Climate Disruption

Simon Donner takes on the great "climate change" vs. "global warming" debate. He argues, albeit somewhat tentatively, for capitulation; we should call a thing what everybody else calls the thing:

Rights and wrongs of the different labels aside, the fact is that there is a disconnect here. We use a term that means less to people. And it puts scientists and others communicating the real scientific consensus at a disadvantage. Do a Google search for "global warming" and "climate change". With "global warming", the term the public is more likely to use, a "skeptical" site comes up second [note: search is done from Canada, others may find different results].

Let me take the opportunity to remind everybody that I'm on record taking the opposite position in my RealClimate article "Imprecision of the Phrase 'Global Warming'"

The problem in capitulating to the common usage is that the common usage is woefully imprecise. As I said in that article:

If someone asks me in my capacity as a climate scientist whether I “believe in “global warming”, they are not asking the question in a literal sense. They are asking “what am I to make of this confusing topic called “global warming”?

In the end they are usually asking some combination of questions like 1) whether greenhouse gases are accumulating? 2) whether the greenhouse effect is established science? 3) whether global warming has been observed? 4) whether future climate change is expected to be big enough to worry about? 5) whether cooling at a single location falsifies the “theory”? 6) whether to expect super-hurricanes? 7) whether the Gulf Stream will shut down instantly glaciating Scandinavia and Britain? 8 ) how you can model climate when you can’t predict weather? etc. Often they will bounce incoherently from one to another of these sorts of exasperatingly-missing-the-point sorts of question.

Once in a while someone will have more sophisticated questions like 1) what’s the magnitude of the anthropogenic forcing compared to natural forcings? 2) what’s the lag time in the system response? 3) what is the magnitude of the most disruptive plausible scenarios? 4) what’s the likelihood of the discontinuous shifts in system regime? etc., When I hear people asking the right questions it makes my day, but it’s pretty rare.

What people outside the field universally don’t mean by “global warming” though, is “a tendency for the global mean surface temperature to increase”!

The first trouble in talking about "global warming" is that when you do, you are already in an area where communication is problematic. And shifting goalposts is a key tactic of obfuscators everywhere. "Nothing could be better than early retirement on Maui, and a peanut butter sandwich is better than nothing, so a peanut butter sandwich is better than early retirement on Maui." That sort of thing is their stock in trade. By starting the conversation with an ambiguity, you leave yourself open to all manner of trickery.

Since I wrote that piece, a whole new set of problems has arisen with "global warming", in that the global mean surface temperature has become an unhealthy obsession of the crowd that calls themselves "lukewarmists", i.e., the McIntyreans. Pretty much the only thing they care about is the observational and proxy record of global mean surface temperature. If "global warming" is the theory, and the observational record (mostly unforced) is ambiguous, well then, we can all go home and do business as usual, can't we?

The bizarre fascination with Mann and Jones, the obsession with every little bounce up and down of the satellite record, all of this turns climate policy into a sport, where the amateur critics of science "root for" downturns in the curve and we find ourselves idiotically hoping for equally meaningless upticks. The actual implications of accumulating greenhouse gases are utterly lost in the shuffle.

The issue, of course, is completely miscast. The global mean surface temperature (or if you insist on hair-splitting, the fourth root of the mean of the fourth power of temperature, which is the arguable alternative and which behaves very similarly) is an interesting and useful diagnostic, especially in the study of paleoclimate. But it isn't what we are worried about.

The global mean temperature does not cause impacts.

Local shifts in climate cause impacts. Changes in the radiative balance cause changes in circulation which cause changes in local climate. Human activity causes changes in radiative balance. Carbon dioxide is the biggest and most difficult but by no means the only component of human forcing of radiative balance. The local changes we are seeing are roughly as expected, and are already meaningful and are accelerating. Errors in our understanding are unlikely to be benign. Those are the salient facts.

Obsession with global mean temperature is a debating trick of the opposition. The fact that people are searching on "global warming" means we have to use it as a tag. But we shouldn't use it to mean what the people searching on the term mean by it, because the very use of the term is generally a sign of confusion.

"Global warming" means an increase in the mean surface temperature of a globe. That's all. It applies to any physical spherical object, typically a planet or a large moon. It applies on many time scales. It isn't itself a problem, and doesn't itself require a response. On the time scale of human forcing, it is an expected symptom of anthropogenic climate change.

Some go with "climate chaos" which has two problems: 1) it prejudges the scope of the problem and 2) it raises nomenclature confusion with a relevant mathematical concept. I think "climate disruption" is a good name for the problem.

---

Image: Dan Farber, a law professor, who I hope has mercy. It's a great picture.