h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

They have named the short period 42000 years ago, when the earth's magnetic poles were reversed for a couple of hundred years, the "Adams Event". I have only just read about this, so excuse me if it's old hat for those living in the UK and communing with scientists on a daily basis.

However, I thought it shouldn't go unmentioned here.

I still can't begin to imagine what it would be like if North were South and vice vers, or even during the transition when the .magnetic field was fluctuating.

Have you read this week's <./>thepost</.> (A88012893)? Also, may I direct you to: A88015133

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When I was a kid, there were plenty of doomsday stories regarding an impending reversal of poles and I just never got it. (I think some people actually thought the globe would upend itself.) I just didn't think we carbon based life forms would be significantly impacted by the reversal of the magnetic field. I could imagine some species being a bit lost for awhile as some birds and other migratory species navigate via small bits of iron in their heads (or something like that, I wasn't paying that much attention.) But generally most electromagnetic fields just don't effect living tissue that much.

Then this latest story was told on NPR and one of the experts finally explained why such a reversal would be so catastrophic. Durr... I get it now. It's the protective effect the Earth's magnetic field has on solar radiation. The Van Allen Belt is part of the Earth's magnetic field and without it, it's unlikely life as we know it would ever have evolved past the microbial stage on Earth. Shifting those around would cause a great increase in the amount of radiation reaching the Earth and could easily cause a great extinction period. Yep, now I'm convinced. Now I also am afraid of a magnetic pole reversal. Well, as much as I'm afraid of any other grand existential threat, like asteroids or supernovae. It's just another small bit of angst considering the timescales make a single life span unlikely to experience such events.

Would this happen suddenly, without warning?

There's a disaster film about shifting magnetism and shifting
poles
http://en.wikipedia.org/wiki/Absolute_Zero_(film)

"suddenly" is, it seems a relative term. I read about this subject once, and they explained that when they talk about the potential for this being a sudden event, they mean it in Geological terms; a few decades or even a century or two. So pretty sudden if you're a rock, not so much for us very short-lived humans.

The one 42,000 years ago lasted around 500 years.
http://scitechdaily.com/42000-year-old-trees-enable-accurate-analysis-of-earths-last-magnetic-field-reversal/

They typically take between 1,000 and 10,000 years but can go as quickly as a human life span and can move around 6° per day according to wikipedia.

I hope it won't go as quickly as Douglas Adams's lifespan. He died kind of young.

If it weakens the protection from solar radiation, maybe quicker is better.

If the magnetic field moves six inches a day, there might be some places where the effects have not yet arrived. I'd want to move to a safer place.

Not inches, degrees. Although I suppose for the longer durations, it could, indeed, move at a rate of 6 inches per day.

If it moves too fast, adjustments might be hard to make.