Here is an interesting editorial on the global warming debate. I have not looked at the underlying paper, but this paragraph is interesting:

As it happens, the project’s initial findings, published last month, show no evidence of an intensifying weather trend. “In the climate models, the extremes get more extreme as we move into a doubled CO2 world in 100 years,” atmospheric scientist Gilbert Compo, one of the researchers on the project, tells me from his office at the University of Colorado, Boulder. “So we were surprised that none of the three major indices of climate variability that we used show a trend of increased circulation going back to 1871.”

I think I understand how to measure someone’s height, and measuring their income is a bit trickier but you can come up with a reasonable procedure. In pharmaceutical research, measuring whether the drug “worked” is a potentially important decision – do we measure the size of the tumor, the increase in lifespan, or the quality of life?

Can you imagine what the three major indices of climate variability are? Could you come up with three different ones that would support a paper that has the opposite result (weather is weirder)?

When and how do we know things like this?