Ceci n’est pas une temperature globale

When Magritte painted the “La trahison des images” (the treachery of images*) which depicts a pipe and the message “this is not a pipe”; when Korzybski noted that “the map is not the territory“, the insanity of the alternative beautifully articulated by Borges in his one-paragraph short story “Del rigor en la ciencia” (On exactitude in science); they illustrated an obvious truth that is nonetheless often overlooked: the representation of a thing is not the thing itself. The same warning extends to every representation of the world including that rendered to us from our own senses. Anyone who doubts this is invited to ponder whether a particular piece of apparel is black and blue or else gold and white.

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All models, all measurements, all of the time

“All models are wrong but some are useful” – George Box

“All measurements are wrong but some are useful… and at least they happened” – John Kennedy

A perfect world, other worlds, this world

Question:

Imagine we could make a perfect climate model, and get perfect climate predictions (and everyone knew it). What would the political process to respond to climate change look like? How would it be different?

— Doug McNeall (@dougmcneall) April 3, 2018

I like questions like this, which involve a collision between an ideal – in this case, a perfect model – and the real world. I’ve wondered about perfect models before when I worked briefly on model assessment. The question I pondered was this:

If we had a perfect model, how would we know?

Life, eh. What’s that all about then?

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Life

A while back now, Nature published a paper suggesting that there was a natural cap on the human lifespan. Readers of this blog who, let’s face it, are mostly in urgent need of an actual monkey diagram* and therefore bitterly disappointed by what they find here, well… they might remember that I thought the paper was rather weak. I banged on about it at some length and even went to the trouble of learning how to make Jupyter notebooks, the better to express my disapproval**. However, I am British, so it’s always possible anyone who read it came away with the clear impression I was rather taken by the paper’s dazzling sophistication.

Wherever the truth may be

Eric Holthaus wrote an article of a kind that appears from time to time. In the article he calculates that “the odds of 400 warm months in a row would be approximately one in 1 x 10^120″*. Someone on twitter helpfully spelled out what that is in regular numbers. It has a lot of zeroes. By warm months, Eric means that the global average temperature was above the 20th century average. The way he looks at it, left to its own devices the climate would be warmer than the 20th century average half the time and cooler than it the other half – just like tossing a coin: heads it’s hot, tails it’s cold.

The climate doesn’t really work like that, but more of that later.

Analogies are like…

(I wrote this years ago, but it still seems relevant)

Never give a scientist an analogy to play with. Scientists like to pull things to pieces and analogies don’t like being pulled to pieces; few things do. I used an analogy in a presentation once and the ensuing discussion consumed the five minutes set aside for questions (as if they were some kind of emergency or unpleasant contingency, which, in this case, they were), continued like the aftermath of some dismal radioactive accident through the first few minutes of the next talk, the evening ice breaker, the conference dinner and the remaining two days of the workshop. During which – and long afterwards – I had a goodly time to think about the error of my ways.