Climate Change and Scientific Fact

climate changeAlthough I have studied science quite rigorously, libertarians and liberals (mostly libs) often claim that I need to read more science due to my skepticism of man-made climate change. Very often I will hear them say things like “man-made climate change is scientific fact!” which in my opinion is a clear indicator that the accuser has actually studied very little science, but rather have read articles about science that they probably don’t even understand. Allow me to explain why.

In physics, an experiment must produce results with a confidence level of 5 (read five sigma) in order to be considered strong evidence.   This means, the experimenter can be 99.9999% certain that they have found what they are looking for. To give an example to illustrate this phenomenon let’s consider a simple experiment of flipping coins. If we flipped 10 fair coins, we would expect to see 5 heads and 5 tails. However, if we actually do the experiment we will not get 5 heads and 5 tails every time. We might see 6 heads and 4 tails the first time, 8 heads and 2 tails the second time, 5 heads and 5 tails the fourth etc. However, over many experiments we will expect the average of heads and tails in each experiment to level out at around 5.

Now, let’s replace one of the fair coins with a 2 headed coin. This means that our expected number of heads will increase to 5.5 per experiment and tails will decrease to 4.5 per experiment. Similar to the fair-sided experiment, we will get results as 6 heads 4 tails, 3 heads and 7 tails etc. However, over time we expect to see this average to settle at 5.5 heads and 4.5 tails. One way to measure how accurate our estimate is to calculate what is called the standard deviation (sigma). As we repeat this experiment over and over our standard deviation will decrease. Once we find an average of 5.5 heads with a standard deviation of 0.1, we can be 99.9999% sure we have a coin with two heads.

As I was writing this piece I became curious as to how many times I would have to perform this experiment to get to a confidence level of 5; so I wrote a computer algorithm to simulate it. So far I have not been able to attain this level no matter how many times I run it. At 50,000 simulations I had an average of 5.49406 with a standard deviation of 1.42 so I gave up (if 50,000 is only 1.42 I would have to allow it to preform hundreds of thousands/millions of simulations to achieve the 5 confidence level and it will take my old mac a long time to perform that many simulations).

This is the statistical measure used by physicists at the LHC. Luckily for them there are billions of collisions each time they collide particles so they can gather ample data to reach the 5 confidence level. However, even when they were 99.9999% confident they had found the Higgs some physicists only claimed they were “fairly certain” they had found it. This is standard practice in physics. Even at 99.9999% confidence they do not claim it to be scientific fact.

This is why when someone tells me man-made climate change is “scientific fact” followed by telling me I need to read more science I usually stop the discussion. However, if their argument is that there is “strong evidence” in favor of climate change, I will gladly consider their opinion.

I would like to point out two more things. First is that I have not argued in favor of man-made climate change nor have I argued against it. I have read good papers for it and good papers against it. The purpose of this was merely to point out that calling it “scientific fact” is absurd. Second is that because someone has not studied climate change does not mean they have not studied science. One could be an expert on string theory, epidemiology, numerical optimization or various other branches of science and not give the slightest thought about climate change. Thus, telling someone to read more science because they are not interested in climate change is equally absurd.

 

– JW

 

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