Sunday, 8 March 2015

How can the pause be both ‘false’ and caused by something?

Judith Curry asked Michael Mann:
"How can the pause be both ‘false’ and caused by something?"
She really did, if you do not believe me, here is the link to her blog post.

I have trouble seeing a contradiction, but I have seen this meme more often among the mitigation sceptics. Questions like, how can you claim there is no hiatus when so many scientists are studying it?

Let's first formulate it abstractly, then give a neutral example, before we go to the climate change case where some people suddenly become too creative.

Abstract

"How can the pause be false" can be translated to: how can you claim A is still related to t?

While "caused by something" can be translated to: A is also related to X, Y, and Z.

I hope the abstract case makes clear that you can claim that A is related to X, Y and Z without claiming that A is not related to t.

Neutral

The neutral, I hope, analogues argumentation would be: How can the claim that economic growth needs free markets, property rights and rule of law be true, at a time that economists are studying the influence of the [[Lehman Brothers]] crash on economic growth?

I know, analogies do not work in the climate "debate". Someone will always claim that they do not fit. Which is always right. That is why they are called analogies.

Climate

There is no statistically significant change in the trend. People who think they see that in a the temperature signal are often just shown a small part of the data and they overestimate the significance of short-term trends. The uncertainty in a 10-year trend is not 10 times as large as the uncertainty of a 100-year trend. A 10-year trend is 100 times more uncertain.

That there is no change in the temperature trend is visually clearly seen by these two elegant graphs made by Tamino.




What causes these deviations from the trend line or the deviations from the average model projections is naturally an interesting question. Something that climatologists used to simply call: natural variability, small stuff, impossible to understand in detail.

It is a great feat that climatologists now dare to say something about these minor deviations. Remember that we had more than half a degree of warming over many decades before climatologists said with any kind of confidence that global warming is real.

Even if these dare devils turn out to be wrong, it tells a lot about the quality of our modern climate monitoring capabilities, climate models and analysis tools, that scientists are willing to stick their neck out and say: I think I know what might have caused these minimal deviations of a tenth, maybe two tenth of a degree Celsius. Pretty amazing.




Related articles

Niamh Cahill, Stefan Rahmstorf and Andrew C. Parnell, 2015: Change points of global temperature. Environ. Res. Lett., 10, art. no. 084002, doi. doi:10.1088/1748-9326/10/8/084002. (open access)

Grant Foster and John Abraham, 2015: Lack of evidence for a slowdown in global temperature. US CLIVAR Variations, Summer 2015, 13. (open access)

8 comments:

Harry Twinotter said...

I pointed out on the Climate Etc blog that Dr Curry's question really only related to the semantics of the title of the article ie a 'false pause' was not a pause but really just a slowdown. If you substitute the word 'slowdown' for 'false pause' the semantic contradiction goes away.

Another example a mollusc has what is called a 'false foot'. Just because the term contains the word 'false' does not make the false foot any less real!

citizenschallenge said...

or that it has five toes.

;- )

Elio Campitelli said...

Of course.
There is no "pause" if by that one refers to the disappearance of an underlying linear trend in the data. Much less real is a "pause" if one refers to reduction of the energetic imbalance of the earth and it's associated increase in global energy storage.

But there is a "pause" if by that one refers only to the specific characteristics of the mean tropospheric temperature cause by every forcing factor and variability of the climate system.

Is not really something that hard for a scientist to understand but is caused, IMHO, by the vagueness inherent in the denialists strategy. The same way a denier selectively denies or accepts different parts of the scientific evidence and has no real alternate hypothesis. The denialosphere has no real working definition of that the "pause" really means.
Sometimes it means no global warming, sometimes it means model-observations disparity, sometimes it's just a meaningless platitude spouted to try tu justify one's position.

Victor Venema said...

It is probably on purpose that the "pause" is not well defined in such statements of mitigation sceptics. Then your followers can shout in newspaper comments: global warming has ended, while you can claim you never said such a thing.

Elio Campitelli said...

Reading Curri's posts it struck me as odd that she bashes Steinman et. al. for using "climate models that don’t correctly simulate internal variability" but gives Robetrs et. al., which uses the same models, a free pass.

May I put forth that the reason for this disparity is that one paper (partially and selectively) confirms her previous opinions while the other does not?

Brandon R. Gates said...

Victor,

"It is probably on purpose that the "pause" is not well defined in such statements of mitigation sceptics."

Ambiguity is a great tactic when the preponderance of evidence speaks against one's position. Hint, insinuate, "leave it to the reader to decide" -- all forms of plausible deniability. The most predictable thing in climate is a contrarian saying, "I never said x" (even though it's transparently obvious that's what I meant).

Bob Tisdale is a master of the form, whom I pick on for his recent WUWT article, "Bad News for Trenberth’s Missing Heat – New Study Finds the Deep Oceans Cooled from 1992 to 2011 and…" which is a ... creative ... reading of Liang et al. (2015), Vertical Redistribution of Oceanic Heat Content. A paper I find quite interesting, sensible, and which does not at all say what Bob's so-called "memorable quotes" paints it out to say.

More along the lines of Curry's "question" to Mann, the comment thread for Tisdale's article contains this absolute gem:

"The atmosphere and oceans are never in a state of equilibrium. [~cf: Lindzen]. That’s the reason for the changing climate in various areas."

One may as well attempt to reason with a cat.

tonylearns said...

the interesting thing to me is that the people using this argument are sophisticated enough to understand that it is a logically invalid critique.
Curry certainly knows about ENSO, solar radiation, Aerosols, and OHC and she champions natural variation as a possible cause of current warming.
but she dithers about last year because, while not technically an EL Nino there were el Nino like aspects to ENSO, and she does the same with OHC, and she just ignores the decrease in solar radiation.
She is an opportunist looking for ways to be a champion of deniers without actually disavowing CO2. that way she can claim she never doubted and was just on the low end of attribution when temps continue to increase int he next 5-10 years.
she once literally told me that there was no reason to think that a 4°C temp increase would be a disaster. Until then I considered her to be possibly a real skeptic.

John Brookes said...

So I visit Judith's post from early 2015 and she says:

"The titles pretty much speak for the articles: The inference is that hiatus has now been explained; and that it should end soon with a warming ‘burst.’"

I tell you what, she is spot on. I won't be saying anything mean about her when she shows such amazing foresight!