Do You Really Want To Understand the Climate?

It's the variation, stupid, to summarize an MIT Professor of Meteorology. But what does he know, anyway?

As I've mentioned before, I analyze statistical data for a living. One of the first things practitioners learn is that one needs to determine whether the mean or the variation matters most (or both, in some cases).

Processes undergo two kinds of variation: special cause and common cause. Common cause may be understood to be the "normal" variation; it's what happens when things are left unattended. Special cause variation is assignable and specific---one can turn it on and off. Sometimes, as when the asteroid which wiped out the dinosaurs struck the Earth some 65 million years ago, it's sudden and catastrophic, completely changing the system. Other times, such as the coal burning which created London's famous pea soup fog, it's subtle and temporary.

How do you know which is which?

Well, we use control charts. The inherent variation of the process determines the parameters for normal variation (aka control limits). If the process is extremely variable, such as surface temperature on Earth, changes in the mean have to be quite significant to outweigh the natural variation. If you're sitting in Death Valley and it's 130 degrees in the afternoon but 20 degrees at midnight, how much would you notice an increase in mean daily temperature of 2 degrees? Not much, one would expect.

Global warming preachers are claiming that manmade CO2 emissions represent significant special cause variation in the climate of Earth which is driving a shift in mean temperatures as well as catastrophic weather effects. This is nonsense on stilts, since a) the mean temperature rise is a fraction of a degree Centigrade over the last century and b) the natural variation in temperature drives more significant weather changes (known as "seasons".)

One other thing good statisticians do---they are extremely hesitant to make predictions outside the bounds of their data. After all, one never really knows when an asteroid will strike and bugger all.