Certainties and risk perception

Back to the “Data or Dogma?” hearing of the US Senate Committee on Commerce, Science and Transportation. In two previous posts (here and here) I gave my thoughts on why the only-few-skeptics-versus-the-rest is not a very good argument. This post will focus on the view point of those who rely on the consensus. At the beginning of the hearing, Senator Peters gave an opening statement in which he explained his viewpoint on the science and how this effects policies. To me it was interesting because it showed where the risk perception came from.

data or dogma? Peters

Peters started with explaining that, when thinking about global warming, there are risks and certainties. He first started with the certainties:

By burning fossil fuels, humans are releasing carbon into the atmosphere that would have otherwise remained locked away. This process creates carbon dioxide, a greenhouse gas, that traps heat that otherwise would have radiated off into spaces. We know that by the law of conservation of energy that additional heat can’t just magically disappear. In stead it causes our planet to get warmer.

What else is certain? We already see the symptoms of a warming planet. Not just in the temperature records, but in the rising sea, shrinking ice levels, in toxic algae blooms that are flourishing in the great lakes that were made worse by increased precipitation, runoff and warmer water temperatures, tainting drinking water for 2.8 million people in recent years. All of that is certain.

The first paragraph is not controversial. Skeptics also agree that burning fossil fuels releases CO2 in the atmosphere, that this is a greenhouse gas, that it therefor has the ability to trap heat and that, all other things being equal, it would be warmer than without that extra CO2. But he stops where it really gets interesting. The theory indeed suggests that humans are the cause of the warming because they are adding CO2 in the atmosphere. However, reality is much more nuanced. In a simple system that would be straight forward, but how does it work in the complex, coupled, chaotic system that is our climate? Anthropogenic CO2 is not the only factor in the equation, there are thousands, maybe millions others and they could all influence each other. How much do we know of this system, knowing that there is only a couple decades or less of reliable historical data? The climate changed in the past without us, so how do we currently differentiate between warming by natural and anthropogenic CO2?

Some other interesting questions would be: how much of that uncertainty is communicated to the policy makers? How politicized is the science? How can we avoid bias? How much can we rely on the mathematical models to project x years into the future? And so on.

The examples he gave in the second paragraph are indeed symptoms of a warming world, but it doesn’t say anything about the cause. That warming could well be natural as anthropogenic or, more likely, a mix of both. It also depends on ones definition of “Global Warming”, some of those effects seems local to me. That aside, So none of these examples accurately helps to advance his case. They don’t suggest that humans are the cause. This would also be true even if that warming was 100% natural (which I don’t think it is).

To me, the stated certainties are not relevant to what he want to do with this knowledge. The first paragraph didn’t take into account the reality of a complex system and therefor over-estimated the certainty. The second paragraph had nothing to do with the anthropogenic aspect of global warming.

Then Peters continued with the risks:

Managing risk is all about looking at a range of possible outcomes and consequences. Looking at the likelihood of each of those consequences and then looking to see if there is anything you can do to reduce the likelihood of those consequences or both.

In can agree with this, but the question arises how that will work out in the complex system that is climate.

From our models and from our understanding of the science we see a range of potential outcomes, a range of possible warming trends, a range of consequences based on those trends. There are implications for our national security, for the economic health of our country, for our food supply and agriculture and for the health and safety of Michiganians, Americans as well as people around the planet.

So here we have it. It is indeed possible to see a range of potential outcomes from mathematical models and the understanding of the science. But how meaningful this potential outcome is, depends on the accuracy of those models or the certainty of the science. A science that is studying a complex, coupled and chaotic system over a long time-frame with only some decades of reliable data. There should be quite some uncertainties there.

As described in the written testimony of Dr. Christy, the models over-estimate the warming at a rate three times that of the real world. This over the past 37 years, in a period with the highest concentration of greenhouse gases in the atmosphere, therefor the effect of the additional CO2 should be large. They don’t do a good job in telling us what should have happened until now, why should we expect them to accurately projecting what will happen in the future? As Dr. Christy worded it at the hearing:

Being off by a factor of three does not qualify in my book as settled science

To me it looks like the science is being oversold to the policy makers. How sure can we be if the warming is overstated three times what is observed in reality and huge uncertainties are not communicated to the policy makers? That brings us to Peters’ following remark:

The possible consequences of all these areas range from the bad to the catastrophic.

Well, of course. If policy makers only hear how good the science is and don’t hear how the models diverge from reality, don’t hear that uncertainties are inherent when working with a complex system with few data to begin with, then I could understand where that comes from. This put a different light on what he said next:

Even our best scientific judgment of our risk posture of the consequences that we face as a civilization and the likelihood of those consequences occurring, we must do what we can to mitigate these risks.

In a science with less uncertainties, with mathematical models that more or less match reality and with plenty of reliable historical data, I would not have any problem with such a statement. But that is not exactly the system we live in.

2 thoughts on “Certainties and risk perception

  1. manicbeancounter

    You say a lot of good things in this article. I would like to draw out this paragraph:-

    Some other interesting questions would be: how much of that uncertainty is communicated to the policy makers? How politicized is the science? How can we avoid bias? How much can we rely on the mathematical models to project x years into the future? And so on.

    The problem of evaluating how a complex theory coheres to the real world is not new, and not limited to climate science. When I studied economics the subject was in crisis. The Keynesian consensus was felt to have failed. The subject looked to the philosophy of science (at the time to Logical Positivists, but also to the later work of Popper, Kuhn, Lakatos anf Feyeraband. There were also methodologists whose work was drew upon these philosophers.

    Rather than divert you (and the readers) with a long reading list, could I point to insights that I draw from this body of work?
    Economics is full of political biases. To get round this, economists have developed standards for data (e.g. National Income Statistics) and also econometrics to test theories. Very little is falsified, but many ideas have been modified, or quietly forgotten, as a result of theory testing. The AGW theory would get modified by such methods. The bold prediction of a large increase in temperatures from a doubling of CO2 does not stack up with real world data, unless you look at very short periods, and the data in very particular ways.

    Quite separately, there is another way to evaluate the competency of the climate scientists. If they are so brilliant at theory evaluation, along with assessing the uncertainties, they would apply this to policy evaluation. At no point did Senator Peters state the obvious from the theory. Global GHG emissions are leading to increases in GHG levels, which in turn is causing increases in average global temperatures. Mitigation policy is to reduce global GHG emissions to near zero by the end of the century. It follows that any policy response at a national level (or in Europe at the EU level) must be in a global context. When policy advocates talk about what we should do, they speak as if the whole world is under their control. They just have to think of a desired scenario, based on a model of the world, then mechanistically pull the correct policy levers. It was this mechanistic form of thinking that got economics in a mess in the 1970s. Yet climate policy it has less theoretical foundation than the macroeconomic policy that lead to ever increasing inflation and unemployment.



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