Global warming and the scientific method

Continuing with discussion of the scientific method and its application, we go back to matt's question:

We can write off any temperature change as as just a shift in global temperature patterns if we want to. The problem with such a method is that since we don't have old enough to data to even grasp what a cycle might look like, broadly (according to some) we couldn't hope to understand what a human-made change might look like. This is an argument I use on theists all the time: what would it take to convince you that your beliefs are false- i.e. that global warming is real?

Question for all the blurkers out there -

Suppose you wanted to find evidence that global warming is a man-made phenomenon. How would you carry out an experiment to do so? And due to the nature of the system, I will grant you superpowers to use in your hypothetical design.

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The simplest (in this

The simplest (in this "superpowers universe"...) approach would be to compare Earth to an identical in every way EXCEPT for an intelligent human population. More specifically, any organism that is capable of advanced reason and thought that enables it to utilize it's environment through the combustion of natural resources. Run the simulator for a few thousand years and see what happens.

Or, on a more onerous other hand, perhaps going back in time and methodically measuring temperatures, weather patterns, and the number of humans and advancement of their technology on the planet. Go back 20 million years and start checking the mercury. If good long-term data is what we lack to accurately guesstimate what global temperature cycles look like, then that would be a very worthwhile endeavor.

Charles, The simplest (in

Charles,

The simplest (in this "superpowers universe"...) approach would be to compare Earth to an identical in every way EXCEPT for an intelligent human population. More specifically, any organism that is capable of advanced reason and thought that enables it to utilize it's environment through the combustion of natural resources. Run the simulator for a few thousand years and see what happens.

This is an excellent design.

Or, on a more onerous other hand, perhaps going back in time and methodically measuring temperatures, weather patterns, and the number of humans and advancement of their technology on the planet. Go back 20 million years and start checking the mercury. If good long-term data is what we lack to accurately guesstimate what global temperature cycles look like, then that would be a very worthwhile endeavor.

I'm not sure this would prove any sort of causation by humans. If the expected cycles break at a certain point, how do we know that humans caused the break?

If the goal is only to

If the goal is only to determine if global warming is a man-made phenomenon, stipulating that GW is true, I would use my super-powers to determine what proportion of all the greenhouse gases entering the atmosphere was coming from artifacts.

Has anyone here ever read _Mother_of_Storms by John Barnes? He imagines a very different sort of man-made warming from the currently fashionable carbon dioxide panic.

Virginia, If the goal is

Virginia,

If the goal is only to determine if global warming is a man-made phenomenon, stipulating that GW is true, I would use my super-powers to determine what proportion of all the greenhouse gases entering the atmosphere was coming from artifacts.

You are assuming that greenhouse gases are... greenhouse gases. Which may be intuitively obvious, but a good design is highly skeptical. (As an example, many people assume that welfare programs end poverty where others assume that welfare programs cause poverty.)

Seeing what proportion of greenhouse gases enter the atmosphere from artifacts (by which I assume you mean man-made objects) also would not imply causation as other factors would not be controlled for.

I think even most greenhouse

I think even most greenhouse skeptics are willing to admit that, ceteris paribus, increases in CO2 levels will lead to some increase in mean temperature. In determining whether it is a SIGNIFICANT phenomenon, the devil is in the details: what is the minimum threshold to trigger the effect? what is the ratio of CO2 increase to temperature increase? how does this effect compare, quantitatively, to non-manmade temperature trends?

One practical step (in the sense of not requiring alternate control universes or time travel) toward a more accurate assessment would be to take all local temperatures away from developed areas, so as to control for the urban heat island effect. I'm not sure the data that global warming advocates use does this.

I think even most greenhouse

I think even most greenhouse skeptics are willing to admit that, ceteris paribus, increases in CO2 levels will lead to some increase in mean temperature.

But the scientific skeptic would say that you cannot make this assumption. In the cause and effect relationship between humans and increase in temperature, CO2 serves as a hypothetical intermediate. In other words, the hypothesis is that humans cause CO2 which then causes an increase in temperature.

This mistake is made all the time in medicine. Drug X causes the release of enzyme Y, which is thought to cause effect Z. Hence it is assumed that Drug X causes effect Z. Yet, when controlled studies are performed, Drug X does not cause effect Z.

This is because the step Y-->Z is not a given. Sometimes, contrary to all logic and current knowledge, Y causes the opposite of Z.

Generally I liked Charles'

Generally I liked Charles' theory. If I had superpowers, though, I would also "de-randomize" other effects in the atmosphere, so as to make the human earth and the non-human earth more compatible. Basically any atmospheric phenomena that uses Chaos theory as a tool would need to be overridden (like Rossby Waves.) Concievably, the Chaos that produces these seemingly random effects could affect temp. change.

Kevin, I would be very surprised if GW scientists didn't consider the urban heat island (or coastal zones, or mountain-valley zones) into account. If they didn't though, it sounds like a good point to me.

Jonathan, I'm not so sure you're right that a scientific sceptic would say that. Greenhouse warming is not controversial, nor is the doctrine that CO2 is a greenhouse gas (to my knowledge.) I still think a good expiriment would consider that increasing greenhouse gases might not increase the greenhouse effect proportionally, but one can only go so far with that before Occam whips his razor out.

Similarly, you might argue that a scientific skeptic would say that cigarettes do not cause lung cancer, because statistical correlation does not prove causation*. And because humans (x) inhale cig. smoke (y) and it seems to cause cancer (z), you could critique it with the selfsame "oftentimes nutritional science is wrong" critique that you used with medicine. Incidentally, I thought those medicine problems (drug x or whatever) were usually a result of assuming that because enzyme y affected z in a petri dish it would do the same in the human body.

*Sir Ronald Fisher, statistician par excellance, actually argued (paid by tobacco comapnies) that "the precancerous condition is one involving chronic inflammation [and] a slight cause of irritation... is commonly accompanied by pulling out a cigarette, and getting a little compensation for life's minor ills that way." Hence, lung cancer can cause smoking, not the other way around.

Pretty dry speculation. We

Pretty dry speculation.

We know plenty about past climate: we know that earth's temperature has fluctuated widely on long and short time scales, in no particular pattern. There are a lot of theories about causation, but the atmosphere is an exceedingly complex system. No one can run reasonable simulations because we don't even know how to set the inputs.

The most important greenhouse gas is water vapor. Warming causes more water to evaporate, but it also causes more reflective clouds to form. Positive and negative feedback operate simultaneously. Distribution of clouds is important too. Polar clouds reflect less heat back to space; equatorial clouds reflect a lot. Furthermore, human activity may increase cloud cover by adding condensation nucleii to the atmosphere. There are too many variables!

Policy-makers don't understand this stuff, and an ignorant public is easy prey for politically-motivated sensationalism.

We know plenty about past

We know plenty about past climate: we know that earth's temperature has fluctuated widely on long and short time scales, in no particular pattern. There are a lot of theories about causation, but the atmosphere is an exceedingly complex system. No one can run reasonable simulations because we don't even know how to set the inputs.
paleontology has produced some estimates of past climates, sure, but as you point out "there's no particular pattern" that we can find. The pattern could very well be a variable that we have no reliable historical data for, like precise historical atmospheric composition. That doesn't mean we should throw up our hands.

As I said before, it's a better idea to just accept the conclusions of mainstream science or not, unless someone here knows the basic science well enough to discuss technical literature.

matt, As I said before, it's

matt,

As I said before, it's a better idea to just accept the conclusions of mainstream science or not, unless someone here knows the basic science well enough to discuss technical literature.

A couple of disagreements:

1) The mainstream has been wrong in a major way in the past more than once. At various times, the mainstream said that the Earth was the center of the universe, that the body is made up of four basic humours, that homeopathic medicine can cure disease, that bedrest is the best course after surgery among other things. The mainstream often is very wrong about reality.

2) Accepting the conclusions of the mainstream leads one susceptible to political bias. It's better to evaluate science on its own merits using your own reason.

3) Although knowledge can be very technical in nature, the average layperson can understand the scientific method, give standards for proof, and make their own evaluations of scientific evidence. All the models, technical knowledge, and experience won't make a difference if the scientific method makes it impossible to set up an experiment to determine causality.

I would rather accept the conclusions of reality rather than rely on the 'mainstream' to spoonfeed me their views.

Also, if we are going to

Also, if we are going to adopt the view of the mainstream, why not apply the same standard to economics? The vast majority of economists reject socialism and embrace free trade. Where does that leave you, matt?

micha, I said "science" not

micha, I said "science" not "psuedoscience" so economics is out.

Jonathan, this is pretty simple. If you wanna disagree with mainstream science in a serious way, you should learn it, and read the tech. stuff. Not doing that leads you solely in politically charged directions. I wonder, for instance, what your thoughts are on HIV causing AIDS? Or Cigarettes causing cancer? They are both technically controversial- do you doubt them and "use your reason" to counter their points? Of course not, because there's no political side effect. Look at the econometric (as scientific as econ. ever got) predictions for oil supply in the 70's- they predicited a crisis. This has just been shown to be false. Environmentally conscious people like myself must bite that bullet, just as you should probably bite this one.

Matt, if you've ever taken a

Matt, if you've ever taken a course in Philosophy of Science, you should know that the distinction between science and pseudoscience is not at all clear, and most modern philosophers seem to maintain that it is a difference in degree, not a difference in kind. Further, the term "pseudoscience" is usually used to refer to such things as Astrology and Creationism, not social or "soft sciences". If anything, global warming falls into the "soft science" category since there is very little to work with and most of it is conjecture.

That being said, I generally accept most of the mainstream science on global warming - i.e that is occuring and that humans have some amount of influence on it. However, I don't believe any of the doomsday scenarios, nor do I accept any of the proposed prescriptions requiring huge restrictions on economic activities.