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The Epidemiology of Global Climate Change

I am first going to admit to 3 things. I am not a doctor, I am not a climatologist and I know you can’t have an epidemiology (see definition) of global climate change. Oh and the book Conjuring Science (see Brain Food) inspired me to write this post.

I have been having a number of discussions regarding Global Warming with someone who I very much wish could see past their conservative politics and actually appreciate the considerable scientific evidence. Personally I think he disagrees with the policy recommendations that many global climate change “believers” propose and therefore rejects the science of global climate change. Obviously this is backwards but nonetheless his position.

I searched for sometime to come up with a good way to explain why I personally accept global climate change. He has put forth a number of different reasons why global warming isn’t real (Milankovitch cycles, delayed CO2 forcing) but there are a few statements that I think are the most common and the most credible accusations to the average Joe,

  1. I’m (the Skeptigator) not a climatologist and therefore unqualified to make any reasonable judgment on my the validity of climate science, which is true.
  2. He brings up Global Cooling and Paul Ehrlich’s Population Bomb as recent examples of science having it wrong and therefore what makes Global Climate change as a scientific position that much better than those.
  3. His last allegation is that if you follow the money, those scientists who say global warming is real get funding, those who don’t are marginalized within the scientific community and therefore do not get the funding. This creates a disparity in the ability of believers finding evidence and deniers not being able to have the resources to find evidence.

As I have time and as I become confident that my rebuttals are logically sound and easily explained to a non-believer I will post them. What I would like to do is explain my rebuttal to the first allegation.

Let me first say that this claim is probably some kind of logical fallacy, probably some variation of the Argument from Authority, meaning if I were some kind of authority I therefore could be believed to be speaking the truth but since I’m not therefore I am not speaking the truth. This might not be correct but let’s be realistic even if it were true pointing out logical fallacies really carry any weight for a normal person. I can’t say, “That’s an Argument from Authority logical fallacy and therefore I don’t have to dignify your statement with a response.”

Anyway, perhaps the best analogy is the science behind smoking and your health. Put simply, we know that smoking is bad for your health by the same methods that we know that global warming is caused by mankind. Let me be clear I don’t know anyone that denies that the Earth is warming anymore, the argument usually lies in whether mankind is the cause (and what we should do about it, but let’s figure out how to accept responsibility first and then work from there).

There are 2 primary methods for doing studies regarding the effects of smoking on health. There are empirical methods (or replicatable demonstrations) for determining causation and there are statistical methods for determining causation. Well, first and foremost you really can’t use replicatable demonstrations since you can’t take one person and clone them and then make one smoke and one not smoke and then see which one got lung cancer or emphysema. Not only is this scientifically impossible it’s probably ethically wrong even if it were. So we are stuck using admittedly an inferior way of knowing something by using epidemiological-statistical methods.

Epidemiological-statistical methods can never give you 100% certainty they can only give you varying confidence levels. A particular study by the EPA will come to the conclusion that second-hand smoke is detrimental to your health with a confidence level of 95% (p <.05). What does that mean? It means that the scientists are pretty damn sure that the results of their study show that the net effect is detrimental to your health. In fact, when it comes to this kind of study having a p-value less than or equal to .05 is about as certain as you are ever going to get.

There are enough studies out there that the preponderance of the evidence/results of these studies show that a staggering 87% of all lung cancer in the U.S. is the direct result of smoking. These studies had to use epidemiological methods for determining that smoking/tobacco use were the single largest contributing factor to the development of lung cancer. If you control for age, weight, sex, ethnicity, income, access to healthcare, work environments and whatever else they do science finds over and over again that smoking is the key factor.

What does this have to do with global warming? You guessed it. We can’t rely on empirical methods alone for determining causation of global warming for several reasons. First and foremost, the time scales involved are too great for humanity to be able to make any reasonable, direct observations, second the scope of observing planetary changes and interactions to the climate in real-time is beyond our current technology. So what are we left with? Our understanding of small-scale, regional effects on weather and lots of statistical data. We know that when you remove most of the trees from a large tropical island there is marked decrease in rainfall. Why is that? It’s because the removal of those trees has interfered with the natural cycling of water from ground to atmosphere. This example is a good demonstration of the kind of man-made interference that has local effects that can be understood and more importantly it reveals important mechanisms of how our planet works.

We can analyze all of this statistical data (with computer models, simulations) and begin to make predictions about what should be happening in the future and validate those predictions against what should have happened in the past. We can continue to refine these models as our understanding of different variables increases. Obviously this is an oversimplification of the process involved but the basic idea is there. Over time we have slowly “controlled” for factors as we were able to measure them, understand their impact and interactions in a very complex system. We have gotten to a point that the evidence is significant enough that the IPCC not only released a consensus report on the reality of global warming but gave a 90% confidence level that mankind is responsible for that warming. What gets lost in translation for many people is that a scientific consensus is a significant thing and that a 90% confidence is pretty damn confident. To put that in perspective, I’m mixing sciences here, many studies regarding the detrimental effects of second-hand smoke have confidence levels of 80-85%. Is long-term exposure to second-hand smoke detrimental to your health? Who knows? But we are 90% sure that mankind is responsible for global warming.

Do I personally think a lot of the rhetoric surrounding global climate change and the imminent disaster to mankind is alarmist? Yes. I personally think people are turned off by all the doom and gloom that surrounds global climate change. The opposing viewpoints are too often given equal weight in the media and too often the talking heads from either side are the worst kind of caricatures, you have the “poor gas in the lake it don’t matter” deniers on one end and the “shit in a bucket and smoke eat grass” hippies on the other.

I think if people could accept that we are the cause of Global Climate Change we can begin to make some concrete changes NOW for our future. Let’s do it now while the cost of those changes is small. Should gas be artificially jacked up to $10.00/gallon? No that’s stupid. Let’s do some reasonable things. Start replacing the most commonly used light bulbs in your house with CFLs. The new 2008 EPA CAFE standards in the U.S. are a good start, let’s keep raising the bar. There’s a whole bunch of common sense things that can be done now. I’ll have to compile a list of things sometime.

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One Response

  1. […] to know one Posted on February 18, 2008 by Skeptigator I recently posted my thoughts on the Epidemiology of Global Climate Change. In that post I detailed 3 arguments global warming skeptics often employ to prove why global […]

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