Begins might be slightly wrong, as we’ve already had the David Rose saga, but it certainly continues. What I’m referring to is an article in the spectator by David Whitehouse (science editor of the Global Warming Policy Foundation) in which he argues that [t]he death of the global warming ‘pause’ has been greatly exaggerated.
What’s a bit annoying about this article, is that it starts quite well; the author clearly understands the topic. For example
Global warming is about energy imbalance. Greenhouse gasses stop heat leaving the earth, so the planet is getting warmer. This is fundamental physics. Temperature goes up; oceans warm up, expand and sea level rises; pole caps melt.
It then, however, descends into a discussion of the so-called “pause” and finishes with a claim that
The 2015-16 El Nino has been one of the strongest on record, temporarily elevating global temperatures by a significant margin. This means that their case rests on the El Nino temperature increase and will be destroyed when the El Nino subsides….
However, what he leaves out, is that his own link which supports his claim that the 15/16 was one of the strongest El Nino’s on record, goes on to say that it is “comparable with the 1997-98 and 1982-83 events. It is too early to establish conclusively whether it was THE strongest.”
The figure on the right shows GISTemp monthly data from November 1966 to November 2016 (blue), with a 12-month running average (red), and an OLS trend (black). You can clearly see spikes corresponding to El Ninos in 82/83, 97/98, and one that is not complete in 15/16. You can also clearly see an underlying warming trend. The reason it is warmer now than it has been in the past is clearly not because of the El Nino, the impact of which is currently waning. It also seems pretty clear that once it has waned, we will not be back in some period that can reasonably be regarded as a “pause”.
Consider, also, the figure on the left which shows the 0-2000 m ocean heat content. It’s clear that even over the period when there was meant to be a “pause” in surface warming, there was no indication of a pause in overall warming. This is probably a key point. Most of the excess energy goes into the oceans (about 93%) while only a small fraction heats the surface. Given intrinsic variability, we don’t expect the surface to warm smoothly and at a constant rate, even if the system as a whole is undergoing unequivocal warming. Using periods when surface warming happens to be slow (despite overall warming continuing) to argue that global warming has paused, is extremely disingenuous.
So, I have no idea what will happen once the impact of the 15/16 El Nino has ended, but even if we do enter another period of slower surface warming, it will almost certainly be at a higher level than the previous period of slower surface warming. One should bear in mind (in my view, at least) that surface warming acts to reduce the energy imbalance and that there is probably a limit to the magnitude of the planetary energy imbalance. Therefore, how much we warm in the long term will likely depend on how much we emit. Even though surface warming will almost certainly be variable, we really should be careful of using this short-term variability to infer things about overall anthropogenic global warming.
When I posted David Whitehouse’s article on Twitter (with a rather exaggerated – unfair? – assessment, I will admit) some responses pointed out that there was much to agree with (as, I will admit, there was). The impression I got was that some regarded this as an indication that maybe there was some common ground to work with. Maybe, but I have a slightly different interpretation. That the beginning of the article actually presented a reasonable description of anthropogenic global warming would seem to indicate that David Whitehouse knows enough to know that his conclusions are disingenuous. That suggests, to me at least, that there is little chance of reaching a common ground; his article seems much more an attempt to regenerate claims of a “pause” than as an attempt to improve public understanding of this topic. I am, however, more than happy to be proven wrong.