether ENSO is really so fundamental to what has been going on with the increases of Arctic amplification, or whether ENSO just became entangled with it.
A good point that Trenberth made in closing his 2010 Science article, however, was that, since many have begun discussing the possible need for us to geoengineer the climate system ourselves, it would surely be necessary to understand such energy transfers better before we could ever attempt to do so. I'm sure that both Lovelock and Trenberth would agree on this, at least, and we do seem to be figuring some important things out these days. So, keep warm through the Arctic chill, and, once again, Happy New Warming Year!