Published on August 23rd, 2018 | by Michael Barnard0
Chaos Theory Does Not Invalidate Or Explain Global Warming
August 23rd, 2018 by Michael Barnard
The idea that the climate is chaotic and therefore global warming can’t be real is an idea that will not die. It’s not a recent idea. Various climate change deniers and ‘skeptics’ have been writing about chaos theory and climate change for years. It’s such a common refrain, it’s #127 of 197 skeptical arguments that Skeptical Science has rebutted, most recently in 2010. That, of course, didn’t stop the ‘independent’ thinkers at WUWT or Judith Curry from writing extensively about it in 2013 and 2016.
It’s worth a brief aside about the butterfly effect. It was originally cited as Does the flap of a butterfly’s wings in Brazil set off a tornado in Texas?, although the location of the butterfly, the meteorological effect, and the location have varied considerably since. Perhaps the reason the concept stuck so strongly was the image to the right. That’s the graphical representation of a particular Lorenz Attractor, the result of a chaos theory equation when drawn upon a computer screen. Many of the results do indeed look like butterflies and often are beautifully colored.
RealClimate published an excellent piece on why chaos theory and math are actually integral to climate modeling in 2008 around the death of Edward Norton Lorenz, meteorologist and chaos theory pioneer. Its summary is worth rereading:
How can climate be predictable if weather is chaotic? The trick lies in the statistics. In those same models that demonstrate the extreme sensitivity to initial conditions, it turns out that the long term means and other moments are stable. This is equivalent to the ‘butterfly’ pattern seen in the figure above being statistically independent of how you started the calculation. The lobes and their relative position don’t change if you run the model long enough. Climate change then is equivalent seeing how the structure changes, while not being too concerned about the specific trajectory you are on. […]
The ensemble approach, and indeed the multi-model ensemble approach, used in IPCC then derives directly from Lorenz’s insights into his serendipitous numerical problem.
This, of course, doesn’t stop the revenant skeptical meme from rising from its grave every year or two, and it appears it’s arising again. A particular variant which laypeople with little understanding of chaos theory like to trot out is how the butterfly effect invalidates climate science, or perhaps explains the global warming that we are seeing.
The Lorenz Attractor graphic is a result of chaos theory and math, and yet it results after a large number of iterations with a clear pattern. No particular iteration is easily predictable, hence the challenges with predicting weather, but overall the result allows clear understanding of where a system that is chaotic in individual interactions is going.
But back to that individual butterfly flapping its wings causing global warming. What about that? As the proviso goes, if the butterfly had not flapped its wings at just the right point in space/time, the tornado would not have happened. Yet some less sophisticated ‘skeptics’ think that what we are seeing is exactly that. Some butterfly or equivalent flapped its wings and so our atmosphere is warming, with all of the attendant implications. Nothing to do with CO2 or humans burning fossil fuels at all. And hence nothing to be done about it.
However, global warming is not a single butterfly’s wings, but is caused by all of the molecules of CO2 in the atmosphere. It’s as if it is not the single butterfly, but all insects in the world working to create a specific outcome with conscious intent. There are something like 300 kg of insects for every kg of humans in the world with a total insect biomass of roughly 500 billion tons, so this is a much more significant impact.
Even then, it doesn’t really achieve the same level of scale. What we have to have is all of the insects in the world working to create a specific outcome with conscious intent for over 100 years. That’s 100s of generations of insects working toward a single outcome.
But even that doesn’t do it justice. Let’s go back to those 500 billion tons of insects on Earth. There are about 8,220 billion tons of CO2 in the atmosphere right now at 411 ppm, of which 3,200 wasn’t in the atmosphere before the Industrial Revolution.
So it’s more like 40 times the mass of all of the insects in the world working for over a hundred years to try to create a specific change. That’s just a bit more than the single theoretical butterfly in Brazil.
Chaos theory helps climate scientists model the changing climate over multiple iterations and multiple models. The consilience of the modeling and the basis of chaos theory give us solid assurance that the models are right.