Climate science and the philosophy of science

No sooner had I completed the BNet debate than I received a missive from my protagonist with a link to new NASA research and a speech originally given in March. (Note: See below - I have been corrected by an anonymous commentor - this is not NASA research but merely uses satellite data)

The debate was intended to be about the difficulty of getting any reform through, but wound up being a debate on climate change. Buried in the midst of that was actually a debate about the nature of "science".

Scientists themselves claim a privileged position for what they do by asserting that it is based on "the facts", that there is some essential linkage between the theory they espouse and all the observations anyone has ever made. So in the context of the debate on climate change each side now abuses the other over the science. When they manage to get away from the perjorative terms such as "alarmists", "warmists", "sceptics" or "denialists" both sides wrap themselves in science. One side says here is our model and here is the confirmatory evidence, the other side explains the limitations of the model and finds other data that they claim contradicts the conclusion.

My protagonist went so far as to say that we shouldn't believe the theory because there had been no definitive experiment to prove it. I pointed out that the only way to do that was to do nothing and just wait to see what happens!

This view is the old inductivist view of science, that science knows what it knows because we infer from repeated examples a universal truth. This was replaced by the positivist theory of verifiability that the theory was confirmed by observations that matched conclusions of the application of the theory.

The problem is verifiability still looks like induction. Popper proposed that the real test wasn't to simply do experiments to confirm a theory but to disprove it by "falsification". Ultimately it was this theory that created a philosophical foundation for a distinction between religion and science, since the propositions of the former are not really capable of generating falsification experiments.

This theory was then itself "falsified" by the work of Thomas Kuhn who, as a historian of science demonstrated that scientists happily continue to use "falsified" theories in the absence of anything better. He described a process of revolutions from theory to theory. Paul Feyerabend went further and noted that in reality scientists use multiple and inconsistent theories.

He did not however promote Anything Goes as a prescriptive rule but more as a statement of fact that there is no rationalist conception of scientific method.

Ultimately Feyerabend agrees with modern day inductivists like David Stove and James Franklin. Formalistically it can be described as a Bayesian approach (see The Theory that Would not Die).

This comes down to saying "Given the circumstances are such that this theory can be applied, it is highly likely that this is the outcome". Very seldom are observations definitive either way.

So let's come to climate science. Firstly as Ziggy Switowski reminds us today it originally is a very old theory based on fairly simple statistical physics that has been adapted massively to deal with the far more complex environment of climate. Noting this he observes;

And as with any model, if you torment the assumptions enough, you can generate any forecast you like. There is plenty of evidence for this in some of our policy making and on both sides of the climate change debate.

One clear difficulty is that this ARE climate models - and it was climate models from which the "butterfly effect" was first named. That is the observation that complex models can be highly dependent on initial conditions. It has a corollary that observations that disagree with predictions can be not inconsistent with the model.

What it does do is leave open this kind of quibbling about the significance of individual observations.

But back to the bits kindly forwarded by Chris Golis.

Firstly the impressive speech by David Evans - whose claim to fame is an understanding of the kinds of complex systems we are discussing. He rightly points out that part of the warming theory is that rising temperatures from the carbon dioxide effect are presumed to increase the atmospheric moisture, and this multiplier is critical to the model.

Evans then goes on to note that weather balloons haven't found a predicted "hot spot" above the tropics. He then rightly notes that any long lasting system contains natural "dampening effects", he asserts however that the this observation proves such dampening occurs in the climate system.

The second item suggests that the NASA studies show that more heat is lost to space from the top of the atmosphere than climate models suggest. This could be the cause of what Evans asserts to be an observation. However, it could equally be wrong, or simply evidence that something else is wrong in the model because an error in the heat exchange at the top would presumably also effect the models that supposedly work to explain thousands of years of stability.

So, where are we. Evans asserts;

You see, in science empirical evidence always trumps theory, no matter how much you are in love with the theory. If theory and evidence disagree, real scientists scrap the theory. But official climate science ignored the crucial weather balloon evidence, and other subsequent evidence that backs it up, and instead clung to their carbon dioxide theory — this just happens to keep them in high-paying jobs with lavish research grants, and gives great political power to their government masters.

This makes climate science a great conspiracy theory - but not of the left but od self-interested scientists and bureaucrats. That such things can happen is evidenced by 90% of theoretical physicists pursuing string theory.

But if we go to the real conception of science, theories that are probably true when applied where the assumptions are appropriate - the theory of global warming is still a serious risk. What we do know is that we are taking the CO2 concentration higher than it has ever been, that in the past this correlates to warming and that there are models that predict it will irreversibly happen in response to human CO2 emissions.

Why wouldn't you decide as a planet to really work hard on using different energy sources to reduce atmospheric carbon?

The only answers I hear are because of some kind of theory of economic damage. Memo to my fellow Australians - if we want to capitalise on our current boom we need to invent the energy sources of the future, and research cheaper energy transport (hydrogen).


NOTE: The "NASA research" is in fact a paper by two University of Alabama in Huntsville academics. It attempts to reconcile certain observations on actual heat exchange to modelled heat exchange and concludes;

We are still faced with a rather large discrepancy in the time-lagged regression coefficients between the radiative signatures displayed by the real climate system in satellite data versus the climate models. While this discrepancy is nominally in the direction of lower climate sensitivity of the real climate system, there are a variety of parameters other than feedback affecting the lag regression statistics which make accurate feedback diagnosis difficult. These include the amount of non-radiative versus radiative forcing, how periodic the temperature and radiative balance variations are, the depth of the mixed layer, etc., all of which preclude any quantitative estimate of how large the feedback difference is.

This is somewhat more equivocal than the way it was first reported. This was by James Taylor from the Heartland Institute - an avowed free market think tank (in the classic US right wing model) - and did misrepresent the research.


Novae Meridianae Demetae Dexter delenda est