by Judith Curry
There is a well-known story in the Bible about arrogance. People were speaking one language, engineering progressed, and they started to build a tower which they intended to make so high it would reach the heavens. In the story of the bible, God descended and confused he language of the people, so that they could not understand each other; and then they were scattered all over the earth.
I think that the meaning of this can be felt in large conferences, where we are thousands of scientists in hundreds of sessions, each one of us working in his own isolated domain, with hardly any knowledge of nearby domains, let alone of the big picture. So we think that what the story is trying to tell us is that good communication leads to progress, progress is followed by arrogance, and arrogance is followed by loss of communication, which leads to stagnation, which is, we think, where science is now.
This gem comes from a presentation by Christofides and Koutsoyiannis [link] (h/t David Hagen):
God and the arrogant species: contrasting nature’s intrinsic uncertainty with our climate-simulating supercomputers
Antonis Christofides* and Demetris Koutsoyiannis
A presentation given at the Air & Waste Management Association’s 104th Annual Conference & Exhibition Session T09-02 Orlando, Florida, 21 June 2011
Read the whole thing, it is short, clever, and profound. Some excerpts:
In the middle ages, people were told they were all sinners, and thus they would burn in hell. However, they could buy indulgence: they could pay an amount of money and get a piece of paper which certified that their sins were forgiven. Today, we are told we are all sinners (because we exhale carbon dioxide, give birth to children who do the same, and we also drive cars), and thus we will burn in hell as the Earth warms up. However, we can buy indulgence: for example, if you fly to London for the weekend, you can buy indulgence for that particular sin. “Offset the carbon emissions” is another way of saying “pay this amount and we’ll pretend that you did not make this trip”. Other forms of indulgence are compact fluorescent lamps and hy- brid cars, which also do not make any difference. To us, climate change is largely a religious issue, which is why we chose to involve God in this presentation.
Although the climate has always been in perpetual change, many scientists who support the anthropogenic global warming hypothesis claim that this time it’s different, because their climate models show that the increase in carbon dioxide fits the current climate change better than any alternative explanation. This argument is circular, since the models reproduce the hypotheses of their programmers. What is most important, however, is that this way of reasoning is rooted in the fallacy that climate can, in principle, be described in deterministic terms; that if we could analyze the system with sufficient granularity and make sufficient measurements then we would be able to produce sufficiently good predictions; and that there must necessarily exist an identifiable causal agent behind every trend or shift. We explain that climate, like many natural systems, exhibits “Hurst-Kolmogorov behaviour”, which means it is intrinsically uncertain, with real limits to the potential for attribution and prediction.
If you calibrate with one data set and test on another, it’s OK; but climate models are not tested in this manner. If you only calibrate and do not test, then “calibration” is a misnomer: it’s actually data fitting. So modelers adjust the parameters so that models behave as they have hypothesized they should behave; then they use this behaviour as evidence that their hypothesis is correct.
In the real world, God makes no warranties on what will happen in the long term. Yes, the sea will most likely continue to rise in the next century, but beyond that, it is really uncertain what [climate] will do.
So when we design a structure, such as a dam, and we try to predict the design flood, then it’s not a good idea to use the notion of the “maximum probable precipitation”, because there is no such thing, and because it can be (and has been) exceeded; it’s also not a good idea to consider a “signal” (e.g. a constant average value) plus “noise” (e.g. variability that follows a distribution), because God does not err, and therefore he does not distinguish between signal and noise. It is better to use Hurst-Kolmogorov dynamics, with which we do not predict the future in a deter- ministic sense; instead, we predict the possible range of outcomes given an uncertainty level (or vice versa), without distinguishing between “signal” and “noise”. The application of this method results in higher uncertainty estimates than with other methods, which un- derestimate uncertainty.
JC comments: Well which analogy do you like better, the tower of Babel or the indulgences? :)
The point I would like to pick up on is this one:
What is most important, however, is that this way of reasoning is rooted in the fallacy that climate can, in principle, be described in deterministic terms; that if we could analyze the system with sufficient granularity and make sufficient measurements then we would be able to produce sufficiently good predictions; and that there must necessarily exist an identifiable causal agent behind every trend or shift.
In the real world, God makes no warranties on what will happen in the long term.
Understanding the limits of predictability is the key challenge. The arrogant species is fooling itself if we think we can ‘project’ the state of the climate in 50 years or 100 years, even if we somehow knew what the anthropogenic forcing would be. Yes, it seems that all other things being equal, the climate would be warmer with more CO2, but there is no reason at all to expect all other factors to remain the same. Some frame the problem is “not if, but when” we will realize dangerous climate change; we know where this is headed, but not sure exactly when this warming will be realized in the surface climate.
Personally, I am in awe of the complexity of the climate system and don’t want to anger the gods with the arrogance of claiming to understand climate change. I understand a few things, and collectively we understand more things, but I suspect the area of ignorance (white area of the Italian flag) remains uncomfortably large.