Statistics

Chu On These Climate Tipping Points

“Beware the Tipping Point, my son!
That little wee thing, the difference it makes!
Beware its Connector Theory, and shun
Its luminous Balderdash!”

With appropriate apologies to the great logician whose words I abused, we consider the mysterious, misunderstood Tipping Point. Beware! for it is as rare as a Jabberwocky, everywhere lurking and ready to pounce, to devour and overcome. We can but sense its approach, its true shape is camouflaged. We only know that it was here after it has gone. Alas!

Or such is the popular imagination. The truth, as it frequently is, is mundane. Tipping point

In physics, a tipping point is that point in a dynamic system where the system switches from one state of equilibrium to another. Take a cardboard box and flick it with your finger. If the box is light enough, it will wiggle a bit but it will return to its resting state. Now push it over, with one of the edges touching the floor acting as a hinge. Then let go. If you push just a little, the box will return to its original state (perhaps after bouncing around). But there will come a point which if you push past it, the box will fall over. That point is literally and physically the tipping point.

The equations of motion and the physical properties of the box govern the tipping point. And, of course, tipping points are present in many, but not all, physical systems. It’s also important to understand that the mere presence of a tipping point, its theoretical possibility, does not guarantee that this point will ever be reached. Finally, there is no “good” or “bad” about states of equilibrium. Those judgments require reference to non-physical criteria. Whether the box lies on this side or that is only interesting if you have money on the outcome or something breakable inside.

The climate is vastly more complex than a falling box. It is impossible—not just unlikely, but impossible—to model the climate precisely (actually, our expertise is such that we can only model an idealization of a box and not even a real box). We do not and cannot measure the climate well. The best models are gross simplifications where we abandon precision and instead seek to mimic statistical properties of the climate. Even that is a tricky, error-prone business.

A tipping point in the climate is that point at which the system changes from one state of equilibrium to another. It is not, it is certainly not, true that the state into which the system changes is inevitably worse than the previous state. If there are true tipping points in our real climate, passing through one does not in any way imply conditions must become worse. They might, they might not is the best we can say (conditions might even improve).

Secretary of Energy Steven Chu wants climate modelers to overcome their squeamishness and place equations for tipping points into climate models. He said, “To be sure, if you start to model the tipping points you put in much larger uncertainties, but there is a difference between uncertainty and inaccuracy.”

Chu is right that there is a difference between uncertainty and inaccuracy, but his reasoning is flawed. If you add, merely for the sake of adding, tipping points into model equations and those equations do not represent reality you introduce inaccuracy and increase uncertainty. And that is not the worst of it.

If you design a model that includes tipping points, and then run that model, you will likely find that the results evince tipping points. But it would be a mistake to issue the press release, “Tipping Points Found In Climate, Scientists Concerned.” You included the tipping points, it is therefore no shock you found what you included. You audience becomes more certain than it deserves to be.

Why, this is just like building into a model subroutines which provide for a positive feedback on temperature with carbon dioxide. When that model is run, it will show positive feedbacks on temperature with carbon dioxide. Is it worth a press release to say so?

Chu is worried that the “long tail of the damage tail is out there” and that climate models aren’t capturing these statistical properties. It is true that climate models do not (so far) make skillful predictions, thus they cannot adequately assess risk. Whether the risk is actually higher or lower is unknown. Including tipping points in climate models to artificially inflate risk, just to produce fatter “long tails”, is not good science. Modelers are right to be leery of tipping points.

Thanks to Marc Morano for the original link.

Categories: Statistics

18 replies »

  1. I’ll have you know we Balderdashians resent the suggestion of discrimination against us even when made in jest.

    Interesting article though. I always thought the “tipping point” occurred around the time of paying the check. For a government bureaucrat to be involved in tipping is a surprise. OTOH, he didn’t say he wants to do the tipping himself — quite the opposite.

  2. Hmmm .. after some thought, check paying isn’t the only tipping point. Another is when passing a lady while wearing a hat. Strange that a hat wearer didn’t mention this at all. I suppose I’ll have to add the box thing to the list.

    Tipping seems to be common. I can understand Chu’s concern that the climate models don’t tip.

  3. The climate modelers are the modern version of the hiruspex. They also have about as much success in fortelling the future as the hiruspex.

  4. Fair point about Chu, oh Nobel One. Elites as a class do not “listen”. “Listening” is not a necessary skill in order for them to function as Elited. Holding firm to a certainty everything displayed on their teleprompter screens springs from the world’s foremost knowledge fount is their only criteria needed to rule. So there is no reason to listen to anyone else. Aamof to do so would be wasteful and disastrous.

  5. My tipping point example is a slot machine. You never know when it will happen, but you keep pumping dollars into the slot in hopes of hitting a really big tipping point. Cha-ching!

  6. Uncertainty and inaccuracy are not identical, but they are related.

    Uncertainty includes the natural variation (aka imprecision) in whatever is being measured, the sampling error from measuring only a few points on the entire globe, the measurement error inherent in the equipment or in the proxies, (which only estimate real measurement with huge error), or worse, indicators (which are proxies of proxies), and the human error in taking or recording the measurements.

    Inaccuracy (aka bias) includes poorly calibrated measurements, human error, and human tendencies to have ulterior motives (sub- and fully conscious) when taking the measurement, recording the measure, selecting which data to use (and which to reject), in selecting the analytical methods, and in making inferences from the analysis.

    True uncertainty requires consideration of both the variation and inaccuracy inherent in the entire measurement-analysis-inference process. Furthermore, the global climate models are used to make predictions about the future, which adds additional uncertainty.

    All those errors inherent in chaotic systems, in measurement, in analysis, and in predictive inference do NOT “balance each other out”. Instead, they aggregate and compound. A half degree error in each category builds until the final prediction may be plus or minus 5 degrees or more.

    Chu’s folly is to make a poor, biased, predictive inference of climate tipping point catastrophe, in one direction only, without real evidence, in contradiction to the known climate record, based on models rife with compounded uncertainty. He is crying wolf, the sky is falling, impending doom, based on a-scientific paranoia. If he wants to carry a sign and proselytize about Thermageddon on street corners, fine, but he’s not the kind of person we want managing a major government department.

  7. There are two tipping points that fascinate me.

    1) The start of this interglacial. Boy did it warm up fast.

    2) The end of this interglacial. Boy will it get cold quick.

    Other than that … its just minor inconsequential changes.

  8. There is only one tipping point involved. It is in the drinking glass that Chu and Hansen are holding to their lips as they drink whatever it is that is causing them to hallucinate about human-caused global warming!

  9. “In physics, a tipping point is that point in a dynamic system where the system switches from one state of equilibrium to another.”

    In climate thereis no equilibrium.

  10. I will be surprised if they do NOT include Chu’s tipping point in the models and then proclaim that the models show that a tipping point will occur in 20##, it’s worse than we thought, and blah blah blah. The MSM will print and broadcast it, the libs will proclaim it to be unequivocal, and the merry-go-round will continue. They will never give up until there is a carbon tax, cap and trade, CO2 sequestration, etc., and the UN runs the world.

  11. A further point relating to this paragraph:

    “A tipping point in the climate is that point at which the system changes from one state of equilibrium to another. It is not, it is certainly not, true that the state into which the system changes is inevitably worse than the previous state. If there are true tipping points in our real climate, passing through one does not in any way imply conditions must become worse. They might, they might not is the best we can say (conditions might even improve).”

    An “equilibrium” may in fact be represented by a suprisingly large range of observable or measurable states. What you witness and describe as a “shift in the equillibrium” might only be a “shift within the equlibrium”.

    Moreover, an equlibrium need not be static, but could be dynamic. A climate equlibrium might in fact be characterised by a very gradually increasing temperatures and sea level increases over time.

  12. Winning a Nobel used to be a crowning achievement, but then Al Gore won the Peace prize for a half-baked sci-fi film. It will be assumed that anybody who wins another Nobel now must have espoused the correct political stance.

    Steve “Paint your Roof White” Chu comes off as more of an idiot with each additional speech he gives.

    Garbage In = Garbage Out
    Extremely Biased Garbage In = Extremely Biased Garbage Out

    Wow! What a shocker!

  13. What Chu is suggesting, I believe, are, at least two things: (1) the ice-albedo feedback effect may not be properly included in many of the current generation climate models. As Arctic ice pack thins, more (comparatively dark), energy absorbing water is exposed, so the insolation reaching the Arctic surface can go into heating the ocean water. This is a positive feedback loop that may not be accounted for in current models. Ditto for the exposed land surface in, say, Greenland as the ice pack melts. (2) Ditto for the impact of permafrost melt. As the Arctic warms, the tremendous amount of greenhouse gas like methane that are locked in the permafrost may be released. I don’t remember the numbers, but the greenhouse gas impact of the release of this carbon is comparable on its own to the contribution from all anthropogenic emissions to date.

    Matt, you know this shit.

    Tom

  14. Another point: what Chu is probably getting at is what is called “hysteresis” in chaotic dynamics. Earth of course exhibits the capability to have a climatic basin of attraction like what we had in the 20th century. Earth may also, with sufficient greenhouse gases, have the capability to support global atmospheric temperatures that are 10K warmer than current, a different climatic basin of attraction. We ought to develop some understanding of the relative facility of the system to go from one basin of attraction to another, and the facility to jump back. Recent work of Susan Solomon certainly suggests that it will be very difficult to jump back to anything like a 20th century climatic basin of attraction once we move into a radically warmer regime, even if we were to cut off GHG emissions tomorrow.

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