One of the things I have been curious about is the impact of the earth’s magnetic shield on climate. According to some charts I have seen (Jose, Landscheidt) there appears to be some correlation with a lower intensity in the magnetic field around earth (geomagnetism) and the occurrence of ice ages in reaction to solar minimums. I admit to not having thought too much more about it than a couple of charts I’ve seen, so I’m not intending here to suggest that I understand that correlation, or even whether or not I fully understood those charts. As time allows, I’ll get back into that.
But that discussion is not really the point of this post. And I’ll state right away that there is no particular conclusion that I’m trying to draw here. But I messed around with some data, so why not post about it?
For some time, I had been intending to look more into the decay rate of the earth’s geomagnetic field, if for no other reason than I’ve heard about these potential reversals. While I heard a lot about the fact that the earth’s field has been decaying for at least 150 years now, and that the last reversal was about 750,000 years ago, I had no idea of what the actual numbers were. Is it a constant decay? Is it accelerating? What’s up with the whole magnetism thing, anyway?
At this point, I won’t go into the things I’ve read about the potential effects of geomagnetic reversals. Nor will I go into the historical record in the lava flows that track these reversals. Nor will I go into the elements in soil deposits that coincide with extinction events that coincide with such reversals. I’m just going to play with data.
In digging around for data, I came across this resource which allows you to pull annual averages from myriad geomagnetic observatories. It makes sense that there is no global average, since, the magnetism intensity is much stronger at the poles. So, in order to do a major study, I’d have to waste some serious time and need a lot of rationalization with my wife to embark on such a thing. So, once I realized that a really large, scientific, study was out the window for the moment, I decided to be far less statistically correct, and just look at what’s been measured in Boulder, Colorado. As we all know, Boulder is the summation of all goodness and light, so it seems a reasonable proxy for the whole world. (Yes, I’m joking.)
The Boulder data starts in 1965 and continues through to 2006. The 1965 average overall intensity was 56,057. The 2006 average intensity was 53,330.
As tempting as it may be to straight-line this, it’s really no fun at all to take such a simple approach. Plus, it isn’t accurate. In playing with the numbers, it was apparent that the drop from year to year has generally accelerated. Here’s a chart of the geomagnetic intensity in Boulder:Read the rest of this entry »